Heart attack is the interruption of cardiovascular function. The most common cause of HEART attack is MYOCARDIAL INFARCTION, a blockage of the CORONARY ARTERIES, usually with a BLOOD clot, that disrupts the flow of blood to the heart (MYOCARDIUM). Other causes of heart attack include ARRHYTHMIA, systemic HYPOXIA (such as may occur with drowning or carbon monoxide poisoning), and ELECTROCUTION. About 1.3 million Americans experience heart attacks each year, and 40 percent of them die as a result. Health experts believe significantly more people could survive heart attack with early treatment. Up to 60 percent of people who die from heart attack do so before ever reaching a hospital.
When the heart is not beating or cannot beat effectively, oxygen does not get to the body’s tissues. Within seconds the body begins to shut down nonessential functions. The BRAIN and the heart itself are the most vulnerable to damage resulting from lack of oxygen; their cells begin to die within three minutes. Immediate CARDIOPULMONARY RESUSCITATION (CPR) can restore OXYGENATION and prevent permanent damage or death. However, the likelihood of survival diminishes by about 10 percent for each minute that passes following the heart’s stoppage.
Symptoms vary far more widely than most people realize. The classic symptoms of heart attack are
Many people, and especially women, do not experience classic heart attack symptoms. Instead, their symptoms are more generalized. The danger is that they delay seeking treatment because they are unsure whether they are having a heart attack. Such a delay can be the difference between surviving and dying from a heart attack. Nonclassic heart attack signs include
Warning signs that persist for five minutes require immediate medical assessment. More people survive heart attacks than do not, and more people could survive heart attacks if they received prompt medical treatment. Cardiologists recommend chewing an aspirin tablet at the first signs of possible heart attack, which helps slow the clotting process.
The diagnostic path begins with ELECTROCARDIOGRAM (ECG), which shows the heart’s electrical patterns and can usually identify the location of the disrupted function. Regardless of cause, heart attack produces arrhythmias (irregularities of the HEART RATE). Blood tests to measure electrolyte levels and certain proteins that a damaged heart MUSCLE releases also help point to the diagnosis. ECHOCARDIOGRAM can show areas of structural damage to the heart, and CARDIAC CATHETERIZATION with ANGIOGRAM can identify the precise sites of occlusions in the coronary arteries.
Treatment begins with stabilizing the heart’s function, which may require various medications including antiarrhythmia medications and drugs that strengthen the heart while reducing the force of its contractions. DEFIBRILLATION may be necessary to restore a functional rhythm to the heart. When doctors can determine within three hours that the cause of the heart attack is a blood clot, they may choose to administer thrombolytic medications (“clot busters”) to dissolve the clot as well as anticoagulant medications to prevent further clots. Beyond three hours, thrombolytic medications are not effective. Supportive measures include OXYGEN THERAPY to increase the amount of oxygen in the blood and intravenous fluids to maintain HYDRATION and restore electrolyte balance.
Once the heart recovers, the cardiologist may recommend interventions such as ANGIOPLASTY or CORONARY ARTERY BYPASS GRAFT (CABG) to restore adequate circulation to the heart. Other treatments typically include medications to help regulate the heartbeat and strengthen the heart, and lifestyle modifications for improved cardiovascular health. Treatment also targets any identified underlying causes of the heart attack such as HYPERTENSION (high BLOOD PRESSURE) and ATHEROSCLEROSIS. Current treatment protocols recommend nearly everyone who has a heart attack take statin medications afterward. Statins are lipid-lowering medications that can reduce CHOLESTEROL BLOOD LEVELS, notably low-density lipoprotein cholesterol (LDL-C) by 30 to 40 percent within three months. Statins also help strengthen the heart. Other medications may include beta blockers or calcium channel blockers to lower blood pressure and regulate rhythm. Depending on the heart attack’s severity (the extent of damage to the heart), a person may return to regular activities within a few weeks or require several months to recuperate. Most people benefit from a structured CARDIAC REHABILITATION program.
The primary risk factors for heart attack are CORONARY ARTERY DISEASE (CAD) and hypertension. Many people are unaware that they have either one, so heart attack becomes the first recognition that these conditions exist. Regular ROUTINE MEDICAL EXAMINATION, including tests to measure cholesterol blood levels and blood pressure, help detect these conditions in their early stages, when therapeutic intervention can thwart their progression to lifethreatening events such as heart attack and STROKE. Key preventive measures include daily physical exercise, nutritious eating habits, WEIGHT LOSS AND WEIGHT MANAGEMENT, SMOKING CESSATION, and management of conditions such as hypertension and DIABETES.
See also CARDIOVASCULAR DISEASE PREVENTION; LIFESTYLE AND CARDIOVASCULAR HEALTH; MEDICATIONS TO TREAT CARDIOVASCULAR DISEASE; PHYSICAL EXERCISE AND CARDIOVASCULAR HEALTH; ROUTINE MEDICAL EXAMINATION.
Resource: Facts On File Encyclopedia Of Health And Medicine
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