Supravalvular aortic stenosis

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Supravalvular aortic stenosis
Synonyms	SVAS
Pronounce	N/A
Specialty	N/A
Symptoms	Heart murmur, chest pain, shortness of breath, syncope
Complications	Heart failure, aortic aneurysm, myocardial infarction
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in the ELN gene
Risks	Williams syndrome, family history
Diagnosis	Echocardiogram, MRI, CT scan
Differential diagnosis	Aortic stenosis, coarctation of the aorta, pulmonary stenosis
Prevention	N/A
Treatment	Surgical repair, balloon angioplasty
Medication	Beta blockers, ACE inhibitors
Prognosis	Variable, depends on severity and treatment
Frequency	Rare
Deaths	Dependent on severity and complications

Other Names: SVAS; Supravalvar aortic stenosis, Eisenberg type; Aortic supravalvular stenosis 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). A rare, congenital or acquired aortic stenosis characterized by localized or diffuse narrowing of the ascending aorta. 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.

Epidemiology

SVAS occurs in 1 in 20,000 newborns worldwide.

Cause

Mutations in the ELN gene cause SVAS. The ELN gene provides instructions for making a protein called tropoelastin. Multiple copies of the tropoelastin protein attach to one another and are processed to form a mature protein called elastin. Elastin is the major component of elastic fibers, which are slender bundles of proteins that provide strength and flexibility to connective tissue (tissue that supports the body's joints and organs). Elastic fibers are found in the intricate lattice that forms in the spaces between cells (the extracellular matrix), where they give structural support to organs and tissues such as the heart, skin, lungs, ligaments, and blood vessels. Elastic fibers make up approximately 50 percent of the aorta, the rest being primarily muscle cells called vascular smooth muscle cells that line the aorta. Together, elastic fibers and vascular smooth muscle cells provide flexibility and resilience to the aorta. Most of the ELN gene mutations that cause SVAS lead to a decrease in the production of tropoelastin. A shortage of tropoelastin reduces the amount of mature elastin protein that is processed and available for forming elastic fibers. As a result, elastic fibers that make up the aorta are thinner than normal. To compensate, the smooth muscle cells that line the aorta increase in number, making the aorta thicker and narrower than usual. A thickened aorta is less flexible and resilient to the stress of constant blood flow and pumping of the heart. Over time, the wall of the aorta can become damaged. Aortic narrowing causes the heart to work harder to pump blood through the aorta, resulting in the signs and symptoms of SVAS. Inheritance This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. However, some people who inherit the altered gene never develop features of SVAS. (This situation is known as reduced penetrance.) In some cases, a person inherits the mutation from one parent who has the mutation. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Signs and symptoms

Some people with SVAS also have defects in other blood vessels, most commonly stenosis of the artery from the heart to the lungs (the pulmonary artery). An abnormal heart sound during a heartbeat (heart murmur) can often be heard during a chest exam. If SVAS is not treated, the aortic narrowing can lead to shortness of breath, chest pain, and ultimately heart failure. The severity of SVAS varies considerably, even among family members. Some affected individuals die in infancy, while others never experience symptoms of the disorder. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Arrhythmia(Abnormal heart rate)
• Supravalvular aortic stenosis

Diagnosis

A heart murmur, click, or other abnormal sound is almost always heard through a stethoscope. The provider may be able to feel a vibration or movement when placing a hand over the heart. There may be a faint pulse or changes in the quality of the pulse in the neck.

• Blood pressure may be low.
• Aortic stenosis is most often detected and then followed using a test called a transthoracic echocardiogram (TTE).

The following tests may also be performed:

• ECG
• Exercise stress testing
• Left cardiac catheterization
• MRI of the heart
• Transesophageal echocardiogram(TEE)

Treatment

Regular checkups by a provider may be all that is needed if your symptoms are not severe. The provider should ask about your health history, do a physical exam, and perform an echocardiogram. People with severe aortic stenosis may be told not to play competitive sports, even if they have no symptoms. If symptoms do occur, strenuous activity must often be limited. Medicines are used to treat symptoms of heart failure or abnormal heart rhythms (most commonly atrial fibrillation). These include diuretics (water pills), nitrates, and beta-blockers. High blood pressure should also be treated. If aortic stenosis is severe, this treatment must be done carefully so blood pressure does not drop too far. In the past, most people with heart valve problems were given antibiotics before dental work or a procedure such as colonoscopy. The antibiotics were given to prevent an infection of the damaged heart. However, antibiotics are now used much less often before dental work and other procedures. Check with your health care provider to find out whether you need antibiotics. People with this and other heart conditions should stop smoking and be tested for high cholesterol. Surgery to repair or replace the valve is often done for adults or children who develop symptoms. Even if symptoms are not very bad, the doctor may recommend surgery based on test results. A less invasive procedure called balloon valvuloplasty may be done instead of or before surgery. A balloon is placed into an artery in the groin, threaded to the heart, placed across the valve, and inflated. However, narrowing often occurs again after this procedure. A newer procedure done at the same time as valvuloplasty can implant an artificial valve (transcatheter aortic valve replacement or TAVR). This procedure is most often done in patients who cannot have surgery, but it is becoming more common. Some children may need aortic valve repair or replacement. Children with mild aortic stenosis may be able to take part in most activities.

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NIH genetic and rare disease info

• NIH info on Supravalvular aortic stenosis

Supravalvular aortic stenosis is a rare disease.

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