[Interpretation of a bundle of His electrogram (using the spike potentials of the sinus node and atrial conduction...

Spike potentials of the sinus node and of the atrial conductivity pathways were recorded by way of heart microcatheterization via the subclavian vein in 40 canine experiments and in 307 patients, using the obtained data for a more precise interpretation of the bundle of His electrogramme taken in the course of these examinations. The importance of the density of the spikes for their successful recording was studied, and it was found that the onset of the atrial A--wave preceeded that of the P-wave by 10-30 ms on ECG tracings recorded from the body surface. The atrial A--complex recorded with the aid of an intracardiac unipolar electrode from the right atrium was found to consist of a slow depolarization wave of the atria and of three spike potentials (A1, A2 and A3). The A2 spike coinsides with the peak of the P-wave in the II lead and reflects the moment of the impulse's arrival at the atrioventricular node along the Bachman and Wenkebach's tract, while the A3 spike coinsides with the termination of the P-wave in the II lead being dependent on the depolarization of the Torel's tract. The P--A interval should be measured between the sinus spike and the A2 spike, while the A--H interval--between the A2 spike and the H-potential.