Department of Cardiology, The Prince Charles Hospital, Rode Road, Brisbane, Queensland, Australia.
School of Medicine and Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
Eur Heart J Cardiovasc Imaging. 2019 Jan 1;20(1):31-39. doi: 10.1093/ehjci/jey131.
Non-invasive left ventricular (LV) pressure-strain loop (PSL) provides a novel method of quantifying myocardial work (MW) with potential advantages over conventional global longitudinal strain (GLS) by incorporating measurements of myocardial deformation and LV pressure. We investigated different patterns of LV PSL and global MW index (GWI) in patients with hypertension (HTN) and dilated cardiomyopathy (CMP).
Seventy-four patients underwent transthoracic echocardiography and strain analysis before coronary angiography. Patients were divided into three groups: control, HTN, and CMP. GWI was calculated as the area of the LV PSL as a product of strain × systolic blood pressure. MW efficiency (GWE) is derived from the percentage ratio of constructive work (GCW) to sum of constructive work (GCW) and wasted work (GWW). Influences of HTN and LV function on its relationship with MW were evaluated. GLS and LV ejection fraction were preserved in the HTN group with no difference from controls. GWI was significantly higher in moderate to severe HTN patients (P = 0.004) as a compensatory mechanism to preserve LV contractility and function against an increase in afterload. GWE was preserved in HTN patients due to the proportional increase in GCW and GWW. GLS, GWI, and GWE were significantly reduced in CMP (P < 0.05), with a trend in rightward shift and reduction in the LV PSL.
GWI is a potential new technique that allows better understanding of the relationship between LV remodelling and increased wall stress under different loading conditions.
非侵入性左心室（LV）压力-应变环（PSL）提供了一种新的量化心肌做功（MW）的方法，通过结合心肌变形和 LV 压力的测量，与传统的整体纵向应变（GLS）相比具有潜在优势。我们研究了高血压（HTN）和扩张型心肌病（CMP）患者 LV PSL 和整体 MW 指数（GWI）的不同模式。
74 例患者在冠状动脉造影前行经胸超声心动图和应变分析。患者分为三组：对照组、HTN 组和 CMP 组。GWI 计算为 LV PSL 的面积，即应变×收缩压的乘积。MW 效率（GWE）是由构建功（GCW）的百分比比值推导出来的，构建功（GCW）和浪费功（GWW）的总和。评估了 HTN 和 LV 功能对其与 MW 关系的影响。HTN 组的 GLS 和 LV 射血分数保持不变，与对照组无差异。中重度 HTN 患者的 GWI 显著升高（P = 0.004），这是一种代偿机制，可维持 LV 收缩力和功能，以对抗后负荷的增加。由于 GCW 和 GWW 的比例增加，HTN 患者的 GWE 得到维持。GLS、GWI 和 GWE 在 CMP 中显著降低（P < 0.05），LV PSL 呈右移和降低趋势。
GWI 是一种潜在的新技术，它可以更好地理解在不同负荷条件下 LV 重构与壁面应力增加之间的关系。
