Alternative Names myocardial infarction, MI, cardiopulmonary arrest
Definition A heart attack happens when part of the heart muscle does not receive the supply of oxygen-rich blood that it needs to function. When the blood supply stops flowing to that part of the heart muscle, that muscle area dies. This can cause an abnormality in the rhythm or rate of the heartbeat, a condition called arrhythmias (a-rith-me-ahs). These arrhythmias can lead to cardiac arrest, in which breathing and heart function stop.
What are the signs and symptoms of the injury? The signs and symptoms of a heart attack vary. Chest pain or pressure usually occurs beneath the sternum, which is the bone in the centre of the chest. The pain may spread to other parts of the chest, arms, usually the left arm, and left shoulder. There can also be pain in the neck, teeth and jaws. The pain tends to occur on the left side, but pain can occur in the right arm, right shoulder and right side of the neck. The pain can also spread to the back. On rare occasions, pain has also occurred in the legs.
In addition, a person having a heart attack may have one or more of the following symptoms:
abdominal pain.
a "pressing" pain that lasts for some time.
pain not relieved by rest.
indigestion-like pain with squeezing, or heavy pressure on the chest. Many people describe the pressure as "someone sitting on my chest" or a "tight band squeezing my chest."
shortness of breath.
light-headedness.
dizziness.
nausea.
sweating.
feeling of "impending doom."
anxiety.
What are the causes and risks of the injury? The causes of a heart attack usually involve blood-clot formation or a spasm of one of the arteries that supplies blood directly to the heart muscle. These arteries are called coronary arteries. When the blood is blocked to a part of the heart muscle, the oxygen-rich blood that is needed by that part of the heart cannot reach it. As a result, the cells in that area are damaged or die. This usually occurs when the coronary artery has been narrowed due to a build-up of fatty deposits in the arteries, a condition known as arteriosclerosis (art-eer-ee-oh-skler-oh-sus).
What can be done to prevent the injury? Controlling risk factors is the most important way to prevent a heart attack.
Blood pressure and cholesterol levels should be controlled. For people with high blood pressure or cholesterol, there are medications that are now used to help control these problems if lifestyle changes are not effective.
Other important ways to prevent heart attacks include dietary changes, weight loss for people who are overweight, and management of diabetes. A daily exercise program is beneficial to help lose pounds or maintain weight and keep the heart healthy.
Smoking and excessive alcohol use must be avoided. Smoking more than doubles the chance of developing heart disease. It is also important to limit alcohol intake, although small amounts of alcohol each day have been shown to reduce the rate of heart attacks in some people.
How is the injury diagnosed? Diagnosis is most often made in the emergency room. The doctor will usually do a test called an ECG to study heart waves. Blood tests may also be done to help determine if the person is having or has had a heart attack.
It is important for anyone suffering from chest pain to seek immediate medical help. The median prehospital delay in Australia was 6.4 hours with 41% of patients delaying presentation by 4 hours, while 28% delayed less than 2 hours. Women usually wait much longer than men. There are many ways to treat heart attacks, but many of these treatments must be administered within the first 6 hours after the chest pain has begun. The sooner a person gets to the emergency room, the better the chances are of surviving and reducing damage to the heart.
It is also important to note that many people do not want to believe that they are having a heart attack. They often deny that the pain they are suffering is a symptom of a heart attack. There is a need to recognise that many men describe their pain as more intense and seek medical care much sooner than women. This means that many women will put off seeking medical care when they are suffering chest pain. They often believe that the heart attack symptoms are something mild or minimal, when in fact they are having a heart attack.
What are the treatments for the injury? Treatments for a heart attack involve some first aid measures.
Have the person keep calm, sit down, and rest.
Do not move the person or get them to exert themselves in any way. Exertion will only increase the heart rate, which will increase the amount of oxygen that the heart needs to work.
Determine if the person is taking any heart medications. If the person has medication, such as nitroglycerin tablets, assist them in taking the medication. If the chest pain does not lessen within 3 minutes of taking the nitroglycerin, someone should call for emergency medical assistance.
Call for emergency medical help and then begin cardiopulmonary resuscitation (CPR) if the person is unconscious or unresponsive.
What are the side effects of the treatments? The medications can sometimes cause headaches and a lowering of blood pressure. If CPR is performed, there can be multiple injuries to the lungs, chest wall, and the structures of the chest cavity during chest compressions. However, the chest compressions may be the only way to save the person's life. For this reason, the lifesaving benefits from CPR outweigh the risk of injury.
What happens after treatment for the injury? After first aid has been given and medical help has arrived, the medical team will take over. The person suffering a heart attack will be transferred to the nearest medical facility for further treatment. The person may undergo a procedure called angioplasty (an-gee-oh-plah-stee), in which a catheter is placed into a large artery and then inserted into the heart to open up the artery. Surgery and grafts designed to bypass the clogged artery area may also be required.
Author: James Broomfield, MD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 24/11/2004 Contributors Potential conflict of interest information for reviewers available on request
