Introduction:

According to the American Heart Association, approximately 1,200,000 individuals in the United States will suffer from a myocardial infarction per year along with nearly 500,000 deaths due to a myocardial infarction per year. A myocardial infarction, or a heart attack, occurs when an area of the cardiac muscle dies or is permanently damaged due to an inadequate supply of oxygenated blood to that area. The damaged or dead cardiac muscle will be replaced by scar tissue, which will not function as muscle and thus, how impaired the heart becomes dependent on the amount of damage. This inadequate supply of oxygenated blood occurs from a sudden blockage of one or more of the coronary arteries. The coronary arteries are blood vessels that supply the cardiac muscle with oxygenated and nutrient-rich blood. Thus, blockage of the coronary arteries will deplete the cardiac muscle of the nutrients and oxygen that they need to survive.

Causes of Myocardial Infarctions :

A h eart attack is caused by the blockage of a coronary artery by plaque or by a thrombus (blood clot). Atherosclerosis is a gradual buildup of cholesterol, fibrous tissue, and other substances in plaques which deposits on the arterial walls. These plaques cause hardening of the arteries and narrowing of the artery. When coronary arteries narrow due to atherosclerosis, this disease is known as coronary artery disease, which is the most common underlying cause of heart attacks. A coronary artery could become completely blocked by plaque. However, the plaques from atherosclerosis could instead rupture and produce a thrombus (or blood clot) and if the clot is in the coronary artery, the blood flow will be interrupted and causes permanent damage and death of cardiac muscle in that area. An uncommon cause of heart attacks is spasm of a coronary artery that interrupts blood flow to a part of the cardiac muscle.

Signs and Symptoms

A heart attack can occur at anytime. There are many signs and symptoms of heart attacks which vary for each individual. Some individuals can have no signs or symptoms. However, the commons signs and symptoms are:

•  Pain in the center of chest (angina)

•  Pain extending beyond the chest to the shoulders, arms, back, neck, teeth and jaw

•  Prolonged pain in the upper abdomen

•  Shortness of breath (dyspnea)

•  Sweating

•  Dizziness

•  Fainting

•  Nausea and vomiting

•  Fever

•  Fatigue and weakness

•  Arrhythmias

Risk factors

There are contributing factors that can increase the risk of a heart attack and most of these factors can be corrected to reduce the risk of having a heart attack. Coronary risk factors include:

•  Smoking

•  Aging

•  High blood pressure (hypertension)

•  High blood cholesterol

•  Lack of exercise

•  Obesity

•  Diabetes

•  Stress or intense physical exertion

•  Alcohol

•  Unhealthy foods especially high in saturated fats

•  Cocaine

•  Family history of heart attacks or heart diseases

•  Acute severe infection such as pneumonia

•  High blood levels of homocysteine, C-reactive protein and fibrinogen

Diagnosing Myocardial Infarctions

Heart attacks are diagnosed through the individual's medical history, physical examination, and various test results. The common diagnostic tests are:

•  Electrocardiogram (EKG) . This is usually the first test and it will determine through measurement of electrical impulses if the cardiac muscle is functioning properly.

•  Blood tests of certain heart enzymes . If the heart has been damaged from a heart attack, certain heart enzymes decrease in concentration.

Additional tests include:

•  Chest X-ray . This will determine the size and shape of the heart and blood vessels.

•  Echocardiogram . This will help to identify if an area of the heart has been damaged and its pumping efficiency.

•  Coronary catheterization (angiogram) . This will show if the coronary arteries are narrowed or blocked.

•  Stress tests . This shows how the heart and blood vessels respond to physical exertion.

•  Nuclear scan . This identifies blood flow problems in the heart.

Complications after Myocardial Infarctions

The complications from a heart attack can vary for each individual, from no pain to death. A heart attack will leave a n area of the dead or permanently damaged cardiac muscle, which is replaced by scar tissue and will not function as muscle and thus, how impaired the heart becomes dependent on the amount of damage. The usual complications from damage of the cardiac muscle are:

•  Heart Failure

•  Abnormal heart rhythms (arrhythmias)

•  Myocardial Rupture

•  Valve problems

Treatment

During a heart attack, call for emergency medical help immediately. If the individual loses consciousness, pulse and respiration, perform cardiopulmonary resuscitation (CPR). Otherwise, keep the individual in a position that minimizes breathing problems and give the person aspirin (antiplatelet effect to inhibit further blood clots) or glyceryl trinitrate (or nitroglycerin) if the individual has it prescribed. If the heart attack has triggered ventricular fibrillation, an automatic external defibrillator should be used to shock the heart back to normal rhythm. After reaching the hospital, the individual will be treated with medications, a surgical procedure or both depending on the condition of the heart. The primary goal is to quickly restore blood flow to the heart muscle by unblocking the artery.

Medications
There are many different types of medications depending on the purpose of the medication and the type of heart attack the individual has. The medications should improve survival and ease the recovery of the heart. The drugs used include: anti-platelet medications to prevent further formation of blood clots, anti-coagulant medications to prevent further growth of blood clots, clot-dissolving medications to open blocked arteries, medications to decrease the work on the heart muscle and the need for oxygen, and medications to prevent abnormal heart rhythms.

Surgical procedures

It is possible that medications are not enough to improve the condition of the heart. One of the following procedures may be needed to treat a heart attack.

• Coronary angioplasty . This will open blocked coronary arteries, increasing blood flow to the cardiac muscle. A catheter with a balloon tip is inserted into the artery and is inflated to open up the artery. A stent may be inserted to keep the artery open.
• Coronary artery bypass surgery . If blood flow is unable to be restored, this surgery may be performed to reroute blood flow to the ischemic cardiac muscle.

If the heart is damaged to an extensive degree that the coronary angioplasty and the coronary artery bypass surgery cannot repair, then heart-assisted devices and heart transplant would be the last options.

Lifestyle changes