Obstructions to the Left Side of the Heart
The aortic valve is the outlet valve from the left side of the heart. It usually forms with 3 leaflets but can form abnormally with only one or two leaflets. Some of these abnormal valves are too small or stenotic when a baby is born. This results in reduced blood flow into the aorta and consequently less oxygen and blood supply to the body.
Aortic valve stenosis can cause the left side of the heart to develop abnormally and may be diagnosed on a prenatal scan. After birth, a heart murmur may be detected when listening to the heart. A baby with this condition may be breathless, pale, sleepy, sweaty and difficult to feed.
Narrowing of the aortic valve (aortic valve stenosis) may be treated by stretching the valve, using a balloon placed through a small catheter in the leg artery in the first days or weeks of life. In many cases, later in life the aortic valve will then eventually need to be replaced. This can occur in infancy, childhood or adulthood. It is performed during open-heart surgery where the heart is temporarily stopped and its function is carried out by a heart-lung machine. The aortic valve is replaced using either an artificial valve (older children, adults) or the child’s own pulmonary valve (infants, babies, children and adults). Replacement of the aortic valve with the child’s own pulmonary valve is called a Ross procedure and necessitates replacement of the pulmonary valve with a donated or artificial valve that will itself eventually need replacement. The benefit of the Ross procedure is that the new aortic valve will grow with the child and may not need replacement in the future.
Your child will usually spend about 7-10 days in the hospital. Most children are active in a few days although complications may occasionally arise. Following discharge, periodic visits are necessary to evaluate valve function.
A fibrous narrowing or membrane can form just beneath the aortic (outlet) valve on the left side of the heart. This can obstruct blood flow out of the heart resulting in a murmur and can sometimes cause leakage of the aortic valve. Most children do not have symptoms despite significant narrowing below the aortic valve. However, subaortic stenosis eventually leads to thickening of the muscle in the left ventricle and leakage of the aortic valve, both of which are reasons for surgery to remove the narrowing and preserve aortic valve function.
Surgery involves use of the heart-lung machine to support the heart while the aorta is opened and the subaortic area and aortic valve are inspected. The fibrous membrane (similar to scar tissue) is carefully removed and a section of muscle from the outlet region of the left heart is excised to prevent the membrane from forming again. The aortic valve leaflets may be thinned if necessary and the aorta is then closed. In many cases this fixes the problem however, in about 10% of cases, a further procedure may be required in the subsequent years as the membrane and narrowing can recur. The stay in hospital after the procedure is about 5-7 days including 1-2 days in the intensive care unit.
Narrowing of the aorta can occur just above the outlet valve from the left heart and is called supravalvar (above-the-valve) aortic stenosis. This is a rare abnormality often associated with a condition called William syndrome.
Supravalvar aortic stenosis does not usually produce symptoms but causes thickening of the muscle in the left ventricle that may eventually be life-threatening. For this reason surgery to relieve the narrowing is recommended. The narrowing can also involve the heart arteries and lung arteries. When associated with William syndrome, it may be identified during infancy or before birth with fetal echocardiography.
Surgical repair of this abnormality involves suturing patches in the aorta to enlarge the narrowed area and relieve the obstruction. This involves open heart surgery and use of the heart-lung machine to support the circulation. When the narrowing occurs over a long segment of the aorta, a synthetic graft may be used to reconstruct the aorta in older children, teenagers and adults. About 5-10% of children who require surgery for supravalvular aortic stenosis will require further heart surgery later in life, most often for abnormal function of the aortic valve. Therefore lifelong follow-up with a cardiologist is recommended following repair.