A number of unique vascular disorders in children and young adults may cause sudden death; these should always be sought assiduously at the time of autopsy even in the absence of a suggestive clinical history. Disorders may be hereditary or acquired and may manifest themselves with increased bruising, hemorrhage, or thromboembolic phenomena. A list of possible vascular causes of sudden death in the young can be found in Table 6.1.
Obstructive lesions of the left ventricular outflow tract are well-known causes of sudden and unexpected death at young ages. Obstruction to the outflow tract may involve the aortic valve or the proximal aorta, with lesions such as supravalvular stenosis and tubular hypoplasia leading to rapid clinical deterioration and death.
Occurrence of sudden death
The frequency of sudden death in one study of 916 patients under 21 years of age with left ventricular outflow obstruction was 1%. Sudden death in children with obstructive lesions may sometimes also be associated with a medical procedure such as cardiac catheterization.
Sudden death in obstructive aortic disease usually results from a complex series of interactions involving myocardial ischemia and arrhythmias. An increase in myocardial mass without an increase in the number of nutrient vessels results in relative reduction in blood flow, unless a compensatory increase in vessel cross-sectional area occurs.