Common atrioventricular canal defect or com­plete atrioventricular septal defect

• There is congestive heart failure in infancy. There may be cyanosis commonly.
• Isolated ASDs result from abnormal development of the septa that partition the common atrium of the developing heart into right and left chambers.
• There may be Down’s syndrome.
• There is marked parasternal heave or right ventricu­lar apical impulse.
• Atrioventricular (AV) canal defects result primarily from mal development of the partitioning of the AV canal by the endocardial cushions.
• There is murmur of mitral regurgitation radiating to left sternal edge.
• There is mid diastolic flow murmur of tricuspid valve . There is wide fixed splitting of second heart sound and P2 is loud.

Common atrioventricular canal defect or com­plete atrioventricular septal defect

• shows left axis deviation and right ventricular hypertrophy.

Chest x-ray:

• shows increased pulmonary vascular­ity and cardiomegaly.
• Note: All may be associated with PR prolongation.
• Ostium secundum: Rightward axis, right ventricular hypertrophy, rSR’ pattern in V1

20 echocardiography :

• shows common atrioven­tricular valve above the ventricular septum.

TREATMENT OF ASD

• To prevent thrombus formation after device deployment, aspirin 325 mg daily for 6 months and clopidogrel 75 mg for a month
• Surgical or non-surgical closure of the defect at ap­propriate age before pulmonary hypertension devel­ops and reversal of shunt (right to left) occurs.
• Closure is usually delayed until preschool age (2–4 years), except for large defects to be repaired earlier.
• Secundum ASDs that are suitable for percutaneous closure should be 35 mm or less in stretched balloon diameter and should have a sufficient (>5 mm) rim of surrounding atrial tissue.