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Heart Attack

Catherine Ford       Volume: 12 (04/06/2005)

A heart attack (myocardial infarction) occurs when an area of heart muscle dies or is permanently damaged because of inadequate supply of oxygen to that area. Most heart attacks are caused by a clot that has blocked one of the coronary arteries, the blood vessels that bring blood and oxygen to the heart muscle. The clot usually forms in a coronary artery that has been previously narrowed from changes related to atherosclerosis. The atherosclerotic plaque inside the arterial wall sometimes cracks, and this triggers the formation of a clot, also called a thrombus.


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Diagram of a heart attack damaged heart
Diagram of a heart attack damaged heart

A clot in the coronary artery interrupts the flow of blood and oxygen to the heart muscle, leading to the death of heart cells in that immediate area. The damaged heart muscle loses its ability to contract, and the remaining heart muscle needs to compensate for that weakened area.

Occasionally, sudden overwhelming stress can trigger a heart attack.

If the blood supply is cut off for more than a few minutes, muscle cells suffer permanent injury and die. This can kill or disable someone, depending on how much heart muscle is damaged.

Angina pectoris is a condition characterized by chest pain that occurs when the muscles of the heart are receiving an insufficient supply of oxygen. This results when the arteries that supply the heart muscle with oxygenated blood are narrowed by arteriosclerosis.. Angina is the primary symptom of coronary artery disease.

The pain is usually experienced under or to the left of the breastbone and radiates to the left shoulder and down the upper arm; occasionally, it spreads to the right shoulder. The attack is usually precipitated by exercise, and it eases when resting; it will normally disappear without residual pain. Unfortunately as it is a warning, the symptoms, can be separated by long periods of time, as long as years. Symptoms usually begin after the age of 50, more prevalent in men than women, and frequently follow physical exertion, excitement, eating, smoking, or exposure to cold. Associated symptoms are faintness and difficulty in breathing.

Significant narrowing of the coronary arteries may require surgical treatment, such as a coronary artery bypass, a procedure that splices healthy blood vessels taken from elsewhere in the body to the affected coronary arteries in such a way that the clogged areas are bypassed. In angioplasty, a balloon-tipped catheter is inserted through the skin into a blood vessel and manoeuvred to the clogged artery. There it is threaded into the blockage and inflated, compressing the plaque against the arterial walls.

Angina is a pertinent protest from the heart muscle that it isn't getting enough oxygen because of diminished blood supply. A heart attack is simply the most extreme state of oxygen deprivation, in which whole regions of heart muscle cells begin to die for lack of oxygen. If the blockage in the arteries serving the heart muscle can be cleared quickly enough, that is within a few hours, then permanent damage can be minimised.

SYMPTOMS

  • Uncomfortable pressure, fullness, squeezing or pain in the centre of the chest lasting more than a few minutes.

  • Pain emanating from the heart towards the shoulders, neck or the arms. The pain may be mild to intense. It may feel like pressure, tightness, burning, or heavy weight. It may be located in the chest, upper abdomen, neck, jaw, or inside the arms or shoulders.

  • Chest discomfort with light-headedness, fainting, sweating, nausea or shortness of breath.

  • Anxiety, nervousness and/or cold, sweaty skin.

  • Paleness.

  • Increased or irregular heart rate.

  • Feeling of impending doom.

RISK FACTORS

  • Smoking

  • High blood pressure

  • Too much fat in your diet

  • Poor blood cholesterol levels, especially high LDL ("bad") cholesterol and low HDL ("good") cholesterol

  • Diabetes

  • Male gender

  • Age

  • Heredity

DIAGNOSIS

  • Review the patient's complete medical history.

  • Give a physical examination.

  • Use an electrocardiogram (or ECG) to discover any abnormalities caused by damage to the heart.

  • Use a blood test to detect abnormal levels of certain enzymes in the bloodstream.

  • Question about the sensations of pain in the chest?

TREATMENT

Thrombolysis is a treatment that helps to dissolve the clot that is blocking the artery. It involves injecting a thrombolytic drug such as streptokinase into the bloodstream. It is imperative this treatment is given as quickly as possible, ideally within the hour of having the first pain. It can be administered up to six hours later, but its effectiveness is reduced by time. If you receive this treatment you will be given a piece of paper notifying the health authorities, in the event of a repeat heart attack you will receive a different thrombolytic drug.

Thrombolytic therapy is not appropriate for people who have had:

  • A major surgery, organ biopsy, or major trauma within the past 6 weeks

  • Recent neurosurgery

  • Head trauma within the past month

  • History of GI (gastrointestinal) bleed

  • Brain tumour

  • Stroke within the past 6 months

  • Current severely elevated high blood pressure

Aspirin, anticoagulants, beta-blockers or anti-arrhythmic drugs may be administered to prevent further attacks. Diuretics or ACE inhibitors may be used to relieve the sensation of breathlessness. Statins or other cholesterol-lowering drugs may be used. Surgery will be required in some cases.




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