Painless myocardial infarction

Introduction to painless myocardial infarction Painless myocardial infarction refers to the absence of typical angina symptoms in patients with acute myocardial infarction, or only mild chest tightness. Older patients with diabetes, occlusive cerebrovascular disease or heart failure are prone to painless myocardial infarction and are easily missed. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: heart failure, shock, arrhythmia, arrhythmia, thrombosis

Painless myocardial infarction

(1) Causes of the disease

Common factors for painless myocardial infarction:

Age (20%):

Most scholars believe that the presence or absence of chest pain in myocardial infarction is related to age. The incidence rate in the elderly group is significantly higher than that in the lower age group. The reason may be related to the elderly, especially after 60 years of age, autonomic neurodegeneration, increased pain threshold, and sensitivity and poor reactivity. related.

Cerebral circulation disorder (20%):

Patients with painful myocardial infarction, especially paroxysmal syncope, severe arrhythmia, and patients with conduction block, have severe cerebral insufficiency, ischemia and hypoxia, resulting in disturbance of consciousness, feeling slow and reduced response to pain.

Diabetes (15%):

40% of patients with diabetes have no chest pain during myocardial infarction, which may be associated with cardiac sympathetic nerves, parasympathetic morphological abnormalities, increased argyrophilicity, density changes, nerve fiber reduction and rupture, especially sympathetic pain fibers. In order to make the painful impulses impeded, the pain threshold of diabetic patients is significantly higher than that of non-diabetic patients, which is related to the delay of pain.

Cardiac complications (15%):

After infarction, especially with concurrent shock, severe heart failure, severe arrhythmia, and stroke, the pain is masked by the severe symptoms of complications, causing painless illusions.

Smoking (10%):

Domestic scholars reported 50 cases of acute myocardial infarction, smoking 20 / d, 20 years in 7 cases, of which 10 cases of painless myocardial infarction, accounting for 58.8%, the two have significant differences, indicating that long-term large number of smokers are painless The incidence of acute myocardial infarction was significantly higher than that of non-smokers.

Location of myocardial infarction (5%):

Painless myocardial infarction mostly in the posterior wall, right coronary artery infarction, and painful patients with left coronary artery infarction, and found in the painless group of myocardial ischemia, necrotic changes scattered, mainly focal, old, Pathological changes in the pain group showed coexistence of fresh and old infarcts.

(two) pathogenesis

Painless myocardial infarction is more common in elderly people over the age of 60. It may be related to cardiac autonomic degeneration, increased pain threshold, and poor sensitivity and responsiveness in the elderly. The elderly often have cerebral arteriosclerosis, which makes them feel dull. The pain response is reduced. Diabetic patients are complicated by autonomic neurofibrosis, especially the changes of sympathetic pain fibers, which impede the transmission of painful impulses, increase the pain threshold, and are also related to the site of infarction. Painless myocardial infarction is on the right. The incidence of coronary artery occlusion is significantly higher than in the left coronary artery.

Painless myocardial infarction prevention

Epidemiological studies have shown that coronary heart disease is a disease affected by many factors, and even some studies have listed 246 influencing factors. Many epidemiologists divide the main risk factors affecting the onset of coronary heart disease into: 1 Factors such as hypertension, hyperglycemia, disorder of fat metabolism and elevated fibrinogen, 2 some habits of coronary heart disease including excessive eating, lack of physical activity, smoking and type A personality, 3 coronary artery involvement Clinical indications, including electrocardiographic abnormalities during rest, exercise or monitoring, and myocardial perfusion, are not risk factors for coronary artery disease, but may indicate a considerable degree of coronary artery disease, 4 other congenital factors For example, a family history of coronary heart disease in the early stage.

