nitinol and Thromboembolism

Atrial fibrillation (AF) is a major cause of stroke and systemic embolism. Although warfarin and the novel oral anticoagulants reduce thromboembolic risk, they are associated with an ongoing bleeding hazard, in addition to other limitations that deter their use. The left atrial appendage (LAA) appears to be the primary source of thrombus in AF; therefore, LAA closure represents a mechanical strategy for stroke prevention in these patients. The WATCHMAN™ LAA closure device (Boston Scientific, Natick, MA) is a nitinol-framed occluder that is implanted percutaneously under echocardiographic and fluoroscopic guidance. Data from two randomized clinical trials support the clinical efficacy of transcatheter LAA occlusion with the WATCHMAN and demonstrate that procedural safety has improved significantly since initial experience. This article summarizes the rationale, procedural technique, safety, and clinical efficacy of the WATCHMAN device in patients with AF at high risk for thromboembolic events.

Topics: Alloys; Atrial Appendage; Atrial Fibrillation; Cardiac Catheterization; Echocardiography, Transesophageal; Equipment Design; Humans; Predictive Value of Tests; Radiography, Interventional; Stroke; Thromboembolism; Treatment Outcome

OBJECT WEB is an innovative intrasaccular treatment for intracranial aneurysms. Preliminary series have shown good safety and efficacy. The WEB Clinical Assessment of Intrasaccular Aneurysm Therapy (WEBCAST) trial is a prospective European trial evaluating the safety and efficacy of WEB in wide-neck bifurcation aneurysms. METHODS Patients with wide-neck bifurcation aneurysms for which WEB treatment was indicated were included in this multicentergood clinical practices study. Clinical data including adverse events and clinical status at 1 and 6 months were collected and independently analyzed by a medical monitor. Six-month follow-up digital subtraction angiography was also performed and independently analyzed by a core laboratory. Success was defined at 6 months as complete occlusion or stable neck remnant, no worsening in angiographic appearance from postprocedure, and no retreatment performed or planned. RESULTS Ten European neurointerventional centers enrolled 51 patients with 51 aneurysms. Treatment with WEB was achieved in 48 of 51 aneurysms (94.1%). Adjunctive implants (coils/stents) were used in 4 of 48 aneurysms (8.3%). Thromboembolic events were observed in 9 of 51 patients (17.6%), resulting in a permanent deficit (modified Rankin Scale [mRS] Score 1) in 1 patient (2.0%). Intraoperative rupture was not observed. Morbidity (mRS score > 2) and mortality were 2.0% (1 of 51 patients, related to rupture status on entry to study) and 0.0% at 1 month, respectively. Success was achieved at 6 months in 85.4% of patients treated with WEB: 23 of 41 patients (56.1%) had complete occlusion, 12 of 41 (29.3%) had a neck remnant, and 6 of 41 (14.6%) had an aneurysm remnant. CONCLUSIONS The WEBCAST study showed good procedural and short-term safety of aneurysm treatment with WEB and good 6-month anatomical results.

Topics: Adult; Aged; Alloys; Angiography, Digital Subtraction; Cause of Death; Combined Modality Therapy; Diffusion Chambers, Culture; Embolization, Therapeutic; Endovascular Procedures; Female; Follow-Up Studies; Humans; Intracranial Aneurysm; Male; Middle Aged; Outcome and Process Assessment, Health Care; Patient Safety; Platelet Aggregation Inhibitors; Postoperative Complications; Prospective Studies; Prostheses and Implants; Stents; Thromboembolism; Treatment Outcome

Thromboembolism due to atrial fibrillation (AF) is a frequent cause of stroke. More than 90% of thrombi in AF form in the left atrial appendage (LAA). Obliteration of the appendage may prevent embolic complications.. We evaluated the feasibility and safety of implanting a novel device for percutaneous left atrial appendage transcatheter occlusion (PLAATO). LAA occlusion using the PLAATO system was attempted in 15 patients with chronic AF at high risk for stroke, who are poor candidates for long-term warfarin therapy. The implant consists of a self-expanding nitinol cage covered with a polymeric membrane (ePTFE). The LAA was successfully occluded in 15/15 patients (100%). Angiography and transesophageal echocardiography (TEE) during the procedure showed that the device was well-seated in all patients and that there was no evidence of perforation, device embolization, or interference with surrounding structures. In 1 patient, the first procedure was complicated by a hemopericardium, which occurred during LAA access. A second attempt 30 days later was successful with no untoward sequela. No other complications occurred. At 1-month follow-up, chest fluoroscopy and TEE revealed continued stable implant position with smooth atrial-facing surface and no evidence of thrombus.. Thus, transcatheter closure of the LAA is feasible in humans. This novel implant technology may be appropriate for patients with AF who are not suitable candidates for anticoagulation therapy. Further trials are needed to show the long-term safety and its efficacy in reducing stroke.

