nitinol and Atrial-Fibrillation

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

In patients with non-valvular atrial fibrillation, efficacy of stroke prevention with oral anticoagulant therapy has been proved. Despite their high risk for thromboembolic events, there are substantial numbers of patients who are not candidates for long-term oral anticoagulant therapy, therefore the interest in alternative treatment strategies are in focus these days. The most common place within the heart for thrombus formation in patients with non-valvular atrial fibrillation is the left atrial appendage. Two devices specifically designed for percutaneous left atrial appendage closure are currently available in Europe: the WATCHMAN LAA system (Atritech, Inc) and the AMPLATZER Cardiac Plug (AGA Medical Corporation). Although present trial results (PLAATO, PROTECT AF) suggest that LAA closure may be performed at acceptable safety and it may reduce the long-term stroke risk, available data are still very limited. At present these procedures may be an acceptable alternative in selected high-risk patients with non-valvular atrial fibrillation who are not or suboptimal candidates for oral anticoagulant therapy. On 28. January, 2010 we performed the first three successful percutaneous left atrial appendage closure procedures in Gottsegen György Hungarian Institute of Cardiology in Hungary.

Topics: Administration, Oral; Aged; Alloys; Anticoagulants; Atrial Appendage; Atrial Fibrillation; Cardiac Surgical Procedures; Clinical Trials as Topic; Contraindications; Echocardiography, Transesophageal; Female; Heart Diseases; Humans; Hungary; Male; Middle Aged; Prosthesis Design; Radiography; Risk Assessment; Risk Factors; Septal Occluder Device; Stents; Stroke; Thoracoscopy; Thrombosis; Treatment Outcome

The aim of this clinical trial was to assess safety, efficacy, and technical handling of a novel ceramic-coated double-disc patent foramen ovale (PFO) occluder.. Though percutaneous PFO closure is performed with increasing frequency worldwide, certain risks such as thrombus formation and incomplete endothelialization remain. The Spider™ PFO occluder was designed to minimize these risks.. The Spider™ PFO occluder is a self-expandable double-disc device with a ceramic coated nitinol wire mesh and an integrated expanded polytetrafluoroethylene (ePTFE) membrane on the right atrial side and ceramic coated nitinol anchors and ePTFE patch on the left atrial side. Study patient assessments were conducted at baseline, periprocedure, and discharge and at 1-, 6- and 12-month follow-up.. Fifty-one patients (mean age 52 ± 14 years; 63% male) were enrolled in the prospective, multicenter clinical trial. Implantation was successful in all patients. Mean procedural time was 30.0 ± 8.6 min. No periprocedural or in-hospital complications occurred. Four patients (8%) had paroxysmal atrial fibrillation (AF) at 1-month follow-up. Otherwise, no procedure or device related adverse events occurred. Importantly, there were no recurrent embolic events. At 1-month follow-up 63% (32/51) of patients had no residual shunt with contrast transesophageal echocardiography during Valsalva maneuver. Of all patients who underwent 6-month echo follow-up to date, 78% (39/50) had no residual shunt during Valsalva maneuver.. Initial results with the novel Spider™ PFO occluder show that the device is safe and easy to use for percutaneous closure of PFO. The overall complication rate was low. The rate of AF needs further investigation.

Topics: Adult; Aged; Alloys; Atrial Fibrillation; Cardiac Catheterization; Ceramics; Chi-Square Distribution; Coated Materials, Biocompatible; Echocardiography, Transesophageal; Female; Foramen Ovale, Patent; France; Germany; Hemodynamics; Humans; Male; Middle Aged; Polytetrafluoroethylene; Prospective Studies; Prosthesis Design; Septal Occluder Device; Time Factors; Treatment Outcome; Valsalva Maneuver

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

Pericardial effusion or pericardial tamponade (PE/PT) is a relatively common complication of left atrial appendage closure (LAAC). However, delayed PE/PT is rare with limited data. The aim of the study was to analyze the incidence and clinical consequences of delayed PE/PT following LAAC.. Patients with nonvalvular AF who were successfully implanted with LAAC devices from October 2014 to April 2021 were consecutively screened. Subjects experiencing delayed PE/PT after LAAC were included. All treatment sessions of the subjects were recorded in detail. After discharge, the patients were followed up for clinical outcomes.. A total of 748 patients with successful LAAC [nitinol cage device (475 Watchman 2.5), nitinol plug device (131 ACP and 142 LAmbre)] were screened. Six patients experienced delayed PE/PT (1 Watchman, 2 ACP, 3 LAmbre). The incidence of delayed PE/PT was higher in patients with a nitinol plug device (1.8% vs. 0.2%, P = 0.027). Bloody PE only occurred in patients with a nitinol plug device (5/273, 1.8%). All the patients accepted pericardiocentesis and discontinuing antithrombotic medication, and none of the patients died or needed cardiac surgery. All patients were followed up for 810 (598, 1174) days after discharge. None of them developed constrictive pericarditis or thromboembolic or major bleeding events.. Delayed PE/PT is rare but can occur, and the incidence of delayed bloody PE/PT for the nitinol plug device was higher than that for the nitinol cage device. The strategy of emergency pericardiocentesis combined with discontinuing antithrombotic medication may be effective for delayed bloody PE/PT.

