Supravalvular aortic stenosis (SVAS) is a heart defect present at birth. It involves a narrowing of the aorta, the body’s main artery, located just above the aortic valve. This narrowing restricts blood flow from the heart to the rest of the body, similar to a kink in a garden hose impeding water flow. SVAS accounts for about 8% to 14% of all congenital aortic stenosis cases. The condition can manifest in different forms, including an hourglass shape, a membranous structure, or a more diffuse hypoplasia of the aortic arch.
Causes and Genetic Links
The underlying cause of supravalvular aortic stenosis often involves genetic factors. Most notably, SVAS is a characteristic finding in individuals with Williams syndrome. This syndrome results from a microdeletion on chromosome 7, specifically in the 7q11.23 region, which includes the elastin gene (ELN). The elastin gene provides instructions for producing elastin, which gives tissues like the aorta their elasticity and resilience.
A shortage of functional elastin leads to thinner and less flexible elastic fibers in the aortic wall. The smooth muscle cells lining the aorta may increase in number, causing the artery wall to become thicker and narrower. This structural change contributes to the stiffening and obstruction of blood flow. SVAS can also occur as an isolated condition, either inherited within families (autosomal dominant) or appearing sporadically without a clear family history or other features of Williams syndrome.
Recognizable Symptoms
A common sign of supravalvular aortic stenosis detected by a doctor is a heart murmur, an extra sound heard during a heartbeat. This murmur is typically systolic and may be heard most clearly at the first intercostal space on the right side. Patients or parents might observe other symptoms, particularly as the narrowing becomes more pronounced. These can include shortness of breath and feelings of chest pain or tightness.
Fatigue is another common complaint. In more severe instances, individuals might experience fainting spells due to insufficient blood flow to the brain. Many individuals with mild forms of SVAS, however, may not exhibit any noticeable symptoms and the condition is only discovered during a routine medical examination.
The Diagnostic Process
Medical professionals use several methods to confirm a diagnosis of supravalvular aortic stenosis. The primary tool is an echocardiogram, often referred to as a cardiac ultrasound. This non-invasive test uses sound waves to create detailed images of the heart and its surrounding blood vessels, allowing doctors to visualize the narrowed segment of the aorta and measure the speed and direction of blood flow through it.
Other tests provide additional information to support the diagnosis and assess overall heart health. An electrocardiogram (ECG or EKG) checks the heart’s electrical activity, which can show signs of the heart working harder, such as left ventricular hypertrophy. A chest X-ray provides an image of the heart’s size and shape, though it might appear normal in mild cases. For more detailed anatomical assessment, especially before surgical planning, a cardiac MRI or cardiac catheterization may be performed to obtain precise images and measure pressures within the heart and aorta.
Treatment Approaches
Treatment for supravalvular aortic stenosis varies based on the severity of the narrowing and the presence of symptoms. For individuals with mild SVAS who are asymptomatic, active intervention may not be immediately necessary. Instead, these patients typically undergo regular monitoring by a cardiologist to track the progression of the condition and watch for any changes.
When symptoms arise or the narrowing is more significant, medications may be prescribed to manage specific issues. Beta-blockers can help reduce the heart’s workload and manage high blood pressure, while calcium channel blockers might alleviate chest pain. However, these medications do not correct the physical narrowing of the aorta itself; they only address the symptoms that result from it.
Surgical intervention is the definitive treatment for moderate to severe cases of SVAS. A common procedure is patch angioplasty, where a surgeon widens the constricted section of the aorta using a patch of synthetic material or the patient’s own tissue, such as pericardium. This patch is carefully sewn into place to enlarge the vessel’s diameter, restoring a more normal blood flow. Various surgical techniques exist. The goal of surgery is to relieve the obstruction, prevent long-term heart damage, and improve the heart’s efficiency.
Living with Supravalvular Aortic Stenosis
After successful surgical repair for supravalvular aortic stenosis, most individuals can anticipate leading full and active lives. Despite successful intervention, lifelong follow-up care with a cardiologist specializing in congenital heart defects remains highly recommended.
These regular check-ups allow medical professionals to monitor the heart’s health, assess the site of the repair for any potential recurrence of narrowing, and address any related issues. Individuals with a history of SVAS, particularly after surgical repair, may have an increased risk of infective endocarditis, a rare but serious infection. Therefore, maintaining good dental hygiene and discussing the need for antibiotic prophylaxis with their doctor before certain dental or surgical procedures is a common recommendation to minimize this risk.