Because epidemiological data show that coronary heart disease is one of the most important diseases causing human death, and there is still no radical measures in clinical practice, it is of great significance for the active prevention of coronary heart disease. The prevention of coronary heart disease involves In the primary prevention and secondary prevention, primary prevention refers to taking measures to control or reduce the risk factors of coronary heart disease in people who have not suffered from coronary heart disease to prevent disease and reduce the incidence rate. Secondary prevention means Patients with coronary heart disease take medicinal or non-pharmacological measures to prevent recurrence or prevent exacerbations.

1. Primary prevention measures

Primary prevention measures for coronary heart disease include two situations:

(1) Health education: educate the whole population on health knowledge, improve citizens' self-care awareness, avoid or change bad habits, such as quitting smoking, paying attention to reasonable diet, exercising properly, maintaining psychological balance, etc., thereby reducing the incidence of coronary heart disease.

(2) Control high-risk factors: for high-risk groups of coronary heart disease, such as hypertension, diabetes, hyperlipidemia, obesity, smoking, and family history, etc., positive treatment, of course, some of these risk factors can be controlled Such as high blood pressure, hyperlipidemia, diabetes, obesity, smoking, less active lifestyle, etc.; and some can not be changed, such as family history of coronary heart disease, age, gender, etc., including the use of appropriate drugs for continuous control Blood pressure, correct abnormal blood lipid metabolism, limit smoking, limit physical activity, control physical activity, control weight, control diabetes, etc.

2. Secondary preventive measures

The secondary prevention content of patients with coronary heart disease also includes two aspects. The first aspect includes the content of primary prevention, that is, the risk factors of various coronary heart diseases should be controlled. The second aspect is to use drugs that have been proven effective. To prevent the recurrence of coronary heart disease and the exacerbation of the disease, the drugs that have been confirmed to have preventive effects are:

(1) Antiplatelet drugs: A number of clinical trials have confirmed that aspirin can reduce the incidence of myocardial infarction and reinfarction rate. The use of aspirin after acute myocardial infarction can reduce the reinfarction rate by about 25%; if aspirin can not tolerate Or allergic, clopidogrel can be used.

(2) -blockers: as long as there are no contraindications (such as severe heart failure, severe bradycardia or respiratory diseases, etc.), patients with coronary heart disease should use beta blockers, especially in the occurrence of acute coronary After the arterial event; there are data showing that the use of beta blockers in patients with acute myocardial infarction can reduce the mortality and reinfarction rate by 20% to 25%. The drugs available are metoprolol, propranolol, Thiolol and so on.

(3) ACEI: used in patients with severe impairment of left ventricular function or heart failure, many clinical trials (such as SAVE, AIRE, SMILE and TRACE, etc.) have confirmed that ACEI reduces mortality after acute myocardial infarction; Therefore, after acute myocardial infarction, patients with ejection fraction <40% or wall motion index 1.2, and no contraindications should use ACEI, commonly used captopril, enalapril, benazepril and blessing Simplice and so on.

(4) statin lipid-lowering drugs: the results of studies from 4S, CARE and recent HPS show that long-term lipid-lowering therapy for patients with coronary heart disease not only reduces the overall mortality rate, but also improves the survival rate; and requires coronary intervention The number of patients with CABG is reduced, which is due to the improvement of endothelial function, anti-inflammatory effects, effects on smooth muscle cell proliferation and interference with platelet aggregation, blood coagulation, fibrinolysis and other functions, simvastatin, and deforestation. Statins, fluvastatin, and atorvastatin all have this effect.

In addition, coronary angiography has coronary atherosclerotic mild stenotic lesions and clinically no ischemic symptoms, although it is not clearly diagnosed as coronary heart disease, it should be regarded as a high-risk group of coronary heart disease, giving active prevention, Long-dose aspirin can also be given for a long time, and risk factors such as dyslipidemia and hypertension can be eliminated.

Painless myocardial infarction complications Complications heart failure shock arrhythmia arrhythmia thrombosis

Myocardial infarction may present with heart failure, shock, papillary muscle dysfunction or rupture, arrhythmia, heart rupture, ventricular aneurysm, thrombosis and embolism, post-infarction syndrome, infarction extension and other complications.

