Electrocardiographic patterns of right atrial overloading in some congenital heart conditions

Abstract

This study analyzes 116 electrocardiograms of patients with congenital heart disease that had some hemodynamic effect on the right atrium. A correlation between the P wave changes and the hemodynamic and radiographic data was attempted. The mean right atrial pressure, the systolic pressure within the right ventricle, the a wave of the right atrium, the peripheral arterial blood oxygen saturation, the age of the patient and the radiographically determined size of the right atrium were analyzed and correlated with the voltage, configuration, duration, axis and other features of the P wave. In congenital lesions characterized by a difficulty in emptying the right atrium the voltage of the P wave was related to the integrity of the atrial septum. In the presence of such difficulty, an atrial septal defect decreased the systolic overloading of the right atrium. Arterial oxygen unsaturation was not related to the voltage of the P wave. No relation was found between the mean right atrial pressure and the changes of the P wave. The a wave in valvular pulmonic stenosis, tricuspid atresia, Ebstein's disease and total anomalous pulmonary venous connection had some relation, although it was not linear, with the P wave alterations. In valvular pulmonic stenosis with intact atrial and ventricular septa the P wave was related to the degree of systolic overloading of the right ventricle, but this was not true in trilogy of Fallot. The greatest voltages of the P wave were seen in valvular pulmonic stenosis, anomalous pulmonary venous connection and tricuspid atresia. In tetralogy of Fallot P wave changes were frequent but not as marked as in the previously mentioned defects. They consisted almost exclusively of peaking of the P wave. The size of the right atrium determined radiologically was generally related to the P wave changes in these congenital defects, but the relation was not linear. In atrial septal defect the P wave changes were slight, consisting almost exclusively of notching and slurring, slowing of the ascending branch of the P wave and, exceptionally, an increase in voltage. It is difficult to attribute P wave changes in different congenital lesions with hemodynamic involvement of the right atrium, to a single factor. In each disease one or a group of factors predominates. The most important one seems to be the resistance encountered by the right atrium in emptying its contents and the integrity of the interatrial septum.