Soltero E R, Glaeser D H, Michael L H, Hartley C J, Earle N R, Li Z, Lawrie G M
Department of Surgery, Baylor College of Medicine, Houston, Texas, USA.
Ann Thorac Surg. 1996 Nov;62(5):1380-7. doi: 10.1016/0003-4975(96)00631-5.
Dynamic cardiomyoplasty is being used clinically worldwide, and evaluated by a clinical trial (phase III) in the United States. Some centers stimulate the skeletal muscle wrap with every heart beat (1:1 [muscle:heart]), whereas others use every other heart beat (1:2). Recent concern over the possible deleterious effects of too-frequent stimulation of the muscles motivated the attempt to evaluate, in a canine model of chronic, double cardiomyoplasty, the effects of two different pacing ratios on several hemodynamic parameters of interest.
Double cardiomyoplasty was performed using both latissimus dorsi muscles in 11 dogs. Fatigue resistance was achieved using the clinical transformation protocol. At a final experiment, acute cardiac failure was induced by administration of propranolol. Hemodynamic measurements of eight physiologic variables were averaged over complete pacing cycles, including the nonpaced beat at a 1:2 pacing ratio.
The net effects of latissimus dorsi muscle stimulation at each of two pacing ratios were compared using nonparametric statistics. With the exception of left ventricular pressure (p = 0.0262) and its first derivative, dP/dt (p = 0.0099), there was no significant difference between hemodynamic performance at the two pacing ratios.
In this canine model, pacing every other beat produces hemodynamic results that are statistically similar to pacing every beat. Less frequent stimulation of the latissimus dorsi muscle may preserve its function and improve clinical results without compromising hemodynamic benefit.
动态心肌成形术正在全球范围内临床应用，并在美国通过一项临床试验（III期）进行评估。一些中心以每次心跳刺激骨骼肌包裹层（1:1[肌肉:心脏]），而其他中心则每隔一次心跳刺激（1:2）。最近对肌肉过于频繁刺激可能产生的有害影响的担忧促使人们尝试在慢性双心肌成形术的犬模型中，评估两种不同起搏比率对几个感兴趣的血流动力学参数的影响。
对11只狗使用双侧背阔肌进行双心肌成形术。采用临床转化方案实现抗疲劳。在最后一次实验中，通过给予普萘洛尔诱导急性心力衰竭。在完整的起搏周期内，对八个生理变量的血流动力学测量值进行平均，包括1:2起搏比率下的非起搏搏动。
使用非参数统计比较了两种起搏比率下背阔肌刺激的净效应。除左心室压力（p = 0.0262）及其一阶导数dP/dt（p = 0.0099）外，两种起搏比率下的血流动力学表现无显著差异。
在该犬模型中，每隔一次搏动起搏产生的血流动力学结果在统计学上与每次搏动起搏相似。减少对背阔肌的刺激频率可能会保留其功能并改善临床结果，而不会损害血流动力学益处。
