nitinol and Graft-Occlusion--Vascular

In the femoropopliteal segment, endovascular revascularization techniques have gained the role as a first line treatment strategy. Nitinol stent placement has improved the short- and mid-term primary patency rates in most lesion types and is therefore widely applied. Stenting has several shortcomings as in-stent restenosis, stent fractures and foreign material being left behind in the vessel. The concept of atherectomy is plaque debulking. This results in a potential reduction of inflation pressure requirements in angioplasty. Stent placement and consecutive in-stent restenosis may be avoided. In this non systematic literature review, the performance of different atherectomy techniques, such as direct atherectomy, orbital atherectomy, laser debulking and rotational atherectomy in the treatment of complex femoropopliteal lesions, including long lesions, moderately to heavily calcified lesions as well as occlusions and in-stent restenosis, has been analyzed.

Topics: Alloys; Atherectomy; Constriction, Pathologic; Equipment Failure; Femoral Artery; Graft Occlusion, Vascular; Humans; Inguinal Canal; Lasers, Excimer; Peripheral Vascular Diseases; Popliteal Artery; Severity of Illness Index; Stents; Treatment Outcome; Vascular Calcification; Vascular Patency

Topics: Alloys; Angioplasty; Arteriovenous Shunt, Surgical; Graft Occlusion, Vascular; Humans; Renal Dialysis; Stents; Vascular Patency

The ideal intervention for degenerated saphenous vein grafts (SVG) is still controversial. We report the first use of a peripheral, self-expanding nitinol stent in the treatment of a patient with symptomatic SVG disease. The procedure was well tolerated, without any short- or long-term complications. Quantitative coronary analysis of a 3-month follow-up angiogram revealed a continued expansion of the nitinol stent. Larger scale trials are warranted to evaluate whether the self-expanding nitinol stents can be used alone or in adjunct to other modalities for the treatment of SVG disease. The case report is followed by a literature review of SVG stenting.

Topics: Aged; Alloys; Blood Vessel Prosthesis; Coronary Artery Bypass; Graft Occlusion, Vascular; Humans; Male; Saphenous Vein; Stents; Treatment Outcome

Although stent-to-vessel (S/V) diameter ratio has been described as a restenotic factor after superficial femoral artery (SFA) stenting, the reference vessel diameter is commonly measured distally at a healthy site. It remains unclear whether S/V ratio assessed at the lesion site would be more predictive than that assessed distally at a healthy site.Methods and Results:A total of 117 patients (mean age, 73±7 years; 74% male) who underwent successful nitinol stent implantation in SFA lesions (mean lesion length, 172±104 mm) on intravascular ultrasound (IVUS) were retrospectively analyzed. S/V ratio at the proximal and distal healthy site, and at the smallest lesion site, was evaluated on IVUS. One-year restenosis predictors were evaluated on multivariate analysis. Mean S/V diameter ratio on IVUS at proximal and distal healthy sites, and at the lesion site, was 0.98±0.11, 1.02±0.11 and 1.15±0.16, respectively. One-year primary patency was 77%. On multivariate analysis, lesion length (OR, 1.06 per 10-mm increment; P=0.046) and S/V ratio measured at the lesion site (OR, 1.34 per 0.1 increment; P=0.032), but not that at the distal healthy site (OR, 1.05 per 0.1 increment; P=0.705), were significantly associated with 1-year restenosis.. S/V ratio assessed on IVUS at the lesion site, but not at the distal healthy site, was independently associated with 1-year restenosis after SFA stenting.

Topics: Aged; Aged, 80 and over; Alloys; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Male; Retrospective Studies; Stents; Ultrasonography, Interventional

Reintervention in the femoropopliteal artery is frequent and a major driver of cost-effectiveness. High wall shear generated by swirling blood flow is associated with reduced occurrence of atherosclerosis and restenosis. This trial investigated the clinical and hemodynamic outcomes of the BioMimics 3D self-expanding tubular nitinol stent with helical centerline geometry compared with a straight stent in the femoropopliteal artery.. In a prospective, multicenter, randomized controlled trial, 76 patients with symptomatic peripheral arterial disease were randomized 2:1 to receive a helical or a straight stent. An independent core laboratory adjudicated angiographic and ultrasound parameters. The primary safety end point was freedom from a composite of all death, target limb amputation, and target lesion revascularization at 30 days. The primary effectiveness end point was freedom from clinically driven target lesion revascularization at 6 months. Patency was a secondary end point. Subjects were followed up for 2 years from intervention. The primary safety (1-sided P<0.01) and efficacy (1-sided P<0.001) end points for the helical stent were met. The proportion of patients treated with the helical stent who maintained patency at 12 and 24 months was 80% and 72%, respectively, compared with 71% and 55% for the control group. The difference was significant through 24 months (P=0.05). Freedom from clinically driven target lesion revascularization for the helical compared with straight stent was 91% versus 92% at 12 months and 91% versus 76% at 24 months.. Both groups had similar safety outcomes and clinically driven target lesion revascularization to 2 years. However, after placement of a BioMimics 3D helical stent, there was improved patency to 2 years.. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02163863.

Topics: Aged; Alloys; Amputation, Surgical; Disease-Free Survival; Endovascular Procedures; Female; Femoral Artery; Germany; Graft Occlusion, Vascular; Humans; Kaplan-Meier Estimate; Limb Salvage; Male; Middle Aged; Peripheral Arterial Disease; Popliteal Artery; Prospective Studies; Prosthesis Design; Recurrence; Risk Factors; Stents; Time Factors; Treatment Outcome; Vascular Patency

The predominant mode of bare nitinol stent failure is diffuse in-stent restenosis, and failure rates correlate to the length and complexity of the treated lesion. Addition of an expanded polytetrafluoroethylene lining to a nitinol stent frame, as found in the VIABAHN endoprosthesis, mitigates the ingrowth of intimal hyperplasia. We compared the long-term outcomes of complex superficial femoral artery disease intervention using the VIABAHN endoprosthesis to those obtained with bare nitinol stent implantation.. One hundred forty-eight patients with symptomatic complex superficial femoral artery disease (TransAtlantic Inter-Society Consensus I class C and D lesions, accompanied by intermittent claudication or ischemic rest pain) were randomized to endovascular intervention using either bare nitinol stent implantation (76 patients) or nonheparin-bonded VIABAHN endoprosthesis deployment (72 patients). Patency, limb hemodynamics, and quality of life were evaluated at 1, 6, 12, 24, and 36 months following intervention.. The average treated lesion measured 18 ± 8 cm in length, and 58.8% of lesions displayed segmental or complete occlusion. At 3 years, primary patency rates (defined by peak systolic velocity ratio ≤ 2.0 and no target lesion revascularization) did not significantly differ between patients treated with the VIABAHN stent graft and those who received a bare nitinol stent (24.2% vs 25.9%; P = .392). Stent fractures were significantly more common in bare nitinol stents (50.0%) than in the VIABAHN endoprostheses (2.6%). Primary-assisted patency rates were higher in those receiving bare nitinol stents than the VIABAHN stent graft (88.8% vs 69.8%; P = .04), although secondary patency rates did not differ between bare nitinol stent and stent graft recipients (89.3% vs 79.5%; P = .304). There were no instances of procedure-related mortality or amputation. The hemodynamic improvement and quality measures improved equally in both groups.. The long-term outcomes of complex superficial femoral artery disease intervention using the VIABAHN endograft and bare nitinol stents are similar. Although primary patency rates are low in both study arms, excellent primary-assisted and secondary patency rates were achieved, with sustained augmentation of limb perfusion and quality-of-life measures. Patency rates diminish most rapidly in the first year after device implantation.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Arterial Occlusive Diseases; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Constriction, Pathologic; Endovascular Procedures; Female; Femoral Artery; Graft Occlusion, Vascular; Hemodynamics; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Polytetrafluoroethylene; Prosthesis Design; Prosthesis Failure; Quality of Life; Stents; Time Factors; Treatment Outcome; United States; Vascular Patency

Saphenous vein graft patency is frequently limited by degeneration. Experimental studies have indicated that rigid external support of venous grafts by a flexible, tubular nitinol mesh may improve graft patency. The study presented was part of a prospective, randomized, multicenter first-in-man trial investigating the safety and effectiveness of nitinol-supported venous grafts in coronary artery bypass graft (CABG) surgery. From our clinic, 25 subjects with multivessel coronary artery disease requiring saphenous vein graft CABG of the right coronary artery (RCA) and the circumflex artery were entered into the trial. Subjects were randomized to receive a mesh-supported graft on one of these arteries; the other vessel received an untreated vein graft. Graft patency was assessed by coronary angiography nine months after surgery. The implantation of mesh grafts was simple and safe. In 10 cases, a nitinol mesh-supported venous graft was anastomosed to the circumflex artery and in 15 cases to the RCA. All patients survived the observation period. A total of 72% of the patients underwent control coronary angiography. The patency rate of mesh-supported grafts was 27.8% nine months postoperatively. Conventional vein grafts showed an 85.7% patency, and arterial grafts had a 100% patency. No complications directly related to the implantation of mesh-supported grafts were observed. The promising experimental results of mesh-supported venous grafts could not be reproduced in the study presented. A critical item seems to be correct selection of nitinol mesh diameter, the anastomotic method and fixation of the mesh tube to the venous graft.

Topics: Aged; Alloys; Coronary Angiography; Coronary Artery Bypass; Coronary Artery Disease; Equipment Design; Female; Germany; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Prospective Studies; Saphenous Vein; Surgical Mesh; Time Factors; Treatment Outcome; Vascular Patency

To evaluate a newly developed self-expanding Misago (Terumo Corp., Tokyo, Japan) nitinol stent with rapid exchange delivery catheter for the treatment of stenotic or occluded superficial femoral (SF) or popliteal arteries.. MISAGO 1 clinical trial enrolled 55 patients undergoing percutaneous intervention of totally occluded or stenotic lesions in SF or popliteal arteries treated with the implantation of 81 stents in five centres across Europe. Primary endpoint was restenosis rate at six months assessed by duplex sonography. Patients (67% male) were 68+/-9 years old, 60% were smokers and 31% had diabetes. Clinical symptoms of ischaemia were present in all patients. Average lesion length was 85+/-50 mm, 64% were totally occluded and 38% classified as TASC C or D. The technical success rate was 100% while the procedural success rate was 98.2% without death, MI, stroke, or major bleeding. At six months follow-up the restenosis rate was 8.5%. One patient (1.8%) died of bronchial carcinoma and two (3.6%) underwent target vessel revascularisation. Mean ankle brachial index improved from 0.70 at baseline to 0.95 at six months while walking capacity on treadmill test improved with an average of 147 m. Rutherford index at six months demonstrated improvement of 72%, without any patients having symptom deterioration. One case of stent fracture was observed.. The results from this first-in-man study indicate good safety and short to medium term efficacy profile of the Misago nitinol stent.

Topics: Aged; Alloys; Arterial Occlusive Diseases; Blood Vessel Prosthesis; Europe; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Incidence; Male; Popliteal Artery; Retrospective Studies; Stents; Time Factors; Treatment Outcome; Ultrasonography, Doppler, Duplex

This is a randomized prospective study comparing the treatment of superficial femoral artery occlusive disease percutaneously with an expanded polytetrafluoroethylene (ePTFE)/nitinol self-expanding stent graft (stent graft) versus surgical femoral to above-knee popliteal artery bypass with synthetic graft material.. One hundred limbs in 86 patients with superficial femoral artery occlusive disease were evaluated from March 2004 to May 2005. Patient symptoms included both claudication and limb threatening ischemia with or without tissue loss. Trans-Atlantic InterSociety Consensus (TASC II) A (n = 18), B (n = 56), C (n = 11), and D (n = 15) lesions were included. Patients were randomized prospectively into one of two treatment groups; a percutaneous treatment group (group A; n = 50) with angioplasty and placement of one or more stent grafts, or a surgical treatment group (group B; n = 50) with a femoral to above-knee popliteal artery bypass using synthetic conduit (Dacron or ePTFE). Patients were followed for 48 months. Follow-up evaluation included clinical assessment, physical examination, ankle-brachial indices, and color flow duplex sonography at 3, 6, 9, 12, 18, 24, 36, and 48 months.. Mean total lesion length of the treated arterial segment in the stent graft group was 25.6 cm (SD = 15 cm). The stent graft group demonstrated a primary patency of 72%, 63%, 63%, and 59% with a secondary patency of 83%, 74%, 74%, and 74% at 12, 24, 36, and 48 months, respectively. The surgical femoral-popliteal group demonstrated a primary patency of 76%, 63%, 63%, and 58% with a secondary patency of 86%, 76%, 76%, and 71% at 12, 24, 36, and 48 months, respectively. No statistical difference was found between the two groups with respect to primary (P = .807) or secondary (P = .891) patency.. Management of superficial femoral artery occlusive disease with percutaneous stent grafts exhibits similar primary patency at 4-year (48 month) follow up when compared with conventional femoral-popliteal artery bypass grafting with synthetic conduit. This treatment method may offer an alternative to treatment of the superficial femoral artery segment for revascularization when prosthetic bypass is being considered or when autologous conduit is unavailable.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angioplasty; Ankle Brachial Index; Arterial Occlusive Diseases; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Constriction, Pathologic; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Polyethylene Terephthalates; Polytetrafluoroethylene; Popliteal Artery; Prospective Studies; Prosthesis Design; Reoperation; Severity of Illness Index; Stents; Time Factors; Treatment Outcome; Ultrasonography, Doppler, Color; United States; Vascular Patency

