nitinol and Arteriosclerosis

New devices for endovascular treatment of thoracic aortic diseases were recently approved for clinical use by European authorities, obtaining the Conformité Européenne (CE) mark. In all patients who underwent endovascular treatment of a thoracic aortic disease in 2002, we used a new CE-marked device, the Endofit stent graft. The device is constituted of nitinol stents and polytetrafluoroethylene fabric, and has a simple design and delivery system.. During 2002, 11 patients (mean age, 75 years; range, 66-85 years) underwent treatment of atherosclerotic aneurysm (n = 9), chronic type B dissection (n = 1), and intramural hematoma (n = 1). Disease involved the descending thoracic aorta in 7 patients and the distal aortic arch in 4 patients.. In all cases the Endofit stent grafts were successfully deployed in the intended position. No postoperative paraplegia or paraparesis was recorded. There were two in-hospital deaths: 1 patient died in the operating room (postmortem examination showed a kinked graft); and the other patient died in the intensive care unit on postoperative day 30, after an intraoperative stroke. One surgical conversion was performed 2 weeks after the procedure, because of total collapse of the graft due to rupture of three stents. Other graft-related complications included type I endoleak (n = 2), type II endoleak (n = 1), and incomplete opening of the device (n = 1).. Endovascular treatment of thoracic disease with the Endofit graft in this small heterogeneous group of patients resulted in several complications, which may arise from both the delivery system and the graft itself. At present, other commercially available endografts may be safer for endovascular treatment of thoracic aortic diseases.

Topics: Aged; Aged, 80 and over; Alloys; Aortic Aneurysm, Thoracic; Aortic Dissection; Arteriosclerosis; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Female; Humans; Male; Polytetrafluoroethylene; Prosthesis Design; Prosthesis Failure; Radiography; Stents

Nitinol monowire stents of original construction were implanted to 35 patients (aged from 36 to 84, mean 53.9) with atherosclerotic lesions of iliac arteries. Arterial stenosis ranged from 50% to 100% (mean 72.2%), ankle-brachial index (ABI) averaged 0.45+/-0.12. Initial success was achieved in 97.1% of procedures. Ultrasonography 3 days since the procedure showed the increase of ABI up to 0.78+/-0.16. Restenoses in the stented site was revealed during follow-up period (mean 24.3+/-18.3 months) in 3 patients (8.3%). In conclusion, new stent appeared to be effective tool for treatment of iliac atherosclerotic lesions. However long-term restenoses resulting from intimal hyperplasia can require repetitive revascularization.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Angiography; Arteriosclerosis; Atherectomy; Female; Humans; Iliac Artery; Male; Middle Aged; Stents

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

To describe a ruptured ulcer of the descending thoracic aorta treated with an endovascular stent-graft deployed under transesophageal echocardiographic (TEE) guidance.. An 82-year-old man with severe chronic obstructive pulmonary disease and congestive heart failure presented with sharp pain in the back radiating to the left flank. Computed tomography (CT) and angiography demonstrated a penetrating ulcer of the descending thoracic aorta associated with aortic dissection commencing 6 cm from the origin of the left subclavian artery with extravasation of contrast outside the aortic wall. The patient remained symptomatic with a decrease in hematocrit from 36% to 23%. Endovascular repair was performed using self-expanding nitinol stents sutured to a 35-mm x 12-cm Dacron conduit. The device was deployed with a 24-F delivery system under TEE guidance and fluoroscopy. Successful exclusion of the ruptured ulcer was demonstrated by TEE Doppler, arteriography, and CT. The patient remains asymptomatic 18 months after the procedure with no CT evidence of endoleak.. Endovascular stent-graft repair under TEE guidance assists in the oftentimes difficult treatment of ruptured penetrating thoracic aortic ulcer.

Topics: Aged; Aged, 80 and over; Alloys; Aorta, Thoracic; Aortic Rupture; Arteriosclerosis; Blood Vessel Prosthesis Implantation; Echocardiography, Transesophageal; Humans; Male; Polyethylene Terephthalates; Stents; Ulcer

Atherosclerotic ailments play a major role in industrial societies. Atherosclerotic disease causes stenotic narrowing of the arterial vessel system. These narrow passages can be widened with balloon angioplasty and stents are introduced to keep the passage open. In this study, stents designed for the aorto-iliac bifurcation are considered. Most of these stents used in peripheral arteries are self-expanding stents made from Nitinol, a thermo-reactive alloy. The insertion is done under radiographic control. However, the delicate metallic structure of the stent usually casts only a weak radiographic shadow and thus is difficult to detect. A stent with an innovative radio opaque tantalum marker (Luminexx, C.R. BARD--Angiomed, Karlsruhe), overcomes this problem. However, the markers extend into the blood flow and the question arises whether the markers may cause the generation of thrombi. In a model study in an enlarged model of the aorto-iliac bifurcation with an inserted stent the flow was visualized. The enlarged scale permits the observation and video recording of the flow in great detail. The Reynolds similarity is kept. A subsequent analysis of the flow in the vicinity of the markers shows a short residence time. These results indicate that the additional markers do not increase the risk of thrombus generation.

