Effect of atrial stimulation site on the electrophysiological properties of the atrioventricular node in man.

The electrophysiological properties of the atrioventricular conduction system were compared in 16 patients using stimulation of the high right atrium (HRA) and a site within the coronary sinus (CS). The site of atrial stimulation significantly altered A-V nodal conduction time and refractoriness in eight patients (Group A) and did not change A-V nodal properties in the remaining patients. His-Purkinje conduction time and refractoriness were not affected by changing the atrial stimulation site. The atrial stimulation site may influence A-V nodal function by changing the site and/or mode of entry of the impulse into the A-V node.