Kawaguchi Osamu, Huang Yi Fei, Yuasa Takeshi, Shirota Kazuaki, Carrington Russell A J, Hunyor Stephen N
Cardiac Technology Centre, Department of Cardiology, Royal North Shore Hospital, Sydney, Australia.
Ann Thorac Surg. 2002 Oct;74(4):1092-6; discussion 1096-7. doi: 10.1016/s0003-4975(02)03847-x.
This study investigates the possibility of reducing myocardial oxygen consumption by dynamic cardiomyoplasty in chronic heart failure. The sheep model used is relevant for cardiac assist using direct mechanical cardiac compression.
In 7 sheep, heart failure was induced by staged intracoronary microembolization followed by dynamic cardiomyoplasty. Six months later, the effect of latissimus dorsi muscle stimulation in the 2:1 mode (on, cardiomyoplasty; off, control) was studied. Left ventricular pressure-volume loops were obtained by conductance, micromanometer, and inferior vena cava occlusion catheter. Myocardial oxygen consumption was derived from left main coronary artery blood flow and oxygen content of arterial and coronary sinus blood.
Cardiomyoplasty had no significant effect on left ventricular hemodynamic variables such as end-systolic pressure. However, cardiomyoplasty increased stroke volume and ejection fraction significantly by 11% +/- 12% and 11% +/- 10%, respectively. Although pressure-volume area and external work did not increase with cardiomyoplasty, myocardial oxygen consumption decreased by 21% +/- 11%. Therefore, cardiomyoplasty increased myocardial efficiency (external work/myocardial oxygen consumption) by 16% +/- 13%.
Despite limited hemodynamic improvement from dynamic cardiac compression by cardiomyoplasty in sheep with chronic heart failure, myocardial oxygen consumption was significantly reduced. These findings provide a rationale for reverse remodeling of the failing heart using direct mechanical compression.
本研究探讨在慢性心力衰竭中通过动态心肌成形术降低心肌氧耗的可能性。所使用的绵羊模型适用于采用直接机械性心脏按压的心脏辅助。
对7只绵羊进行分期冠状动脉内微栓塞诱导心力衰竭，随后进行动态心肌成形术。6个月后，研究背阔肌在2:1模式（开启，心肌成形术；关闭，对照）下刺激的效果。通过电导、微测压计和下腔静脉闭塞导管获取左心室压力-容积环。心肌氧耗由左冠状动脉主干血流以及动脉血和冠状窦血的氧含量得出。
心肌成形术对左心室血流动力学变量（如收缩末期压力）无显著影响。然而，心肌成形术使每搏量和射血分数分别显著增加了11%±12%和11%±10%。尽管压力-容积面积和外功并未随心肌成形术增加，但心肌氧耗却降低了21%±11%。因此，心肌成形术使心肌效率（外功/心肌氧耗）提高了16%±13%。
尽管在慢性心力衰竭绵羊中，心肌成形术通过动态心脏按压对血流动力学的改善有限，但心肌氧耗却显著降低。这些发现为使用直接机械按压使衰竭心脏逆向重构提供了理论依据。
