Mitral valve replacement refers to the surgical process of replacing the damaged mitral valve of the heart with either a mechanical or biological tissue valve. For some patients who experience mitral valve disorders such as mitral stenosis or mitral regurgitation replacement of the faulty valve is the only option available once it has been deemed irreparable by the physician. In such cases mitral valve replacement is done, the procedure being either done robotically or manually.
Mitral valve replacement is necessary when the valve is no longer competent at controlling the direction of flow of blood and when it does not open or close completely. In the case of mitral stenosis, the valve is narrowed blocking the proper flow of blood into the heart leading to blood being static in the heart and causing pressure to build up in the lungs. This may cause blood to leak backward into the lungs and the heart has to do more work and pump harder in order to get all the blood flowing. This is known as volume overload and in the long run it leads to heart failure.
The damaged valve is replaced by either of two types of valves, a metal or mechanical valve and a biological valve or a tissue valve. The main advantage of the metal valve is that it will last a lifetime but the patient has to constantly take blood thinning medication to prevent the blood from clotting as metal surfaces are likely surfaces for blood to clot easily. The biological valve on the other hand is made of animal tissue and does not require the patient to take any blood thinning medication but the main drawback is that its life period is only about 10-15 years.
The patient is first given anesthetic and temporarily put to sleep for the length of the surgery. An incision is made under the left breast and the heart is exposed. The blood from the heart is rerouted to a heart-lung machine which temporarily performs the heart’s function. This machine is also called a cardiopulmonary bypass. Then an incision is made on the left atrium to expose the mitral valve. The faulty valve is replaced and the heart is closed with sutures. After that the patient is taken off the cardiopulmonary bypass and the blood is allowed to flow into the coronary arteries. Sometimes an electric shock is given to the heart if it fails to beat on its own and the incision on the chest is closed.
Patients undergoing mitral valve replacement are susceptible to the following risks. Bleeding, infection, complex reaction to anesthetic. The risk involved in most cases can be determined by the physician and it depends on a variety of factors such as the patient’s age, general condition, specific medical problems and heart functions.
The mortality rate associated with mitral valve replacement is less than 5% in young healthy patients. The risk of death increases with age and associated medical conditions like pulmonary hypertension. In that case the risk rises to about 10-20%. After the procedure more than 80% of the patients have carried on normally for at least 5 years. Older patients above 75 years of age have less predictable outcomes from the procedure.