Don’t Ignore Reverse Differential Cyanosis

Abstract

Reverse differential cyanosis (RDC) is an uncommon but potentially significant finding, as it may be associated with duct-dependent congenital heart disease and cause post-natal collapse if not detected and managed appropriately. We present the case of an apparently well term baby who was found to have an innocent-sounding heart murmur at initial examination with RDC. Echocardiography identified double-outlet right ventricle (DORV) with a sub-pulmonary ventricular septal defect and coarctation of the aorta (CoA). Urgent transfer and surgical intervention was required. There was the potential for cardiac assessment to be delayed as the importance of RDC in a clinically well baby was not initially recognised. In this case presentation we review the physiology and causes of RDC and its frequency in neonatal pulse oximetry screening. We propose that in the absence of screening, RDC is at risk of being under-recognised as a sign of duct-dependent congenital heart disease.