To evaluate the long-term efficacy and integrity of the PROTEGE EverFlex stent in superficial femoral artery (SFA) lesions in symptomatic patients with peripheral artery disease (PAD).. A prospective, multicenter, nonrandomized study enrolled 151 subjects (111 men; mean age 67.8 years, range 42-93) undergoing percutaneous treatment of de novo, restenotic, or reoccluded SFA lesions between August 11, 2006, and June 26, 2007. Subjects were scheduled to receive a single stent and be evaluated through 12 months following the implant procedure. Occlusions were present in 40% of the patients. Mean lesion length was 96.4 mm (range 10-150).. A total of 161 stents (158 EverFlex) were implanted in the 151 patients: single stents in 93.4% (141/151) and a second stent in 6.6% (10/151). One-year follow-up information was available for 88.7% (134/151) of the study participants; of the remaining 17 subjects, 6 subjects withdrew from the study, 2 were lost to follow-up, and 9 died. Freedom from restenosis data were available for 99.3% (133/134) of the subjects who completed a 12-month follow-up visit. The mean Rutherford classification fell from 2.8+/-0.8 (range 1-5) at baseline to 0.6+/-1.1 (range 0-5) at 12 months. The mean ankle-brachial index rose from 0.6+/-0.2 (range 0-1.4) at baseline to 0.9+/-0.2 (range 0-1.2) at 12 months. The rates for freedom from >50% restenosis at 6 and 12 months were 91.3% (95% CI 84.9% to 95.2%) and 72.2% (95% CI 63.8% to 79.6%), respectively. The freedom from target lesion revascularization rate at 12 months was 79.1% (95% CI 71.2% to 85.6%). The 1-year stent fracture rate was 8.1% (95% CI 4.0% to 14.4%).. The high freedom from >50% restenosis and low fracture rate at 12 months suggests that the PROTEGE EverFlex stent offers a safe and acceptably efficacious means of treating SFA lesions in symptomatic subjects with PAD.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Atherosclerosis; Equipment Design; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Peripheral Vascular Diseases; Stents; Time Factors; Treatment Outcome

Primary stenting with self-expanding nitinol stents of the superficial femoral artery yielded improved morphological and clinical results compared with balloon angioplasty with optional stenting until 12 months in a randomized controlled trial. We now report 2-year data on restenosis and clinical outcomes of these patients.. Of 104 patients with chronic limb ischemia and superficial femoral artery obstructions, 98 (94%) could be followed up until 2 years after intervention for occurrence of restenosis (>50%) by duplex ultrasound and for clinical and hemodynamic outcome by treadmill walking distance and ankle brachial index. Restenosis rates at 2 years were 45.7% (21 of 46) versus 69.2% (36 of 52) in favor of primary stenting compared with balloon angioplasty with optional secondary stenting by an intention-to-treat analysis (P=0.031). Consistently, stenting (whether primary or secondary; n=63) was superior to plain balloon angioplasty (n=35) with respect to the occurrence of restenosis (49.2% versus 74.3%; P=0.028) by a treatment-received analysis. Clinically, patients in the primary stent group showed a trend toward better treadmill walking capacity (average, 302 versus 196 m; P=0.12) and better ankle brachial index values (average, 0.88 versus 0.78; P=0.09) at 2 years, respectively. Reintervention rates tended to be lower after primary stenting (17 of 46 [37.0%] versus 28 of 52 [53.8%]; P=0.14).. At 2 years, primary stenting with self-expanding nitinol stents for the treatment of superficial femoral artery obstructions yields a sustained morphological benefit and a trend toward clinical benefit compared with balloon angioplasty with optional stenting.

Topics: Aged; Alloys; Angioplasty, Balloon; Arterial Occlusive Diseases; Exercise Test; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Peripheral Vascular Diseases; Popliteal Artery; Stents; Treatment Outcome; Ultrasonography

Endoluminal treatment of superficial femoral artery lesions is a matter of controversy. The present study was designed to investigate the impact of nitinol stenting of superficial femoral artery lesions with a maximum length of 10 cm on restenosis and clinical outcomes at 1 year.. Two hundred forty-four patients (168 men; 66+/-9 years) with a single superficial femoral artery lesion and chronic limb ischemia were randomized to implantation of a single Bard Luminexx 3 stent (123 patients) or stand-alone percutaneous transluminal angioplasty (PTA) (121 patients). Mean lesion length was 45 mm. Technical success (residual stenosis <50% for PTA, <30% for stenting) was achieved in 96 patients assigned to PTA (79%) and 117 patients assigned to stenting (95%); 13 PTA group patients (11%) "crossed over" to stenting. At 1 year, the primary end point of ultrasound-assessed binary restenosis was reached in 39 of 101 PTA group patients (38.6%) and 32 of 101 stent group patients (31.7%; absolute treatment difference, -6.9%; 95% CI, -19.7% to 6.2%; P=0.377). Target lesion revascularization rates at 1 year were 18.3% and 14.9%, respectively (absolute treatment difference, -3.3%; 95% CI, -13.0% to 6.4%; P=0.595). No statistically significant difference between treatment groups was observed at 12 months in the improvement by at least 1 Rutherford category of peripheral arterial disease.. In the present study of patients with short superficial femoral artery lesions, the hypothesized absolute difference of 20% in binary restenosis at 1 year between the implantation of a single Luminexx nitinol stent and stand-alone PTA could not be demonstrated. A smaller difference requiring a larger trial might have been missed.

Topics: Aged; Alloys; Angioplasty, Balloon; Blood Vessel Prosthesis Implantation; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Ischemia; Male; Middle Aged; Stents; Ultrasonography

A novel, low-profile filter embolic protection device was deployed in 26 patients who underwent stent deployment for saphenous vein graft stenoses in a multicenter trial. Major adverse cardiovascular events were observed in only 2 patients (7.7%) and angiographic flow grades were improved.

Topics: Aged; Alloys; Coronary Angiography; Embolism; Female; Filtration; Graft Occlusion, Vascular; Humans; Male; Saphenous Vein; Stents; Treatment Outcome

To investigate further the safety and efficacy of the sirolimus-eluting S. M.A.R.T. Nitinol Self-expanding Stent by comparison with a bare stent in superficial femoral artery (SFA) obstructions.. This randomized, double-blind study involved 57 patients (29 in the sirolimus-eluting stent group and 28 in the bare stent group) with chronic limb ischemia and SFA occlusions (66.7%) or stenoses (average lesion length, 81.5 mm +/- 41.2). Stent implantation followed standard interventional techniques and a maximum of two stents could be implanted. The primary endpoint was the in-stent mean lumen diameter at 6 months as determined by quantitative angiography.. Both stent types were effective in revascularizing the diseased SFA and allowing sustained patency for at least 6 months. There was no statistically significant difference between treatment groups in the in-stent mean lumen diameter at 6 months (4.94 mm +/- 0.69 and 4.76 mm +/- 0.54 mm for sirolimus-eluting and bare stent groups, respectively; P = .31). Although the diameter of the target lesion tended to be larger and percent stenosis tended to be lower with the sirolimus-eluting stent, there were no statistically significant differences between treatments in terms of any of the variables. The mean late loss values were 0.38 mm +/- 0.64 and 0.68 mm +/- 0.97 for the sirolimus-eluting stent group and the bare stent group, respectively (P = .20). The binary restenosis rates, with a cutoff of 50% at 6 months, were zero in the sirolimus-eluting stent group and 7.7% in the bare stent group (P = .49). Clinical outcomes matched angiographic outcomes with improvements in ankle-brachial index and symptoms of claudication. There was no significant difference between treatments in terms of adverse events.. Although there is a trend for greater efficacy in the sirolimus-eluting stent group, there were no statistically significant differences in any of the variables.

Topics: Aged; Alloys; Angiography; Arterial Occlusive Diseases; Double-Blind Method; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Immunosuppressive Agents; Leg; Male; Recurrence; Sirolimus; Statistics, Nonparametric; Stents; Treatment Outcome

The Symmetry aortic connector uses a nitinol implant to create proximal anastomoses with saphenous vein grafts. Multiple detector-row cardiac computed tomography (MDCT) is used as a noninvasive method of quality control at our institution.. In 50 elective coronary artery bypass grafting patients who participated in a randomized trial comparing automated with conventionally hand-sewn proximal anastomoses, MDC T was performed on postoperative day 5. Fifty-three automated Symmetry anastomoses were created in 34 patients (group 1). Twenty-five conventionally hand-sewn anastomoses created in 16 patients served as controls (group 2). Graft patency and the presence or absence of high-grade stenosis at the proximal anastomotic site were evaluated.. In group 1, 2 (3.8%) of the grafts were found occluded at MDCT or coronary angiography, and no further relevant stenosis was observed. In group 2, at postoperative MDCT all grafts were found patent without significant narrowing of the proximal anastomotic site.. The feasibility of proximal anastomoses using the Symmetry device has been reported. Patency control with invasive angiography has been performed by other groups. With MDCT, noninvasive evaluation of proximal anastomotic quality and graft patency is possible, even if nitinol is implanted.

Topics: Aged; Alloys; Anastomosis, Surgical; Coronary Artery Bypass; Feasibility Studies; Graft Occlusion, Vascular; Humans; Image Processing, Computer-Assisted; Quality Control; Suture Techniques; Tomography, X-Ray Computed; Vascular Patency

Stent implantation for obstructive femoropopliteal artery disease has been associated with poor long-term outcomes. This study evaluated the effectiveness of shape memory alloy recoverable technology (SMART) nitinol self-expanding stents coated with a polymer impregnated with sirolimus (rapamycin) versus uncoated SMART stents in superficial femoral artery obstructions.. Thirty-six patients were recruited for this double-blind, randomized, prospective trial. All patients had chronic limb ischemia and femoral artery occlusions (57%) or stenoses (average lesion length, 85+/-57 mm). Patients were eligible for randomization after successful guidewire passage across the lesion. Eighteen patients received sirolimus-eluting SMART stents and 18 patients received uncoated SMART stents. The primary end point of the study was the in-stent mean percent diameter stenosis, as measured by quantitative angiography at 6 months. The in-stent mean percent diameter stenosis was 22.6% in the sirolimus-eluting stent group versus 30.9% in the uncoated stent group (P=0.294). The in-stent mean lumen diameter was significantly larger in the sirolimus-eluting stent group (4.95 mm versus 4.31 mm in the uncoated stent group; P=0.047). No serious adverse events (death or prolonged hospitalization) were reported.. The use of sirolimus-eluting SMART stents for superficial femoral artery occlusion is feasible, with a trend toward reducing late loss compared with uncoated stents. The coated stent also proved to be safe and was not associated with any serious adverse events.

Topics: Aged; Alloys; Arterial Occlusive Diseases; Double-Blind Method; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Immunosuppressive Agents; Male; Radiography; Sirolimus; Stents; Treatment Outcome

With 70 cm "cutter" valvulotomes for valvulotomy and an electronically steerable nitinol catheter to occlude venous tributaries with platinum coils, endovascular in situ saphenous vein (EISV) bypass can be safely performed from within the saphenous vein. To determine whether EISV bypass could reduce hospital length of stay (LOS) and perioperative morbidity without compromising patency, another 53 EISV bypasses for limb salvage were performed.. Tributary occlusion was accomplished with only fluoroscopic surveillance with a new, smaller, and more steerable silicone-tipped nitinol catheter.. Two (3.7%) wound complications occurred. The mean hospital LOS after operation was 4.2 days (range 2 to 29 days). All tributaries initially embolized remained occluded, and three "missed" arteriovenous fistulas were identified during follow-up extending to 15 month (mean 8.4 months). Eighty-eight percent (49 of 54) of phase II bypasses remained patent, whereas life-table analysis of all bypasses (phase I and II) was 77% (69/99) at 24 months follow-up (mean 13.6 months). By comparison, 41 infrainguinal saphenous vein in situ bypasses with "classic" open techniques were performed concurrently. The mean postoperative LOS was 11.6 days (range 4 to 42 days), wound complications occurred in 24% (10) of patients, and two "missed" arteriovenous fistulas were identified during follow-up. Eighty-three percent (34 of 41) of bypasses remain patent at 24 months follow-up (mean 16.2 months).. If EISV bypass long-term patency rates remain similar to classic in situ bypass patency results, the additional benefits of decreased hospital LOS, reduced wound-related complications, shortened recuperation, and therefore increased health care savings gives this endovascular technique strong consideration as the possible future operation for infrainguinal saphenous veins in situ bypass.

