Perinatal outcome of fetal complete atrioventricular block

Complete atrioventricular block is one of the most severe fetal rhythm disturbances. The objective of this is to report the experience with 14 patients diagnosed and monitored during intrauterine life at a tertiary center. Fourteen cases of complete AV block were identified from January 1991 to July 1996 with post-conceptional age between 22 and 38 weeks at the moment of diagnosis. Twelve cases were referred to the Fetal Cardiology Unit because of low heart rate during obstetric examination. Eight fetuses showed complete AV block without evidence of structural heart disease; maternal collagen tissue disease was diagnosed in 3 of these cases. The patients with anatomic lesions were more likely to present with complex associations. The structural heart defects observed included: complete AV septum defect (5 patients), double outlet right ventricle (2 patients), left atrial isomerism (2 patients) and right atrial isomerism (2 patients). Four neonates were discharged from the hospital, two of them with a permanent pacemaker, one with complete AV block but no pacemaker and the fourth in sinus rhythm. The remaining 7 patients presented with severe heart failure leading to death despite treatment. Complete AV block is a rare fetal condition for which a multitude of treatments have been suggested. Despite the available therapeutic methods and monitoring techniques, this disease still carries a high morbility and mortality, particularly in utero.