Acute myocardial infarction (AMI) is a serious disease of myocardial necrosis in myocardial ischemic hypoxia. The diagnosis is usually based on typical clinical symptoms, ecg and serum biochemical indicators. In the process of myocardial ischemic necrosis, many enzymes, proteins and other products of myocardial cells are released into the blood. These biochemical indicators are detected at this time to provide strong evidence for the diagnosis of AMI. The biochemical indexes usually measured include creatine kinase (CK) and its isozymase CK-MB, lactate dehydrogenase, troponin T and I, myoglobin and so on. Among them, the study of CK-MB is more and deeper.
- The main biochemical characteristics and distribution of CK-MB
Creatine kinase catalyzes creatine phosphate generats the ADP, which produces high energy ATP. The CK is distributed in many tissues, the most with the highest activity in the skeletal muscle. The CK is a dimer consists of two subunits of M and B, and there are three types of kinase, CK-MB, CK-MM, CK-BB. In the myocardium, the CK-MM is 70% ~ 85%, and the rest is CK-MB. The CK-MB is found almost exclusively in the heart muscle, and only a small amount is found in the intestines, the tongue, the diaphragm, the uterus and the prostate. After 3-6 hours of acute myocardial infarction, the content of CK-MB in serum started to rise, and reaching its peak in 12-24 hours, and then rapidly descending to normal in 24-48 hours. If CK-MB is still not elevated within 24 hours after onset of onset, the possibility of acute myocardial infarction was very small, and it was not confirmed that CK-MB was elevated in 48 hours, the acute myocardial infarction can be excluded. Within 3 days after the onset of acute myocardial infarction, if the CK-MB remained high. The result indicates that the infarct area is enlarged and the prognosis is poor. If the reduced CK-MB increases again, there is a recurrence of myocardial infarction. It is generally believed that 3% of the total energy of serum CK-MB is positive threshold. Although the electrocardio can increase the total energy of CK in serum, the CK-MB remains normal. Cardiac catheterization and coronary angiography had no effect on CK-MB, and the likelihood of myocardial injury was considered when CK-MB is elevated. Therefore, the diagnosis of acute myocardial infarction by CK-MB is highly sensitive and specific.
2.The detection method of CK-MB
The CK-MB is specific in the myocardium, It is the only serum index that has been accepted by WHO to diagnose AMI, and its detection method is as follows:
Electrophoresis: Although this method has long analysis time, it is accurate, so it is still the standard detection method for many years. Only if the concentration of CK-MB in blood is high enough to be detected by this method, delay is a serious defect of this method. In 4h of AMI symptoms, the AMI detected was less than 9%.
Immunosuppression: This method is faster than electrophoresis. The mechanism is to use specific target for the CK – MM and CK – MB of the M subunit antibody, inhibiting enzyme activity, and the function of B subbasis in CKMB is still preserved. Therefore, the activity of the CK – MM enzyme is basically blocked, and the enzyme activity of the B-subgroup in CK – MB can be detected. This method provides a quick diagnosis so that the patient can receive timely treatment. Collison applied CK-MB antigen (GLORY SCIENCE CO., LTD, Product NO.: DM130 ) to detect the CK-MB of AMI patients, shortening the length of hospital stay in the coronary care ward from 3 days to 2 days.