From the Institute for Experimental Medical Research (E.K.S.E., J.M.A., G.S.E., L.Z., I.S.) and Center for Cardiological Innovation (O.A.S., T.E., M.E.), Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Oslo, Norway (E.K.S.E., G.S.E., L.Z., I.S.); Bjørknes College, Oslo, Norway (J.M.A.); Norwegian Institute of Public Health, Oslo, Norway (G.S.E.); and Department of Cardiology (O.A.S., T.E.) and Institute for Surgical Research (O.A.S., T.E., M.E.), Oslo University Hospital, Rikshospitalet, Oslo, Norway.
Circ Cardiovasc Imaging. 2015 Feb;8(2):e002695. doi: 10.1161/CIRCIMAGING.114.002695.
Left ventricular (LV) motion and deformation is dependent on mechanical load and do therefore not reflect myocardial energy consumption directly. Regional myocardial work, however, constitutes a more complete assessment of myocardial function.
Strain was measured using high-resolution phase-contrast MRI in 9 adult male rats with myocardial infarction (MI) and in 5 sham-operated control animals. Timing of LV valvular events and LV dimensions were evaluated by cine MRI. A separate cohort of 14 animals (MI/sham=9/5) underwent measurement of LV pressure concurrent with identification of valvular events by Doppler-echocardiography for the purpose of generating a standard LV pressure curve, normalized to valvular events. The infarctions were localized to the anterolateral LV wall. Combining strain with timing of valvular events and a measurement of peak arterial pressure, regional myocardial work could be calculated by applying the standard LV pressure curves. Cardiac output and stroke work was preserved in the MI hearts, suggesting a compensatory redistribution of myocardial work from the infarcted region to the viable tissue. In the septum, regional work was indeed increased in MI rats compared with sham (median work per unit long-axis length in a mid-ventricular slice: 241.2 [224.1-271.2] versus 137.2 [127.0-143.8] mJ/m; P<0.001). Myocardial work in infarcted regions was zero. Additionally, eccentric work was increased in the MI hearts.
Phase-contrast MRI, in combination with measurement of peak arterial pressure and MRI-derived timing of valvular events, represent a noninvasive approach for estimation of regional myocardial work in rodents.
左心室（LV）的运动和变形取决于机械负荷，因此不能直接反映心肌的能量消耗。然而，局部心肌做功构成了对心肌功能的更完整评估。
使用高分辨率相位对比 MRI 在 9 只患有心肌梗死（MI）的成年雄性大鼠和 5 只假手术对照动物中测量应变。通过电影 MRI 评估 LV 瓣膜事件和 LV 尺寸的时间。另一组 14 只动物（MI/假手术=9/5）同时进行 LV 压力测量，并通过多普勒超声心动图识别瓣膜事件，以便生成标准化的 LV 压力曲线，该曲线与瓣膜事件相对应。梗死定位于左室前外侧壁。通过将应变与瓣膜事件的时间结合，并测量峰值动脉压，可以通过应用标准 LV 压力曲线来计算局部心肌做功。MI 心脏的心输出量和每搏功保持不变，这表明心肌做功从梗死区域重新分配到存活组织。在间隔区，MI 大鼠的局部工作确实比假手术组增加（中室切片中部单位长轴长度的局部工作：241.2 [224.1-271.2] 与 137.2 [127.0-143.8] mJ/m；P<0.001）。梗死区域的心肌做功为零。此外，MI 心脏的偏心做功增加。
相位对比 MRI 结合峰值动脉压测量和 MRI 衍生的瓣膜事件时间，可以作为一种非侵入性方法来估计啮齿动物的局部心肌做功。
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