Pulmonary Versus Systemic Outflow Obstruction in Functionally Univentricular Hearts with Isomerism: An Observation.

Our objective was to review our experience with isomerism associated with univentricular hearts and evaluate the prevalence of pulmonary versus systemic outflow obstruction. We identified those prenatally or postnatally diagnosed, between September 2004 and October 2021, with right and left isomerism and a functionally univentricular heart. We identified 62, 51 prenatally and 11 postnatally. Of the 62, 61 had prenatal care for an 84% (51/61) prenatal detection rate. Of the 62, 36 (58%) had right isomerism. Of the 51 prenatally diagnosed, 36 were live-born, 13 had fetal demise, and two underwent elective termination. Of the total 62, 43 had pulmonary outflow obstruction, 14 had systemic outflow obstruction, three had no outflow obstruction, and two had a common arterial trunk. However, between September 2004 and December 2019, 41 of 52 (79%) had pulmonary outflow obstruction, and between January 2000 and October 2021, 2 of 10 (20%) had pulmonary outflow obstruction (p = 001). We noted a statistically significant temporal change in the prevalence of pulmonary versus systemic outflow obstruction in those with isomeric situs and a functionally univentricular heart. Further, prenatal diagnosis exceeded 80% in the general population of Nevada.