Valve surgery: Investigations and procedures

Valve surgery

Valve surgery is used to treat stenosed or regurgitant valves, which cause compromise of cardiac function. Conservative surgery is performed whenever possible. The aortic valve is not usually amenable to conservative surgery and usually requires replacement if significantly diseased. A stenosed mitral valve may be treated by following procedures:

·        Percutaneous mitral balloon valvuloplasty in which a balloon is used to separate the mitral valve leaflets. This is now the preferred technique unless there is coexisting mitral regurgitation.

·        Closed valvotomy uses a dilator that is passed through a left sub-mammary incision into the left atrial appendage.

·        Open valvotomy and valve repair is performed under cardiopulmonary bypass. The valve leaflets are separated under direct vision. This is used for patients with coexisting mitral regurgitation.

Valvular regurgitation when due to dilation of the valve ring may be treated by sewing a rigid or semirigid ring around the valve annulus to maintain size (annuloplasty). If regurgitation is due to areas of flail leaflets, e.g. due to infective endocarditis or chordal rupture, part of the leaflet may be resected or even repaired with a piece of pericardium to restore valve competence.

Valve replacement: Using cardiopulmonary bypass the diseased valve is excised and a replacement is sutured into place. Valves may be divided into mechanical and biological types:

·        Early mechanical valves were ball and cage type such as the Starr–Edwards valve. Current designs all have some form of tilting disc such as the single disc Bjork¨– Shiley valve or the double disc St Jude valve. They are durable, but require lifelong anticoagulation therapy to prevent thrombosis of the valve and risk of embolism.

·        Biological valves may be xenografts (from animals) or homografts (cadaveric). Xenografts are made from porcine valves or from pericardium mounted on a supportive frame. They are treated with glutaraldehyde to prevent rejection and are used to replace aortic or mitral valves. They do not require anticoagulation unless the patient is in atrial fibrillation but have a durability of approximately 10 years. Valve failure may result from leaflet shrinkage or weakening of the valve competence causing regurgitation, or calcification causing valve stenosis.

Valve replacements are prone to infective endocarditis, which is difficult to treat (and may require removal of a mechanical valve).

Valve replacement provides marked symptomatic relief and improvement in survival. Operative mortality is approximately 2%, but this is increased in patients with ischaemic heart disease (when it is usually combined with coronary artery bypass grafting), lung disease and the elderly. Perioperative complications include haemorrhage and infection. Late complications include haemolysis and valve failure. Arrhythmias also occur. All prosthetic valves require antibiotic prophylaxis against infective endocarditis during non-sterile procedures, e.g. dental treatment, lower gastrointestinal or urogenital procedures and they may also become infected from any source of bacteraemia.