Heart attack

Answer 1

Definition

A heart attack is when blood vessels that supply blood to the heart are blocked, preventing enough oxygen from getting to the heart. The heart muscle dies or becomes permanently damaged. Your doctor calls this a myocardial infarction.

Alternative Names

Myocardial infarction; MI; Acute MI; ST-elevation myocardial infarction; non-ST-elevation myocardial infarction

Causes, incidence, and risk factors

Most heart attacks are caused by a blood clot that blocks one of the coronary arteries. The coronary arteries bring blood and oxygen to the heart. If the blood flow is blocked, the heart starves for oxygen and heart cells die.

In atherosclerosis, plaque builds up in the walls of your coronary arteries. This plaque is made up of cholesterol and other cells. A heart attack can occur as a result of the following:

• The slow buildup of plaque may almost block one of your coronary arteries. A heart attack may occur if not enough oxygen-containing blood can flow through this blockage. This is more likely to happen when you are exercising.
• The plaque itself develops cracks (fissures) or tears. Blood platelets stick to these tears and form a blood clot (thrombus). A heart attack can occur if this blood clot completely blocks the passage of oxygen-rich blood to the heart. This is the most common cause.

Occasionally, sudden, significant emotional or physical stress, including an illness, can trigger a heart attack.

Risk factors for heart attack and coronary artery disease include:

• Increasing age (over age 65)
• Male gender
• Diabetes
• Family history of coronary artery disease (genetic or hereditary factors)
• High blood pressure
• Smoking
• Too much fat in your diet
• Unhealthy cholesterol levels, especially high LDL ("bad") cholesterol and low HDL ("good") cholesterol
• Chronic kidney disease

Symptoms

Chest pain is a major symptom of heart attack. You may feel the pain in only one part of your body, or it may move from your chest to your arms, shoulder, neck, teeth, jaw, belly area, or back.

The pain can be severe or mild. It can feel like:

• A tight band around the chest
• Bad indigestion
• Something heavy sitting on your chest
• Squeezing or heavy pressure

The pain usually lasts longer than 20 minutes. Rest and a medicine called nitroglycerin may not completely relieve the pain of a heart attack. Symptoms may also go away and come back.

Other symptoms of a heart attack include:

• Anxiety
• Cough
• Fainting
• Light-headedness, dizziness
• Nausea or vomiting
• Palpitations (feeling like your heart is beating too fast or irregularly)
• Shortness of breath
• Sweating, which may be extreme

Some people (the elderly, people with Diabetes, and women) may have little or no chest pain. Or, they may experience unusual symptoms (shortness of breath, fatigue, weakness). A "silent heart attack" is a heart attack with no symptoms.

Signs and tests

A heart attack is a medical emergency. If you have symptoms of a heart attack, seek immediate medical help. Call 911 or your local emergency number immediately. DO NOT try to drive yourself to the hospital. DO NOT DELAY, because you are at greatest risk of sudden cardiac death in the early hours of a heart attack.

The health care provider will perform a physical exam and listen to your chest using a stethoscope. The doctor may hear abnormal sounds in your lungs (called crackles), a heart murmur, or other abnormal sounds.

You may have a rapid pulse. Your blood pressure may be normal, high, or low.

Tests to look at your heart include:

• Coronary angiography
• CT scan
• Echocardiography
• Electrocardiogram (ECG) -- once or repeated over several hours
• MRI
• Nuclear ventriculography

Blood tests can help show if you have heart tissue damage or a high risk for heart attack. These tests include:

• Troponin I and troponin T
• CPK and CPK-MB
• Serum myoglobin

Treatment

If you had a heart attack, you will need to stay in the hospital, possibly in the intensive care unit (ICU). You will be hooked up to an ECG machine, so the health care team can look at how your heart is beating.

Life-threatening irregular heartbeats (arrhythmias) are the leading cause of death in the first few hours of a heart attack. These arrythmias may be treated with medications or electrical cardioverson/defibrillation.

The health care team will give you oxygen, even if your blood oxygen levels are normal. This is done so that your body tissues have easy access to oxygen and your heart doesn't have to work as hard.

An intravenous line (IV) will be placed into one of your veins. Medicines and fluids pass through this IV. You may need a tube inserted into your bladder (urinary catheter) so that doctors can see how much fluid your body removes.

ANGIOPLASTY AND STENT PLACEMENT

Angioplasty, also called percutaneous coronary intervention (PCI), is the preferred emergency procedure for opening the arteries for some types of heart attacks. It should preferably be performed within 90 minutes of arriving at the hospital and no later than 12 hours after a heart attack.

