Aortic stenosis is a narrowing of the aorta, often caused by congenital malformations or calcification of the valve. It can cause hypertrophy, regurgitation, and damage to growth and brain development. Treatment includes balloon valvuloplasty, valve replacement with mechanical or pig valves, or the Ross procedure. Lifelong observation by a cardiologist is required, and patients should take antibiotics before dental procedures. Surgery can lead to a normal life.
Aortic stenosis is a narrowing of the aorta, the artery connected to the left ventricle of the heart, through which oxygenated blood flows back to the body. The most common cause of aortic stenosis is congenital, present at birth. However, rheumatic fever can also cause aortic stenosis, and aging has been linked to calcification of the aortic valve, causing it to narrow.
In many cases of aortic stenosis, the aortic valve is formed improperly. In the normal heart, the aortic valve has three flaps, which open when the left ventricle pumps blood into the aorta. Malformations of this valve can fuse the leaflets together, or can result in only two leaves or cusps, called a bicuspid aortic valve. Any malformation of the cusps is called valvular aortic stenosis.
A more severe form of valvular aortic stenosis involves both fused leaflets and an underdevelopment of the tissue under the valve, further impeding blood flow to the lungs. Subvalvular aortic stenosis almost always requires immediate surgery. Narrowing may also exist above the valve, called supravalvular aortic stenosis. Mild, trivial aortic stenosis can be left untreated, but visits to a pediatric cardiologist are necessary to make sure the valve is growing properly and to assess whether the stenosis is getting worse. Severe or critical aortic stenosis usually requires surgery.
With a narrowing aorta, the left ventricle has to pump much harder to get blood to the body. While the left ventricle is a strong muscle, if it works too hard, the muscle will harden and begin to widen, a condition called hypertrophy. Hypertrophy can eventually damage the ventricle and cause impaired function. The aorta valve can also leak, causing some blood to flow back into the heart with each pump. This regurgitation can cause hypertrophy and fluid retention.
Less blood going to the body means the tissues are not getting enough oxygen. Over time, untreated aortic stenosis can damage growth, causing clubbing of the extremities and affect brain development. It can also cause exhaustion, fainting and dizziness.
There are essentially three ways to treat aortic stenosis. Balloon valvuloplasty can be used to treat mild aortic stenosis. A catheter with a balloon attached is threaded into the heart. In the aorta, the balloon is inflated to try to open the valve. This treatment can temporarily cause the aorta to open wider and, in mild cases, can cure the condition. Its advantages are that it is a minimally invasive outpatient procedure.
Often, balloon valvuloplasty does not provide the desired results or gradually the aorta becomes stenotic again. In these cases, surgeons recommend valve replacement. There are two substitution techniques.
In the first, the surgeon removes the aortic valve and replaces it with a mechanical or pig valve. Mechanical valves work very well, but have the disadvantage that they contain a much higher risk of blood clotting. Most people with a mechanical valve must take warfarin, a blood thinner.
In children, warfarin can be particularly problematic because children are prone to accidents. Warfarin levels are measured so as not to cause excessive bleeding. This can mean several months of weekly blood tests, as well as dietary changes. Even with monitoring, the risk of excessive bruising and bleeding increases. Even a simple bump to the head can cause a concussion.
The Ross procedure is often preferred to mechanical valve replacement. This surgery removes the pulmonic valve and aortic valve and uses the pulmonic valve to replace the aorta. The pulmonic valve must be replaced by a pig valve or a donor valve. The advantage of this procedure, besides avoiding the mechanical valve, is that the new aortic valve has a chance to grow and develop normally. Although the new pulmonary valve will likely need to be replaced at some point, this is considered a much simpler surgery than aortic replacement.
All levels of severity of aortic stenosis require lifelong observation by a cardiologist. Even in less severe cases of aortic stenosis, patients should take antibiotics before dental exams and procedures to reduce the risk of bacterial endocarditis. Mild to moderate aortic stenosis can limit activity, especially in competitive sports, although occasional participation in recreational sports is acceptable. A patient’s cardiologist will have specific recommendations about what activities can be done. With surgery, a patient with aortic stenosis has a very good chance of living a normal and purposeful life.
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