Lazar H L, Rivers S
Department of Cardiothoracic Surgery, Boston University Medical Center, Mass.
J Thorac Cardiovasc Surg. 1989 Aug;98(2):251-7.
Recent studies have suggested that topical hypothermia may be unnecessary during coronary bypass operations because of possible pulmonary complications resulting from phrenic nerve damage. This study was undertaken to determine whether topical hypothermia is necessary for optimal myocardial protection when distribution of the cardioplegic solution is heterogeneous because of coronary occlusions. Twenty pigs were subjected to 120 minutes of ischemic arrest with multidose potassium crystalloid cardioplegia (4 degrees C). During arrest, the mid-left anterior descending coronary artery was occluded with a snare that was released on reperfusion. Ten of these pigs received topical hypothermia and 10 others served as controls. Hearts protected with topical hypothermia had lower temperatures in the left anterior descending (7.0 degrees +/- 0.7 degree C versus 18.5 degrees +/- 0.5 degree C; p less than 0.05) and circumflex regions (8.9 degrees +/- 0.5 degree C versus 15.5 degrees +/- 0.5 degree C; p less than 0.05). The pH values were higher in hearts protected with topical hypothermia in both the left anterior descending (7.36 +/- 0.09 versus 6.73 degrees +/- 0.07; p less than 0.05) and circumflex regions (7.40 +/- 0.07 versus 7.05 +/- 0.07; p less than 0.05). Topical hypothermia also resulted in better preservation of postischemic stroke work index (0.64 +/- 0.06 versus 0.40 +/- 0.08 gm-m/kg; p less than 0.05) and wall motion scores (1.0 +/- 0.3 hypothermia versus 1.8 +/- 0.4 no hypothermia; p less than 0.05). We conclude that topical hypothermia affords maximal myocardial protection when coronary occlusions are present and should be used during all coronary operations.
近期研究表明，由于膈神经损伤可能导致肺部并发症，在冠状动脉搭桥手术期间局部低温可能并非必要。本研究旨在确定当因冠状动脉阻塞导致心脏停搏液分布不均一性时，局部低温对于实现最佳心肌保护是否必要。二十头猪接受多剂量钾晶体心脏停搏液（4℃）进行120分钟的缺血性停搏。在停搏期间，用圈套器阻断左前降支冠状动脉中段，再灌注时松开。其中十头猪接受局部低温处理，另外十头作为对照。接受局部低温保护的心脏，其左前降支区域温度较低（7.0℃±0.7℃ 对比 18.5℃±0.5℃；p＜0.05），回旋支区域温度也较低（8.9℃±0.5℃ 对比 15.5℃±0.5℃；p＜0.05）。接受局部低温保护的心脏，左前降支区域和回旋支区域的pH值更高（左前降支区域：7.36±0.09 对比 6.73±0.07；p＜0.05；回旋支区域：7.40±0.07 对比 7.05±0.07；p＜0.05）。局部低温还能更好地保存缺血后中风作功指数（0.64±0.06 对比 0.40±0.08 gm-m/kg；p＜0.05）和室壁运动评分（低温组1.0±0.3 对比 非低温组1.8±0.4；p＜0.05）。我们得出结论，当存在冠状动脉阻塞时，局部低温可提供最大程度的心肌保护，应在所有冠状动脉手术中使用。
