Atrial natriuretic peptide (ANP) is like b-type natriuretic peptide (BNP) in the hemodynamic effects. ANP is not measured clinically unlike BNP. It is released in response to myocyte stretch specifically in the atrium which occur in states of decompensated congestive heart failure. Atrial natriuretic peptide has vasodilating properties in both arteries and veins which improve the hemodynamics in heart failure states. ANP increases the excretion of sodium and water causing diuresis and natriuresis helping to relieve the volume overload present in congestive heart failure. Cannon A waves can result in increased release of ANP. An ostium primum atrial septal defect (ASD) occurs when then atrial septum near the atrioventricular valves has a communication between the two-atrium causing a left to right shunt.