Angina
Angina, also known as angina pectoris, is chest pain or discomfort that occurs when the heart muscle does not receive enough oxygen-rich blood, typically due to reduced blood flow from narrowed or blocked coronary arteries.[1][2][3] It serves as a primary symptom of coronary artery disease, the most common underlying cause, where atherosclerosis leads to plaque buildup that restricts blood supply to the heart (myocardial ischemia).[1][2][3] The hallmark symptom of angina is a sensation of pressure, squeezing, tightness, or burning in the chest, often lasting a few minutes and potentially radiating to the shoulders, arms, neck, jaw, back, or upper abdomen.[1][2][3] Accompanying signs may include shortness of breath, fatigue, nausea, sweating, or dizziness, with women more likely to experience subtler manifestations such as neck or jaw discomfort rather than classic chest pain.[1][3] Symptoms are often triggered by physical exertion, emotional stress, cold weather, or heavy meals in stable cases, but can arise unpredictably at rest in more severe forms.[1][3] Angina manifests in several types, each with distinct patterns and implications for urgency. Stable angina is the most common, predictable, and triggered by exertion, typically resolving with rest or medication within 5-10 minutes.[1][3] Unstable angina, an emergency condition, occurs suddenly or worsens without provocation, lasting longer than 20 minutes and signaling a high risk of heart attack.[1][3] Variant (Prinzmetal's) angina results from coronary artery spasms rather than fixed blockages, often striking at rest and more prevalent in younger individuals without traditional risk factors.[1] Other variants, such as microvascular angina, involve dysfunction in smaller heart vessels and disproportionately affect women.[3] The primary cause of angina is coronary artery disease, but risk factors significantly influence its development and severity. These include advancing age (particularly over 60), family history of heart disease, tobacco use, high blood pressure, high cholesterol, diabetes, obesity, physical inactivity, and chronic stress.[1][2] Exposure to secondhand smoke or certain medications can exacerbate vulnerability.[1] Complications of untreated angina are serious, as it can progress to myocardial infarction (heart attack), arrhythmias, or even sudden cardiac death if blood flow is severely compromised.[1][2] In the United States, angina affects approximately 11 million people, underscoring its status as a major public health concern linked to ischemic heart disease, a leading cause of global morbidity and mortality.[2]Overview
Definition
Angina pectoris is defined as transient chest pain or discomfort resulting from myocardial ischemia, which occurs when there is reduced blood flow through the coronary arteries to the heart muscle, leading to an inadequate supply of oxygen without causing permanent tissue damage or necrosis.[4][2] This condition serves as a clinical manifestation of coronary artery disease, where the heart's oxygen demand temporarily exceeds the available supply, often triggered by physical exertion or emotional stress.[1][3] The term "angina pectoris" originates from Latin, with "angina" derived from "angere," meaning "to strangle," reflecting the constricting sensation experienced, and "pectoris" from "pectus," indicating the chest location.[5] This etymology underscores the historical recognition of the symptom as a choking or tightening in the chest, first formally described in medical literature in the 18th century.[6] Unlike myocardial infarction, which involves prolonged ischemia leading to myocardial necrosis and potential permanent heart muscle damage, angina is reversible upon restoration of adequate blood flow and does not result in tissue death.[7] It must also be differentiated from non-cardiac causes of chest pain, such as gastrointestinal disorders like gastroesophageal reflux or musculoskeletal issues, which do not involve coronary insufficiency.[1] At its core, angina arises from the ischemic cascade, a sequence of physiological events initiated by an imbalance between myocardial oxygen supply and demand, beginning with perfusion abnormalities and progressing to metabolic alterations, diastolic and systolic dysfunction, electrocardiographic changes, and finally, the perception of pain.[8][9] This cascade highlights the transient nature of the condition, where early intervention can prevent escalation to more severe ischemic events.[10]Signs and symptoms
Angina typically manifests as chest discomfort, often described as a sensation of pressure, tightness, squeezing, heaviness, or burning in the substernal region.[1][11] This discomfort generally lasts 5 minutes or less in stable cases and may radiate to the arms, neck, jaw, shoulders, or back, sometimes accompanied by shortness of breath, sweating, or nausea.[4][1] Atypical presentations are common, particularly among women, older adults, and individuals with diabetes, where chest pain may be absent or minimal.[1][4] In these groups, symptoms might include shortness of breath, fatigue, nausea, dizziness, epigastric discomfort, or pain in the neck, jaw, back, or abdomen without classic substernal involvement.[11][1] Common precipitating factors include physical exertion, emotional stress, exposure to cold weather, or heavy meals, which increase the heart's demand for oxygen.[1][11] Symptoms are often relieved by rest or sublingual nitroglycerin within a few minutes.[4][1] Red flags indicating unstable angina include episodes occurring at rest, increasing in frequency or severity, or lasting longer than 15 to 20 minutes, which do not fully resolve with rest or nitroglycerin.[1][11] Angina equivalents, such as isolated shortness of breath or epigastric discomfort, can occur without overt chest pain and should prompt evaluation in at-risk individuals.[1][4]Classification
Stable angina
Stable angina, the most common form of angina, is characterized by predictable episodes of chest pain or discomfort triggered by physical exertion or emotional stress, which typically resolve with rest or sublingual nitroglycerin within a few minutes.[12][1] This pattern arises because the pain follows a reproducible threshold, such as occurring consistently at the same level of workload during activities like walking uphill or climbing stairs.[12] Unlike other forms, these episodes are not associated with sudden worsening and signal a stable underlying condition rather than an acute threat.[13] The severity of stable angina is often graded using the Canadian Cardiovascular Society (CCS) classification system, which assesses the degree of limitation in physical activity due to symptoms.[14]- Class I: Angina occurs only with strenuous, rapid, or prolonged exertion at work or recreation.
- Class II: Slight limitation of ordinary activity, such as angina with walking or climbing stairs rapidly, walking uphill, or after meals.
- Class III: Marked limitation of ordinary physical activity, with angina occurring during walking more than two blocks on the level or climbing one flight of stairs at a normal pace.
- Class IV: Inability to carry on any physical activity without discomfort, with symptoms potentially present at rest.[15]