Can acute myocardial infarction be treated?

Myocardial infarction is a disease we often hear about. There are many causes of it, such as overwork, excessive excitement or overeating. Most patients with myocardial infarction have certain symptoms before the onset of the disease, the most common of which are angina pectoris or a decrease in the effectiveness of nitroglycerin treatment. A myocardial infarction can cause sudden death if one is not careful. So can acute myocardial infarction be treated?

1. General treatment

1. Rest in bed for 1 week and keep the environment quiet.

2. Intermittent or continuous oxygen inhalation.

3. Monitoring: ECG, blood pressure, respiration, pulmonary capillary occlusion pressure and venous pressure are monitored in the CCU ward.

4. During nursing care, the patient should not eat too much and should keep bowel movements regular. The patient should rest in bed for the first week. In the second week, the patient should be helped to gradually get out of bed and move around. In the third to fourth week, the patient should be allowed to take a slow walk outdoors.

5. Relieve pain: Nitroglycerin is the most commonly used drug for relieving pain in AMI. Nitroglycerin also has pharmacological effects such as dilating coronary arteries and reducing precardiac load, so it is widely used in the treatment of AMI. After AMI patients are admitted to the hospital, intravenous medication is generally used (see the following content for details). If the pain is not relieved after intravenous drip of sufficient nitroglycerin, narcotic analgesics can be used, such as pethidine 50-100 mg intramuscular injection, or morphine 3-5 mg intravenous injection or 5-10 mg subcutaneous injection, which can be repeated every 4-6 hours; codeine or papaverine 0.03-0.06 g intramuscular injection can also be used.

2. Reperfusion therapy

Reperfusion therapy refers to the treatment that reopens the occluded coronary artery within 6 hours of onset, reperfuses the ischemic myocardium, and reduces the area of ​​necrotic myocardium. Treatments include thrombolytic therapy, coronary intervention, and CABG. Time is the main determinant of reperfusion therapy in AMI. Within 2 to 3 hours of AMI symptom onset, if the patient has no contraindications to thrombolysis, thrombolysis should be performed on site; otherwise, direct interventional treatment should be chosen. If the onset time exceeds 2 to 3 hours and there is still chest pain or ST segment elevation, interventional treatment is the first choice; thrombolysis can also be started immediately; interventional treatment can be selected after thrombolysis. Patients who still have or reappear symptoms of myocardial ischemia, ST segment elevation or combined heart failure after thrombolysis should receive interventional treatment as soon as possible. For those who arrive at the hospital 6 hours after onset, the efficacy of thrombolysis has been significantly reduced; among these patients, if they are elderly, the bleeding complications of thrombolytic therapy are increased. The effect of thrombolytic therapy is more limited in patients whose chest pain has begun to ease or whose elevated ST segment has begun to fall. For these patients, immediate coronary angiography is the best option; patients are stratified based on the angiography results. For patients who are suitable for interventional treatment, interventional treatment should be completed at the same time. For patients who are not suitable for interventional treatment, surgery or other treatment methods can be chosen. Therefore, the choice of reperfusion therapy is not only affected by the onset time, but also limited by hospital conditions. Hospitals that do not have the conditions for direct interventional treatment should choose thrombolytic therapy for patients or transfer them to nearby hospitals with the conditions for direct interventional treatment based on their different conditions.

3. Basic drug treatment

1. Early use of nitroglycerin, a nitrate drug, can reduce the mortality rate of AMI. However, when using nitroglycerin, the patient's blood pressure should be prevented from becoming too low, because low blood pressure can lead to a decrease in coronary perfusion pressure and aggravate myocardial ischemia. Commonly used nitrate drugs include nitroglycerin, isosorbide dinitrate and 5-sorbitan mononitrate. Intravenous infusion of nitroglycerin should start with a low dose, i.e. 5-10 μg/min. The dose can be gradually increased as appropriate, by 5-10 μg every 5-10 minutes, until the symptoms are controlled and the systolic blood pressure in patients with normal blood pressure is reduced by 10 mmHg or the systolic blood pressure in patients with hypertension is reduced by 30 mmHg. This is an effective therapeutic dose. If there is a significant increase in heart rate or systolic blood pressure ≤ 90 mmHg during intravenous infusion, the infusion rate should be slowed down or the drug should be discontinued. Side effects of nitrates include headache, reflex tachycardia, and hypotension. The contraindications of this drug are acute myocardial infarction combined with hypotension (systolic blood pressure ≤ 90 mmHg) or tachycardia (heart rate > 100 beats/min). It should be used with caution in patients with inferior wall right ventricular infarction.

2. Early use of beta blockers can reduce the infarct area, prevent the expansion of the infarct area, prevent malignant arrhythmias and sudden death, and improve prognosis.

3. Anticoagulation and antiplatelet therapy

Contraindications: ① Bleeding, bleeding tendency or history of bleeding; ② Severe liver and kidney dysfunction; ③ Active peptic ulcer; ④ Recent surgery with unhealed wounds.

(1) Aspirin: The platelet-inhibiting effect is irreversible. New platelets are produced every day, and when new platelets account for 10% of the total platelet count, platelet function returns to normal. Therefore, aspirin needs to be taken daily. The dosage is: first take 0.3g/d orally, then change to 75-150mg/d after 1-3 days for long-term use.

(2) Clopidogrel: The first dose is 300-600 mg, and then changed to 75 mg/d the next day.

(4) Low molecular weight heparin: Due to its advantages such as easy application, no need to monitor coagulation time, and low bleeding complications, low molecular weight heparin is recommended to replace ordinary heparin. Commonly used drugs include 0.4-0.6 ml of sulfamethoxazole, twice a day; 40-60 mg of chlorpromazine, once a day; both are subcutaneous injections for continuous use for 7-10 days.

(5) Unfractionated heparin: For AMI with ST-segment elevation, heparin is used as an adjuvant to thrombolytic therapy; for AMI without ST-segment elevation, intravenous heparin is used as routine treatment.

(6) GPⅡb/Ⅲa receptor antagonists: such as abciximab, which have little efficacy when used alone and can be used in combination with aspirin or clopidogrel; they are generally used as auxiliary drugs during interventional treatment to reduce the incidence of restenosis.

(7) Coumarin: Coumarin anticoagulants are only used for patients with AMI combined with atrial fibrillation or heart valve replacement. INR should be monitored regularly during medication to maintain it between 1.8 and 2.4.

(8) Combination medication: Aspirin is the first choice among the above drugs. Those who cannot use aspirin can use clopidogrel in combination. Aspirin or clopidogrel can also be used in combination with heparin. Patients undergoing PCI can use aspirin, clopidogrel, low molecular weight heparin and GPⅡb/Ⅲa receptor antagonists in combination.