Weidemann Frank, Jamal Fadi, Sutherland George R, Claus Piet, Kowalski Miroslaw, Hatle Liv, De Scheerder Ivan, Bijnens Bart, Rademakers Frank E
Department of Cardiology, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
Am J Physiol Heart Circ Physiol. 2002 Aug;283(2):H792-9. doi: 10.1152/ajpheart.00025.2002.
For porcine myocardium, ultrasonic regional deformation parameters, systolic strain (epsilon(sys)) and peak systolic strain rate (SR(sys)), were compared with stroke volume (SV) and contractility [contractility index (CI)] measured as the ratio of end-systolic strain to end-systolic wall stress. Heart rate (HR) and contractility were varied by atrial pacing (AP = 120-180 beats/min, n = 7), incremental dobutamine infusion (DI = 2.5-20 microg. kg(-1). min(-1), n = 7), or continuous esmolol infusion (0.5 mg. kg(-1). min(-1)) + subsequent pacing (120-180 beats/min) (EI group, n = 6). Baseline SR(sys) and epsilon(sys) averaged 5.0 +/- 0.4 s(-1) and 60 +/- 4%. SR(sys) and CI increased linearly with DI (20 microg. kg(-1). min(-1); SR(sys) = 9.9 +/- 0.7 s(-1), P < 0.0001) and decreased with EI (SR(sys) = 3.4 +/- 0.1 s(-1), P < 0.01). During pacing, SR(sys) and CI remained unchanged in the AP and EI groups. During DI, epsilon(sys) and SV initially increased (5 microg. kg(-1). min(-1); epsilon(sys) = 77 +/- 6%, P < 0.01) and then progressively returned to baseline. During EI, SV and epsilon(sys) decreased (epsilon(sys) = 38 +/- 2%, P < 0.001). Pacing also decreased SV and epsilon(sys) in the AP (180 beats/min; epsilon(sys) = 36 +/- 2%, P < 0.001) and EI groups (180 beats/min; epsilon(sys) = 25 +/- 3%, P < 0.001). Thus, for normal myocardium, SR(sys) reflects regional contractile function (being relatively independent of HR), whereas epsilon(sys) reflects changes in SV.
对于猪心肌，将超声区域变形参数、收缩期应变（ε(sys)）和收缩期峰值应变率（SR(sys)）与每搏输出量（SV）以及作为收缩末期应变与收缩末期壁应力之比测量的收缩性[收缩性指数（CI）]进行比较。通过心房起搏（AP = 120 - 180次/分钟，n = 7）、递增多巴酚丁胺输注（DI = 2.5 - 20μg·kg⁻¹·min⁻¹，n = 7）或持续艾司洛尔输注（0.5mg·kg⁻¹·min⁻¹）+随后的起搏（120 - 180次/分钟）（EI组，n = 6）来改变心率（HR）和收缩性。基线时SR(sys)和ε(sys)平均分别为5.0±0.4s⁻¹和60±4%。SR(sys)和CI随DI呈线性增加（20μg·kg⁻¹·min⁻¹；SR(sys)=9.9±0.7s⁻¹，P<0.0001），并随EI降低（SR(sys)=3.4±0.1s⁻¹，P<0.01）。在起搏期间，AP组和EI组的SR(sys)和CI保持不变。在DI期间，ε(sys)和SV最初增加（5μg·kg⁻¹·min⁻¹；ε(sys)=77±6%，P<0.01），然后逐渐恢复到基线。在EI期间，SV和ε(sys)降低（ε(sys)=38±2%，P<0.001）。起搏也使AP组（180次/分钟；ε(sys)=36±2%，P<0.001）和EI组（180次/分钟；ε(sys)=25±3%，P<0.001）的SV和ε(sys)降低。因此，对于正常心肌，SR(sys)反映区域收缩功能（相对独立于HR），而ε(sys)反映SV的变化。
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