Also Known As
Coronary heart disease (CHD)
Coronary artery disease (CAD)
Cardiovascular disease (CVD)
Heart attack (myocardial infarction, MI)
Sudden cardiac arrest (SCA)
Congestive heart failure (CHF)
Atrial fibrillation (afib)
This article was last reviewed on
This article waslast modified on December 22, 2020.
Overview of the Heart

The heart is a muscular, fist-sized organ located within your chest in a space between the two lungs (mediastinum). The heart continuously pumps blood, beating as many as 100,000 times a day. The blood that the heart moves carries oxygen and nutrients throughout the body and transports carbon dioxide and other wastes to the lungs, kidneys, and liver for removal.

The heart ensures its own oxygen supply through a set of coronary arteries and veins. The heart is also an endocrine organ that produces the hormones atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), which coordinate heart function with blood vessels and the kidneys.

The heart is essentially hollow with two halves divided vertically by a septum, and each side of the heart has two internal chambers – an atrium on top and a ventricle on the bottom.

  • Blood returning from the body (oxygen-poor) through the veins enters the right side of the heart through the right atrium and is pumped by the right ventricle to the lungs, where carbon dioxide is released and oxygen is taken up.
  • This oxygenated blood from the lungs is returned to the left atrium and is pumped by the left ventricle into arteries that carry it throughout the body.

Four heart valves regulate the direction and flow of blood through the chambers of the heart. It is their opening and shutting that gives the heart its typical "lub-dub" beat. The heart has an electrical system that controls the rate and rhythm of the heartbeat.

The heart muscle itself is called the myocardium. The endocardium is a membrane that lines the chambers of the heart and the valves. The outside of the heart is encased by the pericardium – a layered membrane that is fibrous on the outside and serous (fluid-secreting) on the inside. The pericardium forms a protective barrier around the heart and allows it to beat in a virtually friction-free environment.

Accordion Title
About Heart Disease
  • What is heart disease?

    Heart disease is a general term that refers to a variety of medical conditions that affect one or more of the components of the heart. Anything that damages the heart or decreases the heart's supply of oxygen, affects the muscle's efficiency, or reduces its ability to pump blood will disrupt the coordinated relationship between the heart, kidneys, and blood vessels and can harm not only the heart but the rest of the body as well. Heart diseases can be present at birth (congenital) or may develop over the course of your lifetime.

    About 610,000 people die of heart disease in the U.S. every year, according to the Centers for Disease Control and Prevention. That is about 1 out of every 4 deaths. Heart disease is the leading cause of death for both men and women.

  • Common diseases of the heart

    Some common diseases of the heart include the following.

    Coronary heart disease (CHD) and coronary artery disease (CAD) are the most common forms of heart disease. They are usually part of cardiovascular disease (CVD), a narrowing of arteries in the heart and throughout the body over time due to a build-up of fatty deposits that form plaques (atherosclerosis). This narrowing can significantly limit the amount of blood carried by the arteries and decrease the amount of oxygen supplied to the tissues and organs, including the heart. Narrowed or blocked arteries can lead to angina, heart attack or stroke.

    Angina is intermittent chest pain frequently caused by inadequate supply of blood and oxygen to the heart (ischemia). Angina symptoms usually do not appear until most of the blood flow is lost to an area of the heart, when it can cause chest pain upon exercise that worsens in frequency and severity over time. Chest pain that develops at rest or with minimum exertion is called unstable angina.

    Heart attack (myocardial infarction, MI) is death of heart muscle cells due to blockage of blood flow in the coronary arteries that provide cardiac cells with oxygenated blood. This can cause an acute onset of chest pain. The forms of acute onset of chest pain that include heart attacks and unstable angina are called acute coronary syndrome (ACS).

    Sudden cardiac arrest (SCA) is when the heart suddenly and unexpectedly stops beating. When this happens, blood stops flowing to the brain and other vital organs. If not treated within minutes, SCA usually leads to death.

    Congestive heart failure (CHF) is when the heart is less effective at pumping blood or completely filling or emptying the chambers and less able to deliver oxygen to other parts of the body. Blood may back up into the legs, hands, feet, lungs, and liver, causing swelling, and the affected person may experience shortness of breath and fatigue. If the cause is temporary, heart failure may also be temporary; however, it usually is a chronic condition that worsens over time but may improve with treatment.

