Congenital defect with an opening in the wall separating the right and left ventricles of the heart (see ventricular septum).
Note: This cardiac anomaly allows reflux of blood back to the right ventricle during left ventricular contraction, producing varying degrees of cyanosis.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 819 (https://doi.org/10.1515/pac-2015-1202)