Heart Attack (Myocardial Infarction)

What is a heart attack (myocardial infarction or MI)?

A heart attack, or myocardial infarction, occurs when one or more regions of the heart muscle experience a severe or prolonged lack of oxygen caused by blocked blood flow to the heart muscle.

The blockage is often a result of atherosclerosis - a buildup of plaque composed of fat deposits, cholesterol, and other substances. Plaque ruptures and eventually a blood clot forms. The actual cause of a heart attack is a blood clot that forms within the plaque-obstructed area.

If the blood and oxygen supply is cut off severely or for a long period of time, muscle cells of the heart suffer damage and die. The result is dysfunction of the muscle of the heart in the area affected by the lack of oxygen.

What are the risk factors for heart attack?

There are two types of risk factors for heart attack, including:

Who is most at risk - inherited (genetic) factors?

• persons with inherited hypertension (high blood pressure)
• persons with inherited low levels of HDL (high-density lipoproteins),  or high levels of LDL (low-density lipoprotein) blood cholesterol or high levels of triglycerides
• persons with a family history of heart disease (especially with onset before age 55)
• aging men and women
• persons with type 1 diabetes
• women, after the onset of menopause (generally, men are at risk at an earlier age than women, but after the onset of menopause, women are equally at risk)

Who is most at risk - acquired risk factors?

• persons with acquired hypertension (high blood pressure)
• persons with acquired low levels of HDL (high-density lipoproteins), high levels of LDL (low-density lipoprotein) blood cholesterol or high levels of triglycerides
• cigarette smokers
• people who are under a lot of stress
• people who drink too much alcohol
• individuals who lead a sedentary lifestyle
• persons overweight by 30 percent or more
• persons who eat a diet high in saturated fat
• persons with Type II diabetes

A heart attack can happen to anyone - it is only when we take the time to learn which of the risk factors apply to us, specifically, can we then take steps to eliminate or reduce them.

Managing heart attack risk factors:

Managing your risks for a heart attack begins with:

• examining which of the risk factors apply to you, and then taking steps to eliminate or reduce them.
• becoming aware of conditions like hypertension or abnormal cholesterol levels, which may be "silent killers."
• modifying risk factors that are acquired, not inherited, through lifestyle changes. See your physician as the first step in starting right away to make these changes.
• consulting your physician soon to determine if you have risk factors that are genetic or inherited and cannot be changed, but can be managed medically and through lifestyle changes.

What are the warning signs of a heart attack?

The following are the most common symptoms of a heart attack. However, each individual may experience symptoms differently. Symptoms may include:

• severe pressure, fullness, squeezing, pain and/or discomfort in the center of the chest that lasts for more than a few minutes
• pain or discomfort that spreads to the shoulders, neck, arms, or jaw
• chest pain that increases in intensity
• chest pain that is not relieved by rest or by taking nitroglycerin
• chest pain that occurs with any/all of the following (additional) symptoms:
  • sweating, cool, clammy skin, and/or paleness
  • shortness of breath
  • nausea or vomiting
  • dizziness or fainting
  • unexplained weakness or fatigue
  • rapid or irregular pulse

Although chest pain is the key warning sign of a heart attack, it may be confused with indigestion, pleurisy, pneumonia, or other disorders.

Responding to heart attack warning signs:

If you, or someone you know exhibits any of the above warning signs, act immediately. Call 911, or your local emergency number.

Treatment for a heart attack:

The goal of treatment for a heart attack is to relieve pain, preserve the heart muscle function, and prevent death.

Treatment in the emergency department may include:

• intravenous therapy - nitroglycerin, morphine
• continuous monitoring of the heart and vital signs
• oxygen therapy - to improve oxygenation to the damaged heart muscle
• pain medication - by decreasing pain, the workload of the heart decreases, thus, the oxygen demand of the heart decreases
• cardiac medication - such as beta-blockers or calcium channel blockers to promote blood flow to the heart, improve the blood supply, prevent arrhythmias, and decrease heart rate and blood pressure
• fibrinolytic therapy - intravenous infusion of a medication which dissolves the blood clot, thus, restoring blood flow
• antithrombin/antiplatelet therapy - used to prevent further blood clotting
• antihyperlipidemics  - medications used to lower lipids (fats) in the blood, particularly Low Density Lipid (LDL) cholesterol. Statins are a group of antihyperlipidemic medications, and include simvastatin (Zocor), atorvastatin (Lipitor), and pravastatin (Pravachol), among others. Bile acid sequestrants - colesevelam, cholestyramine and colestipol - and nicotinic acid (niacin) are two other types of medications that may be used to reduce cholesterol levels.

Once the condition has been diagnosed and the patient stabilized, additional procedures to restore coronary blood flow may be utilized. Those procedures include:

• coronary angioplasty - with this procedure, a balloon is used to create a bigger opening in the vessel to increase blood flow. Although angioplasty is performed in other blood vessels elsewhere in the body, percutaneous coronary intervention (PCI) refers to angioplasty in the coronary arteries to permit more blood flow into the heart. PCI is also called percutaneous transluminal coronary angioplasty (PTCA). There are several types of PCI procedures, including:
  • balloon angioplasty - a small balloon is inflated inside the blocked artery to open the blocked area.
  • atherectomy - the blocked area inside the artery is cut away by a tiny device on the end of a catheter.
  • laser angioplasty - a laser used to "vaporize" the blockage in the artery.
  • coronary artery stent - a tiny coil is expanded inside the blocked artery to open the blocked area and is left in place to keep the artery open.
• coronary artery bypass - Most commonly referred to as simply "bypass surgery," this surgery is often performed in people who have angina (chest pain) and coronary artery disease (where plaque has built up in the arteries). During the surgery, a bypass is created by grafting a piece of a vein above and below the blocked area of a coronary artery, enabling blood to flow around the obstruction. Veins are usually taken from the leg, but arteries from the chest or arm may also be used to create a bypass graft.