Heart attack

 

Alternative Names

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

Definition

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.

The medical term for this is myocardial infarction.

Causes

A 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 may occur when:

  • A tear in the plaque occurs. This triggers blood platelets and other substances to form a blood a clot at the site that blocks blood from flowing to the heart. This is the most common cause of heart attack.
  • A slow buildup of plaque may narrow one of the coronary arteries so that it is almost blocked.

The cause of heart attack is not always known.

Heart attack 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

Many risk factors may lead to the development of plaque buildup and a heart attack.

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 WAIT. 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
  • Pain 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 most often lasts longer than 20 minutes. Rest and a medicine to relax the blood vessels (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 can include:

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

Exams and Tests

A doctor, nurse or other health care provider will perform a physical exam and listen to your chest using a stethoscope.

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

You will have an electrocardiogram (ECG) to look for heart damage. A blood test can show if you have heart tissue damage. This test can confirm that you are having a heart attack.

Coronary angiography may be done right away or when you are more stable.

  • 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:

Treatment

IMMEDIATE TREATMENT

  • You will be hooked up to a heart monitor, so the health care team can look at how your heart is beating.
  • You will receive 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.
  • You may receive aspirin, unless it would not be safe for you. In that case, you will be given another medicine that prevents blood clots.
  • Dangerous abnormal heartbeats (arrhythmias) may be treated with medicine or electric shocks.

EMERGENCY PROCEDURES

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

  • Angioplasty is often the first choice of treatment. It should be done within 90 minutes after you get to the hospital, and usually 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 or during 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.

TREATMENT AFTER A HEART ATTACK

After several days, you will be discharged from the hospital.

You will likely need to take medicines, some for the rest of your life. Always talk to your health care provider before stopping or changing how you take any medicines. Stopping certain medications can be deadly.

While under the care of your health care team, you will learn:

  • How to take medicines to treat your heart problem and prevent more heart attacks
  • How to eat a heart-healthy diet
  • How to be active and exercise safely
  • What to do when you have chest pain
  • How to stop smoking

Strong emotions are common after a heart attack.

  • You may feel sad
  • You may feel anxious and worry about being careful about 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 rehabilitation program.

Support Groups

Many people benefit from taking part in support groups for people with heart disease.

Outlook (Prognosis)

After a heart attack, you have a higher chance of having another heart attack.

How well you do after a heart attack depends on several factors such as:

  • The damage to your heart muscle and heart valves
  • Where that damage is located
  • Your medical care after the heart attack

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

Most people can slowly go back to normal activities after a heart attack. This includes sexual activity. Talk to your health care provider about how much activity is good for you.

References

Anderson JL. ST segment elevation acute myocardial infarction and complications of myocardial infarction. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. Philadelphia, PA: Saunders Elsevier; 2011:chap 73.

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.

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.

Wright RS, Anderson JL, Adams CD, et al. 2011 ACCF/AHA Focused Update of the Guidelines for the Management of Patients with Unstable Angina/Non-ST-Elevation Myocardial Infarction (Updating the 2007 Guideline). A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines Developed in Collaboration With the American College of Emergency Physicians, Society for Cardiovascular Angiograpy and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2011;57:1920-1959.

Review Date: 5/1/2013
Reviewed By: Michael A. Chen, MD, PhD, Assistant Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.