Chapter 33: Percutaneous Treatment of Aortic Valve Disease

INTRODUCTION

The history of percutaneous treatment of aortic valve disease began with the work of Danish researcher, H.R. Andersen, who in the late 1980s experimented in an animal lab with a balloon-expandable stented valve.¹ The technology was later acquired by PVT Company, further developed, and later sold to Edwards. Additional early work was done by Alain Cribier^2,3 and subsequently the valve was adopted in the United States and further modified. The initial approach taken by Cribier was to insert the valve via the femoral vein, then snaking the catheter through the mitral valve and into the aortic annulus via transeptal puncture. This turned out to be a fairly cumbersome and difficult procedure with a fairly high mortality rate and an 8.1% stroke rate. At the same time, animal experiments were carried out by Michael Mack, Todd Dewey, and Lars Svensson,^4,5 using the transapical (TA) approach to insert the aortic valve. Concurrently, John Webb et al^6,7 were also developing a TA aortic valve method, and subsequently they introduced the retrograde transfemoral (TF) artery approach. This latter technique became feasible once Edwards developed a catheter that could be flexed to get around the aortic arch to access the aortic valve. At the same time the Edwards balloon-expandable valve was being developed, Medtronic introduced a nitinol-based, self-expanding percutaneous valve system, the CoreValve. Following feasibility studies,^5,8 the safety and effectiveness of both valves were established through the Placement of Aortic Transcatheter Valves (PARTNER) trial and the US CoreValve pivotal trial and both valves are currently approved by US Food and Drug Administration (FDA) for use in patients who are at extreme or high risk (owing to comorbidities or anatomical considerations) for conventional surgery in the United States.^9-11

VALVES

At present in the United States, there are only two transcatheter valves approved for use in patients who are at extreme or high risk (owing to comorbidities or anatomical considerations) for conventional surgery.

The balloon-expandable Edwards valves consist of bovine pericardium fashioned into a trileaflet valve within a short cylindrical stent, available in sizes 23, 26, and 29 to treat annular sizes from 18 to 27 mm. There are three generations of SAPIEN valves (SAPIEN, SAPIEN XT, and SAPIEN 3) that differ by stent material and construction (Fig. 33-1) as well delivery device size (Table 33-1) and other delivery device characteristics. At the time of publication, the commercially available generation is the SAPIEN XT in the United States with the SAPIEN 3 commercially available only in Europe. However, this generation is almost certain to replace the SAPIEN XT in the United States in the coming years. The SAPIEN valves can be delivered via retrograde (eg, TF, transaortic, transcarotid, transaxillary/subclavian) and antegrade (TA) approaches. The self-expanding Medtronic CoreValve is constructed of porcine pericardium mounted in a nitinol stent that anchors ...