Atrial myocardial infarction

Introduction to atrial myocardial infarction Atrial myocardial infarction has a different clinical course from simple ventricular myocardial infarction, but because of its difficult diagnosis, clinical manifestations are often concealed by the accompanying ventricular myocardial infarction, so it has not received enough attention. Atrial infarction accounts for about 17% of acute myocardial infarction. It is more common in right atrial infarction. Most of the left ventricular infarction involves the right atrium, which is prone to pulmonary or systemic embolism. basic knowledge The proportion of sickness: 0.54% Susceptible people: more common in the elderly Mode of infection: non-infectious Complications: cardiovascular and thromboembolic syndrome arrhythmias

Atrial myocardial infarction

Causes:

The vast majority of atrial infarction is caused by coronary atherosclerotic heart disease. In addition, chronic obstructive pulmonary disease with pulmonary heart disease, primary pulmonary hypertension, muscular dystrophy, hereditary motor disorders, etc. can also cause atrial infarction. Atrial infarction in some patients with normal coronary arteries is likely due to hypoxemia and atrial pressure, resulting in excessive volume overload.

Pathogenesis:

Like the atrium of the atrium, the blood supply comes from the branches of the coronary arteries. Most people have multiple branches in the right coronary artery. The main branches supply the right anterior wall and the right atrial appendage, and then enter the septal wall to form a plexus surrounding the superior vena cava. Sometimes, the first branch of the left coronary artery, around the bottom of the left atrial appendage, up to the right atrium, and finally the vascular plexus surrounding the superior vena cava, some of which originate from the sinus node, and the blood supply to the anterior superior part of the left atrium can come from The second branch of the right coronary artery or the branch of the left coronary artery, the atrial infarction is mostly penetrating, and its clinical manifestations lack specificity.

Atrial myocardial infarction mainly involves the right atrium, right atrial myocardial infarction accounts for about 81% to 98%, left atrial myocardial infarction accounts for about 2% to 19%, bilateral atrial involvement accounts for about 19% to 24%, and the auricular part is involved. About 19% of cases were simple atrial myocardial infarction without involvement of ventricular myocardium. Of the 31 cases of atrial infarction reported by Cushing et al, 27 occurred in the right atrium, 5 in the left atrial infarction, and 3 in the left atrial appendage. In this 31 cases of atrial infarction, only 2 cases involved sinus node, which is of interest in 31 cases of atrial infarction, 6 cases of simple atrial infarction, that is, without ventricular infarction, the location of atrial infarction is often located Near the atrioventricular sulcus, because the wall is very thin, the atrial infarction is often through-wall type. The atrial infarction is the same as the ventricular infarction. The wall thrombosis is common in large-area atrial infarction.

Atrial myocardial infarction prevention

Epidemiological studies have shown that coronary heart disease is a disease that is affected by many factors. Even studies have listed 246 influencing factors. Many epidemiologists divide the main risk factors affecting the onset of coronary heart disease into:

1 factors causing atherosclerosis, including hypertension, hyperglycemia, disorders of fat metabolism, and elevated fibrinogen;

2 Some lifestyle habits that are predisposed to coronary heart disease include overeating, lack of physical activity, smoking, and type A personality;

3 clinical indications of coronary artery involvement, including electrocardiographic abnormalities during rest, exercise or monitoring, and myocardial perfusion, which are not risk factors for coronary artery disease, but may indicate a considerable degree of coronary artery disease;

4 other congenital factors, such as the family history of early coronary heart disease.

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.

Atrial myocardial infarction complications Complications Cardiovascular and thromboembolic syndrome arrhythmias

Complications such as thromboembolism, acute pericardial tamponade, and arrhythmia are common in acute atrial myocardial infarction.

Old-type myocardial infarction cuts, accounting for 10 to 38% of infarcts. It can occur in the early healing phase or in the healing phase of the infarcted fibrosis. The infarcted myocardium or scar tissue forms a ventricular aneurysm under the action of intraventricular pressure, which is limited to outward bulging. The ventricular aneurysm may be secondary to a wall thrombus, arrhythmia, and cardiac insufficiency. Acute pericarditis, transmural infarction, often occurs after myocardial infarction serous or serous fibrinous pericarditis. About 15% of myocardial infarction, often occurs 2 to 4 days after MI. Arrhythmia, cardiogenic shock, accounting for about 10% to 20% of myocardial infarction. When the myocardial infarct size is >40%, the myocardial contractility is extremely weakened, and the cardiac output is significantly reduced, which can cause cardiogenic shock and lead to death.

Atrial myocardial infarction symptoms common symptoms supraventricular arrhythmia tachycardia myocardial infarction myocardial necrosis extensive atrial migratory rhythm surgery wound no longer bleeding pulmonary embolism

In theory, the clinical symptoms of atrial infarction can be divided into two groups, that is, the performance of ventricular myocardium is dominant and the performance of simple atrial myocardial infarction, but it is difficult to distinguish these two cases clinically.

Arrhythmia

Arrhythmia is a common clinical manifestation of atrial infarction, and most of them are supraventricular arrhythmias, the incidence rate is 61% to 74%, while the incidence of simple ventricular infarction is 8%, arrhythmia of atrial myocardial infarction has sudden abrupt Characteristics, including paroxysmal atrial fibrillation, atrial tachycardia, atrial premature contraction, atrial migratory rhythm, etc., sinus sinus infarction may occur, there is no atrial myocardial infarction with ventricular rhythm Reports of abnormalities, early predictions and prevention of these arrhythmias can help improve clinical outcomes and prognosis.

