Heart Valve Surgery
Some patients are born with defective heart valves that affect blood flow through the heart. In addition, infection, rheumatic fever and the aging process can damage healthy heart valves. Surgeons at GW Hospital are recognized nationally for their expertise in valvular surgery. They perform innovative valve repair and replacement procedures using advanced surgical techniques, valve devices and prostheses.
Minimally Invasive Valve Procedures
Surgeons at GW Hospital use an innovative minimally invasive technique — called port access — to repair or replace valves.
Like traditional bypass surgery, conventional valve surgery requires a major incision in the chest and separation of the breastbone. During a port-access procedure, however, surgeons leave the breastbone intact and access the heart through a small incision under the breast.
This approach can’t be used in all patients, but those who undergo minimally invasive surgery usually have shorter hospital stays, quicker recoveries and less scarring.
Port-access techniques also can be used to treat a patient who has both a valve defect and a tumor in the heart or a hole in the wall that divides the heart.
Basic anatomy of the Mitral valve
Mitral valve is a heart valve between the left atrium (upper chamber of the left heart) and the left ventricle (lower chamber of the left heart). It acts as a doorway for the blood to go from the left atrium to the left ventricle every time the heart beats. The mitral valve opens during diastole (the part of cardiac cycle when the heart relaxes) and allows oxygen rich blood from the lungs to flow from the left atrium to the left ventricle that gets filled with this oxygen rich blood in preparation to pump it to the rest of the body. When the left ventricle starts to contract during systole (the part of cardiac cycle when the heart pumps out the blood), the mitral valve closes so that the blood does not go backwards into the left atrium and the lungs.
Mitral valve is shaped as a parachute. The strings of the parachute are attached to the left ventricle muscle and as the left ventricular muscle contracts, the strings of this parachute are pulled down, hence closing the canopy of the parachute and preventing the blood from leaking backwards.
How does the mitral valve get leaky?
There are several causes for the mitral valve to become leaky. The mitral valve is a complex structure and its competency depends on not only the proper functioning of the mitral valve leaflets, it relies on the proper functioning of the left ventricle as well.
Any disease process that affects the mitral valve leaflets can lead to a leaky mitral valve. The most common cause of mitral valve insufficiency (leakiness) is myxomatous degeneration of the mitral valve. In this process, the mitral valve leaflets, which are normally very thin and pliable, become thickened. The strings (called the chordae) that are attached to the mitral valve leaflets at one end and left ventricular muscle at the other, become involved in the process as well, losing their elasticity. Over a period of time, they elongate and eventually break, affecting the closing mechanism of the mitral valve. As the part of the mitral valve that is affected does not have chordae attached to the leaflet anymore, the leaflet, instead of closing and preventing blood from leaking back into the left atrium, opens and allows the blood to leak back during systole. This leads to the mitral valve becoming ineffective in a process called mitral regurgitation.
Another cause of mitral regurgitation is the dysfunction of the left ventricle usually caused by lack of blood supply to the heart muscle due to coronary artery disease. The chordae of the mitral valve are attached to the papillary muscles which are an extension of the left ventricle. As the blood supply to the papillary muscles is affected, they become dysfunctional and the closing mechanism of the mitral valve is affected leading to mitral regurgitation.
If the left ventricle enlarges, that leads to enlargement of the mitral valve ring and hence the mitral valve leaflets cannot close against each other leading to a leaky mitral valve.
Infections (endocarditis) of the mitral valve can also lead to mitral regurgitation. Infections can lead to destruction of the mitral valve apparatus leading to mitral regurgitation.
What are the symptoms of mitral regurgitation?
- Shortness of breath after exertion that develops over the course of months or years
- Irregular heart rhythm can be the first sign of a leaky mitral valve
- High pulmonary (lung) artery pressures
Mitral valve repair
Mitral valve repair is the recommended operation for leaky mitral valves. Most leaky valves can be repaired using the patient’s own tissues. In the most common cause of mitral valve regurgitation, a part of the patient’s mitral valve leaflet, which is not working properly and has torn chordae, is cut out either in a triangular or a quadrangular fashion. The repair is completed using a ring that is either rigid (wire material covered with cloth) or a flexible ring.
Mitral valve replacement
For the mitral valves that cannot be repaired, replacement is another option. The mitral valve in those cases is replaced with an artificial valve. There are two types of mitral valve prosthesis that are used.
Bioprosthetic valves (Biological valves)
Bioprosthetic artificial valves are either bovine (cow) tissue or procine (pig) tissue valves. These valves are stitched in place using sutures.
The advantage of tissue valves is that they do not require patients to be on long term anticoagulation (blood thinning medications such as warfarin), reducing the risks patients face with blood thinning medications.
The disadvantage is their functional deterioration (structural valve deterioration) can lead to the valve not functioning properly and the patient requiring another operation to replace the malfunctioning artificial biological valve.
Mechanical valves (metal valves)
Mechanical valves are totally artificial valves that are made of a metal. These valves have a double disc in the center that opens and allows the blood to flow during diastole and close during systole.
The mechanical valves have a tendency to form thrombus (clots). These valves require the patient to be on life-long anticoagulation (blood thinners).
The advantage of a mechanical valve is that, typically, these valves last for the patients’ life time. There is a very low rate of structural valve deterioration with these valves.
The disadvantage of these valves is that the patients need to stay on life long anticoagulation.
Recuperation and precautions
Patients generally do not require a long recovery period after mitral valve surgery. The in-hospital stay is generally five to seven days and then patients are discharged home. At home, the patients are asked not to lift more than five pounds of weight for about eight weeks. On average, patients whose profession does not require lifting weight go back to work in a couple of weeks.