Heart Valves


Q1. Doctor, what exactly do you mean when you talk about the valves of the heart?

A1. The heart valves are the doors of the heart that allow forward flow of blood, but not backward flow.

Q2. Where in the heart are these valves situated?

A2. The mitral valve is situated in between the left atrium and left ventricle.

The aortic valve is situated in between the left ventricle and the aorta.

The tricuspid valve is situated in between the right atrium and right ventricle.

The pulmonary valve is situated in between the right ventricle and the pulmonary artery.

Q3. How many leaflets do each of these heart valves contain?

A3. Of the four heart valves that I have described, only the mitral valve has two leaflets. All the rest have three leaflets each.

Q4. What do you mean when you say that there is stenosis of a cardiac valve?

A4. It means that the orifice of the valve has become narrowed by some disease process.

Q5. Why do some people’s heart valves become narrowed?

A5.The mitral, aortic and tricuspid valves may be narrowed because of Rheumatic Fever. For unknown reasons, the pulmonary valve is not affected by this disease.

Any of the heart valves may be narrowed even before the child is born; this is one form of congenital heart disease.

The aortic valve is frequently narrowed and heavily calcified in middle aged, and elderly individuals. This is because of senile degeneration.

Q6. What do you mean when you say that someone’s valve is regurgitant?

A6. It means that the valve is leaky, i.e., it allows back flow of blood.

Q7. Why do some people’s valves become regurgitant?

A7. There are different caused of regurgitation of cardiac valves, e.g., rheumatic heart disease, rheumatoid arthritis, congenital heart disease, senile degeneration, infective endocarditis, and so on.

Q8. What do you do when someone’s heart valve is stenotic or regurgitant?

A8. Many of the patients with a mildly stenotic/regurgitant valve can be treated conservatively. When the stenosis/regurgitation is severe, and/or the patient is having serious symptoms, a procedure is usually required. Some of the narrowed valves can be dilated with the help of balloons that are introduced from the patients’ lower limbs. Some other valves have to be dilated during open heart surgery.

Severely leaking valves are repaired or replaced by an open operation.

Q9. Please give me an idea about prosthetic cardiac valves.

A9. When the cardiac valves are severely stenotic and/or regurgitant, an open operation is required. The diseased valve is excised, and an artificial valve is stitched in its place.

Q10. What are the prosthetic valves made of?

A10. Prosthetic heart valves are of two broad categories: mechanical prosthesis, and bio-prosthesis.

A mechanical prosthetic valve is made of a chemical such as pyrolite carbon. It is durable, but has a tendency to develop blood clots. Blood thinners such as warfarin must be administered to the recipients of mechanical prosthetic valves on an indefinite basis. This is a disadvantage because the patients have to come for specialist doctors’ consultation very frequently, and must have periodic testing of their blood for prothrombin time/INR. Failure of do this regularly may have disastrous consequences for the patient. They are usually advised for patients who are younger than 65 years.

Tissue prostheses are obtained from biological sources, e.g., human dead bodies, or carcases of pigs or cattle. Patients who receive implants of these valves do not require the administration of blood thinners on a long term basis. But they have a tendency to degenerate after a few years, and may require frequent re-operations. They are recommended for patients who are over the age of 65 years.

Q11. Doctor, some of the patients in the western countries are undergoing replacement of the aortic valve by catheter based techniques instead of open heart surgery. How good is the technique?

A11. A lot of research work is going on. Trans-catheter Aortic Valve Replacement (TAVR) was initially attempted on elderly, frail patients in whom Surgical Aortic Valve Replacement (SAVR) was considered to be too risky. Encouraged by the success of such procedures, TAVR was attempted on patients in whom the risks of operation were smaller. The results were encouraging in this group a well.

Although TAVR is an exciting option, it has its own problems. First, the cost is prohibitive. Second, the balloon catheter has to be introduced through the femoral artery, which is a blood vessel of the lower limb. This artery may be lacerated, and clots can form i its lumen. Third, manipulation of the balloon catheter through a calcified aortic valve can dislodge small bits of calcium. These can travel into the blood vessels of the brain and cause paralysis of the limbs. Fourth, the valve has to be post-dilated after deployment. Inadequate post-dilatation leads to inadequate expansion, and leakage. Too much post-dilatation may lead to complete heart block. These patients may require the implantation of a permanent pacemaker.


Disclaimer

The information given in this article is intended to increase awareness amongst the members of the public. It is not meant to be a substitute for textbooks, and/or clinical practice guidelines. Please contact your care-giver for advice regarding treatment.