Topics: Alloys; Aorta; Arteriosclerosis; Blood Flow Velocity; Hemorheology; Humans; Iliac Artery; Image Processing, Computer-Assisted; Models, Biological; Models, Cardiovascular; Stents; Thrombosis

To evaluate the effectiveness of nitinol stents in patients with short, complex lesions in the superficial femoral and popliteal arteries and to assess midterm results.. Self-expandable nitinol stents were implanted in 54 extremities in 44 patients to treat complex stenoses (n = 32) and occlusions (n = 22) in the superficial femoral and popliteal arteries. Follow-up was performed for 5-51 months to evaluate early thrombosis and midterm patency rates. Midterm patency rates were compared between the following: stenoses and occlusions, proximal and distal locations, good and poor runoff, and diabetic patients and nondiabetic patients. All patients underwent clinical investigation and color Doppler sonography after 1 month and 6 months and at 6-month intervals thereafter. If restenosis or stent thrombosis was suspected, intraarterial digital subtraction angiography of the superficial and popliteal arteries was performed.. Percutaneous stent implantation was successful in all patients. The mean duration of follow-up was 27 months (range, 5-51 months). No thrombotic occlusion occurred within the first 4 weeks after stent implantation. The primary 3-year patency rate was 76%, and the secondary patency rate was 87%. Three-year primary patency rates were 65% for diabetic patients and 82% for nondiabetic patients.. In patients with short, complex stenoses and occlusions, implantation of nitinol stents may have a positive impact on midterm results.

Topics: Aged; Aged, 80 and over; Alloys; Angiography, Digital Subtraction; Arteriosclerosis; Female; Femoral Artery; Follow-Up Studies; Humans; Life Tables; Male; Middle Aged; Popliteal Artery; Stents; Treatment Outcome; Ultrasonography, Doppler, Color; Vascular Patency

To evaluate the short-term patency and healing characteristics of the Cragg EndoPro covered stent in an atherosclerotic model as one of the Food and Drug Administration requirements before possible approval of the device for human use in the United States.. Seventeen self-expanding stent-grafts were placed in the aorta and right and left iliac arteries of six Yucatan microswine exposed to a regimen of accelerated atherosclerosis. The stent-grafts were constructed from nitinol wire formed into a tubular zigzag configuration. The stent frame was covered by a thin woven polyester fabric tube, with medium permeability, available in multiple diameters and lengths. The animals were killed at 24 hours, 3 months, and 6 months. Assessment was done by angiography and histology.. All stents were patent immediately after deployment. Two stents were occluded at follow-up, indicating an 88% patency rate. Minor lumen narrowing was found at the follow-up intervals. Histologic examination revealed a mixture of mature and immature endothelial cells lining both the native and stented regions in all vessels examined. The new endoluminal surface was composed primarily of fibrocollagen and elastic fibers and smooth muscle cells. Intimal thickness was inversely correlated to medial thickness. Medial compression with atrophy was observed routinely with rare necrosis. Complete tissue ingrowth was seen by 3 months. The degree of vascular inflammation increased over time, as well as the foreign body giant cell reaction to the polyester fabric.. The patency rate does not appear to be better than that with angioplasty or noncovered stent placement in the studied time frame. The progressive vascular inflammatory changes noted should be further investigated in longer-term animal trials to ensure its safety in humans because this device is meant to be permanent.

