Image-Guided Transcatheter Aortic Valve Implantation Assistance System

Transcatheter aortic valve implantation (TAVI) is a recently developed surgical technique to treat symptomatic aortic valve stenosis in elderly and high-risk patients (Eltchaninoff et al., 2008; Ferrari & von Segesser, 2010). Compared to the standard aortic valve replacement surgery, the TAVI limits the surgical access to either a small minithoracotomy (transapical TAVI) or femoral approach (transfemoral TAVI) causing minimal tissue trauma. Independently of the TAVI approach it can be performed on the beating heart without cardiopulmonary bypass support (Walther et al., 2009). Recovery time may be reduced and the patient can eventually return to normal activity more quickly. More than 70,000 transcatheter valve implantations have been performed worldwide (Valle-Fernandez et al., 2010). The TAVI is done via a retrograde (transfemoral, transaxillary) or antegrade (transapical) approach (Singh et al., 2008). The main advantage of the transapical TAVI technique is the direct access to the aortic valve which eliminates the need for a large peripheral vascular access in patients with peripheral vascular disease, small tortuous vasculature, a history of major vascular complications, or previous vascular interventions (Singh et al., 2008). In transapical TAVI (Walther et al., 2009), a stented valve bioprosthesis that is temporarily crimped upon a balloon catheter, is inserted through the apex into the aortic root via a left anterolateral minithoracotomy. For that the apex of the left ventricle is punctured with a needle, and after balloon valvuloplasty the aortic valve prosthesis (AVP) is positioned within the stenotic aortic valve using guide wire techniques. After reaching the correct position, the stented AVP is deployed by an inflatable balloon to reach its final diameter, thus fixing the prosthesis to the aortic annulus (Fig. 1a). The Edwards SAPIENTM prosthesis (Edwards Lifesciences Inc, Irvine, CA, USA) is the most commonly used prosthesis for TAVI in several European countries and the only one approved for transapical approach so far (Thomas et al., 2010). Thus the Edwards SAPIENTM prosthesis has been used in this study. It consists of three bovine pericardial cusps mounted into a stainless-steel balloon-expandable stent (Fig. 1b).