Sequence of ventricular stimulation and contraction in a case of anomalous atrioventricular excitation

Abstract

1. 1. In a case of intermittent anomalous atrioventricular excitation it was found that the interval from the beginning of the P to the end of the QRS was shorter with the anomalous than with the normal beats. 2. 2. These and other data are interpreted to mean that depolarization of the ventricles was mediated entirely through an accessory pathway in the right ventricle, and that there was no conduction through the normal A-V conduction system when the QRS complexes were anomalous. 3. 3. Considerable delay in ejection of the left ventricle compared to the right occurred when the P-R interval was short. 4. 4. It is suggested that in different individuals with the syndrome, and sometimes in the same individual, variations in the relative amounts of ventricular muscle excited by impulses reaching it through the normal pathway on the one hand and through an accessory bundle or bundles on the other, readily explains many observations which have heretofore been regarded as conflicting.