Gründeman P F, Borst C, Verlaan C W, Meijburg H, Mouës C M, Jansen E W
Heart Lung Institute, Utrecht University Hospital, Utrecht, The Netherlands.
J Thorac Cardiovasc Surg. 1999 Aug;118(2):316-23. doi: 10.1016/S0022-5223(99)70222-9.
In off-pump coronary surgery, exposure of posterior vessels via sternotomy causes deterioration of cardiac function. Changes in ventricular geometry, valve competence, and hemodynamics after retraction of the beating heart were studied. Subsequently, the modifying effect of right or left heart bypass was investigated.
In six 80-kg pigs, an ultrasound probe was attached to the backside of the left ventricle and the heart was fully retracted with a suction tissue stabilizer. Five pigs underwent additional pump support.
During retraction, the right ventricle was squeezed between the pericardium and interventricular septum, thereby decreasing its diastolic cross-sectional area by 62% +/- 6% (P <.001) while, concomitantly, right ventricular end-diastolic pressure increased to 165% +/- 19% (P =.004) of basal values. Stroke volume and mean arterial pressure decreased by 29% +/- 6% and 23% +/- 8% (P =.007 and P =.02, respectively). Left ventricular shape became somewhat elliptic without changes in preload pressure, and its diastolic cross-sectional area decreased by 20% +/- 3% (P =.001). All valves were competent. Right heart bypass restored left ventricular cross-sectional area, stroke volume, and mean arterial pressure. In contrast, left heart bypass increased blood pressure only marginally.
Ninety-degree anterior displacement of the beating porcine heart caused primarily right ventricular dysfunction as a result of mechanical interference with diastolic expansion without concurring valvular incompetence. Right heart bypass normalized stroke volume and mean arterial pressure by increasing left ventricular preload; in contrast, left heart bypass failed to restore systemic circulation.
在非体外循环冠状动脉手术中，通过胸骨切开术暴露后方血管会导致心功能恶化。研究了跳动心脏牵开后心室几何形状、瓣膜功能及血流动力学的变化。随后，研究了右心或左心旁路的改善作用。
在6头80千克的猪身上，将超声探头附着于左心室后侧，并用吸引组织稳定器将心脏完全牵开。5头猪接受了额外的泵支持。
牵开过程中，右心室被挤压在心包和室间隔之间，其舒张横截面积减少62%±6%（P<.001），同时，右心室舒张末期压力升至基础值的165%±19%（P=.004）。每搏量和平均动脉压分别下降29%±6%和23%±8%（P分别为.007和.02）。左心室形状变得略呈椭圆形，前负荷压力无变化，其舒张横截面积减少20%±3%（P=.001）。所有瓣膜功能正常。右心旁路恢复了左心室横截面积、每搏量和平均动脉压。相比之下，左心旁路仅使血压略有升高。
跳动的猪心脏向前90度移位主要导致右心室功能障碍，这是由于对舒张期扩张的机械干扰，且不存在并发的瓣膜功能不全。右心旁路通过增加左心室前负荷使每搏量和平均动脉压恢复正常；相比之下，左心旁路未能恢复体循环。
