Repaired Tetralogy of Fallot

Abstract

The anatomy of tetralogy of Fallot (TOF), together with the pathophysiological consequences, was first described by Etienne-Louis Fallot in 1888. The tetrad of overriding aorta, right ventricular (RV) outflow tract obstruction, ventricular septal defect (VSD) and consequent RV hypertrophy is all due to antero-cephalad deviation of the outlet septum during fetal development. TOF is the most common cyanotic congenital heart disease (CHD), accounting for 10 % of CHD patients and occurring in 1 in 3,600 births (Shinebourne et al., Heart 92:1353–1359, 2006). It carries a recurrence risk of 3 % in siblings. There is genetic microdeletion in 22q11 in 15–25 % of TOF patients in whom TOF is part of DiGeorge syndrome. There is a spectrum of morphology, despite the four features that comprise ‘tetralogy’, and the severity of the RV outflow tract (RVOT) obstruction is the major determinant of first clinical presentation. Surgical palliation was achieved using the Blalock–Taussig shunt (subclavian artery to ipsilateral pulmonary artery connection) in 1944, a landmark event as these patients underwent the first cardiac surgery. Subsequently, surgical repair was described in the 1950s with the advent of cardiopulmonary bypass. Primary surgical repair involves patch closure of the VSD and intervention to the RVOT to relieve obstruction. RV muscle bundles are resected. Depending on the size of the outflow tract, pulmonary valve and pulmonary arteries; an RVOT patch, transannular patch and/or pulmonary artery (PA) patch may be required for RVOT reconstruction. In the variants with anomalous coronary arteries or in pulmonary atresia-type Fallot, an RV to PA conduit may be used.