Topics: Aged; Aged, 80 and over; Alloys; Catheterization; Catheterization, Peripheral; Combined Modality Therapy; Female; Femoral Vein; Follow-Up Studies; Graft Occlusion, Vascular; Groin; Humans; Leg; Length of Stay; Life Tables; Male; Middle Aged; Peripheral Vascular Diseases; Popliteal Vein; Postoperative Complications; Saphenous Vein; Silicones; Stents; Ultrasonography; Vascular Patency

Juxta-anastomotic stenosis (JXAS) is a common problem afflicting the arteriovenous fistula (AVF). This study aimed to evaluate the safety and long-term efficacy of an interwoven nitinol stent (Supera, Abbott Vascular, Santa Clara, CA, USA) in the treatment of radiocephalic AVF JXAS.. A single-center, retrospective, observational study was conducted of patients with failing AVF due to JXAS treated with an interwoven nitinol stent. End points included JXAS target lesion primary patency, access circuit primary patency, assisted access circuit primary patency, and endovascular intervention rate (EIR).. Sixty patients were treated with a Supera stent in the JXAS between February 2014 and March 2020. One patient was excluded (AVF used for illicit drug use), leaving 59 patients (67.8% male, mean age 66.9 ± 11.4 years [range: 40-84]) with typical medical comorbidities. Overall, 45.8% of patients had previous AVF intervention. The stent was inserted with a 100% technical success rate with a mean follow-up of 729.6 ± 456.0 days (range: 5-2182 days). Juxta-anastomotic stenosis target lesion primary patency was 68.2 ± 6.6%, 53.3 ± 7.5%, and 46.2 ± 8.1% at 12, 24, and 36 months, respectively. The EIR was .64 (0-3.29) procedures/patient/year, after which the assisted access circuit primary patency rate was 94.3 ± 3.2% at 12, 24, and 36 month time points. Three thrombosed circuits occurred which were all successfully salvaged with no difference in patency by indication for procedure and no AVFs lost/abandoned out to 3 years. Avoidance of stent post-dilatation and the presence of stent mal-apposition were associated with improved primary patency, and reduced EIR, which may suggest an importance in vessel preparation prior to stent implantation.. Interwoven nitinol stent treatment of the failing AVF with JXAS results in promising 3 year JXAS patency, with a low rate of endovascular re-intervention for those circuits developing restenosis. All AVFs were maintained over 3 years, demonstrating this treatment allows for long-term radiocephalic AVF vascular access.

Topics: Aged; Angioplasty, Balloon; Arteriovenous Fistula; Arteriovenous Shunt, Surgical; Constriction, Pathologic; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Renal Dialysis; Retrospective Studies; Stents; Treatment Outcome; Vascular Patency

The aim of this study is to present our personal experience using covered nitinol stent-graft in the treatment of outflow tract stenosis of arteriovenous grafts (AVGs) for hemodialysis access.. Between May 2015 and October 2017, we retrospectively evaluated 36 (24 males, 12 females; mean age: 65.6 years) patients with AVGs on hemodialysis who underwent percutaneous angioplasty followed by endovascular stent-graft deployment for the treatment of stenosis of the venous outflow of the AVG. Indication for treatment included early restenosis (<3 months after previous percutaneous transluminal angioplasty [PTA]), long stenosis (stenoses >50% extending for a length >5 cm), and recoil of the stenosis after PTA performed with a noncompliant high-pressure balloon. Of 36 patients, 27 (75%) required surgical thrombectomy prior to endovascular procedure. Technical success, clinical success, primary and secondary patency, and safety were evaluated.. Technical success was 100%, and clinical success was 94.4%. Primary patency was 94.4%, 72.2%, 63%, 45.9%, and 45.9% at 1, 3, 6, 12, and 18 months (average: 215 days, range: 9-653 days); secondary patency was 94.4% and 86.1% at 1 and 3 months; 80.4% at 6, 12, and 18 months; and 53.6% at 24 months (average: 276.8 days, range: 9-744 days). No deaths were registered.. In selected cases, the use of stent-graft represents an effective and safe solution for the treatment of stenotic complications of the venous outflow of AVGs, even in the setting of access thrombosis.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Arteriovenous Shunt, Surgical; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Endovascular Procedures; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Polytetrafluoroethylene; Prosthesis Design; Renal Dialysis; Reoperation; Retrospective Studies; Risk Factors; Stents; Time Factors; Treatment Outcome; Vascular Patency

Topics: Alloys; Angioplasty, Balloon; Constriction, Pathologic; Graft Occlusion, Vascular; Humans; Iliac Vein; Liver Transplantation; Male; Mesenteric Veins; Portal Vein; Prosthesis Design; Self Expandable Metallic Stents; Treatment Failure; Vascular Diseases; Vascular Grafting; Vascular Patency; Young Adult

The native arteriovenous fistula may remain immature despite adequate arterial inflow after formation. This may occur when the puncturable vein segment (cannulation zone) is too small to be reliably punctured, occluded or too deep under the skin for needle access. We performed stenting (stent-assisted maturation) of arteriovenous fistulas with an immature cannulation zone, allowing for a large subcutaneous channel which could then be immediately punctured for dialysis.. We performed a retrospective review of 49 patients (mean age was 58.7 ± 16.09 (12-83) years, mean arteriovenous fistula age of 162.6 ± 27.28 days) with end-stage renal failure who underwent balloon dilatation and bare-metal stent implantation (1.6 ± 0.67 (1-3) stents, median diameter and length of 8 (5-14) mm and 80 (40-150) mm, respectively) through their cannulation zone (forced maturation). Radiocephalic (35 arteriovenous fistulas), brachiocephalic (10 arteriovenous fistulas) and autogenous loop arteriovenous fistulas (4 arteriovenous fistulas) were included with 30 patients (61.2%) having an inadequate cannulation zone venous diameter, 9 patients (18.4%) having an absent cannulation zone and 10 patients (20.4%) having a patent cannulation zone deeper than 1 cm which was not reliably puncturable. The study was conducted over 9 years (January 2008-December 2016) with implantation of the SMART. At 6 months, 12 months and 4 years, respectively, cannulation zone primary patency was 84.4%, 74.4% and 56.1% and access circuit primary patency was 62.2%, 45.3% and 23.2%; however, assisted primary access circuit patency was 95.6%, 91.1% and 83.8%, achieved with an endovascular re-intervention rate of 0.53 procedures/year with only four thrombosed circuits occurring.. Forced maturation using nitinol stents allows for long-term haemodialysis access with a low rate of re-intervention.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Arteriovenous Shunt, Surgical; Catheterization; Child; Female; Graft Occlusion, Vascular; Humans; Kidney Failure, Chronic; Male; Middle Aged; Prosthesis Design; Renal Dialysis; Retrospective Studies; Stents; Time Factors; Treatment Outcome; Vascular Patency; Young Adult

Topics: Aged; Alloys; Angioplasty, Balloon; Arteriovenous Shunt, Surgical; Collateral Circulation; Female; Graft Occlusion, Vascular; Humans; Kidney Failure, Chronic; Prosthesis Design; Renal Dialysis; Stents; Treatment Outcome; Upper Extremity; Vascular Patency

Percutaneous transluminal angioplasty (PTA) is a common procedure in patients with peripheral arterial disease (PAD) affecting the femoropopliteal segment (F-P). Biomimetic nitinol stents (Supera peripheral stent, SPS) and drug eluting stents (DES) were designed to improve the longevity of F-P PTA; however, their performance has not been compared in a pragmatic setting, taking atherosclerotic plaque characteristics into account.. Overall, 296 consecutive patients (mean age: 73 y, SD: 11 y, 65% male, 68% with chronic limb threatening ischaemia) who underwent F-P PTA using SPS or DES between 2013 and 2018 were identified from a prospectively maintained institutional database. Patient and plaque characteristics, including F-P plaque characterisation based on computed tomography, were collected; 121 case matched pairs were created using a propensity score based on patient and plaque data.. During the median two year follow up, 28% of the cohort (32% SPS vs. 24% DES, p = .07) developed target lesion restenosis (TLR) > 50%. Among the 121 case matched pairs of patients, those with SPS vs. DES were not significantly more likely to develop TLR >50% (31% vs. 27%, p = .34), or stent occlusion (13% vs. 12%, p = .85 - secondary patency rate 87% vs. 88%), have a major amputation (10% vs. 6%, p = .16), require re-intervention (14% vs. 9%, p = .12), or die (7% vs.4%, p = .31). Plaque calcification did not predict restenosis or occlusion in either stent group, both in the matched and non matched populations. Multivariable analysis adjusted for patient and plaque characteristics revealed that the main predictors of restenosis >50% at two years were female sex [odds ratio (OR): 2.05, p = .01], hypertension (OR: 2.10, p = .04) and previous F-P occlusion (OR: 1.35, p = .04).. Medium term results following F-P PTA with either SPS or DES are comparable, regardless of plaque calcification and patient characteristics.

Topics: Aged; Alloys; Angioplasty; Computed Tomography Angiography; Extremities; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Limb Salvage; Male; Outcome and Process Assessment, Health Care; Peripheral Arterial Disease; Plaque, Atherosclerotic; Popliteal Artery; Prognosis; Stents; Vascular Calcification; Vascular Patency

Although percutaneous transluminal angioplasty is an effective therapy against vascular access failure in hemodialysis patients, recurrent stenosis imposes enormous burden for hemodialysis patients. A nitinol scoring element-equipped helical balloon catheter (AngioSculpt. Among patients undergoing hemodialysis in Masuko Memorial Hospital, 16 cases with resistant and recurrent vascular access stenosis underwent AngioSculpt (diameter 6 mm, total length 4 cm) angioplasty. We simultaneously measured the average venous pressures during hemodialysis before and after percutaneous transluminal angioplasty.. The average outflow vessel stenosis rate was 73.0 ± 11.3% before AngioSculpt intervention. Fully enlarged vessels were observed by expanding vessels at maximum pressure of 14 atm in all cases without any complications including vascular ruptures. Their intradialytic venous pressures decreased from 181.8 ± 39.2 mmHg to 150.5 ± 39.3 mmHg ( p < 0.0001).. AngioSculpt may provide a promising option for treating hemodialysis patients with severely advanced vascular access stenosis, who would otherwise need repeated vascular access surgeries and/or conventional percutaneous transluminal angioplasties.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Arteriovenous Shunt, Surgical; Blood Flow Velocity; Equipment Design; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Renal Dialysis; Retrospective Studies; Thigh; Treatment Outcome; Upper Extremity; Vascular Access Devices; Vascular Patency; Veins; Venous Pressure

To evaluate outcomes and patency of arteriovenous grafts (AVGs) created using Gore hybrid vascular grafts in hemodialysis patients with limited venous outflow or challenging anatomy.. A retrospective review was performed in two academic centers of all patients between July 2013 and December 2016 who underwent surgical AVG creation using a Gore hybrid vascular graft in a brachial artery to axillary configuration. Patient characteristics and comorbidities as well as graft patency, function, and subsequent need for percutaneous interventions were recorded.. Forty-six patients including 30 females (65.2%) and 16 males (34.8%) with a mean age of 63 ± 13 years were identified. The most common indications for a hybrid vascular graft were limited surgical accessibility and/or revision of existing AVG due to severe stenotic lesions at the venous outflow in 33 patients (72%). One-year primary unassisted and assisted patency rates were 44 ± 8% and 54 ± 8%, respectively, compared with 1-year secondary patency rate of 66 ± 8%. The rate of percutaneous interventions to maintain graft function and patency was approximately one intervention per graft per year.. Access created with the hybrid vascular graft in a brachial-axillary (brachial artery to axillary vein) configuration is an acceptable option for patients with limited venous outflow reserve and challenging anatomy. Twelve-month primary and secondary patency rates and need for percutaneous interventions were comparable to traditional AVGs.

Topics: Aged; Alloys; Arteriovenous Shunt, Surgical; Axillary Vein; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Brachial Artery; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Polytetrafluoroethylene; Prosthesis Design; Renal Dialysis; Retrospective Studies; Risk Factors; Stents; Time Factors; Treatment Outcome; United States; Vascular Patency

The purpose of this study was to compare the primary and secondary patency rates of percutaneous transluminal angioplasty (PTA) alone with those of metallic stent placement in patients with hemodialysis access and central venous occlusion (CVO) and to compare the respective effects of nitinol and stainless-steel stents on patency. MATERıALS AND METHODS: A total of 150 consecutive patients with hemodialysis access who underwent endovascular treatment for symptomatic CVO with ipsilateral functioning hemodialysis access were evaluated. There were 67 men and 83 women with a mean age of 56.2±15.2 (SD) years (range: 15-86 years). The primary endovascular treatment of CVO was PTA alone. Stent placement either with nitinol or stainless-steel stents was performed as a bailout procedure. The results were analyzed on a per patient basis.. Technical success was achieved in 141/150 patients (94%). Of the 141 patients, 109 (77%) underwent PTA alone and 32 (23%) underwent stent placement. The mean number of interventions in the stent group [4.3±2.5 (SD)] was significantly higher than that in the PTA alone group [2.6±2.8 (SD)] (P=0.002). The primary patency rates at 12, 24, and 60 months for the stent group (58.7%, 41.9%, and 27.9%, respectively) were significantly higher than those in the PTA alone group (42.4%, 36.3%, and 20.2%, respectively) (P=0.036). Secondary patency rates at 12, 24, and 60 months for the stent group (87.6%, 80.7%, and 50.3%, respectively) were significantly greater than those in the PTA alone group (68.4%, 56%, and 38.6%, respectively) (P=0.046). Furthermore, the primary patency rates at 6 and 12 months in the nitinol stent group (89% and 80.9%, respectively) were significantly greater than those in the stainless-steel stent group (78.8% and 38.4%, respectively) (P=0.007). The secondary patency rates at 6, 12 and 24 months for the nitinol stent group (92.8%, 87.7% and 65.8%, respectively) were significantly greater than those in the stainless-steel stent group (85.7%, 76.2% and 65.3%, respectively) (P=0.011). CONCLUSıON: Although PTA alone is an effective interventional treatment strategy of CVO in short term, stent placement yields greater primary and secondary patency rates in the long-term. But the mean number of interventions per vein after stenting is significantly higher. Close follow-up and multiple re-interventions are necessary to ensure long-term patency.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Alloys; Angioplasty; Catheterization, Central Venous; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Renal Dialysis; Retrospective Studies; Stainless Steel; Stents; Vascular Patency; Young Adult

