Aberrant beats of Wolff-Parkinson-White configuration in arteriosclerotic heart disease.

Evidence has been presented by Prinzmetal et al. (1952) and Borduas et al. (1955) that electrocardiographic beats characterized by short P-R and long QRS intervals may occur in the absence of an accessory pathway by-passing the A-V node. In animal experiments, Prinzmetal observed beats ofWPW type after repeated electrical stimulation of the A-V node, and noted in these same animals the spontaneous occurrence of various supraventricular tachycardias. Several arteriosclerotic patients studied by Prinzmetal demonstrated similar electrocardiographic phenomena, and at necropsy were found to have fibrotic disease of the A-V node and no accessory conduction system. These clinical and experimental observations indicate that WPW beats may occur on an acquired basis, secondary to nodal disease. In other experiments, Prinzmetal induced beats ofWPW type in dogs after repeated ventricular stimulation with the A-V node intact. These observations harmonize with those of Kossman et al. (1950) who recorded such beats during cardiac catheterization when the catheter was in direct contact with the endocardial surface. Similar complexes have been observed by Prinzmetal during the course of acute myocardial infarction, frequently in association with ventricular premature beats and ventricular arrhythmias. On the basis of his extensive studies, including high-speed cinematographic techniques, Prinzmetal has deduced that accelerated conduction through part of the A-V node is responsible for aberrant complexes. He believes this to be true both in instances of nodal disease (" nodal " accelerated conduction) and ventricular irritability (" ventricular " accelerated conduction). In this latter type, the accelerated conduction through the A-V node may be on a reflex basis. Five instances of WPW aberration have been seen during the past two years in patients with arteriosclerotic heart disease. Of these, four are considered to be of acquired type, and only one an example of classical, congenital, Wolff-Parkinson-White syndrome (1954).