Traditionally, surgical aortic valve replacement (AVR) is the only effective treatment for adults with symptomatic severe aortic stenosis that carries a poor prognosis. However, the operative risk is increased for elderly patients and patients with other diseases (e.g. concomitant coronary artery disease, peripheral vascular disease, and renal dysfunction).
For these patients at high risk to undergo conventional cardiac surgery, transcatheter aortic valve implantation (TAVI) is an alternative to AVR and plays an important part in the treatment of aortic stenosis. With this novel approach introduced in the UK in 2007, it will be possible to replace the aortic valve without requiring a full open heart surgery.
TAVI is considered as a minimally invasive approach. This heart surgery can be performed using echocardiographic and fluoroscopic guidance for visualization during implantation. During the procedure a valve (a balloon expandable stent combined with a bovine pericardial bioprosthetic tissue valve) is reduced to size and placed on a delivery catheter. The delivery catheter is then inserted either in the femoral artery through a small incision at the top of the leg (transfemoral approach) or between the ribs through the apex of the heart (transapical approach). Once in the heart, the valve is positioned and deployed across the patient’s diseased aortic valve. During the TAVI procedures, computer vision techniques including advanced image processing, real-time interactive segmentation, and motion tracking provide essential guidance to ensure the selection of the optimal access route for valve implantation the placement of the valve in the right position.
Since January 2007, more than 25 active TAVI centres have been developed throughout England and Wales, and over 877 implants have been performed. A number of observational clinical studies have demonstrated its feasibility. The midterm to long-term survival after TAVI is encouraging in this high-risk patient population, with high rates of 78.6% at 1 year and 73.7% at 2 years, respectively.
Article by Feng Zhao, Workshop Developer, Software Alliance Wales