To determine the clinical outcomes in hemodialysis patients after implantation of a Supera stent to treat juxta-anastomotic stenosis in radiocephalic arteriovenous fistulas (AVF).. A single-center retrospective study was conducted of 42 consecutive patients (mean age 66.7 years, range 40-84; 26 men) who had a failing AVF due to juxta-anastomotic stenosis treated with the interwoven Supera stent between February 2014 and February 2018. A third of the patients had previous juxta-anastomotic intervention (either balloon angioplasty or open surgical revision).. The stent was inserted successfully in all patients. Overall mean follow-up was 12.2±8.2 months (range 3.8-38.3). Juxta-anastomotic segment primary patency estimates at 6 and 12 months were 92.5% and 59.8%, respectively, with assisted primary patency rates of 97.5% and 92.9%. Reintervention (elective drug-coated balloon angioplasty) occurred at a rate of 0.31 procedures/year. Two AVFs thrombosed during the 1-year follow-up and were revascularized using balloon angioplasty. Ultrasound measurements of brachial artery flow rates increased significantly from 543.5±96.72 mL/min (range 430-644) before intervention to 919.2±355.9 mL/min (range 200-1600) after intervention (p=0.047). Arterial pressures on hemodialysis improved from -142.3±24.9 mm Hg (range -100 to -180) to -123.4±21.9 mm Hg (range -100 to -184; p=0.051). No AVFs were lost or abandoned during the follow-up period.. The interwoven Supera stent is a promising treatment for failing AVFs with juxta-anastomotic stenosis. Encouraging 1-year primary and assisted primary patency was demonstrated, with a low reintervention rate. This treatment facilitates long-term maintenance of AVF vascular accesses.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Arteriovenous Shunt, Surgical; Endovascular Procedures; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Prosthesis Design; Radial Artery; Renal Dialysis; Retrospective Studies; Risk Factors; Stents; Time Factors; Treatment Outcome; Upper Extremity; Vascular Patency; Veins

The ideal stent combination for chimney endovascular aneurysm repair remains undetermined. Therefore, we sought to identify optimal aortic and chimney stent combinations that are associated with the best outcomes by analyzing the worldwide collected experience in the PERformance of chImney technique for the treatment of Complex aortic pathoLogiES (PERICLES) registry.. The PERICLES registry was reviewed for patients with pararenal aortic disease electively treated from 2008 to 2014. Eleven different aortic devices were identified with three distinct subgroups: group A (n = 224), nitinol/polyester; group B (n = 105), stainless steel/polyester; and group C (n = 69), nitinol/expanded polytetrafluoroethylene. The various chimney stent subtypes included the balloon-expandable covered stent (BECS), self-expanding covered stent, and bare-metal stent. Deidentified aortic and chimney device combinations were compared for risk of chimney occlusion, type IA endoleak, and survival. Effects of high-volume centers (>100 cases), use of an internal lining chimney stent, number of chimney stents, and number of chimney stent subtypes deployed were also considered. We considered demographics, comorbidities, and aortic anatomic features as potential confounders in all models.. The 1- and 3-year freedom from BECS chimney occlusion was not different between groups (group A, 96% ± 2% and 87% ± 5%; groups B and C, 93% ± 3% and 76% ± 10%; Cox model, P = .33). Similarly, when non-BECS chimney stents were used, no difference in occlusion risk was noted for the three aortic device groupings; however, group C patients receiving BECS did have a trend toward higher occlusion risk relative to group C patients not receiving a BECS chimney stent (hazard ratio [HR], 4.0; 95% confidence interval [CI], 0.85-18.84; P = .08). Patients receiving multiple chimney stents, irrespective of stent subtype, had a 1.8-fold increased risk of occlusion for each additional stent (HR, 1.8; 95% CI, 1.2-2.9; P = .01). Use of a bare-metal endolining stent doubled the occlusion hazard (HR, 2.1; 95% CI, 1.0-4.5; P = .05). Risk of type IA endoleak (intraoperatively and postoperatively) did not significantly differ for the aortic devices with BECS use; however, group C patients had higher risk relative to groups A/B without BECS (C vs B: odds ratio [OR], 3.2 [95% CI, 1-11; P = .05]; C vs A/B: OR, 2.4 [95% CI, 0.9-6.4; P = .08]). Patients treated at high-volume centers had significantly lower odds for development of type IA endoleak (OR, 0.2; 95% CI, 0.1-0.7; P = .01) irrespective of aortic or chimney device combination. Mortality risk was significantly higher in group C + BECS vs group A + BECS (HR, 5.3; 95% CI, 1.6-17.5; P = .006). The 1- and 3-year survival for groups A, B, and C (+BECS) was as follows: group A, 97% ± 1% and 92% ± 3%; group B, 93% ± 3% and 83% ± 7%; and group C, 84% ± 7% and 63% ± 14%. Use of more than one chimney subtype was associated with increased mortality (HR, 3.2; 95% CI, 1.4-7.5; P = .006).. Within the PERICLES registry, use of nitinol/polyester stent graft devices with BECS during chimney endovascular aneurysm repair is associated with improved survival compared with other aortic endografts. However, this advantage was not observed for non-BECS repairs. Repairs incorporating multiple chimney subtypes were also associated with increased mortality risk. Importantly, increasing chimney stent number and bare-metal endolining stents increase chimney occlusion risk, whereas patients treated at low-volume centers have higher risk of type IA endoleak.

Topics: Aged; Aged, 80 and over; Alloys; Aortic Aneurysm, Abdominal; Aortic Aneurysm, Thoracic; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Comorbidity; Disease-Free Survival; Endoleak; Endovascular Procedures; Europe; Female; Graft Occlusion, Vascular; Hospitals, High-Volume; Hospitals, Low-Volume; Humans; Male; Multivariate Analysis; Odds Ratio; Polyesters; Polytetrafluoroethylene; Proportional Hazards Models; Prosthesis Design; Registries; Retrospective Studies; Risk Factors; Stainless Steel; Stents; Time Factors; Treatment Outcome; United States

Although nitinol is widely used in percutaneous cardiovascular interventions, a causal relationship between nickel released from implanted cardiovascular devices and adverse systemic or local biological responses has not been established. The objective of this study was to investigate the relationship between nitinol surface processing, in-vivo nickel release, and biocompatibility. Nitinol stents manufactured using select surface treatments were implanted into the iliac arteries of minipigs for 6 months. Clinical chemistry profile, complete blood count, serum and urine nickel analyses were performed periodically during the implantation period. After explant, stented arteries were either digested and analyzed for local nickel concentration or fixed and sectioned for histopathological analysis of stenosis and inflammation within the artery. The results indicated that markers for liver and kidney function were not different than baseline values throughout 180 days of implantation regardless of surface finish. In addition, white blood cell, red blood cell, and platelet counts were similar to baseline values for all surface finishes. Systemic nickel concentrations in serum and urine were not significantly different between processing groups and comparable to baseline values during 180 days of implantation. However, stents with non-optimized surface finishing had significantly greater nickel levels in the surrounding artery compared to polished stents. These stents had increased stenosis with potential for local inflammation compared to polished stents. These findings demonstrate that proper polishing of nitinol surfaces can reduce in-vivo nickel release locally, which may aid in minimizing adverse inflammatory reactions and restenosis.. Nitinol is a commonly used material in cardiovascular medical devices. However, relationships between nitinol surface finishing, in-vivo metal ion release, and adverse biological responses have yet to be established. We addressed this knowledge gap by implanting single and overlapped nitinol stents with different surface finishes to assess systemic impact on minipigs (i.e. serum and urine nickel levels, liver and kidney function, immune and blood count) over the 6 month implantation period. In addition, nickel levels and histopathology in stented arteries were analyzed on explant to determine relationships between surface processing and local adverse tissue reactions. The findings presented here highlight the importance of surface processing on in-vivo nickel release and subsequent impact on local biological response for nitinol implants.

Topics: Alloys; Animals; Female; Graft Occlusion, Vascular; Nickel; Stents; Surface Properties; Swine; Swine, Miniature; Time Factors

Thrombosis due to anastomotic site stenosis is the most common complication in patients with brachio-axillary arteriovenous graft (AVG). Intravascular stent placement may play a special role in the salvage of dialysis grafts that have been previously performed percutaneous angioplasty or surgical procedure on the graft. Herein, we applied a novel stent named Supera which has a high degree of flexibility and resistance to external compression for treating a patient with recurrent venous anastomotic stenosis of brachio-axillary AVG.. We report a case of the patient with end-stage renal disease who presented with brachio-axillary AVG malfunction.. The patient underwent repeated percutaneous angioplasty with thrombectomy for total graft occlusion, and we placed the Supera stent to salvage the graft.. Postprocedural Doppler ultrasonography did not show any restenosis on the 1- and 3-month follow-up periods, and average flow volume in the stent was >1000 mL/min. And he has been on dialysis for 6 months without any problems after stent placement.. The Supera stent is a useful treatment option of interventional procedure for recurrent venous anastomotic stenosis of brachio-axillary AVG in the clinical practice.

Topics: Aged; Alloys; Angioplasty; Arteriovenous Shunt, Surgical; Axillary Vein; Brachial Artery; Graft Occlusion, Vascular; Humans; Kidney Failure, Chronic; Male; Renal Dialysis; Stents; Thrombectomy; Ultrasonography, Doppler; Vascular Patency

Endovascular therapy for long femoropopliteal lesions using percutaneous transluminal balloon angioplasty or first-generation of peripheral stents has been associated with unacceptable one-year restenosis rates. However, with recent advances in equipment and techniques, a better primary patency rate is expected. This study was conducted to detect the long-term primary patency rate of nitinol self-expandable stents implanted in long, totally occluded femoropopliteal lesions TransAtlantic Inter-Society Census (TASC II type C & D), and determine the predictors of reocclusion or restenosis in the stented segments.. The demographics, clinical, anatomical, and procedural data of 213 patients with 240 de novo totally occluded femoropopliteal (TASC II type C & D) lesions treated with nitinol self-expandable stents were retrospectively analysed. Of these limbs, 159 (66.2%) presented with intermittent claudication, while 81 (33.8%) presented with critical limb ischaemia. The mean-time of follow-up was 36±22.6 months, (range: 6.3-106.2 months). Outcomes evaluated were, primary patency rate and predictors of reocclusion or restenosis in the stented segments.. The mean age of the patients was 70.9±9.3 years, with male gender 66.2%. Mean pre-procedural ABI was 0.45±0.53. One-hundred-and-seventy-five (73%) lesions were TASC II type C, while 65 (27%) were type D lesions. The mean length of the lesions was 17.9±11.3mm. Procedure related complications occurred in 10 (4.1%) limbs. There was no periprocedural mortality. Reocclusion and restenosis were detected during follow-up in 45 and 30 limbs respectively, and all were re-treated by endovascular approach. None of the patients required major amputation. Primary patency rates were 81.4±1.1%, 77.7±1.9% and 74.4±2.8% at 12, 24, and 36 months respectively. Male gender, severe calcification, and TASC II D lesion were independent predictors for reocclusion, while predictors of restenosis were DM, smoking and TASC II D lesions.. Treatment of long, totally occluded femoropopliteal (TASC II C & D) lesions with nitinol self-expandable stents is safe and is associated with highly acceptable long-term primary patency rates.

Topics: Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Blood Vessel Prosthesis Implantation; Female; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Peripheral Arterial Disease; Retrospective Studies; Stents; Time Factors; Vascular Patency

This study describes our technique of aggressive angioplasty with juxta-anastomotic stenting (JXAS) in the autogenous arteriovenous fistula and reviews our outcomes with this technique in its mature form.. We developed a JXAS technique during the last 7 years. Since 2006, we have placed 135 JXASs. The study period reviews 68 consecutive JXASs placed from 2008 to 2012 using the mature technique. We retrospectively analyzed the prospectively collected data. Thirty-three fistulas received JXAS for failure to mature, and 35 were mature but inadequately dialyzing fistulas (problem fistulas). The JXAS technique involves (1) treating the JXA segment as a unit, (2) aggressive angioplasty with rupture of stenoses, and (3) placement of an uncovered nitinol stent.. Technical success was 97%. Of the fistulas that had failed to mature, 75% were brought to maturity by 6 months and 88% by 12 months. Adequate dialysis was achieved in all 35 problem fistulas immediately postoperatively. Assisted fistula patency was 90% at 2 years and 80% at 4 years.. JXAS is an effective technique for maturing and maintaining the wrist radiocephalic arteriovenous fistula.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Arteriovenous Shunt, Surgical; Constriction, Pathologic; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Prosthesis Design; Radial Artery; Regional Blood Flow; Renal Dialysis; Retrospective Studies; Stents; Time Factors; Treatment Outcome; Vascular Patency; Veins; Wrist; Young Adult

Saphenous vein conduits are still used in a large proportion of coronary artery bypass graft (CABG) operations. A recently commercialized nitinol mesh seems to improve venous graft patency. The aim of this study was to control nitinol mesh vein graft patency in a series of isolated CABG patients by computed tomographic (CT) scan.. In 25 patients (mean age: 61.0 ± 9.65 years), operated for isolated CABG, the eSVS nitinol mesh (Kips Bay Medical Inc., Minneapolis, Minnesota, United States) was used to wrap one vein graft in each patient. Nitinol mesh vein graft was used to revascularize the right coronary (4 patients; 16%), the posterior descending (18 patients; 72%), and the obtuse marginal (3 patients; 12%) arteries. CT scans were performed at 1, 6, and 12 months postoperatively.. The procedure was uneventful in all patients. CT controls showed an overall patency rate of 86.9, 42.7, and 34.1% at 1, 6, and 12 months, respectively. The 4 mm mesh had a significantly higher patency rate at 12 months (83.33%) than the 3.5 mm one which showed quite unsatisfactory results (20%) (p = 0.02). Patients with graft occlusion underwent stress testing which was mildly positive in two cases. One of them underwent a percutaneous revascularization.. Despite promising early results, use of nitinol mesh for saphenous veins was disappointing in our experience. Further refinements are probably needed.

