Truyền thống cho rằng nhồi máu cơ tim do bệnh tắc nghẽn động mạch vành bất cứ loại nào có thể sản xuất sóng Q bất thường, bất thường đoạn ST, và bất thường sóng T. Q sóng bất thường đã được gán cho một hiệu ứng vùng chết loại bỏ các lực lượng khử cực | 113 The ST Segment Vector of Myocardial Ischemia Tradition holds that myocardial infarction due to obstructive coronary disease of any type may produce abnormal Q waves ST segment abnormalities and T wave abnormalities. The Q wave abnormality has been ascribed to a dead zone effect that removes certain depolarization forces from the endocardial-subendocardial area of the left ventricle permitting the forces of the diametrically opposite myocardium to dominate the electrical field Fig. . The ST segment abnormality has been attributed to an injury current that is thought to be secondary to more intense hypoxia surrounding the dead zone. The T wave abnormality is due to ischemia and is produced by hypoxia that is less intense than that responsible for the injury current. Thus myocardial hypoxia due to coronary disease is thought to result in dead myocardial cells that give rise to abnormal Q waves injured cells that produce abnormal ST segments and ischemic cells that produce abnormal T waves. The purpose of this section is to discuss the ST segment displacement referred to as injury that is caused by myocardial hypoxia. This displacement caused by intense myocardial ischemia injury has captured the interest of many investigators. There is no question that the mean ST segment vector points toward the area of predominant epicardial injury. But why Three theories have been advanced to explain this phenomenon but in order to understand them it is necessary to recall that electrical systole of the ventricles occurs during the QT interval of the electrocardiogram and that electrical diastole occurs during the TQ segment. The QT interval is defined as the interval that begins with the onset of the Q wave and ends with the end of the T wave the TQ segment is the interval that begins with the end of the T wave and ends with the beginning of the Q wave. The depolarization and repolarization of the ventricles occur during the QT interval. The ST segment of the .
