Supravalvular Aortic StenosisEdit
Supravalvular aortic stenosis (SVAS) is a congenital narrowing of the aorta that sits just above the aortic valve. This lesion can be isolated or occur as part of broader syndromic conditions, most notably Williams syndrome, where deletions affecting the elastin gene disrupt normal arterial development. SVAS places a fixed, high afterload on the left ventricle, often leading to left ventricular hypertrophy and, if untreated, progressive heart failure or myocardial ischemia from impaired coronary perfusion. The condition is uncommon, but its implications for growth, exercise tolerance, and survival make accurate diagnosis and careful management essential.
SVAS is best understood in the broader context of congenital heart disease and aortic disease. In isolated cases, the narrowing tends to be focal and may involve the ascending aorta or the region near the coronary arteries. In syndromic cases, such as Williams syndrome, a dose‑dependent defect in elastin results in diffuse arterial stenoses that can complicate repair and require long‑term surveillance of the entire aorta and major branches. For those studying the condition, the relationship between genetic variation at the elastin locus ELN and vascular architecture is a central theme, with measurable consequences for surgical planning and long-term outcomes. The aorta itself and the heart are central to the physiology of SVAS, and patients are typically evaluated with attention to the organization of the great vessels and the left ventricle aorta; left ventricular hypertrophy is a common consequence of the elevated afterload.
Etiology and genetics
Most SVAS cases arise sporadically, but a substantial minority are associated with genetic conditions that affect arterial elasticity. The most well-characterized association is with Williams syndrome, caused by deletions on chromosome 7q11.23 that disrupt the elastin gene ELN and related pathways. This genetic basis explains why many patients with SVAS also show other vascular anomalies and a characteristic neurodevelopmental profile. In isolated SVAS, the disease is usually due to localized abnormalities in the inner lining (intima) and medial layers of the supravalvular aorta, producing concentric narrowing without broader diffuse involvement. Genetic counseling and family history can be informative in planning surveillance for relatives and in anticipating potential additional vascular lesions elsewhere in the arterial tree elastin.
Pathophysiology
The primary physiologic effect of SVAS is an increase in aortic afterload. The narrowed segment creates a pressure gradient between the left ventricle and the aorta, forcing the left ventricle to generate higher systolic pressures to maintain systemic blood flow. Over time, this results in left ventricular hypertrophy and, if left unaddressed, can impair diastolic filling and coronary perfusion. In syndromic forms, diffuse arterial involvement can complicate the picture, increasing the risk of ischemia not only from LV pressure overload but also from altered coronary flow patterns near the ostia of the coronary arteries. Comprehensive imaging often reveals additional vascular anomalies that influence both symptoms and strategy for repair aorta; coronary ostia may be affected in ways that require careful surgical planning.
Clinical features
Presentation depends on age at diagnosis and the severity of the obstruction. Infants with SVAS may exhibit poor feeding, tachypnea, sweating with exertion, or failure to thrive, reflecting heart‑lung inefficiency. Older children and adults with milder disease may have exertional dyspnea, chest discomfort, or reduced exercise tolerance. A systolic murmur, typically best heard at the right upper sternal border, can be present, but the noise may be subtle if the obstruction is not hemodynamically significant. Because SVAS can coexist with other vascular lesions, clinicians watch for signs that suggest broader involvement, such as discrepancies in limb pulses or unexpected hypertension, and they evaluate for associated conditions like mutational or chromosomal disorders linked to elastin ELN.
Diagnosis
Diagnosis rests on imaging that defines anatomy and hemodynamics. Transthoracic echocardiography is usually the first test, providing a view of the supravalvular aorta, measurement of the velocity through the narrowed segment, and assessment of left ventricular size and function. When necessary, cardiac magnetic resonance imaging cardiac MRI or computed tomography computed tomography provides detailed three‑dimensional anatomy of the aorta and can map the relationship of the lesion to the coronary ostia. Cardiac catheterization remains a reference standard for directly measuring the peak-to-peak gradient across the lesion and for evaluating accompanying coronary anatomy when complex involvement is suspected. In Williams syndrome, clinical assessment of the elastin pathway and genetic testing for the ELN locus may be pursued to guide holistic management Williams syndrome; ELN.
Management
Treatment aims to relieve left ventricular afterload, normalize blood flow, and preserve myocardial perfusion, all while considering the patient’s age, anatomy, and associated conditions.
Medical management: For milder cases, careful observation with regular imaging and blood pressure control is appropriate. Antihypertensive therapy may be used to reduce afterload and protect LV function, but it does not correct the anatomic obstruction. Exercise prescriptions and activity guidance are tailored to the individual, particularly in children with broader vascular involvement blood pressure management and cardiology follow‑up are essential.
Surgical repair (patch aortoplasty): The mainstay for significant obstruction is supravalvular aortic repair, typically performed by patch angioplasty to widen the narrowed segment. The procedure aims to restore a smooth aortic lumen and reduce LV pressure overload. Patch materials can include autologous pericardium or xenograft/prosthetic patches, chosen based on age, anatomy, and surgeon preference. This approach has evolved to minimize residual gradients and lessen the risk of restenosis, but durability can vary, and long-term follow‑up is essential aortoplasty; pericardial patch.
Balloon angioplasty and catheter‑based techniques: In selected infants and children, balloon angioplasty (percutaneous balloon valvuloplasty) or stenting may be considered. These less invasive approaches can provide rapid relief of obstruction, but restenosis can occur, and there is particular concern about durability in diffuse elastin‑related disease. Decisions about balloon or stent therapy depend on age, anatomy, and the likelihood of durable results; some centers favor an initial surgical approach for definitive repair in syndromic cases with diffuse involvement angioplasty; balloon angioplasty.
Management of associated lesions: Careful assessment of the coronary ostia and overall aortic arch anatomy is crucial, especially in Williams syndrome. If coronary ostial stenosis or other vascular abnormalities are present, the surgical plan may need modification to protect myocardial perfusion during and after repair. Multidisciplinary teams, including pediatric cardiology, genetics, and cardiovascular surgery, typically coordinate care coronary ostia; Williams syndrome.
Prognosis and follow-up
Outcomes after repair of SVAS are generally favorable in properly selected patients, with improvement in LV mass, symptoms, and functional capacity. However, recurrence of obstruction can occur, particularly in cases with diffuse elastin involvement, requiring long‑term surveillance. Regular echocardiographic monitoring, plus periodic imaging as needed, helps detect restenosis or progression of additional vascular lesions early. In patients with Williams syndrome or ELN deletions, ongoing evaluation for related vascular problems is standard, given the broader arterial involvement that may emerge over time left ventricular hypertrophy; aorta.