EXPERIENCE WITH THE COREVALVE SYSTEM
The CoreValve ReValving system is based on retrograde implantation of the CoreValve prosthesis—a self-expanding aortic valve prosthesis composed of three bovine pericardial leaflets mounted and sutured within a self-expanding 50-mm-long nitinol stent ( Table 1 ).28–30 The inner diameter is 21 to 22 mm. 28–30 This prosthesis has three distinct structural segments. 28–30 The bottom portion exerts a high radial force that expands and pushes aside the calcified leaflets and avoids recoil; the central portion carries the valve, and it tapers to avoid the coronary artery ostia; and the upper portion flares to fixate and stabilize the deployed aortic valve prosthesis in the ascending aorta, thus preventing migration or embolization of the device. 28–30 The main difference between the CoreValve and the Cribier-Edwards valve is that the Core-Valve is self-expanding, which theoretically permits it to conform to different aortic sizes and to anchor well in the aortic annulus. 28–30 This feature allows the CoreValve to be used in patients with severe aortic insufficiency and other noncalcific aortic valvular conditions. The CoreValve has not yet been deployed via antegrade or transapical technique.
The first-generation CoreValve prosthesis was first implanted in a human recipient in 2005. 29 Since then, improvements have been made, leading to the development of second- and third-generation devices. A pilot study of implantation of the first-generation CoreValve 28 via the retrograde approach in elderly patients with poor functional class and severe aortic stenosis had a short-term procedural success rate of 84% (21 of 25 patients), with a significant reduction in the mean aortic valve gradient and improved functional class at 30-day follow-up. 28 At 30 days, 17 (94%) of 18 patients had no or only mild aortic regurgitation. 28 Procedural limitations and complications were similar to those with the Cribier-Edwards valve.
In a study of second- and third-generation devices (50 patients received a second-generation device, and 36 received a third-generation device), 30 again in elderly patients with poor functional class and severe aortic stenosis, the short-term success rate of the device was 88% (76 of 86) in each group. After the procedure, the mean aortic valve gradient decreased significantly and functional class improved significantly. 30 Immediate after implantation, no patient had more than moderate aortic regurgitation, and in 51 patients (66%) the aortic regurgitation remained unchanged or improved after CoreValve implantation. 30 These results were maintained at 30-day follow-up.
CoreValve was approved in May 2007 for clinical use in Europe. 36 Of note, CoreValve has also been used to treat severe aortic regurgitation of a degenerated bioprosthetic aortic valve in an 80-year-old man with multiple comorbidities. 37
EXPERIENCE WITH THE EDWARDS SAPIEN VALVE
The Edwards SAPIEN valve is a modification of the initial Cribier-Edwards valve and is the latest percutaneous aortic valve prosthesis to enter clinical trials ( Table 1 ). It is a trileaflet balloon-expandable stainless steel valve made from bovine pericardial tissue, available in two sizes (23 mm and 26 mm). In September 2007, it was approved for use in Europe with the RetroFlex transfemoral delivery system. The Ascendra transapical delivery system for the Edward SAPIEN valve has received approval in Europe.