Aortic Valve Replacement (AVR)
The aortic valve is the most commonly operated valve in the heart. The aortic valve allows flow out of the heart, and prevents blood from coming back into the heart. The valve can either leak, called aortic insufficiency that allows blood back into the heart, or not open well – a condition call stenosis. Most aortic valve operations are done for aortic stenosis associated with aging. Aortic stenosis prevents blood from flowing easily from the heart out to the body and puts an added workload on the heart leading to thickening of the heart muscle. Often even severe aortic stenosis can have no symptoms. When present, symptoms can include shortness of breath, fatigue, and passing out. Once symptoms are present, over half of patients will die within two years without treatment.
Treatment of aortic valve disease, whether stenosis or insufficiency, involves the removal of the native aortic valve and placement of a prosthetic valve. This can be done using a minimally invasive approach if aortic valve replacement is the only procedure required. Minimally invasive approaches can include a partial division of the breastbone, or an approach between the ribs. If coronary bypass or other procedures are required at the time of surgery, then a standard incision through the breastbone is required.
Mitral Valve Repair/Replacement (MVR)
The mitral valve is between the lungs and the main pumping chamber of the heart, the left ventricle. In rheumatic heart disease the valve typically closes slowly over time resulting in restriction of flow into the heart. This is also often associated with leakage from the valve. Mitral valve disease leads to shortness of breath, fatigue, irregular heart rhythms, and high blood pressure in the lungs. In rheumatic mitral valve disease, the valve usually cannot be repaired and requires removal and replacement with a prosthetic valve.
Mitral valve prolapse and degenerative mitral valve disease leads to leakage of the mitral valve. When the mitral valve leaks, blood is pushed backwards into the lungs with each heartbeat resulting in shortness of breath, fatigue, and eventually irregular heart rhythms and high blood pressure in the lungs. Over time, congestive heart failure develops. Fortunately, the mitral valve can typically be repaired in degenerative mitral valve disorders. Mitral valve repair restores the function of the mitral valve and preserves the function of the heart.
Mitral valve surgery can be accomplished without dividing the breastbone by working through the ribs on the right side of the chest. Both valve repair and, if necessary, valve replacement can be done using this approach. If coronary bypass or other procedures are required, however, a minimally invasive approach cannot be utilized.
Prosthetic Heart Valve Choices
There are two basic types of heart valves that can be implanted – mechanical valves and tissue valves. There is not one option that is right for all patients. You should have an open discussion with your surgeon about the advantages and disadvantages of each option for your particular situation. Mechanical heart valves are made from carbon and have the advantage of being very durable and not wearing out over time. However, they have the disadvantage of requiring blood thinner medication for life to prevent the formation of blood clots on the valve. Tissue valves are made from the tissue from the sac around the heart from a cow (bovine pericardium), or the actual heart valve from a pig (porcine valve). The living cells are removed during processing so there is no rejection of tissue valves. Since they are made from natural tissue, tissue valves have the advantage of not requiring blood thinners, except aspirin. Unfortunately, tissue valves have a limited lifespan, lasting approximately 15-25 years depending on a variety of factors, including the age of the patient at the time of implantation.
In general, mechanical heart valves are favored for younger patients while older patients choose tissue valves. Patients receiving mechanical heart valves require life-long blood thinners (anticoagulation). Blood tests are required one to two times a week to check anticoagulation levels initially, and approximately two to three times a month once a regimen as been established. Anticoagulation can be managed quite well by most patients and has a low annual risk of significant bleeding. For patients choosing tissue valves, aspirin is recommended but no further anticoagulation is necessary. Since tissue valves can wear out over time, your cardiologist will monitor the function of your valve with echocardiograms. If a tissue valve does wear out and need to be replaced, this can be done with another operation, or can be done with a catheter delivered valve in some cases.