Key result
In healthy individuals, controlled preload alterations using continuous positive airway pressure or passive leg raise did not significantly change left atrial contraction strain or peak strain rate.
Why the study?
Assessing left atrial contractile function in disturbed circulatory conditions requires understanding its normal response to loading changes, which remains incompletely understood.
Do controlled preload alterations affect left atrial contraction strain and peak strain rate in healthy individuals?
Do controlled preload alterations affect left atrial contraction strain and peak strain rate in healthy individuals?
Left atrial contraction strain and peak strain rate appear to be preload-independent in healthy individuals, which may aid in assessing left atrial contractile function in disturbed circulatory conditions.
Answers are grounded in this paper and cite their sources.
Left atrial contraction strain may be preload-independent in healthy subjects; hypothesis-generating before testing in cardiovascular disease.
Background In order to assess left atrial contractile function in disturbed circulatory conditions, it is necessary to have a clear understanding of how it behaves in a normal resting state with changes in loading conditions. However, currently the understanding of this relationship is incomplete. We hypothesize that in healthy individuals, left atrial contraction strain and its peak strain rate are increased or decreased by increasing or decreasing preload, respectively. Methods Controlled maneuvers used to change preload included continuous positive airway pressure by mask (CPAP 20 cmH2O) for preload decrease, and passive leg raise (15 degrees angle) for preload increase. Cardiac ultrasound 4-chamber views of the left atria and left ventricle were acquired at baseline and during maneuver. Acquired images were post processed and analyzed offline. Comparisons were made using paired t-test and means with 95% confidence interval. Results There were 38 participants, complete results were obtained from 23 in the CPAP maneuver and 27 in the passive leg raise maneuver. For the CPAP group, left atrial contraction strain was 11.6% (10.1 to 13.1) at baseline and 12.8% (11.0 to 14.6) during the maneuver (p = 0.16). Left atrial contraction peak strain rate was − 1.7 s− 1 (− 1.8 to − 1.5) at baseline and − 1.8 s− 1 (− 2.0 to − 1.6) during the maneuver (p = 0.29). For the passive leg raise-group, left atrial contraction strain was 10.1% (9.0 to 11.2) at baseline and 10.8% (9.4 to 12.3) during the maneuver (p = 0.28). Left atrial contraction peak strain rate was − 1.5 s− 1 (− 1.6 to − 1.4) at baseline and − 1.6 s− 1 (− 1.8 to − 1.5) during the maneuver (p = 0.29). Left atrial area, an indicator of preload, increased significantly during passive leg raise and decreased during CPAP. Conclusion In healthy individuals, left atrial contraction strain and its peak strain rate seem to be preload-independent. Trial registration The study was 2018-02-19 registered at clinicaltrials.gov ( NCT03436030 ).
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Gottfridsson et al. (2022) studied Healthy (n=38). Continuous positive airway pressure (CPAP) and passive leg raise (PLR) vs. Baseline (pre-maneuver) was evaluated on Left atrial contraction strain (LASct) during CPAP (p=0.157). In healthy individuals, controlled preload alterations using continuous positive airway pressure or passive leg raise did not significantly change left atrial contraction strain or peak strain rate.
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