What indicators should be detected in myocardial infarction

Myocardial infarction (Mbcardial infarction) is an emergency. It is due to the acute occlusion of the coronary artery, which causes partial necrosis of part of the myocardium due to ischemia. More than 95% of myocardial infarctions are caused by coronary atherosclerosis in middle-aged and elderly people. Acute myocardial infarction is myocardial necrosis caused by acute and persistent ischemia and hypoxia of coronary artery. Clinically, there is often severe and persistent retrosternal pain, which cannot be completely relieved by rest and nitrates, accompanied by increased serum myocardial enzyme activity and progressive electrocardiographic changes, which can be complicated by arrhythmia, shock or heart failure, which can often be life-threatening.

About half of the patients with acute myocardial infarction have prodromal symptoms 1 to 2 days or 1 to 2 weeks before the onset of the disease, the most common is the exacerbation of the original angina pectoris, the prolonged attack time, or the worsening effect on nitroglycerin; To those without angina pectoris, sudden prolonged angina pectoris.

Commonly used clinical test items:

1. Markers of myocardial injury

Cardiac troponin T (cTnT): When myocardial cells are damaged, TnT is released immediately, and the increase of TnT in the blood can be used to understand the degree of myocardial damage. ①The value of diagnosing myocardial injury: TnT and TnI assays have high sensitivity in diagnosing myocardial infarction. They start to rise early and last for a long time. Generally, they rise at 2.7-4.9 hours of onset, peak at 5.8-29 hours, and return to normal within 5-14 days. , which is helpful for the early and mid-late diagnosis of the disease; ② unstable angina pectoris can be elevated when myocardial injury occurs.

Myoglobin (Mb): It is the most sensitive marker for diagnosing acute myocardial infarction. It appears earlier than other indicators. It begins to increase within 1-2 hours of onset, reaches a peak at 6-8 hours, and basically returns to normal within 24 hours. The diagnosis of acute myocardial infarction can be ruled out if the Mb is still within the normal range 8 hours after the onset of chest pain. Mb decreased and then increased to indicate new infarction, so Mb can not only be used as a valuable indicator for evaluating the size of infarct size and reperfusion success, but also as a marker of new infarction during treatment.

Creatine kinase isoenzyme (CK-MB): increased within 4 hours after the onset, and reached a peak at 16 to 24 hours. The peak value can reflect the scope of the infarction, and usually returns to the level before the onset 3 to 4 days after the onset.

2. Myocardial enzyme spectrum

Myocardial zymography is an important enzymatic index for diagnosing the disease. Creatine kinase (CK) increases within 6 hours after the onset, peaks within 1 day, and returns to the level before the onset in 3-4 days; aspartate aminotransferase (AST) increased 6-12 hours after onset, peaked in 1-2 days, and returned to normal within 1 week; lactate dehydrogenase (LDH) increased 8-10 hours after onset, peaked in 2-3 days, and lasted for 2 weeks decreased to normal; α-hydroxybutyrate dehydrogenase (α-HBDH) is a unique enzyme in the myocardium, which began to increase 6h after the onset, reached a peak at 48h, and returned to normal after 1 week. The ratio of α-HBDH/LDH in normal people is 0.6~0.8, and the ratio is increased in acute myocardial infarction, while this ratio is often decreased in liver parenchymal cell lesions. The above enzymes continue to decrease or increase after decreasing, and there is the possibility of another myocardial infarction.

3. C-reactive protein, blood routine

CRP is directly involved in cardiovascular diseases such as inflammation and atherosclerosis, and is a strong predictor and risk factor for cardiovascular disease.

1 to 2 days after the onset of the disease, WBC and neutrophils increase (neutrophils are more than 80%), and eosinophils decrease or disappear. ESR increases rapidly and can last for 1 to 3 weeks.

4. Coagulation series

Prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), D-dimer (D-D) increased, and fibrinogen content (Fib) decreased. Coagulation series can be used as an observation index for myocardial reperfusion therapy. D-D can also be used as a predictor of recurrence after acute myocardial infarction. After myocardial infarction, if the patient's D-D level continues to be high, the possibility of recurrence is relatively high.