Heart disease is a broad term for conditions that affect the structure or function of the heart. It includes disorders involving the heart muscle, coronary arteries, heart valves, electrical conduction system, chambers, or the heart’s ability to pump blood effectively. Heart disease is therefore not one single illness and does not have one universal cause, symptom pattern or treatment.
Some forms develop gradually during adulthood, some are present from birth, some are inherited, and others result from infection, inflammation, degeneration, abnormal electrical activity or damage to the heart. Coronary heart disease, heart failure, cardiomyopathies, arrhythmias, valve disorders and congenital heart disease are examples of distinct conditions that fall within the wider category.
The heart is a muscular organ whose principal function is to circulate blood through the lungs and the rest of the body. The right side receives oxygen-poor blood and sends it to the lungs, while the left side receives oxygen-rich blood and pumps it into the systemic circulation. The heart itself also requires a continuous supply of oxygenated blood, delivered through the coronary arteries. Disease can interfere with any part of this system.
A narrowed coronary artery can reduce oxygen delivery to heart muscle, a damaged valve can obstruct or permit abnormal blood flow, an electrical disorder can disturb rhythm, and a weakened or stiffened heart muscle can impair pumping or filling. Consequently, the term heart disease encompasses several different physiological problems rather than a single mechanism.
Heart disease is closely related to, but not synonymous with, cardiovascular disease. Cardiovascular disease is the broader category covering disorders of the heart and blood vessels, including conditions affecting arteries and veins outside the heart, such as peripheral arterial disease and some forms of stroke. Heart disease specifically concerns the heart, although many heart conditions arise from abnormalities in the cardiovascular system and may coexist with vascular disease.
Coronary heart disease is a particularly important subtype because it affects the coronary arteries that supply the heart muscle. The terms coronary artery disease and ischaemic heart disease are also commonly used for coronary heart disease, with terminology varying somewhat between clinical contexts and health systems.
The causes of heart disease differ according to the particular condition. Coronary heart disease commonly develops through atherosclerosis, in which atheroma or plaque accumulates within artery walls. High blood pressure, high cholesterol, smoking, diabetes, excess body weight, physical inactivity, increasing age and family history can increase cardiovascular risk. Other heart diseases have different origins.
Congenital heart disease results from structural abnormalities present from birth; cardiomyopathies involve abnormalities of the heart muscle and may sometimes have genetic causes; infective endocarditis affects the inner lining and valves; myocarditis involves inflammation of the heart muscle; and arrhythmias arise from disturbances in electrical activity. It is therefore inaccurate to assume that all heart disease is caused by lifestyle or blocked arteries.
The effects of heart disease range from mild or asymptomatic abnormalities to life-threatening emergencies. Some people have substantial coronary artery disease without recognising symptoms until a heart attack occurs. Others develop exertional breathlessness, chest discomfort, palpitations, dizziness, fainting, swelling or reduced exercise tolerance. The particular symptoms depend on which cardiac structure is affected and how severely its function is impaired.
For example, an arrhythmia may primarily cause an irregular or rapid heartbeat, whereas heart failure may cause breathlessness and fluid retention. Valve disease may produce a murmur and symptoms of reduced cardiac output, while coronary disease may produce angina or myocardial infarction. Some conditions can remain stable for years, whereas others can deteriorate rapidly.
Diagnosis is not based on one universal test because heart disease comprises many conditions. Depending on the suspected disorder, clinicians may use a medical and family history, physical examination, blood pressure measurement, blood tests, electrocardiography, echocardiography, chest imaging, exercise testing, cardiac CT, cardiac MRI, coronary angiography or prolonged rhythm monitoring. The tests are selected according to the suspected mechanism.
An ECG is particularly useful for electrical abnormalities and evidence of certain forms of myocardial injury, while echocardiography provides information about chambers, valves, pumping function and blood flow. Coronary imaging can investigate narrowing of the arteries. A diagnosis therefore involves matching clinical findings with appropriate investigations rather than treating the label heart disease as a single diagnostic entity.
Treatment depends on the specific condition, its severity and the person's overall risk. Management may involve lifestyle measures, medicines, procedures, implanted devices or surgery. Examples include medicines that reduce blood pressure or cholesterol, antiplatelet or anticoagulant medicines in appropriate conditions, drugs that control heart rhythm or improve heart failure, coronary angioplasty and stenting, coronary artery bypass surgery, valve procedures, pacemakers and implantable cardioverter-defibrillators. Prevention and risk-factor management are important because several cardiovascular risk factors are modifiable. Stopping smoking, maintaining appropriate physical activity, eating a balanced diet, controlling blood pressure and cholesterol, managing diabetes and addressing excess weight can reduce cardiovascular risk, although they cannot prevent every form of heart disease.
Heart disease has major public-health significance because cardiovascular conditions collectively affect millions of people and include some of the most important causes of illness and premature death. Coronary heart disease is particularly important because it can produce angina and heart attacks and can progress silently before symptoms appear.
Understanding the distinction between a chronic underlying disease and an acute event is essential: coronary heart disease is a disease of the coronary circulation, angina is a symptom or clinical syndrome caused by inadequate myocardial blood supply, and a heart attack is an acute myocardial injury caused by prolonged interruption of blood flow. These terms are related but should not be used interchangeably. The precise diagnosis matters because the expected course, urgency, treatment and prevention strategy depend on the specific cardiac condition.
