Introduction
Angina pectoris is a major clinical sign of ischemic heart disease (IHD). It occurs when the heart muscle does not get enough blood and oxygen. This usually happens when one or more coronary arteries become narrowed or blocked. Angina typically causes sudden chest pain in the centre of the chest, which can spread to the left arm, right arm, jaw or neck. The pain generally increases when the heart works harder, such as during exercise or stress.
Definition
Angina pectoris refers to chest pain or chest discomfort caused by reduced blood flow to the heart muscles. This reduced blood flow is due to narrowing or blockage of the coronary arteries, a condition known as ischemia.
Classification / Types of Angina
Angina pectoris has three main clinical patterns. These types differ slightly in their causes and presentation.
1. Stable (Typical) Angina
- Also called exertional angina. Triggered by physical activity or emotional stress.
- Occurs because of severe narrowing of a coronary artery due to plaque buildup (cholesterol deposits).
- With exertion, the heart demands more oxygen. If the narrowed artery cannot supply enough blood, chest pain occurs.
- Pain usually reduces with rest.
- ECG shows ST-segment depression during the attack.
- No rise in cardiac enzymes because there is no permanent damage to the heart muscle.
2. Unstable Angina
- Occurs even at rest. The reduction in blood flow is more severe and unpredictable.
- Usually caused by rupture of an atherosclerotic plaque leading to partial thrombosis or vasospasm.
- Heart muscle does not get enough oxygen, increasing the risk of heart attack.
- Emergency condition that needs immediate medical care.
- Distinguished from myocardial infarction by ECG: MI shows ST elevation, while unstable angina usually does not.
3. Variant Angina (Vasospastic or Prinzmetal’s Angina)
- Rare type of angina caused by sudden spasms of the coronary artery.
- Can occur at rest or during activity, even without artery blockage.
- ECG shows ST-segment elevation due to severe but temporary reduction in blood flow.
- Responds well to vasodilators like nitroglycerin.
Another type is Nocturnal Angina, which occurs at night while the patient is sleeping.
Epidemiology
- Angina affects around 112 million people worldwide.
- More common in men (1.7%) than women (1.5%).
- Risk increases with age.
Etiology (Causes)
Angina occurs when the heart muscle does not get enough oxygen-rich blood. The main reason for reduced blood flow is coronary artery disease (CAD), where coronary arteries become narrowed by cholesterol plaques (atherosclerosis).
Triggers of Stable Angina
- Physical activity (walking, climbing stairs)
- Emotional stress
- Cold weather
- Heavy meals
- Smoking
Causes of Unstable Angina
- Plaque rupture in the artery
- Formation of blood clot
- Severe and sudden reduction in blood flow
Causes of Prinzmetal’s Angina
- Sudden coronary artery spasm
- Smoking
- Certain medicines that tighten blood vessels
- Use of cocaine
- Stress
Pathophysiology
In angina, there is an imbalance between oxygen supply and oxygen demand of the heart muscle. When coronary arteries become narrowed due to plaque buildup, the heart receives less oxygen, especially during exertion. This leads to myocardial ischemia, creating chest pain or pressure. In unstable angina, plaque rupture and partial clot formation further reduce blood flow, increasing the risk of a heart attack. In variant angina, coronary artery spasm causes sudden and temporary blockage of blood flow.
Signs and Symptoms
- Chest pain or pressure (squeezing, tightness or heaviness)
- Pain radiating to neck, jaw, back or arms
- Numbness or tingling
- Shortness of breath
- Dizziness or fainting
- Nausea or vomiting
- Excessive sweating
- Irregular heartbeat
- Fatigue
Stable Angina: Predictable episodes, last less than 5 minutes, relieved by rest.
Unstable Angina: Sudden, unpredictable, does not improve with rest, may last longer and needs emergency care.
Variant Angina: Occurs at rest, often at night, may last up to 30 minutes.
Diagnosis
Doctors may conduct different tests to confirm angina and its severity.
- Electrocardiogram (ECG): Checks electrical activity of the heart and can show ischemia.
- Stress Test: Measures heart function during exercise or after medicines that mimic exercise.
- Echocardiogram: Uses sound waves to create heart images and assess blood flow problems.
- Nuclear Stress Test: Radioactive tracer is used to see blood flow in heart muscles.
- Chest X-ray: Shows heart size and helps rule out other causes of chest pain.
- Blood Tests: Detect enzymes that indicate heart muscle damage.
- Coronary Angiography: Dye is injected into coronary arteries to check blockages.
- Cardiac CT Scan: Shows calcification or narrowing in the arteries.
- Cardiac MRI: Provides detailed images of the heart and its blood vessels.
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