J.Jpn. Surg. Soc.. 83(9): 940-944, 1982

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Report on the annual meeting

“ATRIOVENTRICULAR CONDUCTION DISTURBANCES AFTER CARDIAC SURGERY IN THE ATRIAL LEVEL
－SURGICAL IMPLICATION OF SUMMATION OF INPUTS FROM THE ATRIA TO THE A-V NODE－”

Changes in A-V conductivity of 14 clinical cases were studied before, immediately after and late after cardiac surgery at the level of atrium. Intraatrial conduction time (IACT) and A-V conduction time (AVCT) were measured by pacing and monitoring with 3 electrodes placed close to S-A node (E₁), A-V node (E₂) and right ventricular apex (V).
Postoperative IACT, E₁-E₂ time by pacing with E₁ electrode, was not prolonged in range from 30 to 65 msec.. Postoperative AVCT, E₂-V time by pacing with E₁, was extended in 4 cases out of 12. The extended AVCT was shortend by pacing with E₂ electrode in 3 cases from 290, 540, 450 msec. to 225, 200, 250 msec., respectively.
The results would suggest that excitatory input into the A-V node was increased by pacing with E₂ electrode than by pacing with E₁ and that the summation phenomenon at the site of A-V node was proved in clinical cases. Following the summation theory, preservation of the area of triangle of Koch, A-V junction, was stressed as a surgical key for protection of A-V conduction disturbances due to intra-atrial operation.

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