Bupivacaine cardiotoxicity and subendocardial microcirculation

心室颤动和心肌收缩力下降是布比卡因心脏毒性的两个重要因素。在活体心脏不停跳中，观察利多卡因对布比卡因诱发室颤的有效性和布比卡因的缩血管作用。第一组实验中，将0.25%布比卡因、1%利多卡因和0.25%布比卡因+利多卡因溶液以0、1、2、4、8和16 mL/hr的递增顺序注入左冠状动脉前降支（LAD）15 min。超声测微技术评价局部心肌功能。虽然Lid组中没有VF，但布比卡因组中1例在4 mL/hr输注速率下发生VF，7例在8 mL/hr输注速率下发生VF，布比卡因加利多卡因组中1例在8 mL/hr输注速率下发生VF，7例在16 mL/hr输注速率下发生VF。虽然局部心肌功能在三组中以剂量相关的方式降低，但布比卡因的心肌收缩作用显著大于利多卡因，与布比卡因+利多卡因无差异。在第二组实验中，通过放置在5只猪的第一对角分支中的导管将6份含有布比卡因的自体血液（0、0.25、1.25、2.5、5、10 μ g/mL）注入冠状动脉，同时通过针型视频显微镜观察间隔区的左心室内膜下微血管（直径50- 100 μ m）。直径

Ventricular fibrillation (VF) and depression of myocardial contractility are two important factors for bupivacaine-induced cardiotoxicity. The efficacy of lidocaine for bupivacaine-induced VF and the vasoconstricting effects of bupivacaine were examined in the beating hearts in vivo. In the first set of the experiment, 0.25% bupivacaine, 1% lidocaine and 0.25% bupivacaine plus lidocaine solutions were infused into the left anterior descending coronary artery (LAD) in an increasing sequence of 0,1,2,4,8 and 16 mL/hr for 15 min into the LAD in three groups consisting of eight pigs. Regional myocardial function was evaluated by the sonomicrometry technique. While there were no VF in the Lid group, VF occurred in one at 4 mL/hr and seven at 8 mL/hr infusion rates in the bupivacaine group, and in one at 8 mL/hr and seven at 16 mL/hr infusion rates in the bupivacaine plus lidocaine group. Although regional myocardial function decreased in a dose-related manner in the three groups, the myocardial depressant effects of bupivacaine were significantly greater than that of lidocaine, and did not differ with that of bupivacaine plus lidocaine. In the second set of the experiment, six samples of bupivacaine-containing autologous blood (0,0.25,1.25,2.5,5,10mug/mL) were injected into the coronary artery via a catheter placed in the first diagonal branch in the five pigs, while left ventricular subendocardial microvessels (50-100mum in diameter) in the septal region were visualized by a needle type video microscope. Diameter of the