Key result
Dobutamine stress increases LV kinetic energy without altering the turbulent-to-total ratio, suggesting preserved energetic efficiency.
Why the study?
The study was conducted to explore the effects of pharmacologically induced stress on mean kinetic energy and turbulent kinetic energy in the left ventricle of healthy volunteers.
Does dobutamine-induced stress alter the turbulent kinetic energy to total kinetic energy (TKE/KE) ratio in the left ventricle of healthy volunteers?
Observational (n=11)
No
Does dobutamine-induced stress alter the turbulent kinetic energy to total kinetic energy (TKE/KE) ratio in the left ventricle of healthy volunteers?
Absolute Event Rate: 0.41% vs 0.4%
p-value: p=0.62
In healthy left ventricles, dobutamine-induced stress increases both mean and turbulent kinetic energy proportionally, maintaining a preserved energetic efficiency (TKE/KE ratio).
Preserved TKE/KE ratio under stress supports maintained efficiency in healthy LV; leaves open extension to diseased hearts.
The total kinetic energy (KE) of blood can be decomposed into mean KE (MKE) and turbulent KE (TKE), which are associated with the phase-averaged fluid velocity field and the instantaneous velocity fluctuations, respectively. The aim of this study was to explore the effects of pharmacologically induced stress on MKE and TKE in the left ventricle (LV) in a cohort of healthy volunteers. 4D Flow MRI data were acquired in eleven subjects at rest and after dobutamine infusion, at a heart rate that was ∼60% higher than the one in rest conditions. MKE and TKE were computed as volume integrals over the whole LV and as data mapped to functional LV flow components, i.e., direct flow, retained inflow, delayed ejection flow and residual volume. Diastolic MKE and TKE increased under stress, in particular at peak early filling and peak atrial contraction. Augmented LV inotropy and cardiac frequency also caused an increase in direct flow and retained inflow MKE and TKE. However, the TKE/KE ratio remained comparable between rest and stress conditions, suggesting that LV intracavitary fluid dynamics can adapt to stress conditions without altering the TKE to KE balance of the normal left ventricle at rest.
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Riva et al. (2023) conducted an observational in Healthy volunteers (n=11). Dobutamine vs. Rest was evaluated on Diastolic time integral of TKE/KE ratio for the entire left ventricle (p=0.62). Dobutamine-induced cardiac stress increased both mean and turbulent kinetic energy in healthy left ventricles, but the ratio of turbulent to total kinetic energy remained unchanged (0.41 vs 0.40, p=0.62), suggesting preserved energetic efficiency.
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