Prospects for percutaneous valve therapies.

Developmental efforts to achieve percutaneous catheterbased therapies for cardiac valve repair and replacement have advanced rapidly over the past several years. A variety of methods to treat mitral regurgitation (MR) and to replace aortic and pulmonic valves have already been successfully employed in patients. These innovative clinical transcatheter valve therapies were anticipated more than a decade ago by creative experimentalists who helped develop predicate techniques in animal models. For example, in 1992, a catheterdelivered ball-in-cage prosthetic aortic valve was implanted in a canine model by Pavcnik1 and a stent-mounted bioprosthetic valve was placed by Andersen, who used a retrograde transarterial approach in a swine model.2 Clearly, the catheter-based technologies used in clinical studies today in patients with aortic stenosis were derived from the fusion of known successful aortic valve replacement (AVR) surgical devices and adaptive interventional modalities, first studied in experimental animal models. Similarly, approaches for transcatheter treatment of MR have also borrowed heavily from preexisting and accepted surgical techniques, such as the edge-to-edge leaflet coaptation technique and reduction ring mitral annuloplasty.3 Importantly, recognition that the coronary sinus parallels the mitral annulus has spurred unique catheter-based transvenous approaches to treat MR by indirectly reducing mitral annular dimensions.4 Because many of the new percutaneous approaches to valve therapy have been developed by surgeons, a collaboration has emerged between thoughtful surgeons and interventionalists, combining skill sets and experiences to accelerate the developmental pathways of less-invasive transcatheter valve therapies.