Clinical features, management, and outcome of children with fetal and postnatal diagnoses of isomerism syndromes

Background - Isomerism is associated with a complex spectrum of anomalies. There is paucity of data on prenatally detected cases. Methods and Results - Between January 1990 and February 2004, 83 of 166 cases (50%) had a prenatal diagnosis of left isomerism (LAI; 52 of 97) or right isomerism (RAI; 31 of 69) at our institution. The spectrum of anomalies, management, and outcomes was compared for fetal and postnatal diagnoses of LAI and RAI. RAI more often than LAI was associated with AV septal defect (90% versus 56%; P < 0.0001), pulmonary outflow obstruction (91% versus 37%; P < 0.0001), total anomalous pulmonary venous drainage (73% versus 13%; P < 0.0001), and abnormal VA connections (68% versus 33%; P < 0.0001), whereas inferior vena cava interruption (3% versus 93%; P < 0.0001), complete AV block (0% versus 13%; P = 0.004), aortic obstruction (6% versus 33%; P < 0.0001), and extracardiac defects (5% versus 25%; P = 0.006) were less common. The spectrum of lesions was comparable for fetal and postnatal cases, except for AV block ( fetal, 25%; postnatal, 0%; P = 0.0002) and AV septal defect (fetal, 67%; postnatal, 42%; P = 0.023) in LAI. Fetal demise was due mainly to pregnancy termination ( LAI, 42%; RAI, 45%). Survival of actively managed children with LAI was significantly better than for those with RAI (P < 0.0001) but did not differ with regard to fetal versus postnatal diagnosis. Most LAI cases required no intervention or underwent successful biventricular cardiac surgery (65%), unlike RAI cases (13%; P < 0.0001). Conclusions - Prenatal diagnosis did not affect overall survival despite facilitated care. The prognosis of RAI was worse compared with LAI because of more complex associated cardiac defects and the inability to perform successful surgical procedures.