Clinical findings of DORV, VSD, PS vs Tetralogy of Fallot

How is DORV, VSD, PS different from Tetralogy of Fallot in clinical findings?

DORV VSD PS vs Tetralogy of Fallot: A prominent systolic murmur co-existing with severe cyanosis is in favor of double outlet right ventricle (DORV) than Tetralogy of Fallot (TOF). Prominent left parasternal heave is also more likely in DORV. DORV, VSD, PS is a condition with TOF like physiology – cyanotic congenital heart disease with low pulmonary blood flow.
VSD: Ventricular septal defect. PS: Pulmonary stenosis.

In DORV, the shunt across the VSD is called an obligatory shunt. This is because left ventricle has no outlet other than the VSD. Both pulmonary artery and aorta are arising from the right ventricle. So blood (pulmonary venous return) reaching the left ventricle from the left atrium can go out only into the right ventricle across the VSD. Right ventricle ejects both into the aorta and the pulmonary artery. Pulmonary flow will be limited by the severity of pulmonary stenosis. If pulmonary stenosis is severe, more blood will flow into the aorta than the pulmonary artery. Since the whole left ventricular output flows across the VSD, a significant murmur is audible. In TOF as the pulmonary stenosis is severe, blood from the left ventricle will preferentially flow into the aorta than into the VSD. Large VSD in TOF does not produce any murmur because there is no pressure gradient across it. In TOF with severe PS the flow into the pulmonary artery is low so that it will not produce a loud murmur. But cyanosis will be severe because most of the right ventricular output goes into the overriding aorta.

Though ventricular septal defect and obligatory left to right shunt has been mentioned to be mandatory for survival, a rare case with intact ventricular septum has been described by Anand Subramanian, AP Bharath, M Jayaranganath [1]. In their case there was an unguarded left atrioventricular valve which was represented only by a ridge of tissue on the lateral aspect of the left atrioventricular groove. There was free mitral regurgitation, large fossa ovalis atrial septal defect and left to right shunt. Both pulmonary artery and aorta were arising from the right ventricle.

Reference

  1. Anand Subramanian, AP Bharath, M Jayaranganath. Unguarded Left Atrioventricular Orifice: An Unusual Cause of Hypoplastic Left Ventricle and Double-Outlet Right Ventricle With Intact Ventricular Septum. Ann Pediatr Cardiol. May-Aug 2019;12(2):153-155.