Pernot Mathieu, Lee Wei-Ning, Bel Alain, Mateo Philippe, Couade Mathieu, Tanter Mickaël, Crozatier Bertrand, Messas Emmanuel
Institut Langevin, Ecole Supérieure de Physique Chimie Industrielles de Paris, ParisTech, Paris, France; CNRS, Unité mixte de recherche 7587, Paris, France; Institut National de la Santé et de la Recherche Médicale, U979, Paris, France; Université Paris Diderot-Paris7, Paris, France.
Institut Langevin, Ecole Supérieure de Physique Chimie Industrielles de Paris, ParisTech, Paris, France; CNRS, Unité mixte de recherche 7587, Paris, France; Institut National de la Santé et de la Recherche Médicale, U979, Paris, France; Université Paris Diderot-Paris7, Paris, France.
JACC Cardiovasc Imaging. 2016 Sep;9(9):1023-1030. doi: 10.1016/j.jcmg.2016.01.022. Epub 2016 May 25.
The aim of this study was to investigate the potential of shear wave imaging (SWI), a novel ultrasound-based technique, to noninvasively quantify passive diastolic myocardial stiffness in an ovine model of ischemic cardiomyopathy.
Evaluation of diastolic left ventricular function is critical for evaluation of heart failure and ischemic cardiomyopathy. Myocardial stiffness is known to be an important property for the evaluation of the diastolic myocardial function, but this parameter cannot be measured noninvasively by existing techniques.
SWI was performed in vivo in open-chest procedures in 10 sheep. Ligation of a diagonal of the left anterior descending coronary artery was performed for 15 min (stunned group, n = 5) and 2 h (infarcted group, n = 5). Each procedure was followed by a 40-min reperfusion period. Diastolic myocardial stiffness was measured at rest, during ischemia, and after reperfusion by using noninvasive shear wave imaging. Simultaneously, end-diastolic left ventricular pressure and segmental strain were measured with a pressure catheter and sonomicrometers during transient vena caval occlusions to obtain gold standard evaluation of myocardial stiffness using end-diastolic strain-stress relationship (EDSSR).
In both groups, the end-systolic circumferential strain was drastically reduced during ischemia (from 14.2 ± 1.2% to 1.3 ± 1.6% in the infarcted group and from 13.5 ± 3.0% to 1.9 ± 1.8% in the stunned group; p <0.01). SWI diastolic stiffness increased after 2 h of ischemia from 1.7 ± 0.4 to 6.2 ± 2.2 kPa (p < 0.05) and even more after reperfusion (12.1 ± 4.2 kPa; p < 0.01). Diastolic myocardial stiffening was confirmed by the exponential constant coefficient of the EDSSR, which increased from 8.8 ± 2.3 to 25.7 ± 9.5 (p < 0.01). In contrast, SWI diastolic stiffness was unchanged in the stunned group (2.3 ± 0.4 kPa vs 1.8 ± 0.3 kPa, p = NS) which was confirmed also by the exponential constant of EDSSR (9.7 ± 3.1 vs 10.2 ± 2.3, p = NS).
Noninvasive SWI evaluation of diastolic myocardial stiffness can differentiate between stiff, noncompliant infarcted wall and softer wall containing stunned myocardium.
本研究旨在探讨基于超声的新技术剪切波成像（SWI）在缺血性心肌病绵羊模型中无创量化舒张期被动心肌僵硬度的潜力。
舒张期左心室功能评估对于心力衰竭和缺血性心肌病的评估至关重要。心肌僵硬度是评估舒张期心肌功能的重要特性，但现有技术无法无创测量该参数。
对10只绵羊进行开胸手术，在体实施SWI。结扎左前降支冠状动脉的一条对角支15分钟（顿抑组，n = 5）和2小时（梗死组，n = 5）。每次手术后均有40分钟的再灌注期。通过无创剪切波成像在静息、缺血期间和再灌注后测量舒张期心肌僵硬度。同时，在短暂腔静脉闭塞期间，用压力导管和超声测微仪测量舒张末期左心室压力和节段应变，以利用舒张末期应变-应力关系（EDSSR）获得心肌僵硬度的金标准评估。
在两组中，缺血期间收缩末期圆周应变均大幅降低（梗死组从14.2±1.2%降至1.3±1.6%，顿抑组从13.5±3.0%降至1.9±1.8%；p<0.01）。缺血2小时后，SWI舒张期僵硬度从1.7±0.4kPa增加到6.2±2.2kPa（p<0.05），再灌注后增加更多（12.1±4.2kPa；p<0.01）。EDSSR的指数常数系数证实了舒张期心肌僵硬度增加，从8.8±2.3增加到25.7±9.5（p<0.01）。相比之下，顿抑组SWI舒张期僵硬度无变化（2.3±0.4kPa对1.8±0.3kPa，p =无显著性差异），EDSSR的指数常数也证实了这一点（9.7±3.1对10.2±2.3，p =无显著性差异）。
无创SWI评估舒张期心肌僵硬度可区分僵硬、顺应性差的梗死心肌壁和含有顿抑心肌的较软心肌壁。
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