heart attack

Heart Attack

Almost all heart attacks occur when a blood clot suddenly and completely blocks a coronary artery.

This condition is called a coronary thrombosis, or simply a coronary. The part of the heart muscle nourished by the blocked artery becomes damaged by lack of oxygen.

Unless blood flow returns within minutes, muscle damage increases. Heart cells begin to die after four to six hours without blood. The damage can affect the heart's ability to pump and may cause the patient's death. If the clot can be dissolved within four to six hours, damage to the heart can be reduced. Symptoms. Some people have no warning signs at the beginning of a heart attack. But many people experience angina, dizziness, indigestion, or other symptoms. Most heart attacks cause severe pain. Patients describe the pain as a dull, crushing ache in the chest, but discomfort may extend into the neck, jaw, arms, or back.

The pain may last from a few minutes to several hours. Anyone with chest pain who suspects the pain may be due to a heart attack should seek medical help immediately.

Some patients may stop breathing, and their hearts may stop beating. A first-aid technique called cardiopulmonary resuscitation (CPR) can maintain breathing and circulation until a patient can be taken to a hospital. But CPR should be performed only by someone trained in the technique.

Diagnosis and treatment.

Injured heart muscle causes abnormal ECG waves. Soon after a patient reaches the hospital, doctors administer an ECG to determine that symptoms result from a heart attack and not some other disorder. Doctors also use certain blood tests to detect a heart attack. But these tests are not useful until a few hours after an attack. Doctors may administer a strong painkilling drug, such as morphine, to relieve the pain of a heart attack. They also use drugs to dissolve clots in the blocked artery or may perform emergency angioplasty or bypass surgery.

After doctors stabilize the condition of a heart attack patient, they admit the person to the hospital and monitor him or her for complications in the intensive care unit. Some hospitals have a specialized intensive care unit called a coronary care unit for heart patients. Two major complications are heart failure and arrhythmia. Heart failure occurs if the heart cannot pump enough blood because of extensive damage to the heart muscle. In most cases, heart failure can be successfully treated. In arrhythmia, the heart's electrical system produces an abnormal pattern of beats. Most arrhythmias can be readily treated, but a type called ventricular fibrillation can cause sudden death. Ventricular fibrillation occurs when electrical signals in the ventricles fire randomly.

More than 20 percent of heart attack patients who do not get medical care die. Some people die before they can reach a doctor, but other patients ignore their symptoms and delay treatment. The death rate among hospitalized patients ranges from 5 to 10 percent. Heart attack patients with ongoing chest pain, arrhythmias, or heart failure have a greater risk of another attack than do patients without these problems.

Source : World Book 2005




What is Heart Attack?

A heart attack (myocardial infarction, or MI) occurs when one or more of the coronary arteries are blocked. The coronary arteries supply the heart with oxygen-rich blood. A blockage usually occurs when plaque inside the coronary artery breaks open and a blood clot forms around it. The plaque and blood clot obstruct blood flow to the heart muscle cells, depriving them of oxygen and other nutrients. Without blood supply, the heart muscle cells die. If a large area of the heart is damaged by a heart attack, it can cause sudden death. Heart attack requires immediate treatment to restore blood flow.

What do these indicators mean?

Volume. In contrast with some of the surgical procedures included in this report, volume is not reported for conditions. Please refer to the background information for more information on volume indicators.

Death Rate. The heart attack death rate is the percent of patients admitted for heart attack who died in the hospital. Patients who were transferred from another hospital are excluded from this calculation. However, some patients are sicker or more difficult to treat, and some hospitals admit more of these complex patients than others. Each hospital’s death rate is adjusted to help account for differences in these factors, but keep in mind that the adjustment is not perfect. The adjusted death rate is presented in the displays that follow. The average death rate for heart attack in the United States was 9.5% in 2003, the most recent year for which data is available. In Oregon, the in-hospital heart attack death rate was 9.9% in 2005. This report uses the statewide average as the reference rate.

The Summary Table

The summary table tells you which differences in death rates are large enough to be considered “statistically significant,” or outside the margin of error. Statistical differences are based on the margin of errors described below. With the state average as the reference value:
• If a hospital’s rate is significantly lower than the state average, the summary table tells you it is “Better than average.”
• If a hospital’s rate is significantly higher than the state average, the summary table tells you it is “Worse than average.”
• If a hospital’s rate is statistically neither higher nor lower than the state average (within the margin of error), the summary table tells you it is “Average.”

Margin of Error

Each hospital rate is displayed as a point on a line in the graphs displayed at the end of this report. These lines represent the amount of random variation or “noise” in the data. If the hospital line crosses the band representing the state average, the hospital rate is “within the margin of error” and therefore not statistically different than the state average for this condition.

A black line indicates that the hospital rate is NOT statistically different from the state average. A blue line indicates that the hospital rate is statistically worse than the state average, and a green line indicates that the hospital rate is statistically better than the state average. The margin of error is wider for hospitals with fewer heart attack patients.

Source :


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