Introduction, diagnosis and self-test of myocardial infarction

alopah Date:2021-08-18 11:55:25
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Myocardial infarction, refers to ischemic necrosis of the myocardium, which is based on a coronary artery lesion in which the blood flow in the coronary artery is drastically reduced or interrupted, causing severe and persistent acute ischemia in the corresponding myocardium and eventually leading to ischemic necrosis of the myocardium. Patients who develop acute myocardial infarction often have persistent severe retrosternal pain, fever, elevated white blood cell count, elevated serum cardiac enzymes and a series of characteristic evolution of the electrocardiogram reflecting acute myocardial injury, ischemia and necrosis, and may develop arrhythmia, shock or heart failure, which is a severe type of acute coronary syndrome.




The diagnosis of the disease is not difficult based on the typical clinical presentation, characteristic electrocardiographic changes and laboratory findings. The diagnosis is more difficult in patients without pain. The possibility of myocardial infarction should be thought of in any elderly patient with sudden onset of shock, severe arrhythmia, heart failure, epigastric distension or vomiting with no known cause, or pre-existing hypertension with a sudden drop in blood pressure with no cause to be found, or shock after surgery but bleeding and other causes are excluded. In addition, elderly patients with severe and prolonged chest tightness or chest pain should consider the possibility of this disease even if there are no characteristic changes in the electrocardiogram. All of them should be treated as acute myocardial infarction first, and repeated ECG observation and serum cardiac enzyme measurement should be performed within a short period of time to determine the diagnosis.

Myocardial infarction


Differential diagnosis


(1) Angina pectoris: The nature of pain in angina pectoris is the same as that in myocardial infarction, but the attacks are more frequent, each attack lasts for a short period of time, usually less than 15 minutes, and there are often precipitating factors before the attack, not accompanied by fever, increased white blood cells, increased erythrocyte sedimentation rate or increased serum cardiac enzymes, no changes in the ECG or temporary depression or elevation of the ST segment, rarely occurring arrhythmia, shock and heart failure, containing nitroglycerin tablets with good efficacy, etc., which can be differentiated.


(2) Acute pericarditis: especially acute nonspecific pericarditis, there can be more intense and persistent pain in the precordial region, with ST-segment and T-wave changes in the electrocardiogram. However, patients with pericarditis have fever and increased blood leukocyte count at the same time as or before the pain, and the pain is often aggravated by deep breathing and coughing, and physical examination may reveal pericardial friction sounds.


(3) Acute pulmonary embolism: Large embolism of the pulmonary artery can often cause chest pain, shortness of breath and shock, but with the manifestation of a sharp increase in right heart load. For example, the right ventricle is sharply enlarged, the pulsation of the pulmonary valve area is enhanced and the second heart sound there is hyperactive, and a systolic murmur appears in the tricuspid valve area. Fever and leukocytosis also appear early. The electrocardiogram shows that the electrical axis is right deviated, S wave or deepening of the original S wave in lead I, Q wave and T wave inversion in lead III, high R wave in aVR lead, leftward shift of the transition zone in the thoracic lead, and T wave inversion in the left thoracic lead, which are different from the changes in myocardial infarction and can be distinguished.


(4) Acute abdomen acute pancreatitis, peptic ulcer perforation, acute cholecystitis, gallstone, etc. Patients may have epigastric pain and shock, which may be confused with acute myocardial infarction patients with pain waves to the upper abdomen. However, it is not difficult to differentiate with careful history and physical examination, and electrocardiography and serum myocardial enzyme assay can help clarify the diagnosis.


(5) Aortic dissection starts with severe chest pain, which is quite similar to acute myocardial infarction. X-rays, CT, and echocardiography can detect fluid in the aortic wall sandwich, which can be distinguished.


Self-assessment of disease


Myocardial infarction occurs as a result of intense spasm or occlusion of the coronary arteries, causing severe and persistent ischemia or necrosis of the heart muscle. The attack is characterized by severe chest pain, tingling in the precordial region, lasting for several hours, pallor, anxiety, general weakness, clammy and cold skin, profuse sweating, thin and rapid pulse, and irregular rhythm. Once a myocardial infarction occurs, the patient’s life will be seriously threatened. So how do you know in advance that a myocardial infarction will occur? The onset of this disease is sudden, but like everything else, there is a process, and by recognizing the characteristics of this process, we can prevent myocardial infarction from occurring. Myocardial infarction sometimes has precipitating factors before the onset, such as heavy exertion, strong mental stimulation, overeating, drinking, smoking, cold stimulation, etc. With these unfavorable factors, the load on the heart increases, and the blood flow in the coronary arteries cannot be increased accordingly, then the myocardium is in a state of ischemia, which leads to the onset of myocardial infarction. Generally, there are three signs before an attack.


1,The original angina was present, but the myocardial infarction aggravates the original symptoms, increases the number of episodes, and increases the pain and lengthens the duration.


2, There is no history of angina attack, but the pain in the precordial region is suddenly severe and continues to worsen.


3,A few people do not have angina attacks, but only show chest tightness and discomfort, palpitations and shortness of breath with slight activity, and general weakness.


The above three early signs of myocardial infarction to the onset of this period is the golden time to prevent and cure myocardial infarction, regardless of the original symptoms and history of angina pectoris and episodes, should pay sufficient attention, once there is a feeling to the nearby hospital for examination, do not exempt to go to the more distant hospitals to prevent accidents on the way. There are numerous cases of aggravation due to activity, resulting in death. If you know you are suffering from coronary heart disease or have a history of attacks, you should absolutely avoid the above-mentioned triggering factors and actively treat and try your best to prevent the onset of the disease.

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