Key result
Accelerated LV relaxation in rats inversely correlates with minimum diastolic pressure and endsystolic volume.
Why the study?
The rate and depth of myocardial relaxation determine left ventricular filling in early diastole, prompting analysis of the relaxation phase.
May refine preclinical models of diastolic filling; leaves open translation to human HFpEF assessment.
The rate and depth of myocardial relaxation determine left ventricular (LV) filling in early diastole. To analyze the relaxation phase, the method of logarithm of LV pressure fall in rats was used. A gradual acceleration of relaxation was found during the transition from the isovolumic phase to the auxovolumic phase, immediately before the opening of the atrioventricular valves. The relaxation rate constant in this phase has been inversely correlated with the values of the minimum LV diastolic pressure and LV endsystolic volume. The results suggest that the gradual acceleration of relaxation is due to the straightening of the spring-like structure of connectin (titin), which is compressed during contraction.
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Kapelko et al. (2023) studied this question. Analysis of left ventricular pressure fall in rats revealed a gradual acceleration of relaxation that inversely correlated with minimum LV diastolic pressure and LV endsystolic volume.
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