title: Electrocardiographic abnormalities in Ebstein's anomaly. Deductions based on comparison with endomyocardial fibrosis.
abstract: Probable causes of ECG abnormalities in Ebstein's anomaly were investigated by comparing tracings from 18 young patients with the disease (group I) and 20 age-matched patients with a morphologically similar cardiopathy: right ventricular endomyocardial fibrosis (group II). Tall p waves (greater than or equal to 2.5 mm) occurred in about a third of the patients in each group and were attributable to right atriomegaly. 8 patients, 4 from each group, had prolonged P-R intervals (greater than or equal to 17 s) resulting from increased P-R segment (7 cases) and prolonged P-wave duration (4 cases). Right bundle branch block was, however, more prevalent in group I (44%) than in group II (5%), and is thought to result mainly from a paucity of conduction fibres in the atrialized right ventricle in Ebstein's anomaly and partly, in group II especially, from septal fibrosis. In both groups R-wave deflections in V3R and V1 were reduced, probably because of a clockwise cardiac rotation and paucity of right ventricular muscle mass.
mesh_terms: D000293:Adolescent; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis; D006332:Cardiomegaly / Q000150:complications / Q000175:diagnosis; D002648:Child; D002675:Child, Preschool; D004437:Ebstein Anomaly / Q000150:complications / Q000175:diagnosis*; D004562:Electrocardiography; D004719:Endomyocardial Fibrosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D012849:Sinoatrial Node / Q000502:physiology; D014927:Wolff-Parkinson-White Syndrome / Q000175:diagnosis