heart disease

heart disease, broad term encompassing a range of disorders that affect the heart’s structure and function. Heart disease may involve the coronary arteries, the heart muscle, the heart valves, the heart’s electrical conduction system, or surrounding tissues.

Heart diseases—distinct from other vascular disorders but included within the broader category of cardiovascular disease—account for the majority of global cardiovascular deaths and represent the most common forms of cardiovascular disease. In the early 2020s an estimated 315 million people worldwide were living with coronary artery disease, and approximately 64 million had heart failure.

Major types of heart disease

Heart disease constitutes several principal categories.

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A Visit with the Word Doctor: Medical Vocabulary Quiz

• Coronary artery disease manifests as the narrowing or blocking of the coronary arteries, usually due to atherosclerosis (the accumulation of fatty plaques in either or both of the coronary arteries). It often leads to angina pectoris (chest pain) or heart attack.
• Heart failure is a chronic condition in which the heart cannot pump blood efficiently enough to maintain adequate systemic circulation.
• Cardiomyopathy refers to diseases of the heart muscle that cause it to become enlarged, thick, or stiff. These structural changes impair the heart’s ability to pump blood efficiently, often leading to arrhythmias, heart failure, or other complications.
• Arrhythmias are disorders of heart rhythm, including atrial fibrillation (irregular rhythm of contraction of the atria), tachycardia (abnormally accelerated heart rate), and heart block (lack of synchronization in contraction between the atria and the ventricles).
• Valvular heart disease is characterized by the malfunctioning of one or more heart valves, resulting in stenosis (narrowing), which restricts blood flow through the heart, or regurgitation, which causes blood to leak backward within the heart.
• Congenital heart disease consists of structural problems with the chambers, valves, or walls of the heart that are present at birth and affect blood flow. These conditions range from mild, such as septal defects (small openings), to severe, involving malformations or the absence of parts.
• Inflammatory heart disease refers to conditions caused by infection, autoimmune disorders, or other factors that trigger immune responses in heart tissue; examples include myocarditis, pericarditis, and endocarditis.

Although individual conditions differ in cause and presentation, many share common risk factors, including hypertension, high cholesterol, diabetes, smoking, obesity, physical inactivity, and advancing age.

Pathophysiology

The pathophysiological mechanisms underlying heart disease vary according to the specific condition. Coronary artery disease, for example, is driven by atherosclerosis, a condition in which cholesterol-rich plaques accumulate in arterial walls. When these plaques rupture, a clot may form and become lodged in an artery, suddenly blocking blood flow to heart tissue. In dilated cardiomyopathy the heart undergoes structural remodeling in which the ventricular walls stretch and become thin. In hypertrophic cardiomyopathy the ventricular walls become abnormally thick, and in restrictive cardiomyopathy flexible muscle tissue is replaced with rigid scarlike material, causing the ventricles to stiffen. Depending on the form of cardiomyopathy, the changes may be associated with disruptions in calcium signaling in the heart and with chronic activation of stress-related neurohormonal pathways that promote inflammation.

Other major mechanisms underlying various forms of heart disease include electrical anomalies that disrupt normal rhythm and infectious or immune processes that damage heart tissue. Electrical disturbances affect the heart by disrupting the normal sequence of impulses that coordinate each heartbeat. Abnormal signal generation, reentry circuits through scarred tissue, or blocked conduction pathways can cause the heart to beat too fast, too slowly, or irregularly, which can reduce pumping efficiency, increase the risk of blood clots, contribute to heart failure, or in severe cases lead to cardiac arrest. Inflammation caused by infection can damage the heart by directly injuring its tissues and triggering an immune response that further disrupts heart function. In myocarditis, for instance, typically viruses infect the heart muscle, leading to inflammation that weakens muscle fibers. Myocarditis also can arise from autoimmunity, when the immune system mistakenly targets the heart’s own cells.

Clinical factors

Heart disease presents with a broad range of symptoms—including chest pain, shortness of breath, palpitations, fatigue, systemic edema (the accumulation of fluid in the extremities), and fainting—though some forms may remain silent until advanced. Diagnosis typically involves testing, such as with electrocardiography (ECG) to assess heart rhythm, echocardiography or cardiac magnetic resonance imaging (MRI) to evaluate structure and function, and blood tests to detect markers of injury or strain. Treatment depends on the underlying condition and may include medications, lifestyle modification, catheter-based procedures such as angioplasty, surgical implantation of devices such as a pacemaker, or other surgical interventions.

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