Atrial Septal Defect (ASD)

Atrial septal defect (ASD) is one of the commonest congenital heart diseases in the adult. It is a defect in the septum separting the two upper chambers of the heart. The defect in the septum between right and left atrium can be in various locations. The commonest variety which occurs almost in the centre is known as ostium secundum type. If it occurs at the lower end, it is called ostium primum variety. Ostium primum defect is often associated with a cleft of the mitral valve and leakage of the mitral valve (mitral regurgitation). There is another type of defect known as sinus venosus ASD. Sinus venosus ASD can occur near the superior vena cava or inferior vena cava. The former is more common than the later and can be associated with defects in the sinus node, the pacemaker of the heart situated nearby. Atrial septal defect leads to shunting of blood from left atrium to right atrium as the latter is at a lower pressure. This increases the blood flow to the lungs. Increased flow leads to dilatation of pulmonary vessels and in the long term reactive pulmonary hypertension. When the pressure in the blood vessels increase in the long run due to long standing increased flow, it increases the pressure in the right ventricle and thickening of the right ventricular muscles. This leads reduced compliance of the right ventricle and raises the diastolic pressure in the ventricle. This rising pressure is transmitted to the right atrium so that right atrial pressure rises above the lef...
Source: Cardiophile MD - Category: Cardiology Authors: Tags: General Cardiology Source Type: blogs