Mechanisms of AR in operated tetralogy of Fallot
Pulmonary regurgitation is almost universal after corrective repair of tetralogy of Fallot, more so in those who require a trans annular patch for widening of the right ventricular outflow tract. Hence an early diastolic murmur along the left sternal edge following repair of tetralogy of Fallot is most often due to pulmonary regurgitation. But a few cases may also develop aortic regurgitation due to various reasons. Aorta is dilated in tetralogy of Fallot prior to repair because it receives a major portion of the out put from the right ventricle as well as the left ventricular output. This is the reason for a high volume pulse in tetralogy of Fallot. Thus dilatation of the aortic root is one of the potential reasons for aortic regurgitation in tetralogy of Fallot. Other causes are lack of support due to a sub aortic ventricular septal defect and valvular deformation resulting from retraction of the surgical patch.