Author + information
- Received September 7, 1988
- Revision received February 7, 1989
- Accepted March 1, 1989
- Published online August 1, 1989.
- Denise L. Janosik, MD, FACC∗,
- Anthony C. Pearson, MD, FACC,
- Thomas A. Buckingham, MD, FACC,
- Arthur J. Labovitz, MD, FACC,
- Robert M. Redd, MD and
- Denise Mrosek
- ↵∗Address for reprints: Denise L. Janosik, MD. St. Louis University Medical Center, Department of Internal Medicine, Division of Cardiology, 3635 Vista at Grand, Box 15250. St. Louis, Missouri 63110.
The ability to program different atrioventricular (AV) delay intervals for paced and sensed atrial events is incorporated in the design of some newer dual chamber pacemakers. However, little is known regarding the hemodynamic benefit of differential AV delay intervals or the magnitude of difference between optimal AV delay intervals for paced and sensed P waves in individual patients. In this study, Doppler-derived cardiac output was used to examine the optimal timing of paced and sensed atrial events in 24 patients with a permanent dual chamber pacemaker. The hemodynamic effect of utilizing separate optimal delay intervals for sensed and paced events compared with utilizing the same fixed AV delay interval for both was determined.
The optimal delay interval during DVI (AV sequential) pacing and VDD (atrial triggered, ventricular inhibited) pacing at similar heart rates was 176 ± 44 and 144 ± 48 ms (p < 0.002), respectively. The mean difference between the optimal AV delay intervals for sensed (VDD) and paced (DVI) P waves was 32 ms and was up to 100 ms in some individuals. The difference between optimal AV delay intervals for sensed and paced atria] events was similar in patients with complete heart block and those with intact AV node conduction. At the respective optimal AV delay intervals for sensed and paced P waves, there was no significant difference in the cardiac output during VDD compared with DVI pacing. However, cardiac output significantly declined during VDD pacing at the optimal AV delay interval for a paced event and during DVI pacing at the optimal interval for a sensed event. An 8% increment in rest cardiac output was achieved by optimizing the AV delay interval for sensed P waves rather than utilizing the same AV delay interval that was optimal for a paced P wave.
In conclusion, this study demonstrates that in most patients with dual chamber pacemakers, the optimal AV delay interval differs depending on whether a P wave is paced or sensed and that utilization of differential AV delay intervals results in a significant increase in rest cardiac output. This result suggests that the ability to program separate AV delay intervals for paced and sensed P waves is useful in those patients in whom it is critical to maximize rest cardiac output.
- Received September 7, 1988.
- Revision received February 7, 1989.
- Accepted March 1, 1989.