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Acute hemodynamic effects of different atrioventricular intervals in dual chamber pacemakers: is there an optimum
Insights
Optimizing the atrioventricular (AV) interval in dual chamber pacemakers for improved hemodynamic performance is challenging. Adjusting the AV delay between 150-250 msec rarely benefits patients with normal cardiac function at rest.
Area of Science:
- Cardiology
- Biomedical Engineering
- Medical Device Technology
Background:
- Conflicting data exist on optimizing atrioventricular (AV) interval for dual chamber pacemakers.
- Accurate adjustment of AV delay is crucial for maximizing hemodynamic performance.
Purpose of the Study:
- To investigate the impact of different AV intervals on hemodynamic parameters in patients with dual chamber pacemakers.
- To determine if a generalized optimal AV delay can be identified.
Main Methods:
- Eleven patients with complete heart block received dual chamber pacemakers.
- Hemodynamic parameters including cardiac output and ejection fraction were measured at AV intervals of 150, 200, and 250 msec using echo-Doppler techniques.
Main Results:
- No significant differences in cardiac output, ejection fraction, or other hemodynamic measures were observed across the tested AV intervals (150, 200, 250 msec).
- A small improvement in cardiac output was noted in only a minority of patients with specific AV delays.
Conclusions:
- Generalizing an optimal AV delay for dual chamber pacemakers is difficult.
- In patients with normal baseline cardiac function, adjusting the AV interval within the 150-250 msec range offers limited hemodynamic benefits at rest.
Abstract:
Conflicting data have been reported regarding adjustment of atrioventricular (AV) interval to maximise hemodynamic performance of dual chamber pacemakers. Eleven consecutive patients with complete heart block and dual chamber pacemakers were paced at three AV intervals (150, 200, 250 msec) and free running rates (60-93 bpm, mean 73 +/- 12 bpm) with simultaneous measurements of cardiac output, atrial contribution to left ventricular filling, left ventricular ejection fraction, and peak aortic velocity and acceleration by echo-Doppler techniques to define the optimum AV delay. At all the three AV intervals tested there was no difference in cardiac output (4.7 +/- 0.96, 4.83 +/- 1.12, 4.77 +/- 1.19 litres/min respectively, p = NS), left ventricular ejection fraction (60.2 +/- 10.6%, 61.2 +/- 9.9% and 64 +/- 8.3%, p = NS), atrial contribution to left ventricular filling (0.37 +/- 0.10, 0.38 +/- 0.09, 0.36 +/- 0.16, n = 8, p = NS), peak aortic velocity (104 +/- 8, 105 +/- 12, 104 +/- 13 cm/sec, p = NS) and aortic acceleration (19.68 +/- 4.26, 20.4 +/- 5.58 and 19.0 +/- 4.54 m/sec2, p = NS). Compared to AV delay of 150 msec an increase in cardiac output of 0.5 L/minute was observed in three patients at an AV delay of 200 msec and in one patient at the AV delay of 250 msec. These data suggest that it is difficult to generalize an optimum AV delay in patients with dual chamber pacemakers. With the AV interval in the range of 150-250 msec, only a minority of patients could improve their haemodynamics at rest by adjusting this interval if the baseline cardiac function was normal.