Unstable angina

Introduction to unstable angina Unstableanginapectoris is an acute cardiac event of coronary heart disease and an important component of acute coronary syndrome. It is an intermediate clinical syndrome between chronic stable angina and acute myocardial infarction. The nature of chest discomfort in unstable angina is similar to that of typical labor-type angina, usually more severe, often described as pain, lasting up to 30 minutes, and occasionally awakening the patient from sleep. basic knowledge The proportion of illness: 0.003% Susceptible people: no specific people Mode of infection: non-infectious Complications: acute myocardial infarction

Causes of unstable angina

Coronary artery stenosis (20%):

In patients with unstable angina, the vascular response to the contractile substance is enhanced, and it is mostly confined to the atherosclerotic lesion. Because in most coronary arteries with significant lesions, there are normal arterial walls around it, and the wall is normal. The flexible muscle elastic arc provides the possibility of mechanical contraction, resulting in normal vascular tone (vasoconstriction) or abnormally high (vasospasm), which narrows the lumen of the vessel and increases blood flow resistance to limit blood flow.

Thrombosis factor (35%):

Major D-dimers of platelet aggregation, fibrinogen, and fibrin fragments increase, forming coronary intraluminal thrombosis, leading to progressive coronary stenosis.

Other disease factors (20%):

Non-coronary lesions: such as aortic stenosis or aortic regurgitation, syphilitic aortitis, severe anemia, hyperthyroidism, paroxysmal tachycardia, hypotension, increased blood viscosity or slow blood flow. Hypertrophic cardiomyopathy, mitral valve prolapse, etc., the most important of which is coronary heart disease, that is, coronary atherosclerotic stenosis and/or coronary artery spasm.

Pathogenesis

Most patients with unstable angina have severe obstructive coronary heart disease, such as increased myocardial oxygen demand and / or decreased myocardial oxygen supply can induce myocardial ischemia, transient effects of vasoconstrictors and / or platelet thrombosis Caused by a further narrowing of the lumen diameter, resulting in a decrease in myocardial oxygen supply, resulting in spontaneous (resting) angina, increased arterial pressure and/or tachycardia can also increase myocardial oxygen demand, induce unstable angina.

Studies have shown that in many patients with unstable angina, a decrease in oxygen supply, rather than an increase in oxygen demand, induces myocardial ischemia, which is the most common triggering factor for chronic stable angina, in some unstable forms. In the onset of angina pectoris, an increase in myocardial oxygen demand and a decrease in oxygen supply may occur simultaneously. In patients with critical coronary artery stenosis, a slight increase in myocardial oxygen demand and a slight decrease in oxygen supply can produce critical Myocardial ischemia and unstable angina pectoris can explain the variation of ischemic events in patients with unstable angina within 24 hours. In the morning, the incidence of severe ischemia is higher due to the low reserve of coronary arteries.

Unstable angina prevention

Because coronary heart disease is one of the most important diseases causing human death, and there is still no radical treatment in clinical practice, it is of great significance for the active prevention of coronary heart disease. The prevention of coronary heart disease includes primary prevention and secondary prevention. In one aspect, 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, in order to prevent disease and reduce the incidence rate. Secondary prevention refers to taking drugs for patients who have suffered from coronary heart disease. Or non-pharmacological measures to prevent recurrence or prevent exacerbations.

1. Primary prevention measures 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 proper 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., give positive treatment, of course, some of these risk factors can be Controlled, such as high blood pressure, high blood fat, diabetes, obesity, smoking, less active lifestyle, etc.; and some can not be changed, such as family history of coronary heart disease, age, gender, etc., treatment methods include the use of appropriate drugs to continuously control blood pressure Correct abnormal blood lipid metabolism, quit smoking and alcohol restriction, appropriate physical activity, control weight, control diabetes, etc.

2. Secondary prevention uses drugs that have been validated to prevent recurrence and exacerbation of coronary heart disease. Currently, there are certain preventive drugs:

(1) Antiplatelet drugs: Aspirin has been shown to reduce the incidence of myocardial infarction and reinfarction. The use of aspirin after acute myocardial infarction can reduce the rate of reinfarction by about 25%; if aspirin can not tolerate or allergies, optional Clopidogrel.