Topics: Atrial Appendage; Atrial Fibrillation; Cardiac Surgical Procedures; Fibrinolytic Agents; Humans; Pericardial Effusion; Stroke; Treatment Outcome

Recurrence of atrial fibrillation after an ablation procedure remains a major problem which emphasizes the need for improved pulmonary vein isolation techniques.. The aim of this study was to describe an implantation procedure of a pulmonary vein-stent which may possibly serve as an ablation technique in the future and to examine stent safety in a follow-up study in pigs.. Eight pigs were catheterized and nine self-expanding nitinol stents were implanted through a transfemoral or transatrial approach into the antra of the pulmonary veins. After 3 months' follow-up, the animals were euthanized for further examination. During the follow-up phase, no complications were observed. Absence of thrombus formation or pulmonary vein wall dissection was noticed during anatomical and histological evaluation of the heart-lung packages. All implants were almost completely covered by neo-intima, of which thickness varied between 0.2 and 3.9 mm.. Stents can safely be positioned and deployed into the antra of the pulmonary veins without any acute or long-term (3 months) adverse effects. In the future, these implants could function as a permanently implanted ablation device and provide new therapeutic strategies for pulmonary vein isolation in patients with atrial fibrillation.

Topics: Ablation Techniques; Alloys; Animals; Atrial Fibrillation; Models, Animal; Pulmonary Veins; Recurrence; Stents; Swine

Pulmonary vein isolation (PVI) is a well-established method for the treatment of symptomatic paroxysmal atrial fibrillation, but is only partly successful with a high rate of electrical reconnection. We introduce a novel technique in which PVI is accomplished by noninvasive heating of a dedicated thermoresponse implant inserted into the pulmonary veins (PV), demonstrated in a porcine model.. A self-expanding nitinol-based implant was positioned in the common inferior PV of 11 pigs, using a fluoroscopy-guided transatrial appendage approach. Ablation was performed through contactless energy transfer from a primary extracorporal coil to a secondary heat ring (HR) embedded in the proximal part of the implant. Electrophysiological conduction was assessed prior to and postablation, and at 3 months. Histological samples were obtained acutely (n  =  4) and after 3 months (n  =  7).. In total, 13 PV implants were successfully positioned in the inferior PVs of 11 animals. Ablation was performed without injury of adjacent structures. PVI and bidirectional block was electrophysiologically confirmed in all cases immediately at the time of implantation and 3 months later in seven chronic animals in whom testing was repeated. Marked evidence of ablation around the proximal HR was evident at 3 months postprocedure, with scar tissue formation and only mild neointimal proliferation.. Successful PVI can be obtained by external electromagnetic heat transfer to a novel pulmonary vein implant.

Topics: Alloys; Animals; Atrial Fibrillation; Catheter Ablation; Disease Models, Animal; Electromagnetic Phenomena; Fluoroscopy; Prostheses and Implants; Prosthesis Design; Pulmonary Veins; Swine

Esophageal thermal injury is a feared complication of radiofrequency ablation for atrial fibrillation (AF). Rise in luminal esophageal temperature (LET) limits the ability to deliver radiofrequency energy on the posterior wall of the left atrium.. The purpose of this study was to evaluate the feasibility, safety, and efficacy of a mechanical esophageal deviation (ED) tool during AF ablation.. We evaluated 687 patients who underwent radiofrequency ablation for AF. In 209 patients, the EsoSure (Northeast Scientific) was used to deflect the esophagus away from the ablation site. Propensity score matching was performed to obtain 180 patients each in the ED and non-ED arms. ED was used for LET rise seen in 61.7% of patients (111/180) and was used if the esophagus was in the line of ablation on fluoroscopy in 38.3% of patients (69/180).. Mean deviation of trailing edge of esophagus with EsoSure was 2.45 ± 0.9 cm (range 1-4.5). LET rise >1°C was significantly lower in the ED than non-ED group (3% vs 79.4%; P <.001). Mean LET rise was also lower in the ED arm (ED 0.34 ± 0.59 vs non-ED 1.66 ± 0.54; P <.001). Intraprocedural success of pulmonary vein antral isolation, was slightly improved in the ED arm than in the non-ED arm without statistical significance. AF recurrence was lower in the ED arm at 3-month, 6-month, and 1-year follow-up than in the non-ED arm. No ED-related complications were noted.. Mechanical displacement of the esophagus with EsoSure seems to be feasible, safe, and efficacious in enabling adequate radiofrequency energy delivery to the posterior wall of the left atrium without significant LET rise and obvious clinical signs of esophageal injury.

Topics: Alloys; Atrial Fibrillation; Body Temperature; Catheter Ablation; Echocardiography, Transesophageal; Esophagus; Female; Follow-Up Studies; Heart Atria; Humans; Male; Middle Aged; Monitoring, Intraoperative; Postoperative Complications; Pulmonary Veins; Retrospective Studies; Time Factors; Treatment Outcome

Topics: Aged; Alloys; Atrial Appendage; Atrial Fibrillation; Cardiac Catheterization; Echocardiography, Three-Dimensional; Echocardiography, Transesophageal; Female; Humans; Polyesters; Prosthesis Design; Radiography, Interventional; Treatment Outcome

A number of devices are available for percutaneous closure of a clinically significant patent foramen ovale (PFO). The new GORE(®) septal occluder (GSO) is a nonself-centering device consisting of an expanded polytetrafluoroethylene tube supported by a frame of nitinol wire conforming into a double disk. This study reports the first clinical GSO implantation experience.. GSO implantation in 20 consecutive patients is reported. Inclusion criteria were all patients referred with a significant PFO implicated in paradoxical embolism or transient right to left shunting causing desaturation. Procedures were performed under local anaesthesia and intracardiac echocardiography (ICE) in addition to fluoroscopy. Procedural data, acute and early closure rates were examined.. All patients underwent successful day-case device implantation. Eleven patients had previous stroke, five had transient ischemic attacks, two had a history suspicious of PFO-related desaturation, and two had a history suspicious of PFO-related peripheral thromboembolism. Acute closure rates on IVC injection bubble testing were 100% at implant and 100% (14/14) at 1 month. Average PFO balloon size was 8.0 ± 3.6(range 2.0-16.7) mm, mean fluoroscopic implantation time 3.0 ± 1.7(range 0.7-6.3) min, radiation dose 283 ± 340 (range 6-1,431) μGym(2), and total procedural time 34.8 ± 8.0 (range 22-53) min. 5 × 20 mm(2), 7 × 25 m(2), 8 × 30 mm(2) GSO devices were implanted, aiming for device size at least twice balloon PFO size. Cases included aneurysmal septums with up to 30 mm deviation and tunnels up to 12 mm long. Removal and repositioning of two devices was performed on two occasions after uncertainty about device locking. At 1 month follow-up, two patients had brief self-terminating episodes of suspected atrial fibrillation, all had normal resting ECGs. No thromboembolic/neurological events were reported.. The GSO can be implanted under local anaesthesia and ICE with low procedural and fluoroscopy times with high procedural success as a day case. No residual shunts were seen. This initial experience suggests that it is a safe and effective device for PFO closure.

Topics: Adult; Alloys; Anesthesia, Local; Atrial Fibrillation; Cardiac Catheterization; Device Removal; Female; Foramen Ovale, Patent; Humans; Male; Middle Aged; Polytetrafluoroethylene; Prosthesis Design; Prosthesis Failure; Radiography, Interventional; Septal Occluder Device; Time Factors; Treatment Outcome; Ultrasonography; Young Adult

In most patients with atrial fibrillation (AF) and stroke, there is thrombotic embolization from the left atrial appendage (LAA). Percutaneous closure of the LAA is a novel alternative for the treatment of patients with AF at a high risk of stroke, in whom long-term anticoagulation therapy is not possible or not desired. This study details the initial experience with the Amplatzer Cardiac Plug (ACP) in humans.. Investigator-initiated retrospective preregistry data collection to evaluate procedural feasibility and safety up to 24 hr after implantation of the ACP, a nitinol device designed for percutaneous trans-septal implantation in LAA of patients with paroxysmal, permanent, or persistent AF.. In 137 of 143 patients, LAA occlusion was attempted, and successfully performed in 132 (96%). There were serious complications in 10 (7.0%) patients (three patients with ischemic stroke; two patients experienced device embolization, both percutaneously recaptured; and five patients with clinically significant pericardial effusions). Minor complications were insignificant pericardial effusions in four, transient myocardial ischemia in two, and loss of the implant in the venous system in one patient.. The implantation of the ACP device is a feasible method for percutaneous occlusion of the LAA.

Topics: Aged; Aged, 80 and over; Alloys; Anticoagulants; Atrial Appendage; Atrial Fibrillation; Cardiac Catheterization; Europe; Feasibility Studies; Female; Humans; Male; Middle Aged; Prosthesis Design; Retrospective Studies; Septal Occluder Device; Stroke; Time Factors; Treatment Outcome

Topics: Alloys; Anticoagulants; Atrial Appendage; Atrial Fibrillation; Cardiac Catheterization; Evidence-Based Medicine; Humans; Prosthesis Design; Septal Occluder Device; Stroke; Time Factors; Treatment Outcome

An increasing number of transseptal punctures (TSPs) are performed worldwide for atrial ablations. Transseptal punctures can be complex and can be associated with potentially life threatening complications. The purpose of the study was to evaluate the safety and efficacy of a novel transseptal guidewire (TSGW) designed to facilitate TSPs.. Transseptal punctures were performed using a SafeSept TSGW passed through a standard TSP apparatus. Transseptal punctures were performed by standard technique with additional use of a TSGW allowing probing of the interatrial septum without needle exposure and penetration of the fossa into the left atrium (LA). Transseptal puncture using the TSGW was performed in 210 patients. Left atrial access was achieved successfully in 205 of 210 patients (97.6%) and in 96.3% of patients undergoing repeat TSP. Left atrial access was achieved with the first pass in 81.2% (mean 1.4 ± 0.9 passes, range 1-6) using the TSGW. No serious complications were attributable to the use of the TSGW, even in cases of failed TSP.. The TSGW is associated with a high success rate for TSP and may be a useful alternative to transoesophageal or intracardiac echocardiogram-guided TSP.

Topics: Adult; Aged; Aged, 80 and over; Alloys; Atrial Fibrillation; Atrial Septum; Cardiac Catheterization; Catheter Ablation; Equipment Failure; Female; Fluoroscopy; Heart Atria; Humans; Male; Middle Aged; Punctures; Retrospective Studies; 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

The Maze procedure can restore sinus rhythm in patients suffering from chronic atrial fibrillation but often fails to restore the mechanical function of the atrium, the so-called atrial kick and requires long-term anticoagulation most of the time. A micro motorless pump (Atripump) based on artificial muscle technology positioned on the external surface of the atrium could compress the heart chamber, restoring atrium transport function. A bench model reproducing the mechanical function of human atrium and human environment has been developed to assess the circulatory support that such a pump can provide.. Atripump (Nanopowers SA, Switzerland) is a dome-shape, silicone-coated nitinol actuator to be sutured on the external surface of the atrium. A pacemaker-like control unit drives the actuator and manages the external compression of the atrium. The bench model consists of an open circuit made of rubber bladder, 60 cc in volume, connected to a vertically positioned and scaled tube that is filled at different levels reproducing changes in cardiac pre-load and after-load. The pump was placed on the outer surface of the bladder and both were immersed in water having a constant temperature of 37 degrees C. Pressure, volume and temperature at the interface dome-bladder were recorded.. Pump ran 24 h for three consecutive months. During the experiment, no technical failure occurred and the pressure and volume values were repeatable during the experience. Nitinol fatigue was assessed measuring the wire's electric resistance that remained 400+/-10 Omega/m. Contraction rate was 1 Hz with power supply of 12 V, 400 m and heating time of 300 ms. Pre-load ranged from 11 to 15 mmHg. When inserted in the bath at 37+/-0.5 degrees C, maximal temperature between silicone membrane and rubber bladder was 39 degrees C. Maximal volume pumped was 492 ml/min.. This artificial muscle pump can reproduce the mechanical effect of a normal human atrium. It is compact, reliable and follows the Starling law. The surface temperature is in the physiologic range and it could represent a new tool to restore the atrial kick in persistent atrial fibrillation.

Topics: Alloys; Atrial Fibrillation; Atrial Function; Heart Atria; Heart-Assist Devices; Hemodynamics; Hot Temperature; Humans; Middle Aged; Prosthesis Design

Anticoagulation with warfarin for atrial fibrillation is frequently difficult. A transcatheter method to exclude the left atrial appendage from the circulation could be an advantage for selected patients. Percutaneous left atrial appendage transcatheter occlusion is a catheter-based delivery of an occlusive nitinol cage to the neck of the left atrial appendage. The device obliterates the left atrial appendage, eliminating a major source of thromboembolism. Animal studies have confirmed device coverage with an endocardial layer within 6 months and distal atrial appendage fibrosis. A standard transseptal approach from the right femoral vein is used. Patients leave the hospital within 1 day. Six-month follow-up of European and US safety and efficacy trials has shown favorable outcomes in minimizing thromboembolic events and few complications related to placement or healing of the device. Further clinical studies will be needed to establish which patients will be best treated with this device.

Topics: Age Factors; Aged; Aged, 80 and over; Alloys; Animals; Atrial Appendage; Atrial Fibrillation; Disease Models, Animal; Dogs; Echocardiography, Transesophageal; Humans; Middle Aged; Patient Selection; Prostheses and Implants; Risk Factors; Stroke