Angioplasty is a procedure to open narrowed or blocked blood vessels that supply blood to the heart.

A coronary artery stent is a small, metal mesh tube that opens up (expands) inside a coronary artery. A stent is often placed after angioplasty. It helps prevent the artery from closing up again. A drug eluting stent has medicine in it that helps prevent the artery from closing.

THROMBOLYTIC THERAPY (CLOT-BUSTING DRUGS)

Depending on the results of the ECG, certain patients may be given drugs to break up the clot. It is best if these drugs are given within 3 hours of when the patient first felt the chest pain. This is called thrombolytic therapy. The medicine is first given through an IV. Blood thinners taken by mouth may be prescribed later to prevent clots from forming.

Thrombolytic therapy is not appropriate for people who have:

• Bleeding inside their head (intracranial hemorrhage)
• Brain abnormalities such as tumors or blood vessel malformations
• Stroke within the past 3 months (or possibly longer)
• Head injurywithin the past 3 months

Thrombolytic therapy is extremely dangerous in women who are pregnant or in people who have:

• A history of using blood thinners such as coumadin
• Had major surgery or a major injury within the past 3 weeks
• Had internal bleeding within the past 2-4 weeks
• Peptic ulcer disease
• Severe high blood pressure

OTHER MEDICINES FOR HEART ATTACKS

Many different medicines are used to treat and prevent heart attacks. Nitroglycerin helps reduce chest pain. You may also receive strong medicines to relieve pain.

Antiplatelet medicines help prevent clots from forming. Aspirin is an antiplatelet drug. Another one is clopidogrel (Plavix). Ask your doctor which of these drugs you should be taking. Always talk to your health care provider before stopping either of these drugs.

• For the first year after a heart attack, you will likely take both aspirin and clopidogrel every day. After that, your health care provider may only prescribe aspirin.
• If you had angioplasty and a coronary stent placed after your heart attack, you may need to take clopidogrel with your aspirin for longer than one year.

Other medications you may receive during or after a heart attack include:

• Beta-blockers (such as metoprolol, atenolol, and propranolol) help reduce the strain on the heart and lower blood pressure.
• ACE inhibitors (such as ramipril, lisinopril, enalapril, or captopril) are used to prevent heart failure and lower blood pressure.
• Lipid-lowering medications, especially statins (such as lovastatin, pravastatin, simvastatin, atorvastatin, and rosuvastatin) reduce blood cholesterol levels to prevent plaque from increasing. They may reduce the risk of another heart attack or death.

Always talk to your health care provider before stopping any medications, especially these drugs. Stopping or changing the amount of these medicines can be life threatening.

CORONARY ARTERY BYPASS SURGERY

Coronary angiography may reveal severe coronary artery disease in many vessels, or a narrowing of the left main coronary artery (the vessel supplying most of the blood to the heart). In these circumstances, the cardiologist may recommend emergency coronary artery bypass surgery (CABG). This procedure is also called "open heart surgery." The surgeon takes either a vein or artery from another location in your body and uses it to bypass the blocked coronary artery.

Support Groups

See:Heart disease -- resources

Expectations (prognosis)

How well you do after a heart attack depends on the amount and location of damaged tissue. Your outcome is worse if the heart attack caused damage to the signaling system that tells the heart to contract.

About a third of heart attacks are deadly. If you live 2 hours after an attack, you are likely to survive, but you may have complications. Those who do not have complications may fully recover.

Usually a person who has had a heart attack can slowly go back to normal activities, including sexual activity.

Complications

• Cardiogenic shock
• Congestive heart failure
• Damage extending past heart tissue (infarct extension), possibly leading to rupture of the heart
• Damage to heart valves or the wall between the two sides of the heart
• Inflammation around the lining of the heart (pericarditis)
• Irregular heartbeats, including ventricular tachycardia and ventricular fibrillation
• Blood clot in the lungs (pulmonary embolism)
• Blood clot to the brain (stroke)
• Side effects of drug treatment

Calling your health care provider

Immediately call your local emergency number (such as 911) if you have symptoms of a heart attack.

Prevention

To prevent a heart attack:

• Keep your blood pressure, blood sugar, and cholesterol under control.
• Don't smoke.
• Consider drinking 1 to 2 glasses of alcohol or wine each day. Moderate amounts of alcohol may reduce your risk of cardiovascular problems. However, drinking larger amounts does more harm than good.
• Eat a low-fat diet rich in fruits and vegetables and low in animal fat.
• Eat fish twice a week. Baked or grilled fish is better than fried fish. Frying can destroy some of the health benefits.
• Exercise daily or several times a week. Walking is a good form of exercise. Talk to your doctor before starting an exercise routine.
• Lose weight if you are overweight.

