Endovascular Transcatheter Aortic Valve Implantation: An Evolving Standard

Abstract

e u d ABNORMALITIES OF THE aortic valve morphology and function represent the most common cardiac valve lesion, ith relevant implications for medical and surgical treatent. Aortic valve sclerosis affects about one fourth of dults over 65 years of age, whereas severe aortic stenosis AS) is present in 2% to 9% of the same population.1 AS is suspected to be the result of chronic inflammation secondary to risk factors similar to the ones associated with atherosclerosis.2,3 The number of aortic valve procedures performed over the last 10 years increased if aortic valve replacement is considered alone or combined with myocardial revascularization; mitral valve surgery seemed to be constant in the same period.4 In 1968, Ross and Braunwald,5 in their classic review of the natural history of AS, re-emphasized that sudden death occurred predominantly in symptomatic patients. In asymptomatic patients with acquired severe AS, the risk of sudden death was reported to be between 3% and 5%. It was proposed that patients with acquired severe AS have surgery deferred until the onset of symptoms because the mortality increases steeply afterward (Fig 1).6,7 Surgical replacement of the aortic valve (SAVR) reduces symptoms and improves survival in patients with severe AS.8-10 Its current indications are outlined in Table 1. In the absence of serious comorbidities, the procedure is associated with low operative mortality.11,12 However, in clinical practice, at least 0% of patients with severe symptomatic AS do not undergo urgery for replacement of the aortic valve because of advanced ge, left ventricular (LV) dysfunction, or the presence of muliple coexisting medical conditions.13-16 For these patients who re at high surgical risk, a less invasive treatment may be a orthwhile alternative.17,18 Cribier et al19 reported the first successful implantation of a percutaneous aortic valve in animals in 2000. The first human implantation using the antegrade trans-septal approach followed 2 years later. The first retrograde transfemoral approach was performed in 200320 (Fig 2). At present, most of the available data for transcatheter aortic valve implantation (TAVI) are derived from studies on 2 specific devices: the Sapien valve (Edwards Life Sciences, Inc, Irvine, CA; Fig 3) and the CoreValve (Medtronic, Inc, Minneapolis, MN; Fig 4). The Sapien valve is a trileaflet bovine pericardial valve mounted with a tubular slotted balloonexpandable stent composed of a cobalt chromium alloy. It is available in 23and 26-mm sizes in the United States and 23-, 26-, and 29-mm sizes in Europe. The 23-mm valve is preferred for annular diameters of 18 to 21 mm and the