Manifestations of ventricular septal defect depend on the degree of what?

• A. Shunting
• B. Size of defect
• C. Pulmonary vascular resistance
• D. Right ventricular pressure

Answer: (A)

The manifestations hinge on how much blood moves from the left ventricle to the right ventricle through the defect—the left-to-right shunt. When the shunt is small, pulmonary blood flow isn’t markedly increased, so there may be little or no symptoms and only a small murmur. When the shunt is large, substantial pulmonary overcirculation occurs, loading the left heart and raising pulmonary pressures, which leads to tachypnea, failure to thrive, feeding difficulties, and signs of congestive heart failure. The actual size of the hole and the pulmonary vascular resistance influence the amount of shunting, but the clinical picture follows the degree of shunting itself.