Irreversible damage to the heart muscle due to lack of blood supply is called myocardial infarction, commonly known as a heart attack. In most cases, blood supply to the heart through the coronary arteries, gets blocked by formation of clots (thrombosis) around a ruptured atherosclerotic plaque in the arterial wall. A heart attack is the leading cause of deaths in the United States, with an estimated 460,000 people dying, out of the total 1.1 million cases of heart attack. Although a heart attack can happen anytime, it more frequently occurs with 4 AM to 10 AM.
The major symptoms of a heart attack are :
- Excruciating pain in the chest (angina pectoris) radiating to the left arm, neck, jaws and teeth.
- Feeling of heaviness or pressure on the chest
- Dyspnea – shortness of breath
- Arrhythmia (irregular heartbeat) and palpitations
- Heavy sweating
- Malaise (weakness)
These symptoms last for 20 to 30 minutes and may be accompanied by anxiety, nausea, vomiting and dizziness. Diabetic patients may experience a silent attack which does not present any of these symptoms.
If blood supply is not restored within 6 to 8hours, the infarction complicates into ventricular fibrillosis, permanent brain damage, heart failure and death.
The primary cause of heart attacks is atherosclerosis, a chronic hardening of the artery which causes a variety of ailments (syndrome).
Excessive cholesterol in blood gets deposited along the arterial walls which attracts blood macrophages resulting in the plaques formation. Increase in plaque-size causes a progressive narrowing of the blood vessel, restricting blood flow. When the outermost layer of plaque ruptures, it causes blood clotting which completely obstructs the blood supply.
Therefore, factors which promote atherosclerosis and plaque-rupture increase the risk of heart attacks and include :
- Elevated cholesterol (LDL) levels
- Smoking and tobacco use
Heart valve diseases, stress, heredity and aging may also predispose individuals towards heart attack. Drug abuse can trigger coronary artery spasms and result in infarctions.
Seeking prompt medical assistance is the key to surviving a heart attack as delays increase the extent of cardiac muscle damage. The subject may take nitroglycerin or aspirin while waiting for help, if recommended by the doctor. Anyone present near the subject may start cardiopulmonary resuscitation or CPR.
In the hospital, an attack would be diagnosed with electrocardiograms and blood tests that estimate the levels of cardiac enzymes. The following medications may be administered to restore blood flow in the arteries :
- Thrombolytic therapy (clot busters) to dissolve the clot.
- Anticoagulants (heparin, aspirin) to prevent further clotting.
- Vasodilators to widen the arteries.
Additionally, antihypertensive drugs (angiotensin converting enzyme inhibitors, beta blockers and calcium channel blockers) and anti-arrhythmic drugs may be given.
Surgery is often essential in preventing further complications. Coronary angioplasty may be performed to open up the artery and a stent placed to prevent its re-closure. A coronary artery bypass grafting would be necessary if the arteries are damaged.
One heart attack can increase the chances of future attacks and care during convalescence (recovery) is very important to prevent these attacks. It involves :
- Eating a cardio-friendly diet (low LDL cholesterol but is high on HDL cholesterol and omega-3-fatty acids, supplemented with multivitamins and folic acid).
- Regular exercise.
- Controlling diabetes.
- Discontinuing smoking.