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Effects of atrioventricular interval on left ventricular diastolic filling assessed with pulsed Doppler
T Masuyama1, K Kodama, S Nakatani
1Cardiovascular Division, Osaka Police Hospital, Japan.
Insights
Adjusting the atrioventricular interval in pacemakers affects left ventricular diastolic filling. Shorter intervals increase early filling but decrease atrial contribution, especially in older patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Echocardiography
Background:
- The atrioventricular (AV) interval is a critical parameter in dual-chamber pacemakers.
- Optimizing the AV interval is essential for mimicking physiological cardiac function.
- Understanding its impact on diastolic filling is crucial for patient management.
Purpose of the Study:
- To investigate the effects of varying the atrioventricular interval on left ventricular diastolic filling patterns.
- To assess changes in early and atrial diastolic filling velocities and stroke volume.
- To identify patient subgroups that may be more sensitive to AV interval alterations.
Main Methods:
- Pulsed Doppler echocardiography was used to analyze transmitral flow velocity patterns.
- 14 patients with programmable dual-chamber pacemakers were studied.
- Measurements were taken at three distinct atrioventricular intervals (short, intermediate, long) at a constant pacing rate of 80 bpm.
Main Results:
- A shorter AV interval led to a significant increase in early diastolic filling velocity (E) and a decrease in atrial filling velocity (A).
- Stroke volume did not change significantly across different AV intervals.
- Changes in filling patterns were more pronounced in elderly patients and those with pre-existing reduced early diastolic filling.
Conclusions:
- Atrioventricular interval adjustments can significantly alter left ventricular diastolic filling patterns.
- These effects can occur independently of underlying atrial or ventricular dysfunction.
- Careful consideration of the AV interval is warranted, particularly in patients with impaired diastolic function.
Abstract:
Effects of changes in atrioventricular interval on left ventricular diastolic filling were studied using pulsed Doppler echocardiography in 14 patients with programmable dual chamber pacemakers. Peak early diastolic filling velocity (E) and peak atrial filling velocity (A) were measured from the transmitral flow velocity pattern at three different atrioventricular intervals under the same pacing rate of 80 beats.min-1 in each patient. When the atrioventricular interval was switched from intermediate [148(SD10) ms] to short [68(11) ms], stroke volume did not change significantly [60(14) to 58(13) ml], but E increased from 39(12) to 44(11) cm.s-1 (p less than 0.05), and A decreased from 48(8) to 38(9) cm.s-1 (p less than 0.05). At the short atrioventricular interval, incomplete atrial emptying by the atrial contraction seemed to cause a reciprocal increase in the early diastolic filling. When the atrioventricular interval was switched from intermediate to long [234(16) ms], stroke volume, E and A did not change significantly [57(14) ml, 37(13) cm.s-1, 51(8) cm.s-1 respectively]. At the short and long atrioventricular intervals, atrial filling always changed in the direction opposite to that of early diastolic filling. Changes in stroke volume as well as peak early diastolic filling velocity caused by altering atrioventricular interval were pronounced in aged patients and patients with decreased early diastolic filling. In conclusion, left ventricular diastolic filling patterns can be affected by atrioventricular interval even without any concomitant pathological changes in the left atrial or ventricular function. These effects should not be taken lightly, especially in patients with decreased left ventricular early diastolic filling.
