Obstructive Cardiac Lesions
This section deals primarily with ventricular outflow tract lesions. Congenital mitral and tricuspid valve stenoses are relatively rare in children, thus are not discussed here.
Outflow tract obstruction leads to an increase in the pressure proximal to the lesion and secondary myocardial hypertrophy. Turbulent flow across the obstruction produces an ejection systolic murmur. Myocardial hypertrophy leads to increased oxygen consumption with decreased exercise tolerance and possible myocardial ischemia and fibrosis.
Ventricular dilatation is not a usual response to obstruction, and if present suggests ventricular failure.
Children with mild or moderate obstructive lesions usually have few symptoms. Severe obstructive may lead to early CHF symptoms and are often ductus dependent (the patient often requires a patent ductus arteriosus to bypass the obstruction).