nitinol and Acute-Disease

To report the real-world incidence and risk factors of stent thrombosis in the aortoiliac and femoropopliteal arteries in case of bare nitinol stent (BNS) or covered nitinol stent (CNS) placement from a single-centre retrospective audit.. Medical records of consecutive patients treated with peripheral stent placement for claudication or critical limb ischemia were audited for definite stent thrombosis defined as imaging confirmed stent thrombosis that presented as acute limb-threatening ischemia. Cases were stratified between aortoiliac and femoropopliteal anatomy. Cox regression analysis was employed to adjust for baseline clinical and procedural confounders and identify predictors of stent thrombosis and major limb loss.. 256 patients (n = 277 limbs) were analysed over a 5-year period (2009-2014) including 117 aortoiliac stents (34 CNS; 12.8 ± 5.0 cm and 83 BNS; 7.8 ± 4.0 cm) and 160 femoropopliteal ones (60 CNS; 21.1 ± 11.0 cm and 100 BNS; 17.5 ± 11.9 cm). Median follow-up was 1 year. Overall stent thrombosis rate was 6.1% (17/277) after a median of 43 days (range 2-192 days) and affected almost exclusively the femoropopliteal segment (12/60 in the CNS cohort vs. 4/100 in the BNS; p = 0.001). Annualized stent thrombosis rates (per 100 person-years) were 12.5% in case of CNS and 1.4% in case of BNS (HR 6.3, 95% CI 2.4-17.9; p = 0.0002). Corresponding major amputations rates were 8.7 and 2.5%, respectively (HR 4.5, 95% CI 2.7-27.9; p = 0.0006). On multivariable analysis, critical leg ischemia and CNS placement were the only predictors of stent thrombosis. Diabetes, critical leg ischemia, femoropopliteal anatomy, long stents and CNS were independent predictors of major amputations.. Placement of long femoropopliteal covered nitinol stents is associated with an increased incidence of acute stent thrombosis and ensuing major amputation. Risks are significantly lower in the aortoiliac vessels and with use of bare nitinol stents.

Topics: Acute Disease; Aged; Alloys; Amputation, Surgical; Aorta; Causality; Comorbidity; Constriction, Pathologic; Extremities; Female; Femoral Artery; Follow-Up Studies; Humans; Incidence; Intermittent Claudication; Ischemia; Male; Peripheral Arterial Disease; Popliteal Artery; Prosthesis Design; Prosthesis Failure; Retrospective Studies; Risk Factors; Stents; Thrombosis; Time Factors; Treatment Outcome; Vascular Patency

Placement of a single new-generation nitinol stent resulted in acute pericardial tamponade in a 70-year-old man with superior vena cava syndrome.

Topics: Acute Disease; Aged; Alloys; Angioplasty, Balloon; Carcinoma, Squamous Cell; Cardiac Tamponade; Electrocardiography; Hemodynamics; Humans; Lung Neoplasms; Male; Pericardiocentesis; Phlebography; Prosthesis Design; Stents; Superior Vena Cava Syndrome; Tomography, X-Ray Computed; Treatment Outcome

The authors report the case of a patient with acute lower limb ischemia (category IIa) after occlusion of the popliteal artery due to fracture of a long indwelling stent. The patient refused surgical therapy for religious reasons, and an interventional revascularization was performed as acute rescue therapy. After reentry into the distal popliteal artery was achieved, the artery was dilated, and the fragmented stent was crushed, followed by implantation of two helical nitinol stents with high radial force and a third self-expandable nitinol stent. Sufficient primary technical success was achieved, and stent patency was present at midterm follow-up.

Topics: Acute Disease; Alloys; Angiography, Digital Subtraction; Angioplasty, Balloon; Arterial Occlusive Diseases; Constriction, Pathologic; Humans; Ischemia; Lower Extremity; Magnetic Resonance Angiography; Male; Middle Aged; Peripheral Arterial Disease; Popliteal Artery; Prosthesis Design; Prosthesis Failure; Stents; Treatment Outcome; Ultrasonography, Doppler, Color; Vascular Patency

A prototype endovascular electromechanical clot-extraction device was fabricated using a combination of shape memory polymer and shape memory nickel-titanium alloy (nitinol). Five embolic vascular occlusions were created in 4 rabbits by injecting thermally coagulated blood through a 4F catheter in the common carotid artery. Angiography immediately after clot injection showed complete or partial occlusion of the common carotid artery. Posttreatment angiography showed complete (2/5), partial (2/5), or no (1/5) restoration of blood flow.