Topics: Aged; Alloys; Coronary Angiography; Coronary Artery Bypass; Coronary Artery Disease; Equipment Design; Female; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Risk Factors; Saphenous Vein; Surgical Mesh; Time Factors; Tomography, X-Ray Computed; Treatment Outcome; Vascular Patency

A 74-year-old woman complained of claudication due to in-stent restenosis of bare-metal stents in the right superficial femoral artery, and two Zilver PTXs were deployed. However, hemarthrosis developed, and aspirin and clopidogrel were discontinued. Thirty-six days later, she suddenly felt rest pain in her right leg. Angiography revealed total occlusion at the Zilver PTX implantation site, demonstrating late stent thrombosis. Aspiration and thrombolysis yielded adequate flow and symptom resolution. Follow-up catheterization was scheduled 6 months later. While the Zilver PTX stents were angiographically patent, angioscopy demonstrated a large red thrombus and uncovered stent struts. Therefore, dual antiplatelet therapy was continued.

Topics: Aged; Alloys; Angiography; Angioscopy; Antineoplastic Agents, Phytogenic; Drug-Eluting Stents; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Intermittent Claudication; Paclitaxel; Prosthesis Failure; Thrombosis; Time Factors

Topics: Aged; Alloys; Angioscopy; Antineoplastic Agents, Phytogenic; Drug-Eluting Stents; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Paclitaxel; Time Factors

This study was designed to investigate the immediate and one-year outcomes of polymer-free paclitaxel coated drug-eluting stent (DES) implantation in a consecutive series of patients presenting with stenosis of infrainguinal bypass grafts.. Between January 2011 and January 2012, 11 patients with failing infrainguinal bypass grafts were treated in two institutions. Clinical status and Duplex scan parameters were recorded at baseline and over a follow-up period of one year.. DES implantation was successfully performed in all patients. Ten patients received a single stent and one patient received two stents. At one year, one patient showed total bypass graft occlusion (9%). In all the remaining patients, Duplex scan examination documented patency of the treated grafts.. DES implantation in failing infrainguinal bypass grafts can be safely performed and provides satisfactory clinical outcomes. The patency rate of 91% favourably compares with those obtained with other endovascular treatments such as plain balloon or cutting balloon angioplasty.

Topics: Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Cardiovascular Agents; Constriction, Pathologic; Drug-Eluting Stents; Female; Graft Occlusion, Vascular; Humans; Italy; Lower Extremity; Male; Middle Aged; Paclitaxel; Prosthesis Design; Prosthesis Failure; Time Factors; Treatment Outcome; Ultrasonography, Doppler, Duplex; Vascular Patency

Intracranial atherosclerosis may be the underlying pathology in up to 15% of ischemic strokes, but may account for about 40% of strokes in some populations. After an ischemic event determined by intracranial atherosclerosis, patients have a 12% annual risk of stroke recurrence, mostly during the first year.. To evaluate procedural safety, clinical outcome and restenosis rate of Wingspan stent placement.. Twenty-one caucasoid patients were enrolled. Target patients were affected by high-grade, symptomatic, intracranial atherosclerotic lesions, were on antithrombotic therapy and at high stroke risk. All patients were treated with the Wingspan stent system.. Technical success resulted 100%, with all target lesions being reduced to <50%. No stroke or death were observed at 30. The mean percent of stenosis was reduced from a middle value of 84% to a middle value of 17% after stent placement. Medium follow-up was 19.5months (range 6-36months). No stroke or death occurred in any patient. None of the patients presented a <50% stent patency rate at follow-up.. The short-term results and follow up analysis provide evidence demonstrating the safety of the Wingspan system when used in high-risk patient population. Due to concerns regarding long-term stent patency and ischemic events occurrence emerged from clinical trials such as the SAMMPRIS, intracranial angioplasty and stent with the Wingspan system should be considered only for high risk patients in which it may be considered the only viable therapeutic option.

Topics: Aged; Aged, 80 and over; Alloys; Angioplasty; Brain Ischemia; Cerebral Angiography; Constriction, Pathologic; Endpoint Determination; Female; Fibrinolytic Agents; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Magnetic Resonance Angiography; Male; Middle Aged; Plaque, Atherosclerotic; Platelet Aggregation Inhibitors; Recurrence; Stents; Stroke; Survival Rate; Tomography, X-Ray Computed; Treatment Outcome

To compare the performance of small intestinal submucosa (SIS)-covered endografts (SCEs) to bare nitinol stents (BSs) in injured swine iliac arteries.. Twenty-eight nitinol stents were used: 14 externally SCEs and 14 BSs. Devices were implanted in each side of balloon-injured external iliac arteries of 14 swine via carotid approach. Arteriograms were obtained before and after implantation and before animal sacrifice at 4, 8, and 12 weeks. Histopathological and electron microscopy studies of explanted specimens were performed.. Implantation of all SCEs and BSs was technically successful, but one SCE and one BS were obstructed at 8 weeks after implantation. At sacrifice, the other 26 stents were patent, with angiogram showing no significant different luminal narrowing between SCEs and BSs. Proliferating cell nuclear antigen (PCNA) immunohistochemistry examination revealed that the percentage of PCNA(+) cells were lower in SCEs (p<0.05). Additionally, histomorphological analysis indicated that the neointima area and percentage of narrowing area were greater in SCEs, but there was no statistical significance. Greater endothelial cell count in SCEs than in BSs per visual field at 4000 times magnification by scanning electron microscope (p<0.05).. Compared to BSs, no definite decrease of neointima and restenosis was found in SCEs in the present study. However, it is effective in promoting endothelial regeneration and strengthening endothelial function.

Topics: Alloys; Analysis of Variance; Angiography; Angioplasty; Animals; Disease Models, Animal; Graft Occlusion, Vascular; Iliac Artery; Immunohistochemistry; Intestinal Mucosa; Intestine, Small; Microscopy, Electron, Scanning; Prosthesis Design; Stents; Swine

Most arteriovenous hemodialysis grafts fail ≤18 months after implantation, most commonly due to intimal hyperplasia at the venous anastomosis. This open prospective study compared balloon angioplasty vs nitinol stent placement in the treatment of venous anastomotic stenosis after thrombectomy of prosthetic brachial-axillary accesses.. Between February 2007 and December 2010, 61 patients with an initial thrombosis of a prosthetic brachial-axillary access were admitted to our hospital. Of these patients, 28 (46%), treated before June 2008, underwent thrombectomy plus balloon angioplasty of the venous anastomosis (group A), whereas the remaining 33 (54%) patients, who were treated after July 2008, underwent graft thrombectomy plus angioplasty with self-expanding nitinol stent placement (group B). Primary, primary-assisted, and secondary patency rates were calculated using Kaplan-Meier analysis and compared between the two groups with the log-rank test.. Primary patency was 32% at 3 months, 24% at 6 months, and 14% at 12 months in group A, and the respective values were 85%, 63% and 49% in group B. Primary patency was significantly better in group B than in group A (P < .001; log-rank test). Cumulative median patency was 60 days in group A and 260 days in group B. Patient age, sex, comorbidities, graft material, and graft age did not have prognostic significance. Primary-assisted and secondary patency rates were significantly higher in group B.. Graft thrombectomy plus angioplasty with self-expanding nitinol stent placement provides significantly higher patency rates compared with thrombectomy plus plain balloon angioplasty of the venous anastomosis.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Arteriovenous Shunt, Surgical; Axillary Vein; Blood Vessel Prosthesis Implantation; Brachial Artery; Chi-Square Distribution; Female; Graft Occlusion, Vascular; Greece; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Proportional Hazards Models; Prospective Studies; Prosthesis Design; Renal Dialysis; Risk Assessment; Risk Factors; Stents; Thrombectomy; Thrombosis; Time Factors; Treatment Outcome; Vascular Patency

To investigate the safety and efficacy of a Polyzene-F nanocoat on new low-profile self-expandable nitinol stents in minipig renal arteries.. Ten bare nitinol stents (BNS) and 10 stents coated with a 50 nm-thin Polyzene-F coating were randomly implanted into renal arteries of 10 minipigs (4- and 12-week follow-up, 5 animals/group). Thrombogenicity, on-stent surface endothelialization, vessel wall injury, late in-stent stenosis, and peristrut vessel wall inflammation were determined by quantitative angiography and postmortem histomorphometry.. In 6 of 10 BNS, >50% stenosis was found, but no stenosis was found in stents with a nanothin Polyzene-F coating. Histomorphometry showed a statistically significant (p < 0.05) different average maximum luminal loss of 55.16% ± 8.43% at 12 weeks in BNS versus 39.77% ± 7.41% in stents with a nanothin Polyzene-F coating. Stents with a nanothin Polyzene-F coating had a significantly (p < 0.05) lower inflammation score after 12 weeks, 1.31 ± 1.17 versus 2.17 ± 0.85 in BNS. The results for vessel wall injury (0.6 ± 0.58 for Polyzene-F-coated stents; 0.72 ± 0.98 for BNS) and re-endothelialization, (1.16 ± 0.43 and 1.23 ± 0.54, respectively) were not statistically significant at 12-week follow-up. No thrombus deposition was observed on the stents at either follow-up time point.. Nitinol stents with a nanothin Polyzene-F coating successfully decreased in-stent stenosis and vessel wall inflammation compared with BNS. Endothelialization and vessel wall injury were found to be equal. These studies warrant long-term pig studies (≥120 days) because 12 weeks may not be sufficient time for complete healing; thereafter, human studies may be warranted.

Topics: Alloys; Angiography; Animals; Coated Materials, Biocompatible; Graft Occlusion, Vascular; Nanotechnology; Organophosphorus Compounds; Polymers; Radiography, Interventional; Random Allocation; Renal Artery; Statistics, Nonparametric; Stents; Swine; Swine, Miniature

To investigate the use of an expanded polytetrafluoroethylene-coated nitinol stent-graft in patients with failing hemodialysis access circuits and compare grafts with and without a heparin-coated surface.. A single-institution retrospective review of 16 patients (average age, 55 years; seven men) treated for hemodialysis access circuit stenoses was performed. Patients had a prosthetic arteriovenous (AV) graft (n = 10) or autogenous AV fistula (n = 6), all with clinically relevant access stenoses that were refractory to angioplasty alone; 10 patients also had access circuit thrombosis at the time of treatment. Stents were placed in the basilic (n = 4), brachial (n = 7), cephalic (n = 4), and femoral (n = 1) veins. Study endpoints included primary treatment area patency, primary circuit patency, primary assisted circuit patency, and secondary circuit patency, followed to a maximum of 6 months.. Primary treatment area patency rates at 30 days and 180 days were 75% and 31%, respectively. Secondary patency rates at the same time points were 88% and 68%, respectively. Mean primary treatment area patency was 93 days. Thrombosis was a major cause of failure, occurring in seven of 11 cases of primary treatment area patency loss. Subgroup analysis demonstrated that the heparin-coated configuration (n = 7) showed a 6-month primary patency rate of 57%, compared with 11% for the stent-grafts without heparin bonding (n = 9; P = .06).. Overall, the majority of deployed stent-grafts lost primary patency within 6 months, with thrombosis a major cause of failure. However, the addition of a heparin-coated surface appeared to improve results in these otherwise treatment-refractory access circuits.

Topics: Adult; Aged; Alloys; Angioplasty; Anticoagulants; Arteriovenous Shunt, Surgical; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Coated Materials, Biocompatible; Constriction, Pathologic; Female; Graft Occlusion, Vascular; Heparin; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Polytetrafluoroethylene; Prosthesis Design; Renal Dialysis; Retrospective Studies; Secondary Prevention; Stents; Time Factors; Treatment Outcome; Vascular Patency; Venous Thrombosis

Topics: Alloys; Coronary Angiography; Coronary Artery Bypass; Coronary Artery Disease; Female; Graft Occlusion, Vascular; Humans; Male; Saphenous Vein; Surgical Mesh

To investigate the long-term outcomes of nitinol stenting in femoropopliteal lesions and to determine the factors associated with restenosis.. Between December 2003 and December 2009, 861 patients (603 men; mean age 72 years) underwent nitinol stenting of the femoropopliteal segment in 1017 limbs. A quarter (26%) of the patients had critical limb ischemia. Mean lesion length was 152±93 mm. Stent patency was assessed by either duplex ultrasound or angiography and analyzed by Kaplan-Meier estimation. The determinants of restenosis were explored with Cox proportional hazard regression analyses; the results are presented as the hazard ratio (HR) and 95% confidence interval (CI). Risk stratification of primary patency was subsequently analyzed using a score based on the significant prognostic factors identified in the multivariate model.. Stent fracture occurred in 10% (104 limbs) of the lesions. At 1, 3, and 6 years, the primary patency rates were 77%, 67%, and 63%; secondary patency rates were 91%, 87%, and 87%; freedom from femoropopliteal bypass grafting was 99%, 97%, and 96%, respectively. Multivariate Cox regression analysis identified female gender (HR 1.899; 95% CI 1.318 to 2.737, p<0.001), ankle-brachial index <0.6 (HR 1.921; 95% CI 1.348 to 2.736, p<0.001), TASC II C/D lesion (HR 2.068; 95% CI 1.346 to 3.177, p = 0.0009), stent fracture (HR 1.937; 95% CI 1.203 to 3.118, p = 0.006), and the absence of cilostazol administration (HR 2.102; 95% CI 1.394 to 3.172, p<0.001) as strong independent factors associated with restenosis. After assigning a risk score based on the outcomes of the multivariate regression analysis (1 each for female gender, ABI <0.6, TASC II C/D, stent fracture, and absence of cilostazol therapy), primary patency was found to be lower in limb groups with a higher cumulative score (12-month primary patency: score 0: 93%, score 1: 80%, score 2: 73%, score 3; 47%, score 4: 0%, respectively; p<0.001).. Endovascular therapy using nitinol stents for FP lesions yielded acceptable outcomes up to 6 years. Risk stratification for patency can play an important role in estimating future occurrence of restenosis after nitinol stent implantation in FP lesions.

