Endocardial Cushion Defect (Atrioventricular Canal)

4% of all congenital heart disease and 0.3–0.4:1000 live births

40–50% of AV canal defects are associated with trisomy 21

Paradoxical air embolism

Shunt reversal (from left to right to right to left) because of vasodilating volatile and IV anesthetics (reduced systemic vascular resistance)

Endocarditis; prophylactic antibiotics for pts with a complete repair or a jet lesion

Arrhythmias after AV canal repair

Reactive pulmonary vasculature and PAH

Bradycardia

PAH, RV failure, and shunt reversal

Atrial arrhythmias resulting from atrial enlargement

AV canal is associated with atrial and ventricular septal defects manifested by a variety of abnormal communications between the left and right heart structures.

Categorized into atrial septal defects and partial or complete AV canal defect.

Main hemodynamic problems include AV valve dysfunction, interatrial shunting, and interventricular shunting.

L-to-R shunting results in RV or LV dysfunction or failure, frequent resp infections, and failure to thrive.

Chronic L-to-R shunt causes increased pulmonary vascular resistance and shunt reversal (Eisenmenger syndrome), which may preclude surgical intervention.

Diagnosis includes chest radiograph (enlarged heart), physical exam findings (murmur), prolonged electrocardiogram PR interval, and ECHO.

AV canal defects arise from abnormal endocardial cushion development between 4–5 wk gestational age.

Failure of endocardial cushion fusion results in deficiencies in the interventricular septum that can form a common AV valve, common AV valve annulus, or interatrial communication.