Valve Repair & Replacement

Heart Valves: One Way Doors

The main valves of the heart are the Mitral, Tricuspid, Aortic and Pulmonary valves. To control the flow of blood from the atrium to the ventricle and from the ventricle to the main arteries, your heart has valves. These are sets of flaps or cusps of tissue hinged like one way doors to flow forward. They snap shut after each pumping stroke to prevent back flow of blood. The valves do not open automatically but function like a gate that opens only when it is pushed. And each is built in such a way that it will open only in one direction.

Surgery of the Aortic Valve

Anatomically, the normal aortic valve has three leaflets. In 1 to 2% of patients it is bicuspid in nature.

The aortic valve is situated on the left side of the heart (the outflow valve). In the lungs, blood exchanges its carbon dioxide for oxygen and becomes bright red again. It then returns to your heart into the left atrium. When the mitral valve opens, blood flows from the left atrium into your left ventricle. When the left ventricle contracts, the aortic valve opens to allow blood to leave the left ventricle and closes to prevent blood from leaking back into the left ventricle. From the aorta, blood reaches the whole body tissues to nourish them. Thus the aortic valve is the "outflow valve" between the Left Ventricle and Aorta.

Aortic Valve Replacement

The aortic valve gets damaged due to several reasons. The most common cause of aortic valve disease requiring surgery is degenerative calcific aortic stenosis, meaning that the valve has worn out with age. The body deposits calcium on it for reasons that are unknown. The calcium restricts or limits the motion of the valve leaflets. This may prevent the valve from opening (causing stenosis) or closing (causing leakage or regurgitation).

In India, Rheumatic Heart Disease is also another common cause of aortic valve affection leading to leakage or narrowing.

Congenital aortic valve disease: The most common congenital abnormality is a bicuspid aortic valve. This is the second most common cause of aortic valve disease requiring surgery. Such valves may function normally for years but later on become stenotic or regurgitant or both.

Less common causes of aortic valve disease include diseases of the aorta, namely aneurysm of the ascending aorta, aortic dissection, and Marfan's Syndrome.

Mechanical Valves

Bileaflet mechanical valves are most commonly used. Advantage: A mechanical valve has excellent durability. Disadvantage: Blood has a tendency to clot on all mechanical valves, and to prevent this the patient must take anticoagulants for the rest of their life and have blood tests done every 6-8 weeks.

Biological Valves

They are made of porcine tissue (pig tissue), bovine pericardium (cow pericardium) or equine tissue (horse pericardium). Advantage: Reduced risk of blood clot formation. Disadvantage: They have limited durability as compared to mechanical valves. They wear out early depending on a number of factors. Usually they are used for patients who are above 55-60 years of age.

Life after Aortic Valve Replacement

You can expect to return to your preoperative condition or better within a few months. You will require prophylactic antibiotics as a preventive measure against infection whenever you have a dental or any surgical procedure done.

Surgery of the Mitral Valve

Anatomically, the mitral valve has two leaflets.

The mitral valve is situated on the left side of the heart (the inflow valve). From the aorta, blood reaches the whole body tissues to nourish them. After giving up much of its oxygen the blood is now blue in colour. It passes through veins which return it to your heart at the right atrium. From there it goes through the tricuspid valve into the right ventricle, which pumps blood through the pulmonary valve into the lungs. In the lungs, blood exchanges its carbon dioxide for oxygen and becomes bright red again. It then returns to your heart into the left atrium. When the mitral valve opens, blood flows from the left atrium into your left ventricle. When the ventricle contracts to push the blood into the aorta, the mitral valve closes to keep blood from leaking back into the left atrium and lungs. Thus the mitral valve is the "inflow valve" between the Left Atrium and Left Ventricle.

Mitral Valve Repair Surgery

Mitral valve repair is an open heart surgery performed to treat narrowing (Mitral Stenosis) or leakage (Mitral Regurgitation) of the mitral valve.

1. Mitral Stenosis (Narrowing) — Mitral Valve Commisurotomy: When the valve is narrow or "stenotic," either from birth or from damage by Rheumatic fever, it is treated by commisurotomy: 1. Closed mitral commisurotomy. 2. Open mitral commisurotomy (open heart surgery). 3. Balloon mitral commisurotomy — performed in the catheterization laboratory and now routinely done. Using a catheter with a balloon on the end, the balloon is expanded inside the valve, "stretching" it open. In many cases, the valve is too damaged to allow repair, and such valves are replaced.

2. Mitral Regurgitation (Leakage): Congenital mitral regurgitation (a birth defect) may be due to a cleft mitral valve (a valve with a separation or cleft down the middle) associated with a hole in the heart between the two atria. Such valves can sometimes be repaired simply by closing the cleft with sutures. Degenerative mitral valve disease is more commonly repaired. Mitral valves that are regurgitant due to Rheumatic fever are often both stenotic and regurgitant, and are often beyond repair. Not all mitral valves can be repaired. A preoperative echocardiogram helps in predicting the likelihood of repair, but cannot guarantee it.

Results of Mitral Valve Repair

If repair is possible, the likelihood of long-term success is good, particularly for degenerative valve disease. Depending upon the underlying abnormality there may be an 85 to 95% chance of needing nothing further done to the valve over the next 5 to 10 years. If a valve was damaged by rheumatic fever, the disease may progress even after the repair, decreasing the chances of a good long term result. Some surgeons are, therefore, reluctant to repair rheumatic valves. The results of repair of mitral regurgitation associated with coronary artery disease are the most difficult of all to predict.

Mitral Valve Replacement Surgery

In many cases, the valve is too damaged to allow repair, and such valves are replaced. In India, the commonest cause of mitral valve damage is Rheumatic fever and these valves are more often replaced. The mitral valve is replaced by either a mechanical valve or a biological valve.

Mechanical Valves: Bileaflet mechanical valves are most commonly used. Advantage: A mechanical valve has excellent durability. Disadvantage: Blood has a tendency to clot on all mechanical valves, and to prevent this the patient must take anticoagulants for the rest of their life and have blood tests done every 6-8 weeks.

Biological Valves: They are made of porcine tissue (pig tissue), bovine pericardium (cow pericardium) or equine tissue (horse pericardium). Advantage: Reduced risk of blood clot formation. Disadvantage: They have limited durability as compared to mechanical valves. They wear out early depending on a number of factors. Usually they are used for patients who are above 55-60 years of age.

Life after Mitral Valve Replacement

You can expect to return to your preoperative condition or better within a few months. You will require prophylactic antibiotics as a preventive measure against infection whenever you have a dental or any surgical procedure done.