Transcatheter Aortic Valve Implantation

Calcific aortic stenosis (AS) is the most common form of degenerative heart valve disease in developed countries. AS predominantly affects the elderly with a prevalence of 4% in people over the age of 80 years. With increasing longevity and an ageing population the absolute number of people afflicted with AS is set to rise. The clinical course of the disease is insidious at first (Ross & Braunwald, 1968), but is followed by rapid progression once symptoms of congestive cardiac failure, angina and syncope develop (Cheitlin et al., 1979; Otto et al., 1989; Davies et al., 1991; Peter et al., 1993). If left untreated mortality exceeds 50% at two years (Kelly et al., 1988; Turina et al., 1987) and AS is, therefore, set to become a major public health problem in the ensuing decades. Aortic valve replacement (AVR) has been the gold standard intervention for AS for more than 40 years (Charlson et al., 2006) and over 60,000 procedures are performed annually in the European Union. However, one third of patients are denied access to surgery, often due to their advanced age (Iung et al., 2003, 2005). Percutaneous balloon valvuloplasty was heralded initially as a promising breakthrough for high-risk symptomatic patients with AS (Cribier et al., 1986). However, long-term follow-up has yielded unacceptable rates of restenosis and poor event-free survival (Otto et al., 1994; Lieberman et al., 1995). Balloon valvuloplasty is now recommended only as a bridge to emergency AVR or in the palliation of symptoms in the frailest of patients (Ussia et al., 2010; Zahn et al., 2011). Transcatheter aortic valve implantation (TAVI) has recently emerged as an effective therapeutic alternative to conventional AVR for high-risk AS patients. TAVI was developed initially in porcine models (Anderson et al., 1992), but it took a decade for this technology to be translated to humans (Cribier et al., 2002). Initially, an antegrade transseptal approach was used, but this has now been superseded by transapical (Ye et al., 2006; Webb et al., 2007) and retrograde percutaneous techniques (transarterial or transaxillary) (Webb et al., 2006). The range of different approaches has increased the feasibility of TAVI in patients with relative contraindications, such as extensive peripheral vascular disease, porcelain aorta and thoracic radiotherapy. TAVI is also less invasive than open AVR and permits replacement of the native diseased valve in the beating heart without the need for sternotomy and cardiopulmonary bypass. Consequently, TAVI may be less influenced by a patient’s comorbidities and may facilitate faster recovery. A multidisciplinary team consisting of interventional cardiologists, cardiothoracic surgeons, cardiac anesthetists and imaging specialists is best suited to make decisions between open