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The hemodynamic effects of ventricular pacing with and without atrioventricular synchrony in patients with normal and
L A DiCarlo1, F Morady, R B Krol
1Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor.
Insights
Maintaining atrioventricular (AV) synchrony during ventricular pacing is crucial for preserving hemodynamic function. This study found that preserving AV synchrony benefits patients with both normal and reduced left ventricular ejection fraction (LVEF).
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- Ventricular pacing can disrupt normal cardiac function by altering atrioventricular (AV) synchrony.
- The impact of AV synchrony on hemodynamics is critical, especially in patients with varying degrees of left ventricular ejection fraction (LVEF).
Purpose of the Study:
- To evaluate the relative hemodynamic effects of heart rate, inotropic state, and AV synchrony during ventricular pacing.
- To compare these effects in patients with normal versus diminished LVEF.
Main Methods:
- Hemodynamic measurements (cardiac index, stroke volume index, stroke work index) were taken at different AV intervals (130, 0, -130 msec).
- Measurements were performed during ventricular pacing at baseline and increased heart rates, with and without dobutamine infusion.
- The study included patients with normal LVEF (0.66 +/- 0.07) and diminished LVEF (0.34 +/- 0.18).
Main Results:
- A significant decrease in cardiac index, stroke volume index, and stroke work index was observed when AV interval decreased from 130 to 0 msec in both patient groups.
- This decrease was similar between patients with normal and diminished LVEF.
- No further significant hemodynamic decline occurred when the AV interval was changed from 0 to -130 msec.
Conclusions:
- Maintaining AV synchrony during ventricular pacing is beneficial for hemodynamic stability.
- These benefits apply to patients with both normal and diminished LVEF, across various heart rates and inotropic states.
- Optimizing AV synchrony is essential for improving cardiac function during ventricular pacing.
Abstract:
The relative hemodynamic effects of heart rate, inotropic state, and atrioventricular (AV) synchrony during ventricular pacing were evaluated in 10 patients with normal left ventricular ejection fraction (LVEF) (0.66 +/- 0.07, mean S.D.) and in eight patients with a diminished LVEF (0.34 +/- 0.18). Hemodynamics were measured at AV intervals of 130, 0, and -130 msec during ventricular pacing at a baseline rate that was 10 pulses/min greater than the resting heart rate, at 130 pulses/min alone, and at 130 pulses/min during continuous intravenous infusion of dobutamine. During baseline ventricular pacing and during ventricular pacing at 130 pulses/min with and without dobutamine, both groups of patients had a significant decrease in cardiac index, stroke volume index, and stroke work index when the AV pacing interval was decreased from 130 to 0 msec. The observed decrease in these three hemodynamic variables was similar when patients with diminished LVEF were compared to patients with normal LVEF. No further significant decrease in cardiac index, stroke volume index, and stroke work index occurred in either group when the AV interval was changed from 0 to -130 msec during baseline ventricular pacing or during ventricular pacing at 130 with and without dobutamine. Beneficial hemodynamic effects occur during ventricular pacing when AV synchrony is maintained at resting heart rates and during increases in heart rate and inotropic state in patients with normal and diminished LVEF.