8th March 2024

Pathophysiology

ASDs cause a left-to-right shunt, which results in volume overload of the RA and RV. The severity depends on the size of the ASD and filling pressures of the ventricles. Factors which heighten the degree of shunting include elevated LV filling pressures in hypertensive cardiomyopathy or increased LA pressure seen in mitral stenosis. In contrast, factors that reduce the degree of left-to-right shunt include pulmonary hypertension or increased RA pressure in tricuspid stenosis.