Topics: Alloys; Endovascular Procedures; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Multivariate Analysis; Peripheral Arterial Disease; Popliteal Artery; Prosthesis Design; Retrospective Studies; Risk Factors; Stents; Treatment Outcome; Vascular Patency

To compare outcomes with a thermoplastic polyurethane (TPU)-covered self-expanding nitinol stent-graft (TPU graft) with those of a bare self-expanding nitinol stent in a porcine model.. Fourteen TPU grafts and 14 commercially available bare nitinol stents were implanted, one each, in the iliac arteries of 14 minipigs. Follow-up was performed at 1 week (six animals), 4 weeks (four animals), and 12 weeks (four animals). The primary study endpoint was in-stent stenosis assessed with quantitative angiography and microscopy. Secondary endpoints were injury, inflammation, and endothelialization.. After 1 week, the maximum percentage luminal loss was significantly greater in TPU grafts (average, 16.2%; range, 0.0%-35.8%) than in bare nitinol stents (8.2%; 0.0%-17.3%) (P = .04). Three of the four TPU grafts were occluded after 4 weeks, and all four TPU grafts were occluded after 12 weeks. Binary stenosis was seen in three of four bare nitinol stents after both 4 and 12 weeks. At 4-week follow-up, the average percentage luminal loss was significantly greater in TPU grafts (85.2%; 40.8%-100%) than in bare nitinol stents (49.5%; 37.9%-62.4%) (P = .003). The difference in neointimal height and percentage average stenosis between TPU grafts (1,028.7 microm and 68.4%) and bare nitinol stents (1,033.6 microm [918.0-1,118.40 microm] and 68.1% [60.44%-71.99%]) was not statistically significant. After 12 weeks, the average percentage luminal loss was 100% in TPU grafts due to occlusion of all stent-grafts and 24.9% (8.0%-63.9%) in bare nitinol stents (P = .011).. TPU grafts failed to provide improved patency compared with the bare nitinol stents because of excessive neointimal growth and subsequent occlusion. In addition, the bare nitinol stents showed considerable in-stent stenosis at angiography and microscopy.

Topics: Alloys; Animals; Blood Vessel Prosthesis; Coated Materials, Biocompatible; Disease Models, Animal; Equipment Design; Equipment Failure Analysis; Graft Occlusion, Vascular; Hot Temperature; Humans; Iliac Artery; Plastics; Polyurethanes; Porosity; Radiography; Stents; Swine

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angioplasty; Arteriovenous Shunt, Surgical; Blood Vessel Prosthesis; Brachiocephalic Veins; Constriction, Pathologic; Female; Graft Occlusion, Vascular; Humans; Kidney Failure, Chronic; Male; Middle Aged; Recurrence; Renal Dialysis; Stents; Treatment Outcome; Ultrasonography, Doppler; Vascular Diseases; Vascular Patency

Although percutaneous transluminal angioplasty (PTA) has become a common therapeutic standard for peripheral artery disease (PAD), high restenosis rates in the superficial femoral artery (SFA) remain a major problem. Nitinol stent implantation is reported to reduce restenosis in SFA after PTA in the general population; however, little is known about whether the nitinol stent improves primary patency after PTA in hemodialysis patients who are at higher risk of revascularization failure. The aim of this study was to clarify the effects of nitinol stent implantation for primary patency in SFA after PTA in hemodialysis patients with PAD.. Eighty consecutive hemodialysis patients (167 SFA lesions) who underwent PTA with nitinol stents from January 2006 to January 2008 were compared with 64 hemodialysis patients (128 SFA lesions) who received stainless steel stents in the preceding 2 years. In the follow-up study to 2 years, incidence of restenosis, amputation, and all-cause mortality were analyzed. End points between the groups were examined with the Kaplan-Meier and log-rank methods. Prognostic values for end points were calculated by a Cox univariate analysis and Cox multivariable regression models. To statistically minimize the differences in each stent group, a propensity-matched analysis was also performed using the model including male gender, age, diabetes, hypertension, hyperlipidemia, smoking, incidence of ulcer/gangrene, and TransAtlantic Inter-Society Consensus (TASC) type C+D.. The 2-year primary patency rate was 58% in the nitinol group vs 42% in the stainless steel group (hazard ratio [HR], 0.58; 95% confidence interval [CI], 0.39-0.84; P = .0045), despite a higher prevalence of TASC C+D lesion in the nitinol group (68% vs 49%, P = .0014). In 108 lesions matched after propensity score analysis, the primary patency for 2 years was 64% in the nitinol group vs 42% in the stainless steel group (HR, 0.39; 95% CI, 0.24-0.65; P = .0003). Cox multivariate models showed nitinol stent (HR, 0.42; 95% CI, 0.25-0.73; P = .002), age (HR, 1.04; 95% CI, 1.01-1.08; P = .031), and incidence of ulcer/gangrene (HR, 2.35; 95% CI, 1.17-4.75; P = .017) were independent predictors of restenosis.. These data suggest that nitinol stent implantation improves primary patency in SFA after PTA compared with the stainless steel stent, even in hemodialysis patients with PAD.

Topics: Aged; Alloys; Angioplasty, Balloon; Arterial Occlusive Diseases; Constriction, Pathologic; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Proportional Hazards Models; Prosthesis Design; Renal Dialysis; Retrospective Studies; Risk Assessment; Risk Factors; Stainless Steel; Stents; Time Factors; Treatment Outcome; Vascular Patency

The stenting of aorto-ostial lesions in the native coronary circulation, renal arteries, and saphenous vein grafts is technically challenging.. We report the first in the world use of the Ostial Protrade mark, a novel nitinol-based device, utilized in conjunction with standard stenting techniques to assist in the precise placement of stents for the treatment of aorto-ostial lesions.. The Ostial Pro, is a relatively simple nitinol device that is positioned within the guiding catheter. It has distal, self-expanding legs that are advanced just distal to the tip of the guiding catheter after the ostial lesion has been crossed with the coronary guidewire and stent delivery system. The expanded nitinol legs prevent the entry of the guiding catheter into the target vessel, mark the plane of the aortic wall, and align the tip of the guide with the aorto-ostial plane. We report the successful and precise placement of stents in the aorto-ostial location in two patients with; (1) a saphenous vein graft ostial lesion and (2) a right coronary ostial lesion, using the new Ostial Pro stent positioning device. Excellent stent positioning, relative to the aorto-ostial plane, was confirmed by angiography and long axis intravascular ultrasound in both cases.. (1) The Ostial Pro is a new, commercially available (FDA cleared), nitinol device that is simple to use and appears effective in allowing the precise placement of stent(s) at the aorto-ostial location. (2) This approach may provide a simple and effective means to assure accurate stent placement in these difficult to treat lesions.

Topics: Aged; Alloys; Angioplasty, Balloon, Coronary; Cardiac Catheterization; Coronary Artery Bypass; Coronary Restenosis; Coronary Stenosis; Drug-Eluting Stents; Equipment Design; Equipment Safety; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Radiography; Risk Assessment; Sensitivity and Specificity; Treatment Outcome

The use of expanded polytetrafluoroethylene (ePTFE)-covered nitinol stents for salvage of hemodialysis fistulas was retrospectively examined. Seven covered stents were placed in five patients with failing fistulas considered unsalvageable. Indications included recurrent stenoses, thrombosis, and pseudoaneurysm formation. Before intervention, all patients required multiple interventions. The technical success rate was 100%. The primary patency rate was 80%, with secondary patency and lesion patency rates of 100% at 9 months. The incidence of follow-up repeat intervention was 0.3 per year. There were no complications. The use of ePTFE-covered stent placement in dysfunctional autogenous fistulas is technically feasible and, in this small series, was effective in preserving function and preventing access abandonment.

Topics: Aged; Alloys; Angioplasty, Balloon; Arteriovenous Shunt, Surgical; Coated Materials, Biocompatible; Female; Graft Occlusion, Vascular; Humans; Male; Polytetrafluoroethylene; Radiography, Interventional; Renal Dialysis; Retrospective Studies; Salvage Therapy; Stents; Treatment Outcome; Vascular Patency

We present the first reported case of a carotid artery stent fracture where a Nitinol stent was used for the management of carotid artery stenosis. An 83-year-old man underwent right carotid artery stenting in July 2005. On follow-up ultrasound, stenosis of the right internal carotid artery was noted. In January 2006, he underwent left carotid artery stenting and at this procedure, precontrast assessment of the right neck revealed a complete fracture through the waist of the stent in the right internal carotid artery. This fractured segment correlated with the area of stenosis reported at the previous ultrasound. In July 2006, this gentleman underwent successful removal of the carotid stent with uneventful carotid endarterectomy and synthetic patch repair. Carotid artery stenting is a newer and alternative modality to carotid endarterectomy for the treatment of carotid artery stenting. More data are emerging to support its safety and efficacy. An unexpected complication can happen with any procedure and complications help define the follow-up management of subsequent patients undergoing this procedure.

Topics: Aged, 80 and over; Alloys; Blood Vessel Prosthesis Implantation; Carotid Artery, Internal; Carotid Stenosis; Device Removal; Endarterectomy, Carotid; Graft Occlusion, Vascular; Humans; Male; Prosthesis Design; Prosthesis Failure; Radiography; Stents; Ultrasonography, Doppler, Color

The monoclonal antibody (mAb) to the platelet glycoprotein (GP) IIb/IIIa receptor has potent antiplatelet and antithrombotic characteristics shown to reduce thrombus-related major complications after coronary angioplasty. This mAb can be incorporated in drug-eluting stents capable of releasing single or multiple bioactive agents into the bloodstream and surrounding tissues. Stents eluting the monoclonal mouse anti-human platelet glycoprotein IIb/IIIa antibody SZ-262 were tested for their effectiveness in improving the blood compatibility and the antithrombotic characteristics by immunofluorescence and scanning electron microscopy (SEM). The SEM results convincingly demonstrated that the surface of the mAb eluting-stents was completely free of platelet uptake without any sign of cellular debris or proteinaceous deposits, compared with controls. The deformation index of platelets on the L-polylactic acid (L-PLA) coated stents were higher than bare Nitinol intravascular stents, as shown by SEM images. Monoclonal antibody to the platelet GP IIb/IIIa receptor, when eluting from L-PLA polymer-coated stents, effectively inhibits platelet aggregation in the stent microenvironment, thus demonstrating a potential capacity of reducing thrombosis, improving blood flow and arterial patency rates, and inhibiting cyclic blood flow variations. These results highlight the possibility of such monoclonal antibody-eluting stents to reduce or possibly eliminate thrombosis and in-stent restenosis.

Topics: Alloys; Animals; Antibodies, Monoclonal; Blood Platelets; Drug-Eluting Stents; Graft Occlusion, Vascular; Humans; Lactic Acid; Materials Testing; Mice; Platelet Glycoprotein GPIIb-IIIa Complex; Polyesters; Polymers; Thrombosis

Stent fracture has emerged as a new problem in the percutaneous transluminal angioplasty of the superficial femoral artery (SFA). The aim of our study was to delineate the factors influencing nitinol stent fracture in the SFA. Forty consecutive patients with peripheral artery disease who underwent rescue stenting with a nitinol stent (Luminexx, Bard) in the SFA were enrolled between May 2004 and January 2005. Follow-up angiography was performed 13.6+/-1.0 months later to detect stent fracture. Stent fracture occurred in 11 patients (28%). Lesion length>100 mm, the number of stents used, the lesion involving the distal SFA, chronic total occlusion, and walking>5,000 steps per day were more frequently observed in those with stent fracture than in those without fracture. Of these variables, walking>5,000 steps per day was the strongest independent determinant associated with stent fracture by discriminant analysis (p=0.0027). Vigorous exercise adversely affects stent fracture in patients implanted with a nitinol stent in the SFA.

Topics: Aged; Alloys; Angiography; Arterial Occlusive Diseases; Blood Vessel Prosthesis Implantation; Exercise; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Prosthesis Failure; Retrospective Studies; Risk Factors; Stents; Walking

Clinical results following stent implantation in the superficial femoral artery (SFA) are limited due to restenosis, often caused by stent fractures. Therefore new stent devices are desirable. The present study details our initial experience with the routine use of the novel Protégé EverFlex long self-expanding nitinol stent for treatment of long SFA total occlusions or stenoses.. Between February and March 2006 a total of 15 EverFlex nitinol stents were implanted in 12 patients with either total SFA occlusions (n = 9) or long stenoses (n = 3), mean lesion length 14.9 cm (+/- 10.4 cm). All patients presented with claudication stage Fontaine IIb (Rutherford category 3). Stent lengths were 10 cm (n = 6), 12 cm (n = 1), or 15 cm (n = 8), stent diameters were 6 mm (n = 14) and 7 mm (n = 1). Access was gained either by the crossover (n = 9), antegrade (n = 2), or popliteal approach (n = 1). After predilatation, stent placement and postdilatation were performed with 100% technical success. Clinical and apparative follow-up after 6-8 weeks indicated the absence of restenosis or reocclusion in all cases.. The novel long self-expanding EverFlex nitinol stent (10 cm/12 cm/15 cm in length) exhibits excellent technical handling characteristics with good short-term clinical results. Mid-term and long-term clinical results as well as potential stent fractures need to be further examined.

