The dangers of aortic valve disease, or aortic stenosis (AS), have gained public attention by recent reports that 83-year-old former first lady Barbara Bush received an aortic valve replacement and that 57-year-old comedian Robin Williams will probably have similar surgery in the future.
The aortic valve is located between the aorta and the left ventricle, the largest pumping chamber, or ventricle, of the heart. When this ventricle contracts, the aortic valve opens to allow blood to enter the aorta, the largest artery in the body and the one that carries blood to all of the body except the lungs. AS means that this valve is narrowed and can no longer open as widely as it once did; if severe, this narrowing can limit the amount of blood sent into the aorta, thus forcing the left ventricle to pump harder in order to move the requisite volume of blood through the valve.
Although aortic valve disease can be a late complication of rheumatic fever, in the U.S. aortic stenosis is now most often due to calcium deposits in the valve that keep it from opening fully. An inherited abnormal valve—one with 2 cusps ["bicuspid"] on the valve instead of the normal 3 cusps—is more likely to calcify, and at an earlier age, than is a normal valve. As we age, this calcification is more often the result of degeneration of a normal valve during a process similar to that which causes atherosclerosis.
People with mild-to-moderate AS may never have had any symptoms, but over a prolonged period, as the obstruction gradually worsens, they will start noticing some. Common symptoms are shortness of breath on exertion, angina (chest pain with activity), and episodes of loss of consciousness (referred to as syncope) or dizziness. (Most people with angina do not have AS, which is only suspected when a typical heart murmur is detected.)
Shortness of breath and angina are both consequences of the extra exertion required of the left ventricle, and this greater workload leads to enlargement (hypertrophy) of the ventricle. The enlarged ventricle then requires a larger blood supply than can be carried by the coronary arteries. Dizziness and syncope are caused by inadequate blood flow to the brain.
Once even mild symptoms develop, surgical intervention is needed promptly because the average survival time without valve replacement is then only 2 to 3 years, and there is a high risk of sudden death due to a heart-rhythm disturbance.
A calcified aortic valve can be replaced with either an artificial mechanical valve or a biologic tissue valve. You should discuss both of these options, and their pros and cons, with your surgeon before the procedure. And, as is usually the best practice, you should try to choose a surgeon who has done many of these operations.
Surgery for aortic valve replacement is a difficult, open-heart procedure. In more than 1,200 patients who underwent aortic valve replacement at Methodist Hospital in Texas, for example, the mortality rate during and shortly after surgery was 6 percent in those over the age of 80, and 4 percent in younger patients.