An Unexpected Electrocardiogram in Congenital Heart Disease: A Rare Variant of a Common Cyanotic Syndrome.

CASE SUMMARY: A 19-year-old female with a history of tetralogy of Fallot (TOF) with prior right ventricle (RV)-pulmonary artery conduit, RV outflow tract aneurysm, intermittent ventricular arrhythmia, Chiari malformation, and scoliosis presented to establish care at our institution. Electrocardiogram (ECG) demonstrated an unexpected pattern consistent with dextrocardia and right axis deviation. Further investigation noted TOF with situs inversus totalis, a rare TOF variant only previously described several times. She underwent longitudinal monitoring with progression of RV dysfunction and ventricular arrhythmias.

TAKE-HOME MESSAGE: TOF produces characteristic ECG changes that have utility in monitoring RV remodeling, arrhythmogenesis, and RV volume load. When ECG presents unexpected changes, additional defects or compromised repair should be interrogated.