Studies on the Mechanism of Ventricular Activity

Seven clinical cases with electrocardiographic patterns of constant or variable short P-R interval are reported. The QRS complex was either normal or aberrant. These abnormalities were reproduced experimentally in dogs by the injection of various drugs into the region of the A-V node. The theories advanced to explain these phenomena are discussed. The results indicate that accelerated A-V nodal conduction is responsible for the short P-R interval. The form of the ventricular complex may be dependent upon synchronous or asynchronous activity of the A-V node. A classification of A-V nodal dysfunction is presented.