Irtun O, Sørlie D
Department of Surgery, University of Tromsø, Norway.
Eur J Cardiothorac Surg. 1997 Feb;11(2):358-62. doi: 10.1016/s1010-7940(96)01039-1.
The cardioplegic solution is often given at high flow and pressure following aortic clamping clamping to ensure rapid diastolic arrest. With standard setup in clinical practice, it is easy to exceed 200 mmHg in the aortic root. To investigate whether cardioplegic solution delivery pressure has an influence on myocardial protection, intermittent infusions of crystalloid cardioplegia were given at two different pressures using an in vivo pig model.
Fourteen pigs (48-57 kg) were put on cardiopulmonary bypass, aorta-clamped (2 h) and 500 ml St. Thomas' cardioplegia (4 degrees C) was delivered antegradely at either 75 mmHg (group 1, n = 7) or 175 mmHg (group 2, n = 7) pressure via 9-F aortic root cardioplegic needle. Every 20 min, 100 ml cardioplegic were delivered at either one of the two pressures. After 2 h, the aorta was unclamped and the hearts reperfused. Attempts were made to wean pigs from bypass following 20 min reperfusion or, if they were failing, after 40 min. If failing once again, the pigs were reperfused for the last 20 min on the heart-lung machine.
Hearts in group 1 (n = 7) needed significantly longer time to stop after aortic clamping (38 +/- 9 s) than did group 2 hearts (n = 7) (21 +/- 5 s) (P = 0.043). In group 1, all pigs were weaned from bypass, whereas in group 2 only 2 out of 7 pigs were able to sustain circulation without cardiopulmonary bypass (P = 0.01), and then with lower hemodynamic performances. At the end of cardiac arrest, group 1 had significantly higher adenosine triphosphate (19.4 +/- 1.1 mumol/g dry weight and 15.05 +/- 1.8 mumol/g dry weight, respectively) (P = 0.05) and significantly lesser fall in energy charge than group 2 (0.02 +/- 0.01 and 0.05 +/- 0.02, respectively) (P = 0.05). Also at the end of reperfusion, group 1 had significantly higher adenosine triphosphate (16.54 +/- 1.4 mumol/g dry weight and 12.53 +/- 0.95 mumol/g dry weight, respectively) (P = 0.016) than group 2.
Despite a swifter diastolic cardiac arrest, the high cardioplegic solution delivery pressure caused significantly poorer postischemic recovery than a moderate pressure with the same amount of cardioplegic solution.
心脏停搏液常在主动脉阻断后以高流量和压力给予，以确保快速舒张期停搏。在临床实践的标准设置下，主动脉根部压力很容易超过200 mmHg。为研究心脏停搏液输注压力对心肌保护是否有影响，使用活体猪模型在两种不同压力下间歇性输注晶体心脏停搏液。
14头猪（48 - 57 kg）进行体外循环，阻断主动脉（2小时），通过9F主动脉根部心脏停搏针以75 mmHg（第1组，n = 7）或175 mmHg（第2组，n = 7）的压力顺行给予500 ml圣托马斯心脏停搏液（4℃）。每20分钟，在两种压力之一给予100 ml心脏停搏液。2小时后，松开主动脉并使心脏再灌注。在再灌注20分钟后尝试使猪脱离体外循环，如果失败，则在40分钟后尝试。如果再次失败，则在心肺机上对猪进行最后20分钟的再灌注。
第1组（n = 7）的心脏在主动脉阻断后停止跳动所需时间（38±9秒）比第2组（n = 7）的心脏（21±5秒）显著更长（P = 0.043）。在第1组中，所有猪均脱离体外循环，而在第2组中，7头猪中只有2头能够在不进行体外循环的情况下维持循环（P = 0.01），且血流动力学表现较低。在心脏停搏结束时，第1组的三磷酸腺苷含量显著更高（分别为19.4±1.1 μmol/g干重和15.05±1.8 μmol/g干重）（P = 0.05），且能量电荷下降幅度显著小于第2组（分别为0.02±0.01和0.05±0.02）（P = 0.05）。同样在再灌注结束时，第1组的三磷酸腺苷含量（分别为16.54±1.4 μmol/g干重和12.53±0.95 μmol/g干重）也显著高于第2组（P = 0.016）。
尽管舒张期心脏停搏更快，但与相同剂量的中等压力心脏停搏液相比，高压力输注心脏停搏液导致缺血后恢复明显更差。