Topics: Aged; Alloys; Arterial Occlusive Diseases; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Male; Postoperative Complications; Stents; Treatment Outcome; Vascular Surgical Procedures

The purpose of this study was to investigate the proximal anastomosis of CABG grafts created by a nitinol aortic connector. After receiving CABG, 33 patients underwent CT examination of the heart. On the same patients, CT was performed on postoperative day 5 (4-row CT, group A) and again 1 year thereafter (16-row CT, group B). Twenty-three ACVB to RCX and 27 ACVB to RCA grafts were included. Every anastomosis was reviewed under different reformations (MIP, MPR and VRT). Interobserver correlation was determined. Five days postoperatively, 48/50 anastomoses were classified as patent. One year postoperatively, 42/50 anastomoses were classified as patent. In both groups, the aortic connector could be visualized with good quality: 1.82+/-1.10 (group A) and 1.93+/-1.22 (group B) for ACVB to RCA, similar results for ACVB to RCX grafts (MPR). Image quality at the aortic connector site did not display a significant difference for any reformation between groups (P>0.05). Within groups, MPR displayed better visualization than MIP and VRT (P<0.05). In the presence of metal implants, CT provides reliable data in evaluation of the proximal anastomosis. Sixteen-row CT does not bring a significant benefit to image quality. MPR displayed the best visualization within both groups.

Topics: Aged; Algorithms; Alloys; Anastomosis, Surgical; Blood Vessel Prosthesis; Coronary Artery Bypass; Female; Graft Occlusion, Vascular; Humans; Image Processing, Computer-Assisted; Male; Retrospective Studies; Statistics, Nonparametric; Tomography, Spiral Computed; Vascular Patency

Topics: Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon, Coronary; Arterial Occlusive Diseases; Blood Vessel Prosthesis Implantation; Combined Modality Therapy; Femoral Artery; Graft Occlusion, Vascular; Heparin; Humans; Male; Popliteal Artery; Radiography; Reoperation; Stents; Thrombolytic Therapy

The aim of this study was to investigate the occurrence and the clinical impact of stent fractures after femoropopliteal stenting.. The development of femoral stent fractures has recently been described; however, there are no data about the frequency and the clinical relevance.. A systematic X-ray screening for stent fractures was performed in 93 patients. In total, 121 legs treated by implantation of self-expanding nitinol stents were investigated after a mean follow-up time of 10.7 months. The mean length of the stented segment was 15.7 cm.. Overall, stent fractures were detected in 45 of 121 treated legs (37.2%). In a stent-based analysis, 64 of 261 stents (24.5%) showed fractures, which were classified as minor (single strut fracture) in 31 cases (48.4%), moderate (fracture of >1 strut) in 17 cases (26.6%), and severe (complete separation of stent segments) in 16 cases (25.0%). Fracture rates were 13.2% for stented length < or =8 cm, 42.4% for stented length >8 to 16 cm, and 52.0% for stented length >16 cm. In 21 cases (32.8%) there was a restenosis of >50% diameter reduction at the site of stent fracture. In 22 cases (34.4%) with stent fracture there was a total stent reocclusion. According to Kaplan-Meier estimates, the primary patency rate at 12 months was significantly lower for patients with stent fractures (41.1% vs. 84.3%, p < 0.0001).. There is a considerable risk of stent fractures after long segment femoral artery stenting, which is associated with a higher in-stent restenosis and reocclusion rate.

Topics: Alloys; Arterial Occlusive Diseases; Equipment Failure; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Popliteal Artery; Radiography; Severity of Illness Index; Stents; Vascular Patency

To identify a new angiographic parameter associated with poor short- and long-term outcomes with nitinol stenting in the larger infrainguinal arteries.. Nitinol stents have proven to be useful and safe, but imperfect, tools for treating claudication and limb-threatening ischemia. Primary and secondary patency in superficial femoral artery (SFA) occlusions treated with nitinol stents are up to 80% at 1 year, but restenosis is between 40-50% at 2 years. The causes of SFA and popliteal restenosis remain unclear. Stent fracture has been implicated in some cases of restenosis, but this is clearly the minority. Chronic mechanical trauma to the arteries caused by native vessel-stent interaction, intensified by limb motion over time, appears to be a more plausible explanation.. Presented here are 2 cases of restenosis apparently caused by acute and chronic trauma to the native vessel from interaction of the artery with the ends of relatively rigid nitinol stent systems.. The source of some future restenotic and occlusive events are not apparent using routine angiography techniques.. The additional step of an on-table leg bend test at 80-90 degrees will allow the interventionalist to visualize many cases of negative interaction between the native artery and the stents that will occur during routine movement. This allows the operator to potentially avoid stent-induced arterial trauma.

Topics: Aged; Alloys; Angiography, Digital Subtraction; Arterial Occlusive Diseases; Blood Vessel Prosthesis Implantation; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Popliteal Artery; Prosthesis Failure; Stents; Time Factors; Ultrasonography, Interventional

Decades of successful surgical revascularization of coronary artery disease have led to a growing population with saphenous vein graft disease. However, the treatment of degenerated saphenous vein graft still remains controversial. We report a novel but successful use of a peripheral, self-expanding nitinol stent in adjunct to excimer laser coronary atherectomy (ELCA) in the treatment of symptomatic, degenerated saphenous vein graft disease. The procedure was tolerated well without any short- or long-term complications. The case report is followed by a review of the literature on the treatment of vein graft disease.

Topics: Aged; Alloys; Angioplasty, Laser; Atherectomy, Coronary; Combined Modality Therapy; Graft Occlusion, Vascular; Humans; Male; Stents

Reducing the negative side effects associated with extracorporeal circulation is the major advantage of off-pump revascularization. However, side clamping of a calcified aorta for proximal anastomoses can cause emboli, resulting in neurologic damage. This problem has been addressed by introducing a mechanical anastomosis device (Symmetry, St Jude Medical) that allows vein-to-aorta anastomosis without manipulating the aorta. This report describes our experience with this device.. Between June 2001 and April 2002, 77 connectors (1.3 per patient) were deployed in 61 patients (51 men and 10 women; mean age, 68 +/- 8.6 years) undergoing off-pump coronary artery bypass grafting or beating-heart revascularization. Intraoperative quality assessment included transit-time flow measurement (Medistim) and indocyanine green-based angiography (Spy, Novadaq).. The surgeons were meticulously trained in loading of the device. No postoperative neurologic deficits were detected. Fifty-three patients had an uneventful course. However, 8 (13.1%) patients with 12 implanted connectors were symptomatic within 8 months (1 day to 8 months). Angiography revealed significant (95%) stenosis or even occlusion of the proximal vein-to-aorta anastomosis at the level of all connectors. Four patients underwent reoperation (2 dilated-stented and 2 treated with drugs).. On the basis of these observations, the routine use of the connector was halted at our institution. At the moment, the use of this therapy is reserved for patients with severely calcified aortas with no technical alternative. Further investigations appear necessary to evaluate the clinical patterns of this otherwise promising technology.

Topics: Aged; Alloys; Anastomosis, Surgical; Aorta; Aortic Diseases; Calcinosis; Coronary Angiography; Coronary Artery Bypass; Equipment Failure; Female; Graft Occlusion, Vascular; Humans; Male; Postoperative Complications; Veins

To evaluate imaging characteristics and artifacts of a nitinol stent with distal tantalum markers with computed tomography (CT) angiography and magnetic resonance (MR) angiography.. A vascular phantom was built to simulate in-stent restenosis. A nitinol stent with tantalum markers (Luminexx stent) was evaluated with CT angiography in different orientations relative to the z-axis and with MR angiography in different positions relative to both B0 and the readout gradient. Stenosis measurements were compared with conventional digital subtraction angiography for both modalities. In-stent signal intensity obtained with different flip angles was assessed in two nitinol stents with distal markers (Luminexx stent and SMART stent) and one without markers (Memotherm-FLEXX stent).. Stenosis detection was not possible with CT angiography when the stent was perpendicular to the z-axis because of streak-like artifacts induced by tantalum markers. Stenosis evaluation with multiplanar reformation was accurate when the stent was in parallel and oblique orientations relative to the table axis. With MR angiography, metallic artifacts were mostly related to the stent orientation with B0, whereas orientation of the readout gradient had little influence. The mean error (overestimation) for stenosis measurements varied between 0.1% and 7.4% for CT imaging in parallel and oblique positions and 3.6% and 9.5% for MR imaging. Higher flip angles did not improve signal intensity inside the three stents tested.. CT and MR angiography can be used for evaluating the patency of stents with distal markers that are parallel or oblique relative to the table axis (iliac, carotid, or femoral stents). MR angiography is preferred if the stent is perpendicular to the table axis (renal stent).

Topics: Alloys; Angiography, Digital Subtraction; Artifacts; Contrast Media; Graft Occlusion, Vascular; Image Processing, Computer-Assisted; Iothalamate Meglumine; Magnetic Resonance Angiography; Phantoms, Imaging; Stents; Tantalum; Tomography, X-Ray Computed

To evaluate, in a propensity score-adjusted analysis, the intermediate-term primary patency rates associated with nitinol versus stainless steel self-expanding stent placement for treatment of atherosclerotic lesions in femoropopliteal arteries.. The authors analyzed the clinical and imaging data of 175 consecutive patients with peripheral artery disease and either intermittent claudication (n = 150) or critical limb ischemia (n = 25) who underwent femoropopliteal artery implantation of nitinol (n = 104) or stainless steel (n = 123) stents in a nonrandomized setting. The stents were placed owing to either significant residual stenosis (ie, >30% lumen diameter reduction) or flow-limiting dissection after initial balloon angioplasty of the femoropopliteal artery. Patients were followed up for a median period of 9 months (mean, 13 months; range, 6-66 months) for the detection of a first in-stent restenosis, defined as a greater than 50% lumen diameter reduction that was seen at color-coded duplex ultrasonography and confirmed at angiography.. Cumulative patency rates at 6, 12, and 24 months were 85%, 75%, and 69%, respectively, after nitinol stent placement versus 78%, 54%, and 34%, respectively, after stainless steel stent placement (P =.008, log-rank test). There were no statistically significant differences in associated patency among the three different nitinol stents used (P =.72, log-rank test). Multivariate Cox proportional hazard analysis, in which the effect of propensity to receive a nitinol stent was considered, revealed a significantly reduced risk of restenosis with the nitinol stents compared with the risk of restenosis with the stainless steel stents (adjusted hazard ratio, 0.44; 95% confidence interval: 0.22, 0.85; P =.014).. Nitinol stents are associated with significantly improved primary patency rates in femoropopliteal arteries compared with stainless steel stents. Randomized controlled trials are needed to confirm these results.

Topics: Aged; Alloys; Arterial Occlusive Diseases; Arteriosclerosis; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Ischemia; Leg; Male; Middle Aged; Popliteal Artery; Prosthesis Design; Prosthesis Failure; Retrospective Studies; Stainless Steel; Stents; Ultrasonography, Doppler, Color; Vascular Patency

Angioplasty and stenting are becoming increasingly accepted techniques for the treatment of carotid stenosis. However, the optimal stent for carotid intervention is not known.. We compared the short- and intermediate-term results of carotid stenting using either nitinol or stainless-steel self-expanding stents in 178 high surgical risk patients undergoing carotid stenting at our institution. Of these 178 patients, eighty-nine received stainless-steel stents and 89 received nitinol stents. The groups were similar with respect to age, gender, diabetes, hypertension, left ventricular function, and symptom status. There were more patients with contralateral carotid occlusion in the nitinol stent group. Independent neurological evaluation was performed in all patients pre- and post-carotid stenting.. At 6 months, there was a similar incidence of stroke (3.3% versus 2.2%) in the stainless-steel group and nitinol stent group, respectively. There was higher 6-month mortality noted in the stainless-steel stent group, but there were no neurological deaths in either group.. In a single-center patient cohort with similar baseline characteristics, patients receiving nitinol stents and stainless-steel stents had similar neurological outcomes.