(2) -blockers: as long as there is no contraindications, patients with coronary heart disease should use beta blockers, especially after acute coronary events; there are data showing that patients with acute myocardial infarction use beta receptors Blocking drugs can reduce the mortality rate and reinfarction rate by 20% to 25%. The drugs that can be used are metoprolol, propranolol, timolol and the like.

(3) statin lipid-lowering drugs: The results of the study 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 the number of patients requiring coronary intervention or CABC is reduced. In addition to lipid-lowering effects of statins, it improves endothelial function, anti-inflammatory effects, affects smooth muscle cell proliferation and interferes with platelet aggregation, coagulation, fibrinolysis, simvastatin, pravastatin, lovastatin and atorvastatin. All have this effect.

(4) ACEI: Mostly used in patients with severe impairment of left ventricular function or heart failure, many clinical trials have confirmed that ACEI reduces mortality after acute myocardial infarction; therefore, after acute myocardial infarction, ejection fraction <40% Or patients with wall motion index 1.2, and no contraindications, should use ACEI, commonly used captopril, enalapril, benazepril and fosinopril.

Unstable angina complications Complications, acute myocardial infarction, sudden death

Patients with unstable angina have an increased risk of cardiac and non-fatal ischemic events, and acute myocardial infarction and sudden death.

Symptoms of unstable angina pectoris Common symptoms Myocardial infarction Heart failure angina pectoris palpitations Chest pain systolic murmur forced to stop standing dyspnea feces excretion... Trauma

1. Symptoms: Unstable angina The nature of chest discomfort is similar to that of typical labor-type angina, usually more severe, often described as pain, lasting up to 30 minutes, and occasionally awakening the patient from sleep.

Symptoms of the patient, such as the presence of the following characteristics, suggest an unstable angina: a sudden and persistent decrease in the threshold of physical activity that induces angina; an increase in the frequency, severity, and duration of angina; a resting or nocturnal angina Chest pain radiates to nearby or new areas; episodes with new related features such as sweating, nausea, vomiting, palpitations or difficulty breathing, commonly used resting methods and sublingual nitroglycerin treatments can be controlled Chronic stable angina, and usually only temporary or incomplete relief for unstable angina.

The characteristics of various types of episodes of unstable angina are described later. Clinically, two types of angina attacks with special background should be noted:

(1) Unstable angina after coronary artery bypass grafting: This type of angina has accounted for about 20% of unstable angina in developed countries. The long-term prognosis of such patients is not optimistic and may be related to the patency of venous bridge.

(2) Recurrent angina pectoris after coronary intervention: more than 20% within 6 months after intervention, the mechanism is postoperative restenosis. Although the clinical manifestations are similar to those of common angina, the pathophysiological mechanism and The prognosis is different. These patients are mainly caused by vascular smooth muscle hyperplasia rather than thrombosis, so the incidence of myocardial infarction is low, and the complications of re-intervention are not common, but when unstable angina occurs in interventional surgery 6 More than a month, you should consider the possibility of new active lesions.

2. Physical examination: Physical examination is usually not helpful for affirming or excluding angina. Abnormal pulsation in the anterior region, short-term diastolic episodes (S3 and S4) often suggest left ventricular dysfunction, during or after ischemia, There may also be manifestations of acute papillary dysfunction, such as transient apical systolic murmurs, clicks, etc. These results are non-specific, as they can also occur in patients with chronic stable angina or acute myocardial infarction, such as Symptoms with acute congestive heart failure or low circulation of the systemic blood pressure may indicate a poor prognosis.

1. Classification of unstable angina: Unstable angina refers to a group of clinical angina syndrome between stable angina and acute myocardial infarction, including the following subtypes:

(1) First-onset angina pectoris: new angina pectoris within 2 months (from a history of no angina or angina pectoris but no angina pectoris within the last six months).

(2) Deteriorating labor-type angina pectoris: The condition suddenly aggravated, manifested as an increase in the number of chest pain episodes, prolonged duration, and a marked decrease in the threshold of activity for inducing angina pectoris. According to the Canadian Cardiology Society's labor-type angina pectoris grade 1 or above and at least grade III, The effect of nitroglycerin on relieving symptoms is diminished and the course of disease is within 2 months.

(3) resting angina: angina occurs in a resting or quiet state, the duration of the attack is relatively long, the effect of nitroglycerin is poor, and the course of disease is within 1 month.

(4) Post-infarction angina pectoris: angina pectoris occurring within 24 h to 1 month after onset of acute myocardial infarction.

