Heart attack:Thedeathof heartmuscle由于的损失bloodsupply. The loss of blood supply is usually caused by a complete blockage of a coronaryartery, one of the arteries that supplies blood to theheart muscle. Death of the heart muscle,in引起胸痛n and electrical instability of the heart muscletissue.
The electrical instability of the heart causesventricularfibrillation (chaotic electrical disturbances affecting theventