Datasheet1_Impact of dobutamine stress on diastolic energetic efficiency of healthy left ventricle: an in vivo kinetic energy analysis.pdf

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.

血液的总体动能（KE）可分解为平均动能（MKE）和湍动能（TKE），分别与相位平均的流体速度场及瞬时速度波动相关联。本研究旨在探究药物诱导的压力对健康志愿者左心室（LV）内MKE和TKE的影响。在11位受试者中，于静息状态及多巴胺输注后采集了四维流动磁共振成像（4D Flow MRI）数据，心率较静息状态下高出约60%。MKE和TKE通过计算整个左心室的体积积分以及映射到功能左心室血流成分（即直接血流、保留流入、延迟射血血流和残留体积）的数据来获得。在压力状态下，舒张期MKE和TKE增加，尤其是在早期充盈峰值和心房收缩峰值时。增强的LV收缩力和心脏频率亦导致了直接血流和保留流入的MKE和TKE的增加。然而，TKE/KE比值在静息和压力状态下保持相似，表明左心室内腔流体动力学能够适应压力状态，而不会改变静息状态下正常左心室的TKE与KE之间的平衡。