(5) Variant angina pectoris: An angina pectoris that occurs during rest or general activity. The electrocardiogram shows a temporary elevation of the ST segment at the time of onset.

2. Diagnosis of unstable angina The following points should be noted before making diagnosis of unstable angina:

(1) The diagnosis of unstable angina pectoris should be based on the nature of angina pectoris, characteristics, signs of seizures and ECG changes at the time of onset and risk factors for coronary heart disease, combined with clinical comprehensive judgment to improve the accuracy of diagnosis.

(2) The most significant diagnostic value of ECG ST-segment elevation and depression during angina pectoris is the most diagnostic value. The ECG should be recorded in time and after symptom relief. Dynamic ST-segment horizontal or down-tilt depression 1mm or ST-segment elevation ( Limb lead 1mm, chest lead 2mm) has diagnostic significance, if the inverted T wave is pseudo-change (false normalization), the T wave is restored to the original inverted state after the attack: or the previous ECG is normal In the pre-cardiac region, the multi-lead T-wave is deep. In the exclusion of non-Q-wave acute myocardial infarction, the diagnosis of unstable angina should also be considered. When the electrocardiogram shows ST-segment depression 0.5mm but <1mm, Still need to be highly suspected of suffering from this disease.

(3) In the acute phase of unstable angina, any form of stress test should be avoided. These tests should be carried out after the condition is stable.

3. Unstable angina risk stratification Currently there is no uniform risk stratification in the world. This recommendation refers to the 1989 Braunwald unstable angina classification combined with the situation in China to make the following stratification.

The severity of the patient's condition is mainly based on the history of heart disease, physical signs and electrocardiogram, especially the electrocardiogram at the time of onset. The key point in the medical history is the frequency of angina attacks in 1 month, especially the episodes in the past 1 week. Should include:

1 the degree of activity tolerance reduction,

2 the duration of the attack and the severity of the attack,

3 Whether there is a recent resting angina on the basis of the original labor angina pectoris, according to the angina pectoris, the degree of ST segment depression at the onset and some special signs of the patient at the onset of the attack can be divided into high, medium and low risk groups.

4. Non-invasive examination of unstable angina The purpose of non-invasive examination is to judge the severity of the patient's condition and the near and long-term prognosis. The project includes treadmill, active plate, motor nuclide myocardial perfusion scan and drug load test. Wait.

(1) For patients with unstable angina in low-risk group, stable exercise for more than 1 week may be considered for exercise test. If the amount of exercise induced by myocardial ischemia exceeds Bruce III or 6 metabolic equivalents (METs), conservative treatment may be used. Below the above-mentioned activity, angina pectoris is induced, and coronary angiography is required to determine whether to perform interventional or surgical treatment.

(2) For the patients with moderate risk and high risk group, the load test should be avoided within 1 week of the acute phase. After the condition is stable, the symptom-restricted exercise test may be considered. If the evidence of ischemia of the electrocardiogram is available, the condition is stable. Coronary angiography can also be performed directly.

(3) Value of non-invasive examination:

1 Determine whether coronary artery single-cranial lesions require interventional therapy,

2 Identify the ischemic-related blood vessels and provide a basis for revascularization treatment.

3 Provide evidence of survival of the myocardium,

4 as an important comparative data to determine whether there is restenosis after percutaneous transluminal coronary angioplasty (PFCA).

Examination of unstable angina

1. Increased blood lipid concentration: dyslipidemia is closely related to the pathogenesis of coronary heart disease. Typical atherosclerosis is characterized by: TC (total cholesterol), LDL-C, VLDL-C, triglyceride, etc. and HDL-C decline.

2. Blood sugar: Glucose tolerance and diabetes have been shown to be risk factors for coronary heart disease. All patients with suspected coronary heart disease should be tested for fasting blood glucose.

3. Generally no leukocytosis.

4. Most patients with unstable angina have normal serum zymogram. Because these patients often have small myocardial damage or microinfarction, or reperfusion injury due to autolysis of thrombus after transient coronary occlusion, there may be a light serum zymogram. The degree is increased, but does not meet the usual criteria for diagnosing acute myocardial infarction.

5. Cardiac troponin T is a regulatory protein that is a specific marker of myocardial cell injury. In patients with unstable angina, troponin T is more likely to diagnose myocardial cell damage than serum creatine kinase MB activity. Sensitive indicators.

