VSD is a common congenital abnormality in newborns and is present in approximately 1 in 500 normal births.
However, this defect is rarely encountered in adults because nearly 50% of VSDs close spontaneously during childhood, and most large defects are surgically corrected at an early age. VSDs are classified according to their location within the interventricular septum. Most VSDs involve the membranous or muscular portion of the interventricular septum, and, if small, they often close spontaneously during childhood.
In these patients, associated cardiac abnormalities are unusual. A less common type of VSD with ostium primum ASDs, as well as with mitral and tricuspid leaflet abnormalities. This type of VSD is common in patients with Down’s syndrome. High(supracristal) membranous VSDs are located beneath the aortic annulus and often lead to aortic valve incompetence. In patients with uncomplicated VSDs, oxygenated blood from the left ventricle is shunted across the defect into the right ventricle. If the defect is small, right ventricular size and function are normal, and pulmonary vascular resistance does not increase. If the defect is large, the right ventricle dilates to accommodate the increased volume, and pulmonary blood flow increases pulmonary vascular obstruction may develop and may lead to pulmonary artery hypertension, reversal of the interventricular shunt, and systemic desaturation and cyanosis(Eisenmenger’s syndrome).
The clinical course of a patient with VSD depends on the size of the defect. Most small defects spontaneously close, or, if they are still present in adulthood, they are usually not associated with any significant hemodynamic complications. Large defects are usually detected and repaired during infancy. Affected individuals with uncorrected defects who survive to adulthood may present with signs and symptoms of right-sided heart failure. If pulmonary vascular obstruction with Eisenmenger’s physiology develops, cyanosis and clubbing of the fingers may be present. All patients with VSD(or repaired VSD with residual shunt flow) are at risk of bacterial endocarditis that usually involves the right ventricular outflow tract.