2 The condition, current treatments and procedure
2.1 The mitral valve allows blood to flow from the left atrium to the left ventricle. Mitral valve regurgitation happens when the valve does not close properly and blood flows back into the atrium from the ventricle. The heart has to work harder to pump blood from the left ventricle to the aorta, resulting in an enlarged left ventricle. If not treated, this can lead to shortness of breath, fatigue and palpitations (because of atrial fibrillation) and eventually heart failure.
2.2 If symptoms of mitral valve regurgitation are severe enough, mitral valve annulus surgical repair may be done by open heart surgery in patients who are well enough for this kind of operation. A surgical valve annulus repair may fail over time and can result in the need for further intervention.
2.3 The standard treatment after a failed mitral valve annuloplasty is repeat open heart surgery. Repeat open heart surgery is associated with a higher risk of morbidity and mortality than primary surgery. Transapical transcatheter mitral valve-in-ring implantation is a less invasive alternative. It avoids the need for cardiopulmonary bypass and can be used to treat failed annuloplasty rings originally placed during open heart surgery.
2.4 The procedure is usually done with the patient under general anaesthesia and using imaging guidance including fluoroscopy, angiography and transoesophageal echocardiography. Prophylactic antibiotics and anticoagulants are given before and during the procedure. Temporary peripheral extracorporeal circulatory support (usually through the femoral vessels) is sometimes used.
2.5 The mitral valve is accessed surgically through an apical puncture of the left ventricle using an anterior or left lateral mini thoracotomy (transapical approach). A guidewire is placed across the existing native mitral valve and into a pulmonary vein. A balloon catheter delivery system is then advanced over the guidewire into the left atrium. The inner diameter of the mitral valve annulus is measured using transoesophageal echocardiography to establish the size of bioprosthetic valve needed. Using the delivery system, the bioprosthetic valve is then introduced, manipulated into position (to align the valve with the mitral annulus) and slowly deployed within the surgically implanted mitral valve ring under fluoroscopic and echocardiographic guidance. Often, rapid ventricular pacing is used to reduce movement of the heart. After valve deployment, the catheter delivery system, guidewires and pacing wires are removed from the left ventricle and the left ventricular puncture and chest incisions are closed. Valve performance is then assessed using echocardiography and fluoroscopy.