6.C-reactive protein and serum amyloid-like protein A are sensitive indicators for the diagnosis of inflammation. Serum C-reactive protein and amyloid A protein concentrations have increased in normal concentrations of creatine kinase and cardiac troponin T in patients with unstable angina. Is a sign of poor prognosis.

7. Electrocardiogram: In unstable angina, transient ST-segment shift, decline or elevation, and/or T-wave inversion often occur, but not all patients have, ST-segment dynamic bias when symptoms are alleviated Removal (decline or rise 1mm) or partial elimination of T wave inversion is an important indicator of poor prognosis, followed by acute myocardial infarction or death. A transient u wave inversion is a rare, insidious type of unstable angina. ECG performance, patients with ST segment changes in the anterior septal lead, usually have obvious left anterior descending coronary artery stenosis, suggesting high-risk groups, if the previously recorded ECG for comparison, the diagnostic accuracy will be improved.

Usually, ECG changes completely or partially disappear with the relief of pain. The ECG changes lasted for more than 12 hours, suggesting that there is no Q-wave type (now called non-ST-segment elevation) myocardial infarction.

If the patient has a typical history of chronic stable angina, or a defined diagnosis of coronary heart disease (previously with myocardial infarction, abnormal coronary angiography or a positive history of non-invasive exercise testing), the diagnosis of unstable angina can be based on clinical symptoms Made, even without ECG changes, the clinical diagnosis of the patient group without previous evidence of coronary heart disease and without ECG changes would be inaccurate.

It should be mentioned that ischemic chest pain is not a reliable or sensitive indicator of transient acute myocardial ischemia. The reduction of primary coronary blood flow is accompanied by a variety of mild ECG changes that can occur before pain or discomfort. Clinical studies have found that up to 90% of myocardial ischemic events are not associated with chest pain, and ischemic manifestations detected by 24h ambulatory electrocardiography can be used as predictors of adverse outcomes during hospitalization and follow-up.

8. Holter monitoring: In unstable angina, almost 2/3 of the ischemic events are asymptomatic and cannot be detected by conventional electrocardiogram. Therefore, it is meaningful to continuously monitor the ST segment. 15% to 30% of patients with unstable angina have a temporary ST-segment change, mainly ST-segment depression, and these patients have an increased risk of subsequent cardiac events, so Holter monitoring can be used to assess the patient's prognosis.

9. Echocardiography: In the presence of myocardial ischemia, echocardiography can be used to detect transient segmental activity or no movement of the left ventricular wall, and wall motion returns to normal after ischemia recovery.

10. Coronary angiography: Coronary angiography is the most important examination in the diagnosis and treatment of coronary heart disease. For patients with unstable angina in the middle-risk and high-risk groups, coronary artery examination should be performed if conditions permit. The purpose is to clarify the condition of the lesion and guide the treatment. Patients with unstable angina should be considered as strong indications for coronary angiography if:

(1) recurrent angina pectoris: long duration of pain, unsatisfactory drug treatment may consider coronary angiography in time to determine whether emergency interventional therapy or emergency coronary artery bypass grafting (CABG).

(2) The original labor-type angina pectoris frequently appeared in the short-term break.

(3) The tolerance of recent activities was significantly reduced, especially those who were lower than Bruce II or 4 METs.

(4) Post-infarction angina.

(5) The original old myocardial infarction, the recent emergence of labor-type angina caused by non-infarct zone ischemia.

(6) severe arrhythmia, LVEF <40% or congestive heart failure.

Diagnosis and diagnosis of unstable angina

For patients with the first diagnosis of symptoms of acute chest pain, identify the following diseases:

1. Acute myocardial infarction The chest pain time of this disease is longer than that of stable angina pectoris, often more than 30min, and the degree is more serious. There are many other complications, but the main identification point is the dynamic evolution of ECG and onset. After 6-12 hours, the sequence of troponin after myocardial enzyme changes, the prognosis of this disease is even worse, especially when serious complications occur.

2. Aortic dissection This disease is characterized by severe tear-like pain in the chest and back, restlessness, nitroglycerin can not relieve it, physical examination can find pulse asymmetry, blood pressure difference between the limbs and acute aortic regurgitation murmur, attack There is no change in ECG, and the myocardial enzyme is normal. The diagnosis method of this disease is TEE and magnetic resonance imaging technology.

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