Supravalvular aortic stenosis

Aortic valve stenosis (AVS) is a condition characterized by narrowing of the heart's aortic valve opening. This narrowing prevents the valve from opening fully, which obstructs blood flow from the heart into the aorta, and onward to the rest of the body.^[1] AVS can range from mild to severe. Signs and symptoms typically develop when the narrowing of the opening is severe and may include chest pain (angina) or tightness; shortness of breath or fatigue (especially during exertion); feeling faint or fainting; heart palpitations; and heart murmur.^[1][2] Individuals with less severe congenital AVS (present at birth) may not develop symptoms until adulthood. Individuals with severe cases may faint without warning.^[2] The condition can eventually lead to heart failure. AVS can have several causes including abnormal development before birth (such as having 1 or 2 valve leaflets instead of 3); calcium build-up on the valve in adulthood; and rheumatic fever. Treatment may include medications to ease the symptoms, but surgery to repair or replace the valve is the only way to eliminate the condition.^[1]

Aortic valve stenosis can be congenital (present at birth) or can develop later in life. When the condition is congenital, it is typically due to abnormal development of the aortic valve - either it forms abnormally narrow, or it is made up of one flap or leaflet (called a unicuspid valve, which is very rare) or two leaflets (bicuspid valve) instead of the usual three. Having a bicuspid valve can run in families. A bicuspid valve may not cause any problems until adulthood, when the valve begins to narrow or leak. In most cases, the exact underlying cause of congenital aortic valve stenosis is unknown.^[1] Aortic valve stenosis can also be caused by the buildup of calcium deposits on the heart valve with increasing age. This cause is most common in people older than 65. Rheumatic fever can also cause the condition because it may result in scar tissue forming on the valve, causing the leaflets to stiffen and fuse. Rheumatic fever can also cause a rough surface on the valve, which can lead to accumulation of calcium deposits later in life.^[1]

Supravalvular aortic stenosis (SVAS) is a type of heart defect that develops before birth. It is characterized by a narrowing (stenosis) of the section of the aorta just above the valve that connects the aorta to the heart (aortic valve). The severity of SVAS varies from person to person; some individuals may die in infancy while others never experience symptoms. If symptoms develop, they may include shortness of breath, chest pain, murmur, and/or eventual heart failure. Some affected individuals also have defects in other blood vessels, such as the pulmonary artery. SVAS can be caused by mutations in the ELN gene and be inherited in an autosomal dominant manner, although some individuals that inherit the mutated gene never develop features of the condition (called reduced penetrance). SVAS can also be associated with Williams syndrome. Treatment may include surgery to repair the condition in severe cases.^[3][4]

Aortic valve stenosis (AVS) is not usually associated with malformations outside the heart, although it can sometimes occur with other abnormalities and/or be part of several syndromes.^[5] It is often associated with the presence of a unicuspid or bicuspid aortic valve (the presence of 1 or 2 valve leaflets instead of the usual 3). Bicuspid aortic valve (BAV) is now believed to be the most common congenital heart defect with a prevalence of 1-2% in the general population.^[6] Although BAV is usually an isolated defect, it may be associated with other cardiovascular syndromes or abnormalities with at least a third of affected individuals likely to develop serious complications that will eventually require valve surgery.^[6] Studies have suggested that BAV can be inherited in an autosomal dominant pattern, although whether it is present, and how severe the defect is, can vary among family members.^[7][6] BAV is a common congenital heart defect in individuals with a chromosomal disorder called Turner syndrome, but most individuals with BAV do not have Turner syndrome.^[7] A single, specific genetic cause of aortic valve stenosis (AVS) has not been identified.^[7]

Some fetuses diagnosed with AVS will eventually progress to having hypoplastic left heart syndrome (HLHS).^[8] Those with severe AVS can also develop endocardial fibroelastosis, depending on the time of onset during fetal development.^[9]

Supravalvular aortic stenosis (SVAS) can either be isolated or can occur as part of Williams syndrome. Isolated SVAS can be caused by mutations in the ELN gene and may be inherited in an autosomal dominant manner.^[10][11] Some individuals with SVAS have associated abnormalities such as peripheral pulmonary artery stenosis.^[12] Individuals with Williams syndrome have a deletion of the region of chromosome 7 that normally contains the ELN gene.^[10][11]

Aortic stenosis has also been reported in individuals with other disorders including Alagille syndrome and Shone's complex.^[13][5]

Individuals interested in learning more about the syndromes or abnormalities that may be associated with aortic stenosis in a fetus should speak with a perinatologist, cardiologist and/or genetics professional.

Assisted reproductive technology (ART) is known to be associated with an increase in the overall risk of congenital anomalies. However, little specific information exists on the risk of congenital heart defects (CHDs) for fetuses conceived following ART.^[14] Although some studies have reported a increased frequency of CHDs in general in IVF pregnancies, this may be due, in part, to an increased frequency of multiple gestation pregnancies (such as twins or triplets) seen among these individuals, as multiple gestation pregnancies are at increased risk for congenital abnormalities.^[15] We were unable to find evidence that aortic stenosis specifically has been associated with ART.

Aortic valve stenosis (AVS) is not usually associated with malformations outside the heart, although it can sometimes occur with other abnormalities and/or be part of several syndromes or chromosome abnormalities.^[5] Further testing for a fetus with AVS often depends on the severity of the condition, whether other abnormalities are detected, and the nature of other abnormalities that are detected. Examples of types of testing that may be available include ultrasounds, amniocentesis to detect a chromosome abnormality or to look for a specific genetic disorder, and/or fetal echocardiogram to monitor and/or look for any other cardiac abnormalities. Individuals interested in further testing for a fetus diagnosed with aortic stenosis should speak with a perinatologist, pediatric cardiologist and/or genetics professional.

We were unable to locate information about a known association between congenital aortic stenosis and the presence of intrauterine growth restriction (IUGR) and ambiguous genitalia in the family history. It is possible for each of these to occur as isolated abnormalities or they can be associated with a variety of syndromes or other causes of birth defects (either alone or in combination).

There are many factors that influence the recurrence risk of congenital abnormalities, including the nature of the abnormalities and the underlying cause. Congenital abnormalities can be inherited in a specific manner, can be due to an exposure during pregnancy, or can occur sporadically by chance. Unfortunately, in some cases the cause and recurrence risk are unknown. If the congenital abnormalities are known to be associated with a specific underlying condition that was diagnosed, the recurrence risk for associated abnormalities might be that of the specific condition.

Recurrence risks also depend upon whether a subsequent pregnancy is conceived with an egg and sperm from the same individuals as in the previous pregnancy. For example, if congenital abnormalities are due to an autosomal recessive genetic condition, the risk for the same two parents to have an affected child with each pregnancy would be 1 in 4 (25%). However, if the pregnancy is achieved with a different partner, the risk for recurrence would likely be significantly reduced. Likewise, if an affected pregnancy is conceived with egg or sperm donation, estimated recurrence risks in a subsequent pregnancy might depend on whether the same egg and/or sperm donors were used.

Unfortunately, we are unable to estimate the recurrence risk for congenital abnormalities because each situation is different. We recommend speaking with a genetics professional for individuals interested in obtaining a personal risk assessment.

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.