The aortic valve sits between the heart's main pumping chamber, the left ventricle, and the body's major artery, the aorta. The valve's job is to keep blood from falling back into the left ventricle after a contraction pushes blood out into the aorta.
Aortic stenosis is a condition in which the aortic valve becomes stiff, its opening becomes narrowed, and the valve gets in the way of the smooth flow of oxygen-rich blood out of the heart and into the aorta, and from there to the rest of the body.
Causes of aortic stenosis
There are three main causes of aortic stenosis:
The aortic valve is normally made up of three sections called leaflets. Some people are born with two leaflets in the aortic valve, not three. This usually doesn't pose a problem in childhood. Later in life, though, the leaflets can stiffen to the point where the valve can't open fully.
Another cause of aortic stenosis is degeneration of the aortic valves later in life.
The third cause is rheumatic fever. Once common in the United States and other developed countries, rheumatic fever has become rare in developed countries due to improved sanitation and living conditions. But it is still common in developing countries.
In each type of aortic stenosis, more and more scar tissue builds up on the valve, making the valve less able to open. Because the left ventricle is pumping against increasing resistance, it must work harder. As a consequence, the muscle of the left ventricle becomes thicker and thicker.
Symptoms and consequences of aortic stenosis
Aortic stenosis does not cause symptoms for many years. When it does, symptoms include:
- feeling short of breath, especially after exertion
- fatigue or feeling tired after physical activity
- chest pain as the heart works overtime to pump blood through the faulty valve
- heart palpitations
- fainting spells
- a heart murmur that can be heard through a stethoscope
Once symptoms develop, the outlook for aortic stenosis is not good; 75% of people with the condition die within a few years if they don't get proper treatment.
Over time, an overworked left ventricle can weaken. This can lead to heart failure.
Diagnosing aortic stenosis
Aortic stenosis is usually diagnosed when a doctor listens to the heart with a stethoscope. He or she hears a "whooshing" sound called a murmur as blood flows backward from the aorta to the left ventricle.
An echocardiogram is very helpful in making the diagnosis and in determining how severe the condition is.
Your doctor will monitor your condition with regular echocardiograms. When your left ventricle shows signs of enlarging, when your heart is no longer pumping with full force, it's time to consider treatment even if you have no symptoms.
Treating aortic stenosis
The only way to truly fix the problem is by repairing or replacing the damaged valve. Medications can't slow or reverse aortic stenosis. Medications may be used to control symptoms, such as a diuretic ("water pill") to reduce fluid accumulation, or a beta blocker to slow the heart rate.
Surgery was once the only way to replace the aortic valve. With an experienced surgical team, the risks of surgery are low and the development of future symptoms is prevented. If you put off the surgery until you develop symptoms or until the heart shows signs of failing, the results of surgery may not be as good.
For people who can't tolerate open-heart surgery, a less invasive procedure is now available. It is called transcatheter aortic valve replacement. A thin tube called a catheter carries the replacement valve. Catheter and valve are inserted into the artery at the top of the thigh and gently maneuvered into the opening between the heart and the aorta. Once in place, the device expands and anchors the new valve inside the old one. The replacement valve takes over, helping blood flow freely from the heart to the rest of the body.
In some cases, a catheter with a balloon is maneuvered into the aortic valve and the balloon is opened. This widens the aortic valve, but doesn't yield permanent results.