Fujita K, McGrath G E, Morita T, Robinson B L, Davis J W, Morris J J
Division of Cardiovascular and Thoracic Surgery, Mayo Clinic and Foundation, Rochester, Minn 55905.
J Thorac Cardiovasc Surg. 1994 Sep;108(3):477-86.
So that we could better characterize the effects of left heart assist on right ventricular myocardial muscle mechanics and ventricular mechanical coupling in the injured heart, nine dogs underwent 30 minutes of global cardiac ischemia supported by cardiopulmonary bypass followed by randomly varied levels of left heart assist at 0, 1.0, and 2.0 L/min (0, 37 +/- 4, and 74 +/- 7 ml/kg per minute). A centrifugal pump with left ventricle-to-aorta bypass was used with the intent to cause left ventricular volume unloading but without complete left ventricular pressure unloading. Right ventricular regional free wall and septal-free wall dimensions were measured by a sonomicrometer and right ventricular pressure by a micromanometer. Pressure and dimension data were acquired over a range of preloads produced by transient vena caval occlusion and at steady state at an initial control point and after ischemia at each level of left heart assist. Right ventricular regional early diastolic function was assessed by percent segmental relaxation during the first third of diastole, end-diastolic compliance by the end-diastolic pressure-dimension relationship, systolic contractile performance by the slope (Mw) and dimension axis intercept (Lw) of the linear preload recruitable stroke work relationship, and right ventricular isovolumic relaxation by the pressure decay time constant. Ischemia reduced Mw of both the free wall (38.3 +/- 16.1 to 16.4 +/- 4.2 erg.cm-3 x 10(3), p < 0.01) and septal free wall (30.2 +/- 12.7 to 13.4 +/- 4.9 erg.cm-3 x 10(3), p < 0.01) and shifted Lw rightward (1.3 +/- 0.3 to 1.4 +/- 0.3 mm, p < 0.01, and 2.8 +/- 0.8 to 3.0 +/- 0.9 mm, p < 0.01), which confirmed myocardial ischemic injury. There were no effects of left heart assist on free wall or septal-free wall systolic contractile performance assessed by Mw and Lw or on early diastolic relaxation assessed by percent segmental relaxation during the first third of diastole in either right ventricular region (all p = not significant). There were also no observed characteristic alterations of free wall or septal-free wall end-diastolic pressure-dimension relationships with left heart assist. The pressure decay time constant decreased with increasing levels of left heart assist (51 +/- 14, 49 +/- 16, and 43 +/- 11 msec, p < 0.05), which indicated an improvement in right ventricular isovolumic relaxation attributable to left heart assist. These data demonstrate that mechanical ventricular interactive effects during left heart assist are beneficial, but limited to isovolumic relaxation in the injured heart.(ABSTRACT TRUNCATED AT 400 WORDS)
为了更好地描述左心辅助对受损心脏右心室心肌力学和心室机械耦合的影响，9只犬在体外循环支持下经历30分钟全心缺血，随后随机给予0、1.0和2.0 L/min（0、37±4和74±7 ml/kg每分钟）的不同水平左心辅助。使用带有左心室到主动脉旁路的离心泵，目的是使左心室容量卸载，但不完全卸载左心室压力。用超声微测仪测量右心室局部游离壁和室间隔游离壁尺寸，用微测压计测量右心室压力。在短暂腔静脉阻塞产生的一系列前负荷范围内、初始控制点的稳态以及每个左心辅助水平缺血后采集压力和尺寸数据。右心室局部舒张早期功能通过舒张期前三分之一期间的节段性松弛百分比进行评估，舒张末期顺应性通过舒张末期压力-尺寸关系进行评估，收缩期收缩性能通过线性前负荷可募集搏功关系的斜率（Mw）和尺寸轴截距（Lw）进行评估，右心室等容舒张通过压力衰减时间常数进行评估。缺血使游离壁（38.3±16.1至16.4±4.2 erg.cm-3×10(3)，p<0.01）和室间隔游离壁（30.2±12.7至13.4±4.9 erg.cm-3×10(3)，p<0.01）的Mw降低，并使Lw向右移位（1.3±0.3至1.4±0.3 mm，p<0.01，以及2.8±0.8至3.0±0.9 mm，p<0.01），这证实了心肌缺血损伤。左心辅助对通过Mw和Lw评估的游离壁或室间隔游离壁收缩期收缩性能以及通过舒张期前三分之一期间的节段性松弛百分比评估的舒张早期松弛均无影响（所有p=无显著性差异）。也未观察到左心辅助对游离壁或室间隔游离壁舒张末期压力-尺寸关系的特征性改变。压力衰减时间常数随左心辅助水平的增加而降低（51±14、49±16和43±11毫秒，p<0.05），这表明左心辅助可改善右心室等容舒张。这些数据表明，左心辅助期间的机械心室相互作用是有益的，但仅限于受损心脏的等容舒张。（摘要截短至400字）