Topics: Alloys; Animals; Arteriosclerosis; Disease Models, Animal; Female; Postoperative Complications; Stents; Swine

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

Metallic stents in small vessels go along with a significant risk of restenosis and reocclusion. Different models of stents and covering materials have been purported to prevent intraluminal neointimal proliferation by cover-based closure of the spaces in the wire mesh.. Tantalum stents covered with polyethylacrylate/polymethylmethacrylate (PEM) were implanted in the infrarenal aorta of six New Zealand white rabbits by aortotomy and compared with eight rabbits treated with uncovered tantalum stents. For deployment, covered and uncovered stents necessitated a 7-French (F) and 5-F sheath, respectively. In addition, nine human patients with arteriosclerotic lesions of the superficial femoral arteries (stenosis > 5 cm or total occlusion) were treated percutaneously with a Dacron-covered nitinol vascular stent via a 9-F sheath. Patients were followed for a mean of 13.5 months, and control angiography was performed after 6 months.. Experimental placement of the tantalum Wiktor stent was feasible technically in all cases. Five of six stents covered with PEM were occluded 3 days after placement despite the intravenous use of heparin and aspirin. In the group with uncovered stents, no area of stenosis greater than 10% was observed. There was a neointimal layer of 89 +/- 68 microns around the stent wires. Stent placement was successful in all patients. In four patients, a hyperergic reaction occurred, resulting in noninfectious periarteriitis. This complication was treated successfully with nonsteroidal antiinflammatory drugs. The primary patency was 50%, and the secondary patency (after application of a second covered stent in two patients) was 63%.. The uncovered stent induces little neointimal proliferation around the stent wires. The insertion of stents covered with PEM into the rabbit aorta was accompanied by a strong thrombotic reaction, despite sufficient anticoagulation. Dacron-covered nitinol stents showed a surprisingly high restenosis rate after 9 months of follow-up. Further research concerning the in vivo properties of new covering materials is mandatory before routine vascular clinical application.

Topics: Aged; Alloys; Animals; Aorta, Abdominal; Aortic Diseases; Arteriosclerosis; Biocompatible Materials; Constriction, Pathologic; Equipment Design; Female; Femoral Artery; Humans; Iliac Artery; Male; Polyethylene Terephthalates; Polymethacrylic Acids; Rabbits; Recurrence; Stents; Tantalum; Thrombosis

To study the effects of nitinol alloy stent in the treatment of atherosclerotic arterial stenosis, eight miniature pigs were subject to abdominal aortic balloon denudation and high-fatty food. Then 8 nitinol alloy stents were implanted into each abdominal aortas of pigs. The pigs were equally divided into two groups. One group was given captopril (3 mg/kg/d). All animals were sacrified for pathological examination 6 to 10 months after stent implantation. The degree of arterial intima proliferation in the areas of stent implantation not significantly different from that of areas of balloon denudation alone; the atherosclerotic lesions were found at the arterial surface of stent implantation sites. The intima layer was rich in smooth muscle cells, with atherosclerotic plaque formed around the stent wire. On the other hand, significant decrease in arterial intima proliferation was found in group II with no atherosclerotic plaque. The arterial stenosis resulting from atherosclerotic lesion could not be prevented by implantation of intravascular stent, and on the contrary, the mechanical stress of stent wire might worsen the atherosclerosis. Captopril might impede the development of atherosclerotic stenosis after stent implantation.

Topics: Alloys; Angiotensin-Converting Enzyme Inhibitors; Animals; Aorta, Abdominal; Aortic Valve Stenosis; Arteriosclerosis; Captopril; Stents; Swine; Swine, Miniature

To determine the effectiveness of a prototype nitinol stent in the iliac arteries.. Fourteen patients with arteriosclerotic lesions of the iliac arteries (nine stenoses, five occlusions) were treated percutaneously with a prototype nitinol vascular stent (Cragg stent) after unsuccessful percutaneous transluminal angioplasty.. In 13 patients available for follow-up, the mean ankle-brachial index (ABI) increased from 0.4 +/- 0.32 (standard deviation) before the procedure to 0.81 +/- 0.27 after the procedure (P < .01). After 6, 12, and 24 months, the mean ABI was 0.97 +/- 0.2, 0.87 +/- 0.15, and 0.89 +/- 0.1, respectively. In two patients, radial stiffness of the stent was too low to completely eliminate a high-grade, calcified stenosis; long-term patency of the vessel, however, was preserved. In all other patients, stent placement achieved good vascular reconstitution. No stent occlusion or restenosis was observed.. The results with the Cragg stent were similar to those with other commercially available stents. These preliminary results require confirmation with a larger series.

Topics: Aged; Alloys; Arteriosclerosis; Female; Humans; Iliac Artery; Male; Middle Aged; Radiography, Interventional; Recurrence; Stents; Vascular Patency

Topics: Alloys; Arteriosclerosis; Blood Vessel Prosthesis; Femoral Artery; Humans; Iliac Artery; Intraoperative Care; Laser Therapy; Male; Middle Aged; Radiography