卡维地洛对猪急性心肌梗死再灌注后无再流的影响

【关键词】  急性心肌梗死

    Beneficial effects of carvedilol on myocardial noreflow in miniswine models of acute myocardial infarction and reperfusion

　　ZHAO JingLin, YANG YueJin,  JING ZhiCheng, WU YongJian, YOU ShiJie, YANG WeiXian, MENG Liang, TIAN Yi, CHEN JiLin, GAO RunLin, CHEN ZaiJia

　　Department of Cardiovasology, Cardiovascular Institute, Fuwai Cardiovascular Disease Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China

　　【Abstract】 AIM: To evaluate the effects of carvedilol (beta blocker) on myocardial noreflow in a miniswine model of acute myocardial infarction (AMI) and reperfusion. METHODS:  Twentyfour miniswine were randomized into 3 groups: control, carvediloltreatment ［1 mg/(kg・d)］ and shamoperation groups (n=8). Animals in the former 2 groups were subjected to 3 h of coronary occlusion followed by 60 min of reperfusion. Data on hemodynamics and coronary blood flow volume (CBV) were collected and the area of noreflow (ANR) was evaluated with both myocardial contrast echocardiography (MCE) in vivo and pathological means. Necrosis area (NA) was measured with triphenyltetrazolium chloride (TTC) staining. RESULTS:  ① In control group, left ventricular systolic pressure (LVSP), maximal rate of increase and decline in left ventricular pressure (±dp/dtmax) and cardiac output(CO) significantly declined (P<0.05), while pulmonary capillary wedge pressure (PCWP) and left ventricular enddiastolic pressure (LVEDP) significantly increased at the end of 3 h of left anterior descending (LAD) occlusion (P<0.01). Compared with those at the end of 3 h of occlusion, ±dp/dtmax further significantly declined (P<0.05) at 60 min of reperfusion. In carvedilol group, the changes of LVSP, ±dp/dtmax, CO and LVEDP were the same as those in the control group after 3 h of AMI. In contrast, LVSP, ±dp/dtmax, CO, LVEDP and pulmonary capillary wedge (PCWP) recovered significantly at 60 min of reperfusion. ② In control group, the coronary ligation areas (LA) were similar (P>0.05) on both MCE in vivo and pathological evaluation and ANR was also both similar as high as 78.5% and 82.3% respectively, with final NA reaching 98.5% of LA. There was no significant difference in LA by both MCE and pathological evaluation between carvedilol and control groups, though ANR by both methods was significantly decreased to 24.9% and 25.8% respectively (both P<0.01), with final NA being also significantly decreased to 74.4% of LA in carvedilol group (P<0.05). ③ In control group, CBV was significantly declined to 45.8% and 50.6% of the baseline immediately after release of occlusion (3 h) and at 60 min of reperfusion (both P<0.01). In carvediloltreated group, CBV was also significantly declined immediately after release of occlusion (3 h) and at 60 min of reperfusion (both P<0.05), though significantly increased to 70.6% and 74.1% of the baseline, which were both significantly higher than those in control group (both P<0.01). CONCLUSION:  Carvedilol is effective in preventing myocardial noreflow, improving left ventricular function and reducing infarct area during AMI and reperfusion in miniswines.

　　【Keywords】 carvedilol;  noreflow;   acute myocardial infarction;  swine;    echocardiography

　　【摘要】 目的：评价卡维地洛防治猪急性心肌梗死（AMI）再灌注后无再流的作用. 方法：将中华小型猪24只随机分成对照组、卡维地洛组1 mg/(kg・d)和假手术组，每组8只. 冠状动脉结扎3 h, 松解1 h制备AMI再灌注模型. AMI前、后和再灌注后均行血流动力学测定和心肌声学造影(MCE)检查，最终行病分析. 结果：① 与AMI前相比，对照组AMI后3 h主动脉收缩和舒张压（SBP 和DBP）、左室收缩压（LVSP）,心排量（CO）和左心室内压最大收缩和舒张变化速率（±dp/dtmax）均显著下降（P<0.05）, 肺毛细血管楔压（PCWP）和左室舒张末压（LVEDP）均显著升高（P<0.01）；再灌注后1 h仅LVSP显著恢复（P<0.05）,±dp/dtmax继续显著下降（P<0.05）；而卡维地洛组AMI后3 h各项指标变化与对照组相同；但再灌注后1 h  LVSP, LVEDP, ±dp/dtmax和CO均显著恢复（P<0.05）且比对照组更显著（P<0.05）. ②对照组MCE和病理染色所测的冠脉结扎区心肌范围（LA）高度一致，再灌注后无再流面积（ANR）分别为78.5%和82.3%，心肌坏死面积（NA）占LA的98.5%；而卡维地洛组%LA虽与对照组相当，但两方法所测ANR仅分别为24.9%和25.8%，NA仅为74.4%,均显著小于对照组（P<0.05）. ③对照组再灌注即刻和再灌注后1 h冠脉血流量仅占AMI前的45.8%和50.6%(P<0.01)，而卡维地洛组冠脉血流量分别提高到70.6%和74.1%，均比对照组显著增加（P<0.01）. 结论：卡维地洛能有效地防治AMI再灌注后无再流，改善其心功能，缩小梗死面积.

