The syndrome of right isomerism -- prenatal diagnosis and outcome

To evaluate the accuracy of the prenatal diagnosis of right isomerism and to assess possible diagnostic and prognostic markers.

Retrospective review of all cases of right isomerism identified between 1989 and 2003 in two tertiary referral centres in Germany.

Among 21 foetuses, 16 had a correct prenatal diagnosis of right isomerism. 19 showed different types of viscerocardiac heterotaxy, 12 of them in combination with juxtaposition of vena cava inferior and aorta. 20 had cardiac defects, with a high prevalence of atrioventricular septal defect (CAVSD) (62 %), right outflow tract obstruction (48 %), anomalous pulmonary venous return (33 %) and double outlet right ventricle (29 %). 4 out of 6 cases with total anomalous pulmonary venous return were overseen on prenatal ultrasound. Only 6 children survived. The highest loss occurred in the neonatal period. Two out of 6 survivors underwent single ventricle palliation, while another two had a biventricular repair. One child is awaiting mitral valve replacement. The remaining case has no cardiac defect and lives with supraventricular re-entry tachycardia. Only the presence of CAVSD was significantly correlated with non-survival (p < 0.05).

The prenatal diagnosis of right isomerism remains a difficult task. Important sonographic markers are viscerocardiac heterotaxy, complex cardiac malformations and juxtaposition of vena cava inferior and aorta. Special attention has to be paid to the pattern of pulmonary venous drainage, as it is often misdiagnosed. The mortality in neonates is high, especially in the presence of CAVSD. Survivors suffer from significant morbidity.