Monge García Manuel Ignacio, Jian Zhongping, Settels Jos J, Hunley Charles, Cecconi Maurizio, Hatib Feras, Pinsky Michael R
Unidad de Cuidados Intensivos, Hospital Universitario SAS de Jerez, C/Circunvalación, s/n, 11407, Jerez de la Frontera, Spain.
Edwards Lifesciences, Irvine, CA, USA.
Ann Intensive Care. 2019 Apr 16;9(1):48. doi: 10.1186/s13613-019-0526-7.
The aim of this study was to quantify the impact of different cardiovascular factors on left ventricular ejection fraction (LVEF) and test a novel LVEF calculation considering these factors.
10 pigs were studied. The experimental protocol consisted of sequentially changing afterload, preload and contractility. LV pressure-volume (PV) loops and peripheral arterial pressure were obtained before and after each intervention. LVEF was calculated as stroke volume (SV)/end-diastolic volume (EDV). We studied global cardiac function variables: LV end-systolic elastance (Ees), effective arterial elastance (Ea), end-diastolic volume and heart rate. Diastolic function was evaluated by means of the ventricular relaxation time (τ) and ventricular stiffness constant (β) obtained from the end-diastolic PV relationship. Ventriculo-arterial coupling (VAC), an index of cardiovascular performance, was calculated as Ea/Ees. LV mechanical efficiency (LVeff) was calculated as the ratio of stroke work to LV pressure-volume area. A linear mixed model was used to determine the impact of cardiac factors (Ees, Ea, EDV and heart rate), VAC and LVeff on LVEF during all experimental conditions. LVEF was mainly related to Ees and Ea. There was a strong relationship between LVEF and both VAC and LVeff (r = 0.69 and r = 0.94, respectively). The relationship between LVEF and Ees was good (r = 0.43). Adjusting LVEF to afterload ([Formula: see text]) performed better for estimating Ees (r = 0.75) and improved the tracking of LV contractility changes, even when a peripheral Ea was used as surrogate (Ea = radial MAP/SV; r = 0.73).
LVEF was mainly affected by contractility and afterload changes and was strongly related to VAC and LVeff. An adjustment to LVEF that considers the impact of afterload provided a better assessment of LV contractility.
本研究的目的是量化不同心血管因素对左心室射血分数（LVEF）的影响，并测试一种考虑这些因素的新型LVEF计算方法。
对10头猪进行了研究。实验方案包括依次改变后负荷、前负荷和心肌收缩力。在每次干预前后获取左心室压力-容积（PV）环和外周动脉压。LVEF计算为每搏输出量（SV）/舒张末期容积（EDV）。我们研究了整体心脏功能变量：左心室收缩末期弹性（Ees）、有效动脉弹性（Ea）、舒张末期容积和心率。通过从舒张末期PV关系获得的心室舒张时间（τ）和心室僵硬度常数（β）评估舒张功能。心室动脉耦联（VAC）是心血管性能的一个指标，计算为Ea/Ees。左心室机械效率（LVeff）计算为每搏功与左心室压力-容积面积的比值。使用线性混合模型确定在所有实验条件下心脏因素（Ees、Ea、EDV和心率）、VAC和LVeff对LVEF的影响。LVEF主要与Ees和Ea相关。LVEF与VAC和LVeff均有很强的相关性（r分别为0.69和0.94）。LVEF与Ees的关系良好（r = 0.43）。将LVEF调整为后负荷（[公式：见正文]）在估计Ees方面表现更好（r = 0.75），并且即使使用外周Ea作为替代指标（Ea = 桡动脉平均动脉压/SV；r = 0.73），也能改善对左心室收缩力变化的跟踪。
LVEF主要受心肌收缩力和后负荷变化的影响，并且与VAC和LVeff密切相关。考虑后负荷影响的LVEF调整能更好地评估左心室收缩力。
