Transcatheter aortic valve implantation (TAVI) for native aortic valve regurgitation

Aortic regurgitation (AR) is the leakage of blood backwards from the aorta into the left ventricle during diastole (when the heart relaxes and fills with blood). It develops when the aortic valve pathology prevents normal closure of the valve in diastole. AR is usually the result of leaflet degeneration, aortic root dilatation with aortic annulus enlargement, or both. People may remain asymptomatic for years but eventually they present symptoms, most often with shortness of breath. In severe cases this leads to heart failure.

For people with severe symptomatic AR who are well enough for surgery, surgical aortic valve replacement (SAVR) with a biological or mechanical prosthetic valve is standard treatment.

For some people, surgery is not an option. This can be because of medical comorbidities or technical considerations, such as a calcified aorta or scarring from previous cardiac surgery. For these people, the risks of SAVR outweigh the potential benefits, and so medical treatment is the standard treatment. But for some of these people, medical treatment is not effective.

TAVI provides a less invasive alternative to open cardiac surgery for treating AR, avoiding the need for cardiopulmonary bypass and median sternotomy.

TAVI is usually done under local anaesthesia with sedation. Or it may be done under general anaesthesia. Imaging guidance, including transoesophageal echocardiography (if general anaesthesia is used), fluoroscopy or angiography is used to help with prosthetic valve size selection, valve positioning and assessing the implanted prosthetic valve post procedure. Prophylactic antibiotics and anticoagulation medication are administered before and during the procedure.

A bioprosthetic aortic valve is implanted within the damaged native aortic valve. Access to the aortic valve can be percutaneous, with entry to the circulation through the femoral artery (endovascular approach). Alternatively, subclavian access may be used if the anatomy of the femoral arteries is not suitable. Deciding how to achieve catheter access to the aortic valve may depend on a number of factors related to the person having the procedure, such as femoral artery anatomy and the presence of aortic calcification.

The new prosthetic valve is manipulated into position and deployed over a guide wire passed through the native aortic valve.

Rapid ventricular pacing is used to temporarily reduce cardiac motion and blood flow through the native aortic valve during placement of the new prosthetic aortic valve. The new valve may be mounted on a metal stent that is self-expanding. Or, it may be expanded by inflating a large balloon on which the stented valve has been crimped. Positioning the new valve obliterates the native aortic valve. The catheter is removed once the valve has been successfully placed.