If you have one or more risk factors for Heart disease, talk to your doctor about possibly taking aspirin to help prevent a heart attack. Aspirin therapy (75 mg to 325 mg a day) or another drug such as prasugrel or clopidogrel may be prescribed.

New guidelines no longer recommend hormone replacement therapy, vitamins E or C, antioxidants, or folic acid to prevent heart disease.

After a heart attack, you will need regular follow-up care to reduce the risk of having a second heart attack. Often, a cardiac rehabilitation program is recommended to help you gradually return to a normal lifestyle. Always follow the exercise, diet, and medication plan prescribed by your doctor.

References

Anderson JL, Adams CD, Antman EM, Bridges CR, Califf RM, Casey DE Jr., et al. ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine. J Am coll Cardiol. 2007;50:e1-e157.

Kushner FG, Hand M, Smith SC Jr, King SB 3rd, Anderson JL, Antman EM, et al. 2009 Focused Updates: ACC/AHA Guidelines for the Management of Patients WithST-Elevation Myocardial Infarction (updating the 2004 Guideline and 2007 Focused Update) and ACC/AHA/SCAI Guidelines on Percutaneous Coronary Intervention(updating the 2005 Guideline and 2007 Focused Update): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2009 Dec 1;120(22):2271-306. Epub 2009 Nov 18.

Antman Em. ST-Elevation myocardial infarction: management. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsever; 2007:chap 51.

Goodman SG, Menon V, Cannon CP, Steg G, Ohman EM, Harrington RA, et al. Acute ST-segment elevation myocardial infarction: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th edition). Chest. 2008;133:708S-775S.

Answer 2

A heart attack is often life-threatening because the individual suffering this event usually has severe damage to the heart muscle itself. There are several different causes of heart failure, but the most common is a deterioration of the heart tissue brought on over time by a decreased blood flow to this important muscle. Persons with a partially obstructed or blocked coronary artery are at great risk for heart failure.

Damaged Coronary Artery

The heart is made of living tissue and therefore needs proper nutrition delivered to its cells just like the rest of the body. The coronary artery is the blood vessel that supplies food and oxygen to the heart, but if this vessel is blocked by a buildup of saturated fats and cholesterol deposits the blood flow is severely restricted. Over a period of months or even years the tissue of the heart muscle begins to weaken, eventually resulting in a failure of nerve impulses to stimulate contraction of the muscle fibers. The result is a coronary heart attack.

In many cases the restricted blood flow can begin to affect the health of the heart valves. If a valve ceases to function properly the pumping action of the heart becomes useless. The heart muscle will begin to fibrillate, the blood flow to the lungs, brain and rest of the body will cease and the individual will need immediate emergency medical attention to prevent death.

Information For a Healthy Heart

Eating a balanced diet in combination with regular exercise is the best defense against heart disease. Foods that are high in saturated fat should be consumed in extreme moderation. Fat deposits in the bloodstream are the major cause of most heart attacks. Eating a healthy amount of foods rich in dietary fiber helps to sweep much of the cholesterol and saturated fat from the body before it has a chance to be absorbed into the bloodstream. Aerobic exercise puts a strain on the heart and makes it pump more rapidly because there is a need for increased oxygen in the muscles being used. This actually strengthens the heart in the same manner as Weightlifting strengthens the muscles of the arms and legs.

Many individuals over the age of 40 will become more sedentary, exercise less often and pay less attention to their diet. However there is no medical evidence to support the idea that working out less rigorously at an advanced age is detrimental to the body's systems. On the other hand there is a mass of evidence supporting the idea that a healthy lifestyle reduces or eliminates the chances of a heart attack.

Answer 3

Definition

A heart attack occurs when blood flow to a part of your heart is blocked for a long enough time that part of the heart muscle is damaged or dies. Your doctor calls this a myocardial infarction.

Alternative Names

Myocardial infarction; MI; Acute MI; ST-elevation myocardial infarction; non-ST-elevation myocardial infarction

Causes, incidence, and risk factors

Most heart attacks are caused by a blood clot that blocks one of the coronary arteries. The coronary arteries bring blood and oxygen to the heart. If the blood flow is blocked, the heart is starved of oxygen and heart cells die.

A hard substance called plaque can build up in the walls of your coronary arteries. This plaque is made up of cholesterol and other cells. A heart attack can occur as a result of plaque buildup.

