Greenberg Neil L, Firstenberg Michael S, Castro Peter L, Main Michael, Travaglini Agnese, Odabashian Jill A, Drinko Jeanne K, Rodriguez L Leonardo, Thomas James D, Garcia Mario J
Cardiovascular Imaging Center, Department of Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio OH 44195, USA.
Circulation. 2002 Jan 1;105(1):99-105. doi: 10.1161/hc0102.101396.
Myocardial fiber strain is directly related to left ventricular (LV) contractility. Strain rate can be estimated as the spatial derivative of velocities (dV/ds) obtained by tissue Doppler echocardiography (TDE). The purposes of the study were (1) to determine whether TDE-derived strain rate may be used as a noninvasive, quantitative index of contractility and (2) to compare the relative accuracy of systolic strain rate against TDE velocities alone.
TDE color M-mode images of the interventricular septum were recorded from the apical 4-chamber view in 7 closed-chest anesthetized mongrel dogs during 5 different inotropic stages. Simultaneous LV volume and pressure were obtained with a combined conductance-high-fidelity pressure catheter. Peak elastance (Emax) was determined as the slope of end-systolic pressure-volume relationships during caval occlusion and was used as the gold standard of LV contractility. Peak systolic TDE myocardial velocities (Sm) and peak (epsilon'(p)) and mean (epsilon'(m)) strain rates obtained at the basal septum were compared against Emax by linear regression. Emax as well as TDE systolic indices increased during inotropic stimulation with dobutamine and decreased with the infusion of esmolol. A stronger association was found between Emax and epsilon'(p) (r=0.94, P<0.01, y=0.29x+0.46) and epsilon'(m) (r=0.88, P<0.01) than for Sm (r=0.75, P<0.01).
TDE-derived epsilon'(p) and epsilon'(m) are strong noninvasive indices of LV contractility. These indices appear to be more reliable than S(m), perhaps by eliminating translational artifact.
心肌纤维应变与左心室（LV）收缩力直接相关。应变率可通过组织多普勒超声心动图（TDE）获得的速度空间导数（dV/ds）来估算。本研究的目的是：（1）确定TDE衍生的应变率是否可用作收缩力的无创定量指标；（2）比较收缩期应变率与单独TDE速度的相对准确性。
在7只开胸麻醉的杂种犬的5个不同变力阶段，从心尖四腔视图记录室间隔的TDE彩色M型图像。使用联合电导-高保真压力导管同时获取左心室容积和压力。将峰值弹性（Emax）确定为腔静脉闭塞期间收缩末期压力-容积关系的斜率，并用作左心室收缩力的金标准。通过线性回归比较在基底间隔处获得的峰值收缩期TDE心肌速度（Sm）以及峰值（ε'(p)）和平均（ε'(m)）应变率与Emax。在用多巴酚丁胺进行变力刺激期间，Emax以及TDE收缩期指标增加，而在输注艾司洛尔时降低。与Sm（r = 0.75，P < 0.01）相比，Emax与ε'(p)（r = 0.94，P < 0.01，y = 0.29x +
0.46）和ε'(m)（r = 0.88，P < 0.01）之间的相关性更强。
TDE衍生的ε'(p)和ε'(m)是左心室收缩力的强大无创指标。这些指标似乎比S(m)更可靠，可能是通过消除平移伪影。