Topics: Alloys; Atrial Appendage; Atrial Fibrillation; Cardiac Catheterization; Coronary Angiography; Feasibility Studies; Humans; Polytetrafluoroethylene; Prostheses and Implants; Skin; Stroke; Thromboembolism

It is difficult to treat a thrombotic embolism in the common femoral artery or popliteal artery (POP A), i.e., the non-stenting zone. We report a new technique for the treatment of thrombotic embolism in the non-stenting zone using a self-expandable nitinol stent. Case 1 had an external iliac artery (EIA) occlusion that occurred over several months. A self-expandable nitinol stent was placed in the right EIA lesion via a retrograde approach using a distal 9-Fr balloon protection guide catheter in the right femoral artery. A thrombotic embolism occurred at the balloon protection site. It was too big to be removed using an aspiration catheter; therefore, we attempted removal with a self-expandable stent. Using a crossover approach, we delivered a nitinol self-expandable stent to the distal site of the thrombus, opened the tip of the stent, and pulled it up to the proximal site. Finally, we "grabbed a clot," moved it to the stenting zone, and "held on" the vessel wall without occurrence of a distal embolism. We named this the "GACHON technique." Case 2 underwent endovascular therapy for an acute thrombotic embolism in POP A after thoracic endovascular aortic repair for dissection. This thrombus was too big to aspirate, and we successfully treated it using the "GACHON technique." The "GACHON technique" may be considered as a choice of treatment for a thrombotic embolism in the non-stenting zone. © 2016 Wiley Periodicals, Inc.

Topics: Aged; Aged, 80 and over; Alloys; Angiography; Angioplasty, Balloon; Humans; Iliac Artery; Male; Popliteal Artery; Prosthesis Design; Self Expandable Metallic Stents; Thrombectomy; Thromboembolism; Treatment Outcome; Ultrasonography, Interventional

In this study, a polymeric membrane has been designed and developed for carotid stents to prevent detachment of emboli from the arterial wall and subsequent stroke, while maintaining side-branch flow. Prototypes of different geometrical design parameters have been fabricated and their performance has been evaluated in vitro under physiological pulsatile flow condition in a life-size silicone anastomotic model of carotid artery bifurcation. These evaluations include both quantitative and qualitative experimental (in vitro) assessments of emboli prevention capability, side-branch flow preservation, and flow visualization. The covered stents with the novel membrane demonstrated significantly higher emboli prevention capability than the corresponding bare nitinol stent as well as some earlier related designs, while preserving more than 93% of the original flow of the external carotid artery (ECA). Flow in the ECA through these covered stents was uniform without evidence of undesirable flow recirculation or retrograde flow that might predispose the vessel wall to intimal thickening and atherosclerotic plaque formation. This study demonstrated the potential of these novel covered stent designs for the treatment of carotid atherosclerotic stenosis and prevention of late embolic stroke. However, further in vivo investigations of biological effects and mechanical performance of this covered stent design (e.g., its thrombogenicity potential and biocompatibility) are warranted.

Topics: Alloys; Blood Flow Velocity; Carotid Arteries; Carotid Stenosis; Coated Materials, Biocompatible; Humans; Membranes, Artificial; Models, Anatomic; Models, Cardiovascular; Polymers; Prosthesis Design; Pulsatile Flow; Stents; Stroke; Thromboembolism

Transcatheter aortic valve implantation is a widely performed procedure for treatment of symptomatic severe aortic stenosis. According to the current literature, major stroke has been reported as occurring in 3-6% of patients during the first 30 days following valve implantation. Several pathological mechanisms may be involved in the development of periprocedural ischaemic stroke with the majority being due to thromboembolism and atheroembolism. One approach to reduce the incidence of procedural cerebral thromboembolic events is the use of cerebral protection devices, either deflecting (Embrella, TriGuard) or capturing (Claret, Embol-X) embolic material. We decided to review the current evidence on this important issue focusing on the four cerebral protection devices currently available.

