Transcatheter Aortic Valve Implantation02 November 2009
Transcatheter Aortic Valve Implantation (TAVI) is a new procedure that has been introduced at London Bridge Hospital which can be used as an alternative to standard surgical aortic valve replacement. The procedure is performed on the beating heart without the need for a sternotomy (an incision in the centre of the chest) or cardiopulmonary bypass (takes over the function of the heart and lungs during surgery).
The aortic valve is located between the left ventricle and the aorta, which is the main artery that takes blood from the heart to the body. The aortic valve has three flaps or ‘cusps.’ Blood flows through the valve when the left ventricle contracts at the early stage of the heartbeat. When the left ventricle relaxes the aortic valve closes and the mitral valve (which lies between the left atrium and the left ventricle) opens to allow more blood into the ventricle ready for the next heartbeat.
Aortic stenosis refers to a narrowing of the aortic valve in the heart which restricts blood flow through the valve. The heart then needs to contract harder to pump blood into the aorta. Mild narrowing may not cause symptoms, however more severe narrowing can cause symptoms and lead to heart failure. Surgery may then be needed to replace the valve.
The TAVI procedure involves a new valve being inserted via a catheter into the heart. The catheter can be inserted into the body through a large blood vessel, usually found in the groin. Alternatively, it can be inserted directly into the heart through a small incision in the chest, under general anaesthetic.
In general TAVI should be performed for symptomatic severe degenerative aortic stenosis. It is expanding rapidly across the UK and is a technology that holds enormous potential. It is currently be reserved for those patients that have been seen to by multidisciplinary team, including two surgeons and two interventional cardiologists, who consider TAVI to pose less risk to the patient than open heart surgery.
The evidence on TAVI for aortic stenosis is limited to small numbers of patients who were considered to be at high risk for conventional cardiac surgery. It shows good short-term efficacy but at present there is little evidence on long-term outcomes. However patients on whom this procedure has been performed have a poor prognosis without treatment and are at a higher risk if treated by open heart surgery