What Is Unstable Angina?

Unstable angina pectoris is a clinical manifestation between fatigue-stable angina pectoris and acute myocardial infarction and sudden death. It mainly includes primary angina pectoris, worsening angina pectoris, resting angina pectoris with ECG ischemic changes and early angina pectoris after myocardial infarction. It is characterized by a progressive increase in the symptoms of angina pectoris, the onset of new episodes of rest or nocturnal angina pectoris or the prolonged duration of angina pectoris. Because of its unique pathophysiological mechanism and clinical prognosis, patients may develop acute myocardial infarction if they cannot be treated in a timely and appropriate manner.

Basic Information

nickname: Unstable angina pectoris
English name: unstable angina
Visiting department: Cardiology

Common locations: heart
Common causes: Often induced by lighter work or emotional agitation
Common symptoms: Chest pain, chest discomfort
Contagious: no

Causes of unstable angina pectoris

1. Progress of coronary atherosclerosis

Most patients with unstable angina pectoris have severe obstructive ischemic heart disease. The development of coronary atherosclerosis can cause progressive coronary stenosis.

Platelet aggregation

Coronary artery stenosis and intimal injury, platelet aggregation occurs, and the vasoconstrictor substance thromboxane A2 is produced, while the concentration of anti-aggregation substances produced by normal endothelial cells such as prostacyclin, tissue plasminogen activator and endothelial relaxant factor Decreased, causing coronary artery contraction, increased lumen stenosis and even occlusion, and increased dynamic coronary artery resistance.

3. Thrombosis

Platelet aggregation, D-dimer, the main component of fibrinogen and fibrin fragments, increases, forming thrombus in the coronary lumen, leading to the formation of progressive coronary stenosis.

4. Coronary arterial spasm

Clinical, coronary angiography, and autopsy studies have confirmed that coronary artery spasm is an important mechanism that causes unstable angina pectoris.

Clinical manifestations of unstable angina pectoris

Clinical symptoms

The nature of chest pain or chest discomfort is similar to that of typical stable angina pectoris, but the pain is more severe, often lasting up to 30 minutes, and occasionally during sleep. Bed rest and nitrate-containing medications showed only brief or incomplete chest pain relief.

Clinical signs

Transient third and fourth heart sounds can be heard in the apex, apical lift pulses can be seen in left heart failure, and systolic mitral regurgitation murmur can be heard during or immediately after ischemic attack.

Unstable angina pectoris

ECG examination

(1) The ST segment depression or elevation of conventional ECG and / or T wave inversion are usually transient and disappear completely or partially with the relief of angina pectoris. If ST-T changes persist for more than 6 hours, non-Q wave myocardial infarction is indicated. ST-T is also unchanged.

(2) Dynamic ECG monitoring for more than 24 hours. Most patients have asymptomatic myocardial ischemia, and 85% to 95% of the changes in the dynamic ECG are not accompanied by angina. For the prognosis of unstable angina pectoris, dynamic ECG is more sensitive than conventional ECG. The dynamic electrocardiogram is not only helpful for detecting the dynamic changes of myocardial ischemia, but also can be used as a reference indicator for the evaluation and decision of conventional antianginal medications for patients with unstable angina pectoris.

(3) Exercise ECG is suitable for patients whose symptoms have stabilized or disappeared, and is often used to judge the prognosis of unstable angina pectoris. Those with normal resting electrocardiogram and negative exercise test have a 5-year survival rate of> 95%; those with normal resting electrocardiogram and negative exercise test but with chest pain have a relatively low incidence of fatal myocardial ischemia; Changes in ischemic ST-T, reduced heart rate-blood pressure product, and symptoms of chest pain have a higher incidence of fatal myocardial ischemic attacks and deaths.

2. Echocardiography

Showing transient wall motion abnormalities. Those with abnormal wall motion are persistent, suggesting a poor prognosis. Radionuclide myocardial imaging can determine the location of myocardial ischemia. TI myocardial imaging showed sparse or absent radioactivity in the ischemic area of the myocardium at rest, indicating that the myocardium was in a state of low blood flow perfusion.

3. Cardiac catheterization

Coronary angiography shows that most patients have two or more coronary lesions, of which about half are three coronary lesions, but patients with recent episodes of angina pectoris and those without a history of myocardial infarction or chronic stable angina pectoris have a single coronary Most of the patients were affected. Coronary artery disease is more serious, plaque rupture and / or partial thrombus dissolution, mostly manifested as eccentric stenosis. Coronary endoscopy often shows obstructive lesions with a complex plaque and / or thrombosis.

4. Laboratory Enzymatic Examination

There may be increased blood cholesterol, no abnormal changes in myocardial enzymes such as CKMB and troponin.

Diagnosis of unstable angina pectoris

1. The nature of the original stable angina pectoris changes, that is, angina pectoris is frequent, severe, and prolonged.

2. Onset of angina pectoris at rest.

3. Angina pectoris can also be induced by recent mild physical activity that occurred recently in the past month. If one or more of the three items are accompanied by changes in the ECG ST-T, a diagnosis can be established. If there is a previous history of stable angina pectoris, myocardial infarction, abnormal coronary angiography, and positive exercise test, even if there is no ST-T on the ECG, but it has typical unstable angina symptoms, the diagnosis can be established. Angina pectoris occurs within two weeks after myocardial infarction, which is called unstable angina pectoris.

Differential diagnosis of unstable angina pectoris

The same as the differential diagnosis of stable angina pectoris. In particular, it is necessary to identify acute myocardial infarction, which is more severe in pain. The electrocardiogram has infarction patterns and specific changes in myocardial enzymes can be identified.

Treatment of unstable angina pectoris

1. General treatment: rest in bed for 1 to 3 days, 24-hour ECG monitoring at the bedside. Patients with dyspnea and cyanosis should be given oxygen, morphine can be given for irritability and severe pain, and myocardial necrosis markers should be repeated if necessary.

2. Relieve pain: nitroglycerin can be given orally or intravenously. Calcium channel blockers have the best effect on variant angina pectoris.

3. Anticoagulation: Aspirin and heparin are important treatments for unstable angina pectoris, the purpose of which is to prevent thrombosis and prevent the disease from progressing towards myocardial infarction.

4. Conditional hospitals should perform emergency coronary angiography or elective coronary angiography.

Further examination and long-term treatment in the remission phase are the same as those in stable labor angina.

Prognosis of unstable angina pectoris

Elderly patients with persistent resting angina pectoris and coronary artery thrombosis, left heart failure, and multiple coronary artery lesions often indicate a poor prognosis. Patients with angina pectoris or ischemic ST-segment depression or decreased heart rate-blood pressure product during exercise tests have higher rates of myocardial infarction and recurrent unstable angina pectoris and mortality.