Myocardial Infarction (Heart Attack)

What is a heart attack? A sudden blockage or slow blood flow to one of the coronary arteries (the blood vessels that deliver oxygen to the heart). During a heart attack, there isn't enough oxygenated blood getting to the heart's tissue, so the tissue becomes damaged. A heart attack can be a life-threatening situation, so it's important to understand the condition and learn to recognize the signs and symptoms.

Causes

  • Sudden blockage: usually, if the artery is being blocked, it's because of the formation of a blood clot. The blood clots typically form in a coronary artery that is narrowed by fatty deposits on the inside walls. Platelets in the blood, which help form clots, can also stick to the plaques that build up on the inner wall of blood vessels.
  • Slow blood flow: a heart attack can happen if the heart is beating very fast, or if the person has low blood pressure. If enough oxygen isn't being supplied to the muscle of the heart (which makes it beat), a heart attack can happen without a blood clot. Slow blood flow is more likely to be responsible for a heart attack if a person's coronary artery is narrowed by fatty deposits, this process is called atherosclerosis.
  • Atherosclerosis is a condition in which the inside walls of blood vessels (veins and arteries) are narrowed or blocked by fatty deposits (also called plaques) that build up and affect blood flow. It is normal to have some amount of plaque buildup, but it's important to limit atherosclerosis, because it can be very difficult and costly to remove the plaque. Atherosclerosis is an important process because it can cause extremely slow blood flow, which is one of the possible causes of a heart attack.

Symptoms

Chest pain is the most common symptom of a heart attack. The chest pain is often focused in the center of the chest or below the center of the rib cage, though it can spread to the abdomen, neck, arms, or lower jaw. Other possible symptoms of a heart attack include anxiety, a fast heart rate, vomiting, lightheadedness, nausea, sweating, breathlessness, and sudden weakness. In some cases, because of the chest pain, nausea, and vomiting, a patient will think that the cause of their symptoms is indigestion.

Women are more likely than men to have certain symptoms, though chest pain is the most common symptom for both men and women. Women experiencing heart attacks are more likely to feel:

  • Nausea,
  • Vomiting,
  • Jaw pain,
  • Upper back pain,
  • Lightheadedness,
  • Or shortness of breath.

Diagnosis

To figure out if a patient has had a heart attack, a doctor will often run diagnostic tests, including an echocardiogram, an EKG, a stress test, or an angiogram to check for blockages. An echocardiogram is used to look at the physical structure of the heart. A stress test checks how the heart responds to exercise. An electrocardiogram (EKG) measures the heart's electrical activity. These tests are used to diagnose a heart attack, as well as being used to determine the best treatment options for a patient.

Treatment

Because heart attacks are sudden and life-threatening conditions, patients should be taken to the hospital for immediate treatment.

Procedures: A procedure called an angioplasty is often used to unblock the coronary arteries and allow blood supply. A physician may also want to use a coronary artery bypass graft (CABG) to reroute blood vessels to ensure blood supply despite the blockage, though in many cases a CABG is performed a few days after a heart attack.

Medications are often used as part of treatment for a heart attack. Blood thinners, thrombolytics, antiplatelet drugs, nitroglycerin, Beta-blockers, pain relievers and ACE inhibitors are often used as part of the treatment. Each of these medications has a specific use as part of treatment:

  • Blood thinners are used to improve blood flow and break up clots.
  • Aspirin is a common example of a blood thinner.
  • Thrombolytics are frequently used to dissolve clots.
  • Antiplatelet drugs prevent the formation of new blood clots or growth of existing clots.
  • Nitroglycerin is used to widen the blood vessels.
  • Beta-blockers and ACE inhibitors both lower blood pressure.
  • Pain relievers are also often given to patients who have had heart attacks to ease any discomfort they feel.

Causes

The main cause of heart attacks is atherosclerosis. There are cases in which a heart attack is caused by another condition, such as hypercoagulability, congenital abnormalities of the coronary arteries, cocaine abuse, a collagen vascular disease, lupus, etc.

Risk Factors

Risk factors for a heart attack include high levels of cholesterol in the blood, low levels of HDL (which is also called "good cholesterol"), high blood pressure, diabetes, obesity, as well as cigarette smoking and a family history of coronary artery disease. Men have higher risk of a heart attack than women until menopause, at which point a woman's level of risk increases.

Prevention

There are a number of lifestyle factors that can help lower the risk of a heart attack. Controlling blood pressure, regular exercise, a healthy diet, limiting LDL cholesterol, not smoking cigarettes or using tobacco, and maintaining a healthy weight can all contribute to lowering the risk of a heart attack.

In order to prevent atherosclerosis (the clogging of blood vessels), a person should moderate their fat and cholesterol intake. Certain fats, including saturated and trans fats, contribute to the plaques that build up in the blood vessels. LDL (low-density lipoprotein) cholesterol, also known as "bad cholesterol" also contributes to forming plaques.