Since the introduction of the 18-Fr CoreValve self-expanding transcatheter aortic valve replacement (TAVR), over 70,000 implants have been performed worldwide. The use of this self-expanding bioprosthesis has provided an alternative to surgery in patients who are suboptimal for conventional surgical aortic valve replacement and has resulted in improved survival and quality of life for thousands of patients worldwide. There are a number of potential advantages of a self-expanding bioprosthesis over alternative transcatheter designs, including the progressive self-expansion of the inflow frame reducing the degree of paravalvular regurgitation (PVR) over time; supra-annular location of the porcine pericardial valve, which improves hemodynamics and potentially improves long-term durability; and large cell diameter, which provides access to coronary arteries after implantation.
The purposes of this chapter are to review the CoreValve self-expanding frame design and newer iterations of the self-expanding prosthesis, discuss the clinical evidence for use of the self-expanding devices in an expanding population, and outline the risks and benefits of this device in patients with aortic stenosis.
COREVALVE SELF-EXPANDING BIOPROSTHESIS
The CoreValve System consists of 3 components: a transcatheter bioprosthesis, the delivery catheter system, and the compression loading system. The transcatheter bioprosthesis is composed of a self-expanding nitinol frame that supports a trileaflet porcine pericardial valve available in 23-, 26-, 29-, and 31-mm diameters that treat an annulus range from 18 to 29 mm1 (Fig. 44-1). The inflow portion of the frame is designed to conform to the annulus and to stabilize the frame at the annular location.1 The lowest 12 mm of the frame contains a porcine pericardial skirt to seal the annulus.1 The valve is located in a supra-annular position at the waist (constrained portion) of the valve frame.1 The outflow portion of the valve frame is constructed to support the valve commissures and orient the frame to facilitate laminar flow. All valve sizes are delivered using an 18-Fr catheter delivery system. The valve is deployed without rapid pacing and is partially repositionable until annular contact with the transcatheter heart valve (THV) is made. The CoreValve bioprosthesis has now been replaced commercially with the Evolut R transcatheter system (see below), which allows repositioning of the valve if the initial deployment is suboptimal.
CoreValve self-expanding bioprosthesis. (Adapted from Popma JJ, Adams DH, Reardon MJ, et al. Transcatheter aortic valve replacement using a self-expanding bioprosthesis in patients with severe aortic stenosis at extreme risk for surgery. J Am Coll Cardiol. 2014;63:1972-1981.)
EARLY COREVALVE REGISTRIES
Early European registries between 2007 and 2010 demonstrated the value of self-expanding transcatheter replacement in patients who were not optimal candidates for surgical valve replacement,2-4 but transcatheter replacement was limited by 2-dimensional echocardiographic-based valve sizing, the availability of only 26- and 29-mm sizes, and delivery systems ...