The Pseudo P Pulmonale

Abstract

One hundred consecutive patients whose electrocardiograms presented a P pulmonale pattern were studied to determine the specificity of the ecg pattern. It was found that 49 patients had diseases in which right atrial enlargement might be expected. Forty-six patients failed to reveal any clinical condition which would predispose to right atrial abnormality. Vectrocardiograms were recorded in 20 of the 100 patients. Vectorcardiographic diagnoses of atrial enlargement agreed with the clinical findings in nearly 90% of the cases. In 36 patients, the P pulmonale pattern probably represented left, instead of right, atrial enlargement. The assumption was supported by the clinical findings, analysis of the P wave in Lead V1, associated QRS and T wave changes and vectorcardiographic findings. The possible mechanism for the appearance of P pulmonale pattern in left atrial enlargement and the reason for the improved accuracy of the vectorcardiographic diagnosis were offered. It is concluded that the ecg pattern of P pulmonale is not so specific as has been generally believed. Vectorcardiography may be a valuable additional tool in the diagnosis of atrial abnormality.