ABSTRACT
Supravalvar aortic stenosis (SAS) is a complex syndrome, which has a wide range of clinical and morphologic expression. Congenital SAS may be localized (most common) or diffuse obstruction of the ascending aorta, starting immediately above the aortic valve. It affects both sexes equally and the presentation may vary from infancy to adulthood. Frequently, it is associated with the Williams syndrome,1 an autosomal dominant genetic disorder characterized by infantile hypercalcemia, unusual ‘elfin’ facies, mental retardation, mild growth deficiency, and cardiovascular disease. These patients may have associated cardiac anomalies, such as peripheral pulmonary artery stenosis, coarctation of the aorta, involvement of the supra-aortic ostial trunks, and mitral valve prolapse. However, SAS can also present as an isolated form or in familial forms of the disease without the Williams syndrome. The stenosis may vary from a localized supravalvar diaphragm to a diffusely hypoplastic ascending aorta. Because of the inability of the dysplastic aortic wall to grow adequately, its natural history shows a progression of the gradient across the aortic arch in many patients, and poor prognosis in those with severe obstruction.2,3 From a pathophysiologic point of view, the SAS produces a left ventricular obstruction commencing above the aortic sinuses. This creates a high pressure chamber between the aortic valve and the origin of the stenosis. Besides the strain on the left ventricle, this high pressure chamber may affect competence of the aortic valve and alter coronary artery perfusion. The high coronary artery perfusion pressure may promote the development of coronary artery disease. Cardiac symptoms are common in neonates who frequently require early surgery. After 1 year of age, progression in the severity of SAS is common, whilst the severity of associated pulmonary arterial stenosis tends to improve, and only rarely alters prognosis.2,4 Compared with an age-matched normal population, the risk of sudden death is much higher in patients with Williams syndrome.5 Thus, life-long followup is necessary in all patients, even after treatment, because of the significant associated risks in a progressive disease.