Topics: Acute Disease; Alloys; Animals; Cerebral Angiography; Disease Models, Animal; Embolectomy; Equipment Design; Intracranial Embolism; Polymers; Rabbits

This registry aims at evaluating the use and efficacy of the EndoFit stent graft (LeMaitre Vascular, Burlington MA, USA) for the treatment of acute and chronic aortic type B dissections.. Indications for treatment are: recurrent pain, persistent hypertension, serious organ malperfusion in patients with acute or subacute type B aortic dissection and progression of aneurysm size despite maximal medical therapy in patient with chronic type B dissection. Exclusion criteria are: age under 18 years old, pregnancy, coagulopathy or bleeding disorders, connective tissue disease. Straight or tapered EndoFit stent graft will be used in acute or chronical dissection respectively.. The primary endpoint is the assessment of the safety and the efficacy of the EndoFit Thoracic Endoluminal Stent Graft in the exclusion of the thoracic aortic false lumen in acute and chronic type B aortic dissections. The assessment includes: technical success, thrombosis of the thoracic false lumen at 6 months, rate of aorto-enteric, aorto-esophageal and aorto-bronchial fistula, serious adverse events including death, stroke, paraplegia, myocardial infarction, multi-organ failure and renal insufficiency. Secondary endpoints are: the technical feasibility of device implantation in 2 different shapes (straight for acute dissection and tapered for chronic dissection), the technical feasibility of endovascular placement of tapered grafts in vessels of different size and shape, the integrity of the device fabric and wire structure, the occurrence of device migration, the patient's neurological, cardiac and cardiovascular status, the blood flow supply to abdominal and visceral organs arteries and any secondary intervention including stentgraft extension, coiling or surgical conversion. One hundred patients enrolled have been defined to allow reliable findings and results.. The DEDICATED is the first prospective data collection registry focusing on the role of tapered stentgrafts in chronic aortic dissection and their efficacy in excluding the dissected thoracic false lumen.

Topics: Acute Disease; Alloys; Aortic Aneurysm, Thoracic; Aortic Dissection; Blood Vessel Prosthesis; Chronic Disease; Disease Progression; Europe; Humans; Pilot Projects; Polytetrafluoroethylene; Prospective Studies; Prosthesis Design; Registries; Safety; Stents; Treatment Outcome

The aim of the paper was to investigate the performance of the ABSOLUTE .035 Peripheral Self-Expanding Stent System in preventing restenosis of superficial femoral or proximal popliteal arteries. Due to a lack of large controlled trials proving its long-term durability femoropopliteal artery stenting is still a matter of debate. In this paper we report the study design, the acute and short-term results of a prospective European registry on the treatment of TASC B and C femoropopliteal lesions with the use of the ABSOLUTE stent.. This prospective, non-randomized, multi-centre study enrolled 122 patients with symptomatic peripheral occlusive disease at 14 sites in Europe. Patients were included with obstructed femoropopliteal arteries. Key inclusion criteria were de novo lesions > or = 4.0 mm and < or = 7.0 mm in diameter, and > or = 40 mm and < or = 200 mm in length. Single target vessel treatment had to be performed with a maximum of three stents.. Mean target lesion length was 108 +/- 44 mm (range 22.2 to 200 mm) and mean reference vessel diameter 4.6 +/- 0.8 mm by quantitative angiography; 71% of the lesions analyzable by quantitative angiography (QA) had total occlusions. A total of 227 stents were implanted, 224 of which were deployed successfully (98.7%). Mean percentage of diameter stenosis was reduced from 90.9 +/- 15.5 % (range 41.3 to 100) to 19.0 +/- 8.4% (range 2.3 to 41.5). Device and procedural success were 83.6% each whereas technical success reached 100%. Sixteen lesions had a > or = 30% residual stenosis post-procedure, 6 of them (37.5%) rated as being calcified. Eleven patients experienced major complications (9.1%) and 6 patients experienced minor complications (5%) within 30 days. Duplex ultrasound based 1-month restenosis rate was 9.3%. Target lesion revascularization (TLR) and target vessel revascularization (TVR) rates were 0.8% and 1.7%, respectively and amputation rate was 0.8%. Mean ankle-brachial index (ABI) at rest and after exercise increased significantly from baseline to 30 days follow-up by 0.63 +/- 0.20 to 0.94 +/- 0.17 and from 0.44 +/- 0.23 to 0.85 +/- 0.21, respectively (P<0.001 each).. The treatment of TASC B and C femoro-popliteal lesions with use of the ABSOLUTE stent is safe and feasible. Short-term follow-up documents persistent improvement of hemodynamics. The 6- and 12-month data have to be awaited for further conclusions:

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Alloys; Angiography; Arterial Occlusive Diseases; Confidence Intervals; Europe; Female; Femoral Artery; Humans; Male; Middle Aged; Popliteal Artery; Postoperative Complications; Prospective Studies; Prosthesis Design; Stents; Treatment Outcome

Our objectives were to quantify the thrombogenicity and extent of vascular injury created by slotted-tube geometry stainless steel and nitinol coronary stents in a rabbit carotid artery model.. Stents were implanted in rabbit right carotid arteries without antiplatelet therapy. Stainless steel stents were implanted for 4 days while nitinol stents were placed for 4 and 14 days (n = 8, 8, and 6, respectively). Stent thrombosis was assessed by thrombus weight, grading thrombus encroachment of the lumen, and by blood flow in the stented and contralateral arteries. Stainless steel stents at 4 days contained more thrombus than 4- and 14-day nitinol stents (20.0 +/- 5.9 versus 2.5 +/- 0.6 and 2.7 +/- 0.3 mg, respectively; P < .000001). Stainless steel stents were more often occluded by thrombus (6 of 8) or contained more subocclusive thrombus (2 of 8) than nitinol stents (0 of 14, P < .002). Resting blood flow was reduced in arteries with stainless steel stents compared with 4- and 14-day nitinol stents (1.5 +/- 2.8 versus 24.0 +/- 2.0 and 25.5 +/- 1.9 mL/min, respectively, P < .000001). Stainless steel stents were less uniformly expanded, had deeper strut penetration into the vascular wall, and were associated with more extensive medial smooth muscle cell necrosis. There were strong correlations (r = .77 to .95) between variables of thrombosis extent (thrombus weight and grade) and histologically determined vascular injury (strut penetration and medial necrosis).. Slotted-tube stainless steel stents were more thrombogenic and created more extensive vascular injury than nitinol stents in a rabbit carotid artery model. The mechanisms underlying these differences probably are related to metallurgic and design geometry properties of the two stent types.

Topics: Acute Disease; Alloys; Animals; Carotid Arteries; Carotid Artery Injuries; Carotid Artery Thrombosis; Equipment Design; Male; Microscopy, Electron, Scanning; Necrosis; Rabbits; Stainless Steel; Stents; Tunica Media; Wounds and Injuries

This study was designed to evaluate the potential obliteration of an experimental aortic dissection using an intravascular stent introduced via the femoral artery. Twenty-two adult dogs were divided into four groups: in group A (n = 6) a thoracoabdominal aortic dissection was surgically created to observe the natural course of this lesion; in group B (n = 6) a nitinol coil graft was introduced into the aorta via the femoral artery; in group C (n = 3) a nitinol coil graft was introduced via the femoral artery into a dissected aorta in an attempt to obliterate the dissection; and in group D (n = 7) an expandable intraluminal vascular graft (Palmaz stent) was introduced via the femoral artery into a dissected aorta in an attempt to obliterate the dissection. Arteriographic evaluation was performed postoperatively and again 6 weeks later before the aortas were explanted. Gross and light microscopic examinations were performed on all explanted aortas. In group A dissection was achieved and a postoperative aortogram demonstrated evidence of aortic dissection in all animals. Autopsy revealed persistence of dissection with a reentry tear near the celiac axis in five animals. In group B there was incomplete expansion of the nitinol coil graft in five dogs, resulting in aortic thrombosis in one. In group C the nitinol coil graft failed to obliterate the aortic dissection in all animals and resulted in aortic thrombosis in two. In group D placement of a balloon-expandable intraluminal stent solely at entry and reentry sites resulted in only partial obliteration of the dissection (n = 3), but when the entire length of the dissected aorta was treated, the dissection was completely obliterated (n = 3).

Topics: Acute Disease; Alloys; Animals; Aortic Aneurysm, Abdominal; Aortic Aneurysm, Thoracic; Aortic Dissection; Blood Vessel Prosthesis; Constriction; Dogs; Femoral Artery; Materials Testing; Models, Biological; Polytetrafluoroethylene; Prosthesis Design; Radiography; Stents; Treatment Outcome; Tunica Intima