The heart has four valves that keep blood flowing in the correct direction. These valves are the mitral valve, tricuspid valve, pulmonary valve and aortic valve. Each valve has flaps (cusps or leaflets) that open and close once during each heartbeat. Sometimes, the valves do not open or close properly. If a valve doesn’t fully open or close, blood flow is reduced or blocked. If a valve does not close well and blood can flow in both directions, it is called regurgitation and may also need treatment.
Aortic Stenosis: The aortic valve is the valve between the left ventricle and the aorta. The heart pumps blood into the body through this valve. When this valve becomes narrowed (stenosis) and flow is restricted, pressure builds up in the left ventricle and left atrium. With time, this will get worse. With medications, symptoms can be controlled, but ultimately this valve will need to be replaced.
Historically, rheumatic fever was the most common cause of aortic valve stenosis. However, with antibiotics, rheumatic fever has become very rare. These days, some people have aortic stenosis because congenitally the valve is malformed with only two leaflets (bicuspid) instead of the normal three. With time this valve gets stenotic. However, the most common reason now is age-related. With age, calcium and scarring damage the valve and narrow it. About 20% of older Americans develop aortic stenosis. Symptoms don’t develop until the patient is 70-80 years old, and often patients can be asymptomatic for awhile. As the aortic valve opening is narrowed, the heart has to work harder to pump enough blood into the aorta and the body. The extra work of the heart can cause the left ventricle to thicken and enlarge. Eventually the strain can cause a weakened heart muscle and can ultimately lead to heart failure and other serious problems.
Most often, patients may have a heart murmur that is heard by their doctor. An echocardiogram may determine if, indeed, the aortic valve is thickened and narrowed. The valve narrowing may be classified as mild, moderate or severe. If severe, a determination will have to be made if it is symptomatic. Sometimes patients may not be symptomatic but, since they are not active, may be masking their symptoms. In these patients, it may be necessary to unmask any symptoms by stress testing. Untreated or undiagnosed, the heart function may also start to decline.
Symptoms are chest pain, shortness of breath or passing out. Once symptomatic, it is critical that surgery be planned as quickly as possible. The risk of dying once symptomatic goes up. Surgical aortic valve replacement (SAVR) has been the standard for a long time. The valve can be replaced with a mechanical valve or with a biological (made of tissue) valve. The former lasts longer but requires lifelong anticoagulation, with Coumadin.
Since a lot of patients with aortic stenosis now are older and more frail with other conditions, open surgery has been risky. Many patients have bad lung disease, cancer and/or poor exercise capacity. Most of these patients would not have been candidates for surgery. Now we have technology that permits this valve to be replaced percutaneously, like a stent. The TAVR approach (Transcatheter Aortic Valve Replacement) delivers a fully collapsible replacement valve to the valve site through a catheter. The new valve is placed inside the diseased one. Originally, it was done only in patients at high risk. Now it is approved for severe stenosis in patients with moderate and even low risk.
Since this is a catheter-based technique, it is done by a combination of interventional cardiologists and cardiac surgeons. Usually, in most hospitals, the case is discussed by a team of interventional cardiologists, surgeons, and other cardiologists detailing risk and why the patient is too high a risk for open surgery. A CT scan is done to assess vascular anatomy and the size of the valve to be placed. A heart catheterization is also done to assess any blockages present, too. Since this is done like a complex stent procedure, the patient usually can go home in 24-48 hrs.
So in summary, patients with high or prohibitive risk for surgery can be looked at for possible TAVR. In patients who are not high risk, if younger than 65 years, surgical replacement would be recommended. If over 65, a decision can be made based on risk factors.