Jain U
Anesthesia Service, University of California San Francisco.
J Card Surg. 1994 May;9(3 Suppl):413-6. doi: 10.1111/jocs.1994.9.3s.413.
Many modalities are available for monitoring for ischemia. Electrocardiography (ECG) is the most suitable modality for monitoring for perioperative ischemia. The detection and monitoring of myocardial stunning is more difficult. T wave inversion or peaking may be caused by ischemia. However, numerous nonischemic causes may lead to perioperative T wave changes. Inverted T waves may also indicate myocardial stunning. ST deviation is the most commonly used feature of ischemia. ST depression may be indicative of subendocardial ischemia while ST elevation may be associated with transmural ischemia or injury. Perioperatively, ST deviation may be caused by many nonischemic causes. Fixed ST deviation may be caused by left ventricular hypertrophy (LVH), cardiac conduction changes, old MI, coronary artery disease, and other causes such as drugs, including digitalis. New ST deviation may be caused by changes in body position. During cardiopulmonary bypass, ST deviation may be caused by hypothermia and defibrillation. ST deviation may be caused by new cardiac conduction changes and pericarditis. Ischemia may cause changes in other features of the ECG including the R wave, Q wave, U wave, QRS axis, and the angle between QRS axis and T wave axis. However, the specificity of these features for ischemia is even lower than that of the ST segment.
有多种方法可用于监测缺血情况。心电图（ECG）是围手术期缺血监测最合适的方法。心肌顿抑的检测和监测则更为困难。T波倒置或高耸可能由缺血引起。然而，许多非缺血性原因也可能导致围手术期T波改变。倒置的T波也可能提示心肌顿抑。ST段偏移是缺血最常用的特征。ST段压低可能提示心内膜下缺血，而ST段抬高可能与透壁性缺血或损伤有关。在围手术期，ST段偏移可能由多种非缺血性原因引起。固定性ST段偏移可能由左心室肥厚（LVH）、心脏传导改变、陈旧性心肌梗死、冠状动脉疾病以及其他原因如药物（包括洋地黄）导致。新出现的ST段偏移可能由体位改变引起。在体外循环期间，ST段偏移可能由低温和除颤导致。ST段偏移可能由新的心脏传导改变和心包炎引起。缺血可能导致心电图的其他特征发生变化，包括R波、Q波、U波、QRS电轴以及QRS电轴与T波电轴之间的夹角。然而，这些特征对缺血的特异性甚至低于ST段。
