Myocardial Infarction (Heart Attack)

           Myocardial Infarction (MI) is the medical term also known as a heart attack. It is usually caused by a blood clot, which stops the blood flowing to a part of your heart muscle. You should call for an ambulance immediately if you develop severe chest pain. Treatment with a clot-busting medicine or an emergency procedure to restore the blood flow through the blocked blood vessel are usually done as soon as possible. This is to prevent or minimise any damage to your heart muscle. Other treatments help to ease the pain and to prevent complications. Reducing various risk factors can help to prevent a myocardial infarction.

Causes
1. Atherosclerotic plaques
2. Coronary artery vasospasm
3. Left ventricular hypertrophy [LVH]
4. Idiopathic hypertrophic subaortic stenosis [IHSS]
5. Hypoxia due to carbon monoxide poisoning
6. Acute pulmonary disorders
7. Coronary artery embol
8. Aneurysms of the coronary arteries
9. Increased afterload or inotropic effects
10. Pediatric coronary artery disease

Sign & Symptoms
One-third of all heart attacks occur with no prior warning signs. In the remainder, attacks of chest pain (angina) brought about by stress or exertion occur periodically for months or years prior to a heart attack. In some cases, a mild heart attack produces no symptoms and is often referred to as a “silent heart attack.”
Here are a few of the warning signs you should know :
1. Chest pain or pressure, tightness, squeezing, burning, aching, or heaviness in the chest lasting longer than 10 minutes. The pain or discomfort is usually located in the center of the chest just under the breastbone and may radiate down the arm (especially the left), up into the neck, or along the jaw line.
2. Shortness of breath.
3. Profuse sweating.
4. Dizziness.
5. Muscle weakness.
6. Nausea and vomiting.
7. A choking sensation.
8. Anxiety or a feeling of impending doom.
9. No symptoms occur with a silent heart attack.

Diagnostic Tests
1. Coronary angiography
2. Electrocardiogram (ECG)
3. Blood tests
4. Cardiac enzymes
5. Nuclear scan
6. Chest radiographs
7.

Treatment
Time is critical during treatment of heart attack. Most heart attack deaths result from an abnormal heart rhythm during delays in reaching the hospital. A stopped heartbeat must be restarted immediately by cardiopulmonary resuscitation (CPR) or by a device known as an electrical defibrillator. The longer the time from the onset of a heart attack to re-establishing blood flow to the heart, the more permanent heart damage can occur.
1. Chew on an aspirin at the onset of the symptoms of a heart attack as it may help break up a blood clot.
2. Thrombolytic or clot-dissolving drugs such as tissue plasminogen activator (tPA), streptokinase or urokinase may be injected immediately to dissolve arterial blockage. This technique is most effective within three hours of the onset of a heart attack.
3. Painkillers such as morphine or meperidine may be administered to relieve pain.
4. Nitroglycerin may be given to reduce the heart’s oxygen demands and to lower blood pressure.
5. Antihypertensive drugs such as beta-blockers, ACE inhibitors or calcium channel blockers may also be administered to lower blood pressure and to reduce the heart’s oxygen demand. Diuretics may enhance the effect of these drugs.
6. Oxygen may be administered through nasal tubes.
7. Anticoagulants such as heparin, aspirin or warfarin may be administered to reduce the risk of blood clots.
8. Digitalis glycosides, such as digoxin, may be prescribed in some cases to strengthen heart muscle contraction.
9. Dopamine or dobutamine may be administered to increase blood flow to the heart and strengthen the heartbeat.
10. Angioplasty, a procedure to open up narrowed arteries, may be performed. Using local anesthesia, the doctor will insert a catheter -- a long, narrow tube with a deflated balloon at its tip -- into the narrowed part of the artery. Then the balloon is inflated, compressing the plaque and enlarging the inner diameter of the blood vessel so blood can flow more easily.
11. Coronary bypass surgery may be performed to go around blocked blood vessels and restore adequate blood flow to the heart.
12. Electronic implants such as a pacemaker or a defibrillator may be attached to the heart to maintain strong, regular contractions of the heart muscle.
13. Severe cases that badly damage heart tissue may require a heart transplant.

Prevention
1. Don’t smoke. Your doctor may recommend methods for quitting, including nicotine replacement.
2. Eat a diet low in fat, cholesterol and salt.
3. See your doctor regularly for blood pressure and cholesterol monitoring.
4. Pursue a program of moderate, regular aerobic exercise. People over age 50 who have led a sedentary lifestyle should check with a doctor before beginning an exercise program.
5. Lose weight if you are overweight.
6. Your doctor may advise you to take a low dose of aspirin regularly. Aspirin reduces the tendency for the blood to clot, thereby decreasing the risk of heart attack. However, such a regimen should only be initiated under a doctor’s expressed recommendation.