Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.
Cardiology Department, Wroclaw Medical University, Wroclaw, Poland.
Eur Heart J Cardiovasc Imaging. 2017 Sep 1;18(9):1001-1007. doi: 10.1093/ehjci/jew135.
Load dependence is an important source of variation in left ventricular (LV) deformation. This impacts on the precision of information obtained from serial measurements. However, it is clinically important to distinguish actual myocardial dysfunction from changes associated with altered loading conditions. We sought to investigate the association of changes of loading parameters with changes in LV longitudinal (GLS) and circumferential (GCS) strains.
Baseline and a 12-month follow-up 2D echocardiograms were performed in 191 Stage A heart failure patients with uncomplicated hypertension. These patients underwent simultaneous measurement of conventional and central blood pressures (BPs) and haemodynamic measurements by applanation tonometry. Significant, but weak correlations (r = 0.15-0.28) of LV strain parameters and their changes over the follow-up period were shown for the majority of LV afterload-associated variables, including central and brachial systolic, diastolic, and mean BPs; 24-h systolic and diastolic BPs; peak reservoir and excess pressures; central augmented pressure (CAP) and pulse pressure; augmentation index; and arterial elastance index (EaI). Central mean BP, EaI, and changes in CAP and EaI over follow-up were independent contributors to LV deformation in multivariable analysis. No improvement in the Bland-Altman 95% limits of agreement and correlation coefficients was seen with LV afterload correction of GLS and GCS using central BP indices.
LV longitudinal and circumferential strains in a population without apparent heart disease is relatively insusceptible to changes in LV afterload within physiological range, which, therefore, seem unlikely to be a significant confounder in repeated GLS or GCS observations.
负荷依赖性是左心室（LV）变形的重要变异源。这会影响从连续测量中获得的信息的精度。然而，从临床角度来看，区分实际心肌功能障碍与与改变负荷条件相关的变化非常重要。我们试图研究LV 纵向（GLS）和圆周（GCS）应变变化与负荷参数变化之间的关系。
191 例高血压合并无症状心力衰竭患者进行了基线和 12 个月的二维超声心动图随访。这些患者接受了同步测量常规和中心血压（BP）以及平板张力测量的血流动力学测量。大多数 LV 后负荷相关变量的 LV 应变参数及其随访期间的变化之间存在显著但较弱的相关性（r = 0.15-0.28），包括中心和肱动脉收缩压、舒张压和平均 BP；24 小时收缩压和舒张压；峰值储备和过量压力；中心增强压（CAP）和脉搏压；增强指数；以及动脉弹性指数（EaI）。多变量分析显示，中心平均 BP、EaI 以及 CAP 和 EaI 的随访变化是 LV 变形的独立贡献者。使用中心 BP 指数对 GLS 和 GCS 的 LV 后负荷进行校正后，Bland-Altman 95%限界和相关系数没有改善。
在没有明显心脏病的人群中，LV 纵向和圆周应变相对不易受到生理范围内 LV 后负荷变化的影响，因此，在重复 GLS 或 GCS 观察中不太可能成为一个重要的混杂因素。