• The plaque can develop cracks or tears. Blood platelets stick to these tears and form a blood clot. A heart attack can occur if this blood clot completely blocks oxygen-rich blood from flowing to the heart. This is the most common cause of heart attacks.
• The slow buildup of plaque may almost block one of your coronary arteries. A heart attack may occur if not enough oxygen-rich blood can flow through this blockage. This is more likely to happen when your body is stressed (for example, by a serious illness).

The cause of heart attacks is not always known. Heart attacks may occur:

• When you are resting or asleep
• After a sudden increase in physical activity
• When you are active outside in cold weather
• After sudden, severe emotional or physical stress, including an illness

See: Coronary artery disease to learn about risk factors

Cardiogenic shock is a state in which the heart has been damaged so much that it cannot supply enough blood to the organs of the body. This condition is a medical emergency.

Symptoms

A heart attack is a medical emergency. If you have symptoms of a heart attack, call 911 or your local emergency number right away.

• DO NOT try to drive yourself to the hospital.
• DO NOT DELAY. You are at greatest risk of sudden death in the early hours of a heart attack.

Chest pain is the most common symptom of a heart attack. You may feel the pain in only one part of your body, or it may move from your chest to your arms, shoulder, neck, teeth, jaw, belly area, or back.

The pain can be severe or mild. It can feel like:

• A tight band around the chest
• Bad indigestion
• Something heavy sitting on your chest
• Squeezing or heavy pressure

The pain usually lasts longer than 20 minutes. Rest and a medicine called nitroglycerin may not completely relieve the pain of a heart attack. Symptoms may also go away and come back.

Other symptoms of a heart attack include:

• Anxiety
• Cough
• Fainting
• Light-headedness, dizziness
• Nausea or vomiting
• Palpitations (feeling like your heart is beating too fast or irregularly)
• Shortness of breath
• Sweating, which may be very heavy

Some people (the elderly, people with diabetes, and women) may have little or no chest pain. Or, they may have unusual symptoms (shortness of breath, fatigue, weakness). A "silent heart attack" is a heart attack with no symptoms.

Signs and tests

A doctor or nurse will perform a physical exam and listen to your chest using a stethoscope.

• The doctor may hear abnormal sounds in your lungs (called crackles), a heart murmur, or other abnormal sounds.
• You may have a rapid pulse.
• Your blood pressure may be normal, high, or low.

A troponin blood test can show if you have heart tissue damage. This test can confirm that you are having a heart attack.

Coronary angiographyis often done right away or when you are more stable. You may also have tests such as anelectrocardiogram(ECG).

• This test uses a special dye and x-rays to see how blood flows through your heart.
• It can help your doctor decide which treatments you need next.

Other tests to look at your heart that may be done while you are in the hospital:

• Echocardiography
• Exercise stress test
• Nuclear stress test

Treatment

You will most likely first be treated in the emergency room.

• You will be hooked up to a heart monitor, so the health care team can look at how your heart is beating.
• The health care team will give you oxygen so that your heart doesn't have to work as hard.
• An intravenous line (IV) will be placed into one of your veins. Medicines and fluids pass through this IV.
• You may get nitroglycerin and morphine to help reduce chest pain.

Abnormal heartbeats (arrhythmias) are the leading cause of death in the first few hours of a heart attack. These arrythmias may be treated with medications or cardioversion.

EMERGENCY TREATMENTS

Angioplasty is a procedure to open narrowed or blocked blood vessels that supply blood to the heart. Usually a small, metal mesh tube called a stent is placed at the same time.

• Angioplasty is often the first choice of treatment. It should be done within 90 minutes after you get to the hospital, and no later than 12 hours after a heart attack.
• A stent is a small, metal mesh tube that opens up (expands) inside a coronary artery. A stent is often placed after angioplasty. It helps prevent the artery from closing up again.

You may be given drugs to break up the clot. It is best if these drugs are given within 3 hours of when you first felt the chest pain. This is called thrombolytic therapy.

Some patients may also have heart bypass surgery to open narrowed or blocked blood vessels that supply blood to the heart. This procedure is also called open heart surgery.

AFTER YOUR HEART ATTACK

The following drugs are given to most people after they have a heart attack. These drugs can help prevent another heart attack. Ask your doctor or nurse about these drugs:

• Antiplatelet drugs (blood thinners) such as aspirin, clopidogrel (Plavix), or warfarin (Coumadin), to help keep your blood from clotting
• Beta-blockers and ACE inhibitor medicines to help protect your heart
• Statins or other drugs to improve your cholesterol levels

You may need to take some of these medicines for the rest of your life. Always talk to your health care provider before stopping or changing how you take any medicines. Any changes may be life threatening.