    Cardiomyopathy is an abnormality of the heart muscle itself:

    • Dilated cardiomyopathy—one or more chambers of the heart enlarge or dilate
    • Hypertrophic cardiomyopathy—one or more of the walls of the heart thicken
    • Restrictive cardiomyopathy—occasionally, abnormal material accumulates in the wall of the heart, reducing the flexibility of the walls of the ventricles
    • Ischemic cardiomyopathy--decreased blood flow to the heart
    • Idiopathic cardiomyopathy—no obvious cause

    Myocarditis refers to inflammation of the muscle of the heart. It often presents with a rapid onset of shortness of breath or an irregular heart beat and can cause heart failure to develop quickly.

    Pericardial disease is a disease of the sac surrounding the heart. Pericarditis, an inflammation of the pericardium, may cause increased friction "rub" and pain in the chest cavity.

    Endocarditis is an inflammation of the membrane lining the heart and heart valves.

    Atrial fibrillation is a quivering or irregular heartbeat (arrhythmia) that can lead to blood clots, stroke, heart failure, and other heart-related complications.

    Heart valve conditions may include:

    • Prolapse—part of the heart valve protrudes into the atrium, preventing a tight seal, which may lead to regurgitation (backflow of blood) and an increased risk of endocarditis
    • Stenosis—narrowing of the heart valve opening, which can affect blood flow rate; depending on the valve(s) affected, it is called pulmonary valve stenosis, aortic valve stenosis, or mitral valve stenosis.

    A variety of conditions or factors can cause or contribute to the development of heart disease. Examples include:

    • Alcohol abuse
    • Amyloidosis—a rare, progressive disorder that occurs when abnormal proteins, called amyloids, are produced and deposited in various organs in the body such as the heart, causing tissue and organ damage
    • Anabolic steroid use
    • Atherosclerosis—deposits made up mostly of lipids (fats) form on artery walls, narrowing and hardening the arteries and causing decreased blood flow
    • Autoimmune conditions such as lupus
    • Congenital defects—those present at birth
    • Diabetes
    • Diet, especially when high in saturated fat and cholesterol
    • Drug use, such as cocaine
    • Drugs used to treat cancer or HIV/AIDS
    • Exposure to chemicals or toxins, such as mercury
    • High blood pressure (hypertension)
    • Infection caused by bacteria, viruses or fungi
    • Injury or trauma
    • Rheumatic fever—this rarely occurs in the U.S. now
    • Sedentary lifestyle
    • Smoking cigarettes
    • Thyroid dysfunction (underactive or overactive thyroid)
  • Signs and Symptoms

    Heart diseases may have a rapid onset (acute) or develop over time (chronic). They may be transient (come and go), relatively stable, or progressive. They may cause a variety of signs and symptoms that frequently change and/or worsen over time.

    Chronic heart diseases can have episodes with acutely worse symptoms. These may resolve on their own or with treatment, persist, or become life-threatening.

    People with early heart disease may experience few or vague symptoms, such as:

    • Fatigue
    • Shortness of breath
    • Dizziness
    • Nausea

    However, these symptoms do not indicate the particular type of heart disease present. These symptoms may also be seen with a variety of other conditions.

    As the disease progresses, signs and symptoms may worsen and include additional ones, such as:

    • Swelling of feet, legs, and/or abdomen
    • Irregular heart beat or changes in the strength of heart contractions (arrhythmia)
    • Chest pain, discomfort or pressure
    • Pain in the left shoulder, arm, back, or jaw
    • Dilation—stretching of one or more of the heart chambers, causing their interiors to become larger because of increased pressure
    • Inability to keep up with increased demands for oxygen and clearance of waste products, such as during physical activity
    • Insufficient contraction—chambers of the heart do not empty or fill completely as the heart pumps blood
    • Ventricular hypertrophy—increased thickness of the walls of the heart, causing a decrease in the size of the chambers and also a decrease in the flexibility of the heart
  • Testing

    Laboratory blood tests

    Screening for risk of cardiovascular disease
    Cardiac risk testing is performed to screen asymptomatic people to help determine their risk of developing coronary heart disease. A cardiac risk assessment is a group of tests and health factors that have been proven to indicate the chance of having a cardiovascular event such as heart attack or stroke. The factors considered include age, family history of heart disease, diet, physical activity, and blood pressure. Laboratory tests may include:

    • Lipid panel (LDL-C,HDL-C, cholesterol, triglycerides)—a group of tests that measure the amount and type of lipids (fats) in the blood
    • hs-CRP—detects low levels of C-reactive protein, a marker of inflammation that is associated with atherosclerosis, among other conditions
    • Lp(a)—may be used to identify an elevated level of lipoprotein (a), a modification to LDL-C that increases risk of atherosclerosis; the test may be used in conjunction with a routine lipid panel to provide additional information.

    Several other tests are being studied as potential markers for heart disease. See the article on Cardiac Risk Assessment for more on these.

