Flameng W J
Department of Cardiac Surgery, Katholieke Universiteit Leuven, Belgium.
Ann Thorac Surg. 1997 Jun;63(6 Suppl):S18-22. doi: 10.1016/s0003-4975(97)00356-1.
Minimal invasive coronary artery bypass grafting is often performed on the warm, beating heart. This setting requires special measures for protection of the myocardium during acute regional ischemia under normothermic conditions.
A first possibility to enhance the tolerance to ischemia during short episodes of coronary artery occlusion is based on a pharmacologic approach. A second possibility is mechanical unloading of the ischemic heart during and after regional ischemia.
To interfere with the ionic imbalances leading to necrosis, blockade of the Na(+)-H+ exchanges can be induced. It is shown that the selective Na(+)-H+ exchange inhibitor HOE 694 is able to prevent ischemic contracture in the experimental setting. Another pharmacologic approach is the use of endogenous adenosine accumulation in the ischemic myocardium. This can be achieved by the use of nucleoside transport inhibitors (lidoflazine or nitrobenzylthioinosine) having the ability to accumulate adenosine at the site of its production. Adenosine has a strong cardioprotective effect via adenosine A1 receptor stimulation and induces bradycardia by opening K+ channels and increasing the potassium current. It is also shown that left ventricular unloading by an axial flow pump (Hemopump) improves postischemic myocardial dysfunction (stunning) in an experimental model of short regional ischemia and reperfusion.
Further clinical investigation of both pharmacologic and mechanical techniques for cardioprotection during minimally invasive coronary artery bypass grafting is required.
微创冠状动脉旁路移植术通常在心脏跳动的常温状态下进行。这种情况下，在常温条件下急性局部缺血期间需要采取特殊措施来保护心肌。
增强冠状动脉闭塞短时间内对缺血耐受性的第一种可能性基于药理学方法。第二种可能性是在局部缺血期间及之后对缺血心脏进行机械性减负。
为了干预导致坏死的离子失衡，可以诱导钠氢交换的阻断。研究表明，选择性钠氢交换抑制剂HOE 694在实验环境中能够预防缺血性挛缩。另一种药理学方法是利用缺血心肌中内源性腺苷的蓄积。这可以通过使用核苷转运抑制剂（利多氟嗪或硝基苄硫肌苷）来实现，这些抑制剂能够在腺苷产生部位蓄积腺苷。腺苷通过刺激腺苷A1受体具有强大的心脏保护作用，并通过开放钾通道和增加钾电流诱导心动过缓。研究还表明，在短时间局部缺血和再灌注的实验模型中，使用轴流泵（Hemopump）进行左心室减负可改善缺血后心肌功能障碍（心肌顿抑）。
需要对微创冠状动脉旁路移植术中心脏保护的药理学和机械技术进行进一步的临床研究。