　　【关键词】 卡维地洛；  无再流；  急性心肌梗死； 猪； 超声，心动描记术

　　0引言

　　Ito等［1］使用心肌声学造影（myocardial contrast echocardiography, MCE）发现，急性心肌梗死（acute myocardial infarction, AMI）冠脉再通后，心肌组织再灌注并不完全，称为无再流现象，发生率高达37%. 卡维地洛（carvedilol）是第三代β受体阻断剂,具有防治AMI左室重塑的作用［2］，但其确切机制不明确，研究表明它具有内皮保护作用［3］. 而内皮结构和功能损伤致微血管痉挛、栓塞和完整性破坏是产生无再流的主要机制［4］. 因此，我们建立猪AMI再灌注模型，应用MCE技术评价卡维地洛对AMI再灌注后无再流的影响，为卡维地洛在AMI中的应用提供新的依据.

　　1材料和方法

　　1.1材料

　　选用中华小型猪24只，雌雄不拘，体质量30 kg左右，随机分成对照组、卡维地洛［1 mg/(kg・d)，每日喂药1次，共3 d］治疗组和假手术组，每组8只. 卡维地洛由上海罗氏制药有限公司提供. 治疗组和对照组建立AMI再灌注模型.

　　1.2方法

　　1.2.1猪AMI及再灌注模型的制备于胸骨正中打开胸腔，纵行切开心包膜，暴露心脏，并将心包膜缝合于胸壁呈吊篮状，于冠状动脉左前降支远端1/3~1/2处，将结扎线穿入一长约3～4 cm的硅胶管腔内结扎3 h，再松解1 h，建立AMI及再灌注模型.  假手术组冠脉下只穿线，不结扎，无AMI，也无再灌注.

　　1.2.2血液动力学和冠脉血流量测定各组于AMI前5 min,对照和卡维地洛两组于AMI后3 h和再灌注后1 h用导管法行血液动力学测定，指标包括：左室收缩压（left ventricular systolic pressure, LVSP），左室舒张末压(left ventricular enddiastolic pressure, LVEDP），左心室内压最大收缩和舒张变化速率（maximal rate of increase and decline in left ventricular pressure, ±dp/dtmax），心排量（cardiac output, CO）. 各组使用电磁流量计于AMI前5 min，对照和卡维地洛两组于再灌注后即刻和60 min时记录冠脉血流量(coronary blood flow volume, CBV).

　　1.2.3MCE检查和图像分析对照和卡维地洛两组使用HP5500型超声仪，置探头于心脏表面的水囊中,取左心室短轴乳头肌水平切面，于AMI前、AMI后3 h和再灌注1 h 3个不同时间点采用二次谐波和间歇触发成像等技术进行MCE检查，从右侧股静脉以弹丸注射方式推注0.05 mL/kg声学造影剂 SONOVUE (Bracco Inc., Geneva, Switzerland)，用录像带持续记录自造影剂注射前30 s至心肌显影消失的MCE图像. 图像分析时，在超声仪上回放MCE录像，用描迹方法先测量AMI 3 h的左心室室壁心肌面积和无心肌显影的灌注缺损区面积即结扎区心肌面积. 两者之比为结扎区心肌范围（ligation area，LA）. 同样,测量再灌注60 min时的无心肌显影灌注缺损区面积即无再流区面积, 无再流区面积与结扎区心肌面积之比为无再流范围(Area of noreflow，ANR).

　　1.2.4病理下无再流及心梗面积的测定再灌注1 h后, 从左心室注入40 g/L硫磺素（thioflavinS）(1 mL/kg)，使再灌注区着色，无再流区不着色；再于原位重新结扎前降支，从左心室再注入Evans蓝，使结扎区外着蓝色，结扎区不着蓝色. 立即取出心脏,并沿心脏长轴分为5～6心肌短轴切片，结果非结扎区心肌呈蓝色，结扎区在荧光下无再流区不显色，有再流处显色. 出左心室室壁心肌面积、结扎区（无蓝色）心肌面积及无再流区（荧光下不显色）面积；同样依结扎区心肌面积/左心室室壁心肌面积计算出LA范围，依无再流区面积/结扎区心肌面积计算出心肌ANR. 最后，将整个心肌切片放入10 g/L的四氮唑红（triphenyltetrazolium chloride，TTC）溶液（pH 7.4）中，37℃孵箱中孵化15 min，梗死心肌不着色，非梗死心肌呈砖红色,立即对切片进行拍照, 计算出梗死心肌面积，以梗死心肌面积与 结扎区心肌面积之比作为坏死心肌范围（necrosis area，NA）.

　　统计学处理: 所有资料均用SPSS 10.0统计学软件进行统计学处理,资料以x±s表示，两组间均数的比较用t检验, 多组间均数的比较用方差分析，同组间均数的比较用重复测量方差分析.