Nemours Cardiac Center and Nemours Biomedical Research, Alfred I, duPont Hospital for Children, 1600 Rockland Rd, Wilmington, DE 19103, USA.
J Transl Med. 2013 Aug 7;11:183. doi: 10.1186/1479-5876-11-183.
Wall stress is a useful concept to understand the progression of ventricular remodeling. We measured cumulative LV wall stress throughout the cardiac cycle over unit time and tested whether this "integrated wall stress (IWS)" would provide a reliable marker of total ventricular workload.
We applied IWS to mice after experimental myocardial infarction (MI) and sham-operated mice, both at rest and under dobutamine stimulation. Small infarcts were created so as not to cause subsequent overt hemodynamic decompensation. IWS was calculated over one minute through simultaneous measurement of LV internal diameter and wall thickness by echocardiography and LV pressure by LV catheterization. At rest, the MI group showed concentric LV hypertrophy pattern with preserved LV cavity size, LV systolic function, and IWS comparable with the sham group. Dobutamine stimulation induced a dose-dependent increase in IWS in MI mice, but not in sham mice; MI mice mainly increased heart rate, whereas sham mice increased LV systolic and diastolic function. IWS showed good correlation with a product of peak-systolic wall stress and heart rate. We postulate that this increase in IWS in post-MI mice represents limited myocardial contractile reserve.
We hereby propose that IWS provides a useful estimate of total ventricular workload in the mouse model and that increased IWS indicates limited LV myocardial contractile reserve.
壁应力是理解心室重构进展的一个有用概念。我们测量了单位时间内整个心动周期内的累积 LV 壁应力，并测试了这种“综合壁应力（IWS）”是否可以作为总心室工作量的可靠标志物。
我们在实验性心肌梗死（MI）后和假手术小鼠以及休息和多巴酚丁胺刺激下应用 IWS。小梗死的形成是为了避免随后出现明显的血流动力学失代偿。通过超声心动图同时测量 LV 内径和壁厚以及 LV 导管测量 LV 压力，IWS 在一分钟内进行计算。在休息时，MI 组表现出同心性 LV 肥厚模式，LV 腔大小、LV 收缩功能和 IWS 与假手术组相当。多巴酚丁胺刺激可使 MI 小鼠的 IWS 呈剂量依赖性增加，但在假手术小鼠中则没有；MI 小鼠主要增加心率，而假手术小鼠则增加 LV 收缩和舒张功能。IWS 与峰值收缩壁应力和心率的乘积具有良好的相关性。我们推测，MI 后小鼠 IWS 的增加代表有限的心肌收缩储备。
我们提出 IWS 可提供小鼠模型总心室工作量的有用估计，并且 IWS 的增加表明 LV 心肌收缩储备有限。