Topics: Aged; Aged, 80 and over; Alloys; Carotid Artery, Common; Carotid Artery, External; Carotid Stenosis; Equipment Safety; Female; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Incidence; Male; Middle Aged; Ohio; Postoperative Complications; Radiography; Stents; Stroke; Survival Analysis; Time Factors; Treatment Outcome

Topics: Alloys; Carotid Artery, Common; Carotid Artery, External; Carotid Stenosis; Equipment Safety; Graft Occlusion, Vascular; Humans; Postoperative Complications; Stents; Stroke; Treatment Outcome

Percutaneous peripheral interventional procedures as well as coronary interventions can be complicated by dissections and traumatic lesions of peripheral arteries. The aim of this study was to evaluate the efficacy of fabric covered endoprostheses for percutaneous repair of traumatic peripheral arterial lesions.. In this study we used the EndoPro 1/Passager device (Boston Scientific, USA), which is a self-expanding nitinol stent covered by an ultrathin layer of dacron fabric. In 27 patients a total number of 31 endoprostheses (mean length 7.3 cm) were implanted in iliac (n = 20), femoral (n = 6) and popliteal arteries (n = 1). Indications for stenting were large dissections (n = 24), arterial perforations (n = 2) and one traumatic arterio-venous fistula.. An immediate exclusion of the lesion could be achieved in all cases. There were no major procedural complications. However, within 24 hours after implantation 14 patients (51.9%) developed fever. WBC and CRP were elevated in 13 (48.1%) and 17 (63%) patients, respectively. Repeated blood cultures could not show any bacterial growth. The primary patency after a mean follow-up of 19 (5 to 31) months was 85.2%. In two cases with markedly impaired peripheral run-off subacute graft occlusions occurred. In 2 other cases the angiography revealed relevant restenoses (> 75%). The patency could be restored in 2 of these 4 cases leading to a secondary patency rate of 92.6%.. The EndoPro 1/Passager endoprosthesis seems to be safe and effective to seal large dissections and traumatic lesions of peripheral arteries, showing a high long-term patency rate.

Topics: Adult; Aged; Alloys; Angiography; Angioplasty, Balloon; Aortic Dissection; Coated Materials, Biocompatible; Equipment Failure Analysis; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Iliac Artery; Male; Middle Aged; Polyethylene Terephthalates; Popliteal Artery; Retreatment; Stents; Systemic Inflammatory Response Syndrome

To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion.. The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis.. Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers.. Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.

Topics: Aged; Aged, 80 and over; Alloys; Aortic Aneurysm, Abdominal; Biocompatible Materials; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Electron Spin Resonance Spectroscopy; Female; Graft Occlusion, Vascular; Humans; Male; Polyesters; Prosthesis Failure; Radiography; Stents

To develop a novel endovascular thrombosis model in the porcine iliac artery for the evaluation of thrombolysis and angioplasty.. A stent-inversion-graft (SIG) model combining either a 3-mm or 5-mm tapered expandable polytetrafluoroethylene (ePTFE) graft attached within a self-expandable, 10-mm nitinol stent was placed in the left common iliac artery via an ipsilateral common femoral artery approach in 24 pigs. When the iliac artery was thrombosed, urokinase (250,000 IU) plus heparin (1,000 units) were pulse sprayed via a contralateral femoral approach (n = 12). Saline pulse-spray was used as a control group (n = 12). Balloon angioplasty was performed to eliminate the stenotic tapered graft within the stent after successful thrombolysis. The efficacy of the thrombolysis was assessed with use of intravascular ultrasound (IVUS) and arteriogram.. Both the 3-mm tapered and 5-mm tapered SIG models caused iliac artery occlusion in 22 +/- 5 and 41 +/- 9 minutes, respectively, after the deployment. Luminal patency was re-established successfully in all occluded arteries after urokinase infusion. Angioplasty was successful in eliminating the tapered stenosis and restoring the normal diameter in all iliac arteries treated with urokinase. Complete thrombolysis was achieved in both models treated with urokinase.. This novel endovascular approach of inducing arterial thrombosis is simple to perform and reliably produces arterial thrombosis. The intraluminal stenosis is also amenable to angioplasty. This model is useful for the evaluation of antithrombotic treatment modality and adjunctive endovascular interventions.

Topics: Alloys; Angiography; Angioplasty, Balloon; Animals; Anticoagulants; Biocompatible Materials; Blood Vessel Prosthesis; Disease Models, Animal; Graft Occlusion, Vascular; Heparin; Iliac Artery; Injections, Intra-Arterial; Plasminogen Activators; Polytetrafluoroethylene; Prosthesis Failure; Swine; Thrombolytic Therapy; Thrombosis; Ultrasonography, Interventional; Urokinase-Type Plasminogen Activator

To assess whether the use of a prosthesis covered by a Dacron sheath might prevent pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt (TIPS).. A TIPS procedure was performed in nine pigs, after creation of a portal vein microembolization model of portal hypertension, by using a Dacron-covered nitinol stent. The first centimeter on the lower extremity of this specially made prototype was uncovered, to avoid portal vein thrombosis. Three weeks later, the seven surviving animals underwent transjugular hemodynamic and angiographic follow-up and were then killed for gross and histologic evaluation.. Shunt insertion was possible in all pigs; two died of complications of the procedure. After 3 weeks only two shunts were patent, although a 50%-60% narrowing of the initial portion of the shunt was present; the remaining shunts were occluded. Histologic examination showed pseudointimal hyperplasia associated, in the cases of occlusion, with a luminal thrombosis.. This Dacron-covered stent did not prevent pseudointima formation over the stent and resulted in a high early occlusion rate, probably related to a pronounced tissue fibrotic response likely due to Dacron-induced inflammation.

Topics: Alloys; Angiography; Animals; Disease Models, Animal; Embolism; Equipment Design; Fibrosis; Follow-Up Studies; Graft Occlusion, Vascular; Hemodynamics; Hepatic Artery; Hyperplasia; Hypertension, Portal; Polyethylene Terephthalates; Portal Vein; Portasystemic Shunt, Transjugular Intrahepatic; Stents; Surface Properties; Survival Rate; Swine; Thrombosis; Tunica Intima; Vascular Patency

The authors assess a new ePTFE-nitinol stent for its long-term patency, healing, and properties of endothelialization.. Adult greyhounds (n = 18) underwent bilateral iliofemoral placement of an endoprosthesis (Hemobahn) consisting of a nitinol stent lined with an ultrathin expanded polytetrafluoroethylene (ePTFE) material. Histologic and quantitative morphometric analyses were performed on devices explanted at 2 weeks and 1, 3, 6, and 12 months. The source of endothelialization was examined in four additional devices modified by sealing either the proximal and distal ends or the entire graft with poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), a nonporous laminate to prevent potential transgraft endothelial cell migration.. Device patency assessed with both intravascular ultrasound and histologic study showed minimal arterial stenosis, irrespective of implant duration. The neointima at less than 3 months consisted of fibrin and inflammatory infiltrate; at later time points, it was composed of mostly smooth muscle cells. Flow surfaces were more than 75% endothelialized by 3 months, which was nearly complete by 6 months. Modified endoprostheses entirely enveloped with FEP resulted in endothelialization of only the proximal and distal ends; the middle regions showed nonocclusive thrombi. Conversely, devices wrapped proximally and distally showed nearly complete endothelialization.. This ePTFE-nitinol endoprosthesis demonstrated long-term patency at up to 1 year after implantation and showed early and nearly complete endothelialization by 6 months. The design promoted rapid endothelialization of flow surfaces, particularly in the midregion of the device possibly by transgraft migration.

Topics: Alloys; Animals; Blood Vessel Prosthesis; Cell Movement; Dogs; Endothelium, Vascular; Female; Femoral Artery; Fibrin; Follow-Up Studies; Graft Occlusion, Vascular; Hemorheology; Iliac Artery; Image Processing, Computer-Assisted; Male; Microscopy, Electron, Scanning; Muscle, Smooth, Vascular; Polytetrafluoroethylene; Prosthesis Design; Stents; Surface Properties; Tunica Intima; Ultrasonography, Interventional; Vascular Patency; Wound Healing

Our objective was to compare intravascular sonography with digital subtraction angiography (DSA) in the assessment of luminal dimension and morphologic features of endovascular stents and stent grafts.. Thirty-seven pelvic and 24 femoral stents (12 Wall-stents; 27 covered and 22 uncovered nitinol stents) in 50 patients were evaluated 15 +/- 10 months after implantation by DSA and intravascular sonography. The degree of maximum instent restenosis as revealed by DSA and intravascular sonography was compared for each location. Morphologic features of the stents and stenoses were also assessed.. Intravascular sonography and DSA correlated well (R2 = .96) in determining in-stent restenosis. In-stent restenosis was underestimated by 13% +/- 6% by DSA compared with intravascular sonography. Differences in determining in-stent restenosis with intravascular sonography and DSA were not associated with severity of stenosis or type of stent. Intravascular sonography revealed incomplete expansion of stents in 21 cases, whereas DSA revealed incomplete expansion of stents in seven cases. The intra- and interobserver variabilities in our study were 4% and 5%, respectively.. In-stent restenoses are underestimated with DSA. Intravascular sonography is superior to DSA for detection of incomplete stent expansion.

Topics: Alloys; Angiography, Digital Subtraction; Ankle; Arterial Occlusive Diseases; Arteriosclerosis; Blood Pressure; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Brachial Artery; Evaluation Studies as Topic; Female; Femoral Artery; Graft Occlusion, Vascular; Humans; Intermittent Claudication; Male; Middle Aged; Observer Variation; Pelvis; Peripheral Vascular Diseases; Prosthesis Design; Recurrence; Regression Analysis; Sensitivity and Specificity; Stents; Surface Properties; Ultrasonography, Interventional

To determine the rate of complications of transluminally placed endovascular stent-grafts in patients with abdominal aortic aneurysms and to assess efficacy of secondary radiologic intervention.. In 28 patients, covered nitinol stents were implanted. Frequency and outcome of complications were evaluated after stent-graft placement (mean follow-up, 8.2 months).. In 27 patients, 11 tube and 16 bifurcated grafts were implanted successfully. In one (4%) patient, distal migration of a bifurcated graft necessitated conversion to standard open repair. Technical success rates (successful deployment of the device and complete exclusion of the aneurysm at intraoperative angiography) for bifurcated and tube grafts were 24% (four of 17 patients) and 91% (10 of 11 patients). After surgery, leaks were seen in six bifurcated and five tube grafts. After secondary intervention, the final exclusion rate for bifurcated and tube grafts was 88% (15 of 17 patients) and 100% (11 of 11 patients), respectively; the overall success rate was 93% (26 of 28 patients) for exclusion of aortic abdominal aneurysms. Stent-graft thrombosis necessitated local thrombolysis in one patient. Overlapping of accessory renal arteries occurred in two patients.. Complications after stent-graft placement in abdominal aortic aneurysms are frequent. Secondary radiologic intervention is successful in most cases.

Topics: Aged; Aged, 80 and over; Alloys; Aortic Aneurysm, Abdominal; Blood Vessel Prosthesis; Female; Femoral Artery; Follow-Up Studies; Graft Occlusion, Vascular; Humans; Male; Middle Aged; Radiography, Interventional; Reoperation; Treatment Outcome; Vascular Patency

The study evaluated the deployment and healing of a novel self-expanding modular bifurcation endovascular prosthesis in a canine abdominal aortic aneurysm model. The endoluminal prosthesis consists of self-expanding nitinol stents lined by a synthetic prosthesis. One component of the device is a bifurcated body with a 12- to 14-mm diameter aortic segment and an integral 7- to 8-mm diameter iliac limb. The bifurcated body also has a stent-reinforced opening (pant-leg) for subsequent insertion of a contralateral 7- to 8-mm diameter iliac limb component.. Seventeen bifurcated prosthesis were placed; 7 were inserted through the left common carotid artery and 10 from the femoral arteries. With either route of access the 16F or 17F aortoiliac limb and the 13F iliac limb delivery catheters enabled easy passage and secure positioning of the bifurcated prostheses. Predeployment and postdeployment inspection of the dimensions and continuity of the aortoiliac prosthetic components were evaluated by cinefluoroscopy and intravascular ultrasonography (IVUS).. After deployment was done, interval patency was assessed with angiography, IVUS, and contrast-enhanced computed tomography with the prostheses removed for analysis at 1 week (n = 4), 1 month (n = 3), 3 months (n = 4), and 6 months (n = 6). Five of the first seven implanted prostheses had occlusion of segments of the device. In two dogs the bifurcated body and both legs were occluded. In the other three the nonoccluded leg and bifurcation body were fully patent. In the first seven animals IVUS at implantation showed compression of an iliac leg by the orifice of the contralateral iliac component. After concentric fixation of the flow divider was performed, only one additional iliac limb occlusion occurred in the next 10 animals. Cinefluoroscopy, computed tomography, IVUS imaging, and histologic analysis of retrieved specimens demonstrated healing of the aortoiliac prostheses without evidence of perigraft leaks.. This feasibility study demonstrates the ability to deploy and maintain acceptable patency of a self-expanding endoluminal, modular bifurcation prosthesis in a canine aortic model. Clinical evaluation of the device is planned for the near future.

Topics: Alloys; Animals; Aortic Aneurysm, Abdominal; Blood Vessel Prosthesis; Dogs; Feasibility Studies; Follow-Up Studies; Graft Occlusion, Vascular; Prosthesis Design; Stents; Time Factors; Vascular Patency

To test an expandable nitinol intraluminal stent for hoop strength, biocompatibility, corrosion resistance, and patency.. Forty-four stents were implanted in the iliac arteries of 22 sheep. Follow-up was performed with angiography and histologic examination for up to 6 months.. All but one stent remained widely patent during the follow-up period. Two stents in two sheep were placed incorrectly early in the study; these sheep were not followed up. Hoop strength was found to be superior to that of a similar, commercially available, self-expanding stent. Minimal corrosion was seen at 6 months, and the stent appears to be biocompatible. The stent has good radiopacity and deploys with minimal foreshortening.. The stent can be reliably and safely deployed in the vascular system. Clinical trials in humans are warranted.

Topics: Alloys; Angiography; Animals; Biocompatible Materials; Corrosion; Equipment Design; Graft Occlusion, Vascular; Iliac Artery; Sheep; Stents; Stress, Mechanical; Vascular Patency