2. Embolization

Another common complication of atrial infarction is atrial wall thrombosis and embolism. Cushing et al reported that 8% of patients with atrial infarction had wall thrombosis, and in another report, the incidence of pulmonary embolism during atrial infarction For 24%, the incidence of pulmonary infarction is significantly higher than systemic embolism because most of the atrial infarction occurs in the right atrium.

3. Atrial rupture

In patients diagnosed with atrial myocardial infarction, the incidence of atrial rupture was 4.5%. The clinical manifestations of atrial rupture were similar to ventricular rupture. Almost none of the patients with atrial rupture survived within 24 hours after rupture. The longest survived. For 15 weeks, only 15% of patients with atrial rupture survived for more than 24 hours, while patients with ventricular rupture survived more than 2% of 24h, so there is a greater chance of surgical repair of atrial rupture if highly suspected or confirmed atrial infarction In the event of pericardial tamponade, effective measures must be taken as soon as possible.

4. Hemodynamic changes

Atrial contraction can effectively increase cardiac output, cardiac output is reduced when atrial fibrillation and supraventricular tachycardia, and atrioventricular sequential pacing can increase cardiac output, indicating the importance of atrial contraction, atrium In myocardial infarction, atrial myocardium ischemia and necrosis due to atrial contractility reduce the hemodynamic changes, it is more difficult to maintain left ventricular filling pressure, thereby reducing cardiac output, its hemodynamic changes and right ventricle Myocardial infarction is similar, including central venous pressure, increased right atrial pressure (whether the pulmonary capillary wedge compression varies depending on the location of the atrium), and reduced cardiac output. Therefore, similar to right ventricular infarction, a large amount of fluid replacement for atrial infarction A person with a significant decrease in cardiac output may be beneficial.

Atrial myocardial infarction

1. Increased serum myocardial enzymology

In acute atrial myocardial infarction, abnormally elevated abnormal changes such as CK, CK-MB, aspartate aminotransferase, and lactate dehydrogenase may occur.

2. ESR increases

3. Blood lipids, blood sugar

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

4. ECG examination

The P-liquid is equivalent to the atrial depolarization solution, and the atrial repolarization wave Ta overlaps the PR segment, so the atrial infarction mainly affects the P wave and the P-Ta or PR segment.

Diagnostic criteria for electrocardiogram:

(1) Main criteria:

The 1P-Ta segment was elevated above 0.05 mV in the I, aVE, aVL, V5, and V6 leads, and was mostly left atrial infarction in the II, III, aVF, V1, and V2 leads.

The 2P-Ta segment was elevated above 0.5 mV in the aVL:aVR lead, and the middle pressure in the I, II, III, aVF, V1, and V2 leads was mostly right atrial infarction.

3 often accompanied by supraventricular arrhythmia and sinus node failure.

(2) Secondary criteria:

The 1P wave anomaly has a notch: widening, conduction block in the room, M-type IV or irregular.

Atrial infarction cannot be diagnosed if the 2P-Ta segment is low in degree and there is no corresponding lead elevation.

It is worth noting that the P-Ta segment of the electrocardiogram, the change of the P wave morphology and the supraventricular arrhythmia are lack of specificity and sensitivity. The conventional ECG sometimes does not reflect the atrial infarction, due to the thin atrial wall, low voltage and ventricular depolarization. The reason can also make the ECG changes of atrial infarction absent and confusing.

P-Ta segment changes are important ECG indicators for the diagnosis of atrial infarction, but can also occur in normal people, pericarditis, atrial overload and angina patients, but the P-Ta segment depression during angina attacks can disappear with the relief of angina However, the P-Ta segment of the atrial infarction slowly returns to the baseline as the infarct heals, and the dynamic observation of ECG evolution is helpful for differential diagnosis.

5. High-gain body surface atrial mapping, atrial electrocardiogram and esophageal lead electrocardiogram

May contribute to the identification of atrial myocardial infarction.

6. Echocardiography

At present, the diagnostic value of atrial infarction is limited, mainly because the conventional standard section can not display the atrium well, especially the right atrium. Esophageal echocardiography can better display the atrium, and examination of the wall motion can help diagnose.

Diagnosis and diagnosis of atrial myocardial infarction

diagnosis

Electrocardiogram is the most important method for diagnosing atrial myocardial infarction. However, due to the low voltage generated by the atria, thin atrial wall and large ventricular depolarization, the electrocardiogram of atrial infarction is often ignored or cannot be revealed. However, at present, Some ECG indicators for the diagnosis of atrial infarction are still proposed, including P-Ta changes, changes in P wave morphology, and the presence of supraventricular tachycardia. Unfortunately, these indicators are neither specific nor diagnostic for the diagnosis of atrial infarction. sensitive.

Domestic Zhou Weirong proposed the diagnostic criteria for atrial myocardial infarction:

1. Myocardial infarction with typical clinical and electrocardiographic findings.

2. The P wave has significant dynamic changes and/or the PR segment has a meaningful change.

3. Some patients have atrial or other arrhythmias.

Differential diagnosis

P-Ta segment changes are important ECG indicators for the diagnosis of atrial myocardial infarction, but can also occur in normal people, pericarditis, atrial overload and angina pectoris. Some atrial myocardial infarctions show a P-Ta depression of >1 mV without The improvement of the P-Ta segment corresponding to the lead, these factors affect the sensitivity and specificity of the index, therefore, the slight P-Ta segment depression without the corresponding lead elevation, can not be used as a basis for the diagnosis of atrial myocardial infarction In the past, people with P-wave changes should also carefully explain the changes in their P-Ta segments. In addition, the P-Ta segment depression during angina can disappear with the relief of symptoms, while the P-Ta segment of the atrial myocardial infarction heals with the infarction. Gradually return to the equipotential line and observe the electrocardiogram dynamically to help identify the two.

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