Department of Cardiovascular Sciences, Division of Cardiovascular Imaging and Dynamics, Catholic University of Leuven, Leuven, Belgium.
JACC Cardiovasc Imaging. 2013 Apr;6(4):419-28. doi: 10.1016/j.jcmg.2012.10.022. Epub 2013 Mar 14.
The aim of this study was to test the hypothesis that the noninvasively constructed slope of the relationship between left ventricular (LV) regional systolic strain and stretch during atrial contraction represents LV inotropic state.
LV systolic response to a changing preload depends on its inotropic state. Changing the preload has allowed constructing the slope of the end-systolic pressure-volume relationship that is used as an invasive measurement of LV inotropy. We assumed that the slope of the relationship between regional systolic LV strain (total_S) and stretch during atrial contraction (preS) depends on the LV inotropic state as well and can thus be used as a LV inotropy index.
Strain curves (tissue Doppler) were extracted from 27 healthy individuals to determine the normal stretch-strain relationship at rest, during a low-dose dobutamine (LD) challenge and during passive leg-lift (LL). The method was also applied in 7 patients with breast cancer before and after chemotherapy with anthracyclines.
PreS and total_S correlated closely in all subjects (r = 0.82). Total_S values increased (p < 0.05) with LD (-20.44 ± 3.89% vs. -24.24 ± 5.55%) and LL (-19.65 ± 3.77% vs. -24.05 ± 3.67%), whereas preS increased only with LL (5.96 ± 1.72% vs. 8.61 ± 2.18%), but not with LD (6.83 ± 2.34% vs. 7.29 ± 2.24%). No changes of total_S or preS were observed after the exposure to chemotherapy (-21.23 ± 2.93% vs. -21.49 ± 2.89% and 8.11 ± 1.03% vs. 8.59 ± 1.73%, respectively). The slope of stretch-strain relationship got steeper with LD (-1.47 ± 0.36 vs. -2.34 ± 0.36, p < 0.05), declined after the chemotherapy (-1.68 ± 0.15 to -0.86 ± 0.23, p < 0.05) and did not change with LL (-1.39 ± 0.57 vs. -1.51 ± 0.38, p = NS).
The slope of the regional stretch-strain relationship can be regarded as a noninvasive index of myocardial inotropic state. It gets steeper with increasing inotropy, does not change with preload induced changes of LV systolic function, and flattens after the exposure to a cardiotoxic drug.
本研究旨在验证如下假设，即通过心房收缩时左心室（LV）局部收缩应变与拉伸的无创构建斜率来表示 LV 的变力状态。
LV 对前负荷变化的收缩反应取决于其变力状态。改变前负荷可以构建收缩末期压力-容积关系的斜率，该斜率可作为 LV 变力的有创测量。我们假设 LV 应变（总_S）与心房收缩时拉伸的关系斜率也依赖于 LV 的变力状态，因此可以用作 LV 变力指数。
从 27 名健康个体中提取应变曲线（组织多普勒），以确定静息时、低剂量多巴酚丁胺（LD）挑战时和被动腿抬高（LL）时的正常拉伸-应变关系。该方法还应用于 7 名接受蒽环类药物化疗前和化疗后的乳腺癌患者。
在所有受试者中，前 S 和总_S 密切相关（r = 0.82）。LD（-20.44 ± 3.89% vs. -24.24 ± 5.55%）和 LL（-19.65 ± 3.77% vs. -24.05 ± 3.67%）增加了总_S 值（p < 0.05），而前 S 仅在 LL 时增加（5.96 ± 1.72% vs. 8.61 ± 2.18%），但在 LD 时没有增加（6.83 ± 2.34% vs. 7.29 ± 2.24%）。化疗后，总_S 或前 S 均无变化（-21.23 ± 2.93% vs. -21.49 ± 2.89%和 8.11 ± 1.03% vs. 8.59 ± 1.73%）。LD 使应变-应变关系斜率变陡（-1.47 ± 0.36 对 -2.34 ± 0.36，p < 0.05），化疗后斜率下降（-1.68 ± 0.15 至-0.86 ± 0.23，p < 0.05），而 LL 则不变（-1.39 ± 0.57 对 -1.51 ± 0.38，p = NS）。
区域拉伸-应变关系的斜率可以看作是心肌变力状态的无创指标。它随着变力的增加而变陡，不会随 LV 收缩功能的前负荷变化而变化，并且在接触心脏毒性药物后变平。
