Pacing with an atrioventricular interval of 160 ms prolonged right ventricular effective refractory periods compared to an interval of 0 ms (mean difference 3.8 ms at 400 ms; P<0.01).
Does atrial and ventricular pacing with an AV interval of 160 ms alter right ventricular effective refractory periods compared to an AV interval of 0 ms in humans?
Right ventricular refractory periods are shorter at an AV interval of 0 ms than at 160 ms, which is associated with differences in ventricular volumes rather than autonomic tone, suggesting atrial systole timing should be controlled for precise refractoriness determinations.
Mean Difference: 3.8
p-value: p=<0.01
Right ventricular refractory periods obtained using atrial and ventricular pacing with an atrioventricular (AV) interval of 160 ms were compared with those obtained with an AV interval of 0 ms in a group of 53 patients. The mean right ventricular effective refractory periods were longer at an AV interval of 160 ms than at an AV interval of 0 ms at pacing cycle lengths of 600 (mean 2.5 +/- 1.8 ms difference) and 400 ms (mean 3.8 +/- 2.4 ms difference; P less than 0.01). In a subset of 10 patients, left ventricular volumes measured by two-dimensional echocardiography demonstrated that pacing with an AV interval of 160 ms was associated with a higher end-diastolic volume and stroke volume than pacing with an AV interval of 0 ms (P less than 0.001). Autonomic blockade did not alter the relationship between AV interval and ventricular refractoriness. We conclude that 1) right ventricular refractory periods are shorter at an AV interval of 0 ms than at an AV interval of 160 ms; 2) these differences are not caused by changes in autonomic tone but are associated with differences in ventricular volumes; and 3) if precise determinations of ventricular refractoriness are desired, then the timing of atrial systole should be controlled by atrial pacing.
Kadish et al. (Thu,) reported a other. Pacing with an atrioventricular (AV) interval of 160 ms vs. Pacing with an AV interval of 0 ms was evaluated on Right ventricular effective refractory periods (MD 3.8 ms, p=<0.01). Pacing with an atrioventricular interval of 160 ms prolonged right ventricular effective refractory periods compared to an interval of 0 ms (mean difference 3.8 ms at 400 ms; P<0.01).
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