Sample and methodology: 111 patients (54 men) with atrioventricular stimulation of an average age 56.5 ± 14.3 were examined. Permanent cardiostimulation was indicated in 56 patients for sick sinus syndrome and in 55 patients for complete AV blockade. Average LV EF was 52.1 ± 5.7 % and LA endsystolic dimension was 39.8 ± 4.0 mm. All patients were done esophageal electrocardiography under synchronous atrioventricular stimulation regimen. Values of interatrial conduction were compared in relation to placement of stimulation electrode in atrium. Results: Interatrial conduction in the whole sample was 79.8 ± 19.5 (40 - 150) ms, for placement of an electrode in heart auricle, in lateral or in anteroseptal wall of the right atrium it was 79,9 ± 17,9 ms, 108,3 ± 16,3 ms, 61,5 ± 16,2 ms. Difference between programmed AV interval and AV interval set up via esophageal electrocardiography was 40,9 ± 19,7 (5 - 95) ms. Value of interatrial conduction in the monitored sample depended on placement of the electrode in atrium and the size of the left atrium (r = 0,24, p < 0,009). We did not prove relation of the interatrial conduction value to LV EF or indication diagnosis. Conclusion: Interatrial conduction affects value of the real AV interval in atrioventricular stimulation, depends on placement of stimulation electrode in atrium and on the size of the left atrium. Interatrial conduction can be assessed via esophageal electrocardiography.

        Key words: Esophageal ECG - Atrioventricular stimulation - Interatrial conduction