The electrocardiographic recognition of right atrial abnormality in children

Abstract

P waves of normal children and of patients with either atrial septal defect (ASD), pulmonary stenosis (PS), or Fallot's tetralogy (TET) were analyzed and compared relative to right atrial abnormality (RAA). In the normal group P amplitude was consistently greater in infants. Normal P waves ▪ 2.5 mm. were rarely (0.05 per cent) found, but only in neonates. Maximal P amplitude (P max) in 61 per cent of patients exceeded the ninetieth percentile, age-related, normal values, but in only 19 per cent was P > 2.5 mm., the conventional criterion of RAA. The initial-P-V 1-index (IPI), a new measure of RAA obtained by multiplying positive P-V 1 amplitude by duration, exceeded ninetieth percentile values in 59 per cent of patients and was abnormal in 22 per cent of those with a normal P max. A formula in which IPI and P max are combined was derived for assessment of RAA. By its use, 78 per cent of the patient group had evidence of RAA when diagnostic specificity was 90 per cent. In about 90 per cent of patients with TET, either P max or IPI was abnormal. In patients with PS, P abnormality was found to be related to right ventricular systolic pressure; P waves in about 90 per cent of those with right ventricular pressure ▪ systemic pressure were abnormal. P-V 1 was diphasic in the majority of those with TET, but infrequently so in those with PS. Features useful in distinguishing sometimes prominent, terminal negative P-V 1 deflections of patients with RAA from those of patients with left atrial enlargement were found. In about three quarters of those with ASD either P max or IPI was abnormal, but P abnormality could not be related to either size of left-to-right shunt or height of right ventricular pressure. It is concluded that sensitivity in the diagnosis of right atrial abnormality, whatever its cause, can be improved by use of criteria developed in this study while still maintaining acceptable diagnostic specificity.