Intensive Care Unit, Hospital Universitario SAS Jerez, Jerez de la Frontera, Spain.
Edwards Lifesciences, Irvine, California, USA.
Physiol Rep. 2023 Feb;11(4):e15607. doi: 10.14814/phy2.15607.
Left ventricular mechanical dyssynchrony (LVMD) refers to the nonuniformity in mechanical contraction and relaxation timing in different ventricular segments. We aimed to determine the relationship between LVMD and LV performance, as assessed by ventriculo-arterial coupling (VAC), LV mechanical efficiency (LV ), left ventricular ejection fraction (LVEF), and diastolic function during sequential experimental changes in loading and contractile conditions. Thirteen Yorkshire pigs submitted to three consecutive stages with two opposite interventions each: changes in afterload (phenylephrine/nitroprusside), preload (bleeding/reinfusion and fluid bolus), and contractility (esmolol/dobutamine). LV pressure-volume data were obtained with a conductance catheter. Segmental mechanical dyssynchrony was assessed by global, systolic, and diastolic dyssynchrony (DYS) and internal flow fraction (IFF). Late systolic LVMD was related to an impaired VAC, LV , and LVEF, whereas diastolic LVMD was associated with delayed LV relaxation (logistic tau), decreased LV peak filling rate, and increased atrial contribution to LV filling. The hemodynamic factors related to LVMD were contractility, afterload, and heart rate. However, the relationship between these factors differed throughout the cardiac cycle. LVMD plays a significant role in LV systolic and diastolic performance and is associated with hemodynamic factors and intraventricular conduction.
左心室机械不同步（LVMD）是指不同心室节段的机械收缩和舒张时间的非均匀性。我们旨在确定 LVMD 与左心室性能之间的关系，左心室性能通过心室动脉偶联（VAC）、左心室机械效率（LV）、左心室射血分数（LVEF）和舒张功能来评估，同时在负荷和收缩条件的连续实验变化期间。13 头约克夏猪经历了三个连续阶段，每个阶段有两个相反的干预措施：后负荷（苯肾上腺素/硝普钠）、前负荷（出血/再灌注和液体冲击）和收缩力（艾司洛尔/多巴酚丁胺）的变化。使用电导导管获得左心室压力-容积数据。通过整体、收缩期和舒张期不同步（DYS）和内部流量分数（IFF）评估节段性机械不同步。收缩晚期 LVMD 与 VAC、LV 和 LVEF 受损有关，而舒张期 LVMD 与左心室舒张延迟（逻辑 tau）、左心室峰值充盈率降低和心房对左心室充盈的贡献增加有关。与 LVMD 相关的血流动力学因素是收缩力、后负荷和心率。然而，这些因素在整个心动周期中的关系不同。LVMD 在左心室收缩和舒张功能中起着重要作用，并与血流动力学因素和室内传导有关。
