True about ASD –

Hemodynamics ofASD                               There is abnormal connection between left and right atrium, which is due to defect in atrial septum (not a patent foramen ovale). Blood flows from left atrium to right atrium because left atrium has slightly higher pressure than right atrium → Left to right shunt. Because the pressure difference between two atria is small, blood passes at a narrow pressure difference No shunt murmur. There is volume overload to right atrium because of left to right shunt →.Right atrial dilatation and hypertrophy. During diastole large amount of blood passes from right atrium to right ventricle through tricuspid valve → delayed diastolic murmur and accentuation of first heart sound. Volume overload to right ventricle → Right ventricular hypertrophy that produces parasternal heeve. Large blood volume passes through pulmonary valve → Pulmonary ejection murmur. Prolonged blood passage along pulmonary valve causes delayed closure of pulmonary valve → P2 is delayed and accentuated, wide split and fixed S2. Increased blood flow through pulmonary circulation → Pulmonary plethora that may cause pulmonary hypertension