After a heart attack, you may feel sad. You may feel anxious and worry about being careful in everything you do. All of these feelings are normal. They go away for most people after 2 or 3 weeks. You may also feel tired when you leave the hospital to go home.

Most people who have had a heart attack take part in a cardiac rehab program. While under the care of a doctor and nurses, you will:

• Slowly increase your exercise level
• Learn how to follow a healthy lifestyle

LIVING A HEALTHY LIFESTYLE

To prevent another heart attack:

• Keep your blood pressure, blood sugar, and cholesterol under control.
• Don't smoke.
• Eat a heart-healthy diet rich in fruits, vegetables, and whole grains, and low in animal fat.
• Get plenty of exercise, at least 30 minutes a day, at least 5 days a week (talk to your doctor first).
• Get checked and treated for depression.
• Limit yourself to no more than one drink a day for women, and no more than two drinks a day for men.
• Stay at a healthy weight. Aim for a body mass index (BMI) of between 18.5 and 24.9.

Support Groups

See: Heart disease -- resources

Expectations (prognosis)

After a heart attack, your chance of having another one is higher.

How well you do after a heart attack depends on the damage to your heart muscle and heart valves, and where that damage is located.

If your heart can no longer pump blood out to your body as well as it used to, you may have heart failure. Abnormal heart rhythms can occur, and they can be life threatening.

Usually a person who has had a heart attack can slowly go back to normal activities, including sexual activity.

Calling your health care provider

Immediately call your local emergency number (such as 911) if you have symptoms of a heart attack.

References

Anderson JL, Adams CD, Antman EM, Bridges CR, Califf RM, Casey DE Jr., et al. ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine. J Am coll Cardiol. 2007;50:e1-e157.

Kushner FG, Hand M, Smith SC Jr, King SB 3rd, Anderson JL, Antman EM, et al. 2009 Focused Updates: ACC/AHA Guidelines for the Management of Patients WithST-Elevation Myocardial Infarction (updating the 2004 Guideline and 2007 Focused Update) and ACC/AHA/SCAI Guidelines on Percutaneous Coronary Intervention(updating the 2005 Guideline and 2007 Focused Update): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2009 Dec 1;120(22):2271-306. Epub 2009 Nov 18.

Antman EM. ST-segment elevation myocardial infarction: pathology, pathophysiology, and clinical features. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsever; 2011:chap 54.

Cannon CP, Braunwald E. Unstable angina and non-ST elevation myocardial infarction. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsever; 2011:chap 56.

Reviewed By

Review Date: 05/23/2011

Michael A. Chen, MD, PhD, Assistant Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Answer 4

Heart attack refers to the interruption of sufficient blood flow to the heart muscle. This interruption may be partial and temporary, a condition known as angina pectoris or complete and permanent. In the latter situation, a portion of the heart muscle dies and a myocardial infarction is said to have occurred. In either circumstance the underlying pathology is a narrowing in one of the arteries that supply blood to the heart muscle, the coronary arteries.

The three coronary arteries are like any other artery in that they are susceptible to the buildup of deposits of fats and cholesterol on their walls. Although this buildup begins early in life, these deposits generally do not cause problems until decades later.

Symptoms of a Heart Attack

If a coronary artery cannot deliver sufficient blood to the heart muscle during times that the heart is under extra stress from, say, physical work, the heart muscle will respond by producing pain of a specific type that travels through the body in a recognizable pattern. This pain, angina pectoris, begins under the chest bone ("sternum") and has been described as "oppressive," or crushing." The pain of angina pectoris is often accompanied by sweating and nausea.. In many instances, the pain of angina will radiate ("travel") into the neck and down the inside of the left arm. Anginal pain represents a true medical emergency since it can signal the early stages of a heart attack.

Treatment

If the victim of a heart attack is promptly brought to an Emergency Room, treatment to re-establish blood flow to the heart muscle (such as "clot busters" or "TPA") can be given. If successful, the patient is taken to the cardiac lab for further testing. Depending on the the type and location of the arterial disease, a procedure known as angioplasty ("balloon angioplasty") may be offered to the patient. If there is more than one obstruction present, open-chest coronary artery bypass grafting many be suggested. In some cases, the physician may decide that the patient is best treated by medical management rather than by surgery.

To conclude, a heart attack occurs when the blood supply to a portion of the heart muscle is interrupted. This event is a true medical emergency and medical care should be immediately sought. If the appropriate medical treatment is started early, most of the damage occurring during a heart attack can be minimized without resorting to surgery.