Topics: Alloys; Aortic Valve; Aortic Valve Stenosis; Cardiac Catheterization; Contraindications; Equipment and Supplies; Equipment Design; Heart Valve Prosthesis; Heart Valve Prosthesis Implantation; Humans; Incidence; Risk Factors; Stroke; Thromboembolism; Treatment Outcome

Atrial fibrillation is a very common heart arrhythmia, associated with a five-fold increase in the risk of embolic strokes. Treatment strategies encompass palliative drugs or surgical procedures all of which can restore sinus rhythm. Unfortunately, atria often fail to recover their mechanical function and patients therefore require lifelong anticoagulation therapy. A motorless volume displacing device (Atripump) based on artificial muscle technology, positioned on the external surface of atrium could avoid the need of oral anticoagulation and its haemorrhagic complications. An animal study was conducted in order to assess the haemodynamic effects that such a pump could provide.. Atripump is a dome-shape siliconecoated nitinol actuator sewn on the external surface of the atrium. It is driven by a pacemaker-like control unit. Five non-anticoagulated sheep were selected for this experiment. The right atrium was surgically exposed, the device sutured and connected. Haemodynamic parameters and intracardiac ultrasound (ICUS) data were recorded in each animal and under three conditions; baseline; atrial fibrillation (AF); atripump assisted AF (aaAF).. In two animals, after 20 min of AF, small thrombi appeared in the right atrial appendix and were washed out once the pump was turned on. Assistance also enhanced atrial ejection fraction. 31% baseline; 5% during AF; 20% under aaAF. Right atrial systolic surfaces (cm2) were; 5.2 +/- 0.3 baseline; 6.2 +/- 0.1 AF; 5.4 +/- 0.3 aaAF.. This compact and reliable pump seems to restore the atrial "kick" and prevents embolic events. It could avoid long-term anticoagulation therapy and open new hopes in the care of end-stage heart failure.

Topics: Alloys; Animals; Anticoagulants; Atrial Fibrillation; Atrial Function, Right; Equipment Design; Heart-Assist Devices; Materials Testing; Sheep; Stroke; Thromboembolism

In more than 90% of patients with atrial fibrillation (AF), stroke is due to thrombotic embolization from the left atrial appendage (LAA). Transcatheter occlusion with percutaneous left atrial appendage transcatheter occlusion (PLAATO), a self-expanding, membrane- covered spherical nitinol cage, is feasible and an alternative to anticoagulation therapy.. This was a single-center prospective registry study for verification of stroke risk reduction in patients with AF 2 years after PLAATO.. Seventy-three patients with AF (permanent 65, paroxysmal 8) in whom anticoagulation therapy was contraindicated or rejected underwent transcatheter LAA occlusion with PLAATO. One patient died periprocedurally due to implant embolization, and 1 patient underwent open-heart surgery because of implant instability. The remaining 71 patients were followed for 24 months. In 52 patients a stable anchoring of the PLAATO device without migration or dislocation was documented by transesophageal echocardiography (TEE). No thrombotic deposition was found on the LA luminal surface of the device. Statistically, in our patient cohort, 7 strokes would have been expected without any treatment within 24 months. In fact, no strokes were reported. Ten out of 71 patients died during follow up: 6 in our hospital and 4 at home. None of them died from a stroke.. Ninety-seven percent of AF patients were successfully treated with PLAATO. After mechanical LAA occlusion, the 2-year risk of stroke in AF patients is markedly reduced. Therefore, this therapeutic concept is a clear alternative for patients with AF and contraindications for oral anticoagulation.

Topics: Aged; Aged, 80 and over; Alloys; Angioplasty, Balloon; Anticoagulants; Atrial Fibrillation; Cardiac Catheterization; Contraindications; Female; Follow-Up Studies; Humans; Male; Middle Aged; Prospective Studies; Prostheses and Implants; Registries; Retrospective Studies; Risk Factors; Stroke; Thromboembolism; Treatment Outcome