This document discusses a study that examined the deformation patterns of fetal left ventricles destined to function in univentricular versus normal biventricular circulations. The study found that the fetal left ventricle destined for univentricular circulation demonstrated similar deformation patterns to a normal left ventricle. It also found that the single left ventricle demonstrated Doppler changes suggesting enhanced early diastolic relaxation and greater reliance on atrial contraction for filling. The document then discusses how previous case reports provide limited information on how these conditions may progress in later stages of pregnancy. It notes that the current study retrospectively reviewed prenatal and postnatal echocardiograms of 21 fetuses with left heart obstructive lesions.