    Diagnosing heart damage and heart attacks
    When someone presents to the emergency room with a possible heart attack (myocardial infarction, MI), the person is evaluated with a variety of laboratory blood tests and other tests, such as imaging procedures (see below). These are used to determine the whether the person is actually having a heart attack and what part of the heart is affected. Since some treatments for a heart attack must be given within a short period of time to minimize heart damage, an accurate diagnosis must be quickly confirmed.

    Tests for proteins that are released when muscle cells are damaged, often called cardiac biomarkers, are frequently ordered when someone has symptoms of acute coronary syndrome (ACS), such as chest pain, pain in the jaw, neck, abdomen, back, or that radiates to the shoulder or arms, nausea, shortness of breath, and lightheadedness.

    Tests include:

    • Troponin (high-sensitivity troponin)—high-sensitivity troponin tests are primarily ordered to help diagnose a heart attack and rule out other conditions with similar signs and symptoms. An elevated troponin and even slight elevations may indicate some degree of damage to the heart. If you have significantly elevated troponin levels and, in particular, a rise and/or fall in the results from a series of tests done over several hours, then it is likely that you have had a heart attack or some other form of damage to the heart. Levels of troponin can become elevated in the blood within 3 to 6 hours after heart injury and may remain elevated for 10 to 14 days.
    • CK-MBCK and CK-MB were once the primary tests ordered to detect and monitor heart attacks, but they have now largely been replaced with the troponin test. Sometimes, the CK test may be used if a heart attack is suspected and a troponin test is not available. In this case, when CK is elevated, a CK-MB test may be used as a follow-up test to determine whether the increase is due to heart damage or skeletal muscle damage.
    • BNP or NT-proBNP—released by the body as a natural response to heart failure; increased levels of BNP, while not diagnostic for a heart attack, indicate an increased risk of cardiac complications in persons with ACS.

    Tests for other heart diseases

    • BNP—because BNP is also released by the heart when it is stretched, BNP is also measured in those who have swelling of the legs or abdomen or shortness of breath to assist in diagnosis of heart failure.
    • Pericardial fluid analysis—by analyzing the fluid in the sac that surrounds the heart, healthcare practitioners may be able to tell if the heart tissues are inflamed or have been damaged by trauma or infection or whether congestive heart failure has caused fluid to accumulate around the heart.
    • Blood culture—may be done to identify infection of the heart (endocarditis)

    More general blood tests that may be ordered include:

    Other evaluations
    A range of other evaluations and tests are used to assess chest pain and other symptoms. These include:

    • A medical history, including an evaluation of heart disease risk factors such as age, weight, diabetes, and smoking
    • A physical examination
    • An electrocardiogram (ECG or EKG)—a test that looks at the heart's electrical activity and rhythm
    • Echocardiography—ultrasound imaging of the heart

    Based on the findings of these tests, other procedures may be necessary, including:

    • Stress testing (see a description on the Mayo Clinic website)
    • Chest X-ray
    • CT (computerized tomography) scan
    • Continuous ECG monitoring (sometimes also called Holter monitoring)—the person being tested wears a monitor that evaluates heart rhythm over a period of time.
    • MRI (magnetic resonance imaging)
    • PET (positron emission tomography)
    • Radionuclide imaging
    • Cardiac catheterization—in this procedure, a thin flexible tube is inserted into an artery in the leg or arm and threaded up to the coronary arteries to evaluate blood flow and pressure in the heart and the status of the arteries in the heart. A blocked artery can be stretched and a device called a stent placed inside to keep it open during this procedure.
    • Coronary angiography—X-rays of arteries using a special dye to help diagnose CAD; this procedure is performed during coronary catheterization.
    • Tilt table test—ordered to evaluate syncope

    For more information on imaging tests, visit

  • Treatment

    Treatment of heart disease depends on the specific condition and its severity. Acute conditions, such as a heart attack, require prompt medical intervention to minimize heart damage. For chronic conditions, your healthcare practitioner may recommend that you modify your diet, lose excess weight, exercise (under supervision), manage stress, and quit smoking. Conditions such as hypertension and diabetes should be controlled to minimize their effect on the heart. Heart failure often requires treatment with a low salt diet and diuretics to try to reduce the amount of fluid accumulating, as well as drugs such as digoxin to improve the function of the heart muscle.

    Medications may be necessary to help manage symptoms and control heart diseases. Surgical procedures may be required to bypass blocked arteries, replace defective heart valves, or fix congenital abnormalities. Infections are treated with antibiotics.

    New medications, procedures, and guidelines for addressing heart disease continue to be developed. If you are living with heart disease, you should talk to your healthcare provider about the best treatment options for your condition. For more about treatments, see the links in Related Content below.

View Sources

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