Painless myocardial infarction symptoms common symptoms abdominal pain heart failure lower abdominal pain arrhythmia hypertension chest tightness palpitations nausea shock convulsions

Clinical classification of painless myocardial infarction:

1. Painless symptoms: common symptoms include upper abdominal blockage, discomfort, nausea, vomiting, chest tightness, belching, hypotension, shock, sudden palpitations, arrhythmia, stroke, infection, etc., only suspected myocardial infarction during physical examination .

2. Pain in other areas: mainly manifested as ectopic pain, such as abdominal pain, toothache, jaw pain, shoulder and arm pain, lower abdominal pain, toe pain, etc.

3. Completely asymptomatic: no symptoms, only electrocardiogram found suspicious myocardial infarction pattern, no myocardial enzymology changes, can be confirmed by ECG vector, more common in focal or old myocardial infarction.

In the case of the following conditions, it is necessary to make timely electrocardiogram and dynamic observation of myocardial enzymology in order to detect painless myocardial infarction early.

Sudden heart failure over 40 years of age or sudden aggravation based on chronic heart failure cannot be explained by other reasons:

(1) middle-aged or above: sudden hypotension, no shock, and shock.

(2) sudden disturbance of consciousness, syncope, convulsions, hemiplegia and other cerebral circulation disorders.

(3) Sudden insanity, irritability.

(4) Sudden flustered, arrhythmia with nausea, vomiting.

(5) Sudden upper abdominal pain, nausea, vomiting and sweating.

(6) Sudden ectopic pain without obvious cause.

(7) On the basis of chronic bronchitis infection, sudden chest tightness, shortness of breath, increased hernia, and non-compliance with lung signs.

(8) On the basis of high blood pressure and diabetes, sudden chest tightness, shortness of breath, difficulty breathing, sweating, and blood pressure drop.

Painless myocardial infarction

1. Increased serum myocardial enzymology: In acute atrial myocardial infarction, abnormally elevated CK, CK-MB, aspartate aminotransferase, lactate dehydrogenase and other abnormal changes may occur.

2. ESR increases.

3. The patient may have blood lipids and the blood sugar concentration increases.

4. At the site of the corresponding myocardial infarction, typical pathological Q waves, ST-T changes, etc. can be performed, and qualitative and localized diagnosis can be performed.

5. Radionuclide: the characteristic of selective uptake of radionuclides and their labeled compounds by ischemic myocardium. Radionuclide myocardial imaging can detect infarction, determine the extent and extent of infarction, and measure collateral blood flow. Myocardial injury and ventricular function can be estimated prognosis.

6. Echocardiography: By measuring ventricular volume, wall motion and left ventricular ejection fraction, it is helpful to establish the infarction site, infarct size and left and right ventricular dysfunction of acute myocardial infarction, and provide prognostic information. Dimensional echocardiography revealed regional wall motion abnormalities in almost all patients with transmural acute myocardial infarction.

Diagnosis and diagnosis of painless myocardial infarction

Diagnosis of painless myocardial infarction should pay attention to the following points

(1) In addition to the 12-lead ECG: traces such as V7-V9, V3R-V5R should be added, if necessary, between the high-intercostal or intercostal marks, or the chest mark.

(2) Before the changes of ECG such as characteristic pathological Q wave: attention should be paid to the changes of ST-T in the corresponding lead and the conduction block in the acute injury zone.

(3) If the electrocardiogram is not changed immediately, the changes of serum myocardial enzyme should be detected early.

When the patient is over 40 years old and has a history of hypertension, diabetes, etc., no obvious cause of sudden heart failure, hypotension, shock, disturbance of consciousness, dyspnea, etc., the possibility of painless myocardial infarction should be considered. Sexual and early dynamic observation of ECG and myocardial enzymology changes for early diagnosis.

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