Development and Testing of the Helex Septal Occluder, a New Expanded Polytetrafluoroethylene Atrial Septal Defect Occlusion System

Abstract

Background-A variety of transcatheter atrial septal defect (ASD) occluders are currently in use around the world.Although for the most part effective, all of these devices lack features that would be desirable in a "perfect" device. The Helex septal occluder is a new type of device designed to improve the results of transcatheter ASD closure. This study was designed to examine the effectiveness and safety of this occluder in an animal model. Methods and Results-The Helex was implanted into 24 dogs with surgically created ASDs. Procedural details focusing on deployment, removal, and early closure rates were examined. Follow-up consisted of sequential transesophageal echocardiography and fluoroscopy as well as epicardial contrast echocardiography and angiography at the time of death. Specimens were examined grossly and histologically, and devices were tested for metal fatigue. All animals had successful ASD closure. Implantation was uncomplicated (mean fluoroscopy time 11.7 minutes), and removal or repositioning was always possible. Closure rate as judged by transesophageal echocardiography was 88% initially and 100% at 2-week follow-up. Devices rapidly became infiltrated with connective tissue without inflammation and were endothelialized over time. There were no instances of thromboembolism. A single wire-frame fracture occurred secondary to a prototype delivery system malfunction. Conclusions-The

Magnetic Resonance Image-Guided Transcatheter Closure of Atrial Septal Defects

“…Transcatheter closure of secundum ASD under fluoroscopy with the use of retrievable devices has become a standard procedure in most pediatric cardiology centers and is considered to be a relatively straightforward procedure. 6,7,10 Therefore, the purpose of this study was to explore the ability of MRI to (1) interactively control catheter tracking and targeting of the ASD with the use of recently developed intravascular antenna guide wires; (2) determine ASD size by high-resolution MRI, and compare it with balloon sizing by using radiographic fluoroscopy and postmortem examination; (3) perform ASD device closure under real-time and highresolution MRI with the use of the ASO; and (4) measure outcome results from the intervention such as changes in right cardiac volumes.…”

Long-term complications evidenced studying the explanted Gore® HELEX® atrial septal defect occluder seven years after implantation: a case report

“…In contrast to the former, to our knowledge, there are no morphological studies on explanted Gore® HELEX® atrial septal defect occluder in humans, except for the only one study performed on dogs [7].…”

“…Th e elastic property of nitinol is used to form the wire frame into two opposing disks that bridge and close the septal defect. Th e ePTFE is specially designed to facilitate rapid cell penetration, thereby promoting rapid tissue ingrowth, resulting in permanent defect closure and device stability [7]. Endothelial, interstitial and infl ammatory cells that are located at the biomaterial interface can release various tissue mediators, remodel, and, even, degrade the tissue increasingly expressing matrix metallo proteinases (MMPs) [2].…”

Initial experience in Brazil with the Helex septal occluder for percutaneous occlusion of atrial septal defects

“…Three small metal loops also called "eyelets" are found in the center of the disks, one more distal (outside the disk on the left side), one between the 2 disks, and another proximal, (outside the disk on the right side). Within the proximal waist is a retrieval cord made of polytetrafluoroethylene 18,19 . The Helex septal occluder comes preshaped out of the 9Fr delivery catheter, connected to its components the mandrel, control or implant catheter, and the retrieval cord that runs parallel to the mandrel within the control catheter ( fig.1), and this within the delivery catheter, forming a tricoaxial implantation system.…”

“…Recently, a new device, the Helex septal occluder (W.L. Gore and Associates, Flagstaff, AZ) was introduced for clinical use after encouraging results from experimental studies 18 . We report herein the initial experience at 2 Brazilian centers with the new Helex device.…”