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Relationship between atrial function, left ventricular isovolumic relation time, and early filling in dual
1Department of Internal Medicine, University of Modena, Italy.
Insights
Shortening atrioventricular delay in DDD pacemaker patients improves early diastolic filling but reduces atrial systolic function. Atrial ejection force and filling fraction correlate with diastolic parameters, impacting ventricular filling.
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- Atrial systolic function is crucial for optimal ventricular filling.
- DDD pacemakers allow for adjustable atrioventricular (AV) delay, influencing cardiac hemodynamics.
- Understanding the impact of AV delay on atrial function is vital for pacemaker optimization.
Purpose of the Study:
- To investigate the effects of modifying atrioventricular delay on atrial systolic function in patients with DDD pacemakers.
- To evaluate the relationship between atrial systolic performance and diastolic parameters.
Main Methods:
- 36 patients with DDD pacemakers for complete atrioventricular block were studied.
- Atrial systolic and diastolic parameters were recorded at varying AV delays (200, 150, 100 ms) at a pacing rate of 70 bpm.
- Key parameters measured included isovolumic relaxation time, early and late diastolic velocities, atrial filling fraction, and atrial ejection force.
Main Results:
- Progressive shortening of AV delay increased early diastolic peak velocity but decreased isovolumic relaxation time, atrial peak velocity, atrial filling fraction, and atrial ejection force.
- Significant correlations were found between isovolumic relaxation time, early peak velocity, and atrial filling fraction/ejection force.
- Atrial ejection force directly correlated with atrial filling fraction, with both decreasing as AV delay shortened.
Conclusions:
- Shortening AV delay in DDD pacemaker patients enhances early diastolic ventricular filling but impairs atrial systolic function.
- Atrial ejection force and atrial filling fraction are reliable indicators of atrial systolic performance and decrease with shorter AV delays.
- The interplay between atrial emptying and isovolumic relaxation time is important for maintaining ventricular filling across different AV delays.
Abstract:
This investigation was performed to study atrial systolic function is response to modification of atrioventricular delay in a sample of 36 patients with a DDD pacemaker implanted for complete atrioventricular block. The relation between atrial systolic performance and diastolic-related parameters was also evaluated. Isovolumic relaxation time, early diastolic peak velocity, late (atrial) diastolic peak velocity, atrial filing fraction, and atrial ejection force were recorded at a pacing rate of 70 impulses/min and at atrioventricular delay of 200, 150, and 100 msec. Our data showed that the progressive shortening of atrioventricular delay induced a gradual increase in early peak velocity (median value 46 to 53 to 61.5 cm/sec, respectively, at 200, 150, and 100 msec intervals) and a gradual decrease in isovolumic relaxation time (median 92.6 to 81.5 to 69.7 msec at 200, 150, and 100 msec, respectively), atrial peak velocity (59 to 52 to 44.5 cm/sec at 200, 150, and 100 msec, respectively), atrial filling fraction (50.5% to 40% to 23.5% at 200, 150, and 100 msec, respectively), and atrial ejection force (17.2 to 14.7 to 8.5 kilodynes at 200, 150, and 100 msec, respectively). For every atrioventricular delay value detected, we found a significant correlation between isovolumic relaxation time and early peak velocity with atrial filling fraction and atrial ejection force. In addition, atrial ejection force was related directly to atrial filling fraction at studied atrioventricular delays. The two indexes of atrial systolic performance showed a parallel decrease by shortening the atrioventricular delay, and they can quantify atrial systolic performance equally in sequentially paced patients. Furthermore, our results are in accordance with the hypothesis that the interaction between the effectiveness of active left atrial emptying and isovolumetric relaxation time may play an important role in maintaining an ideal ventricular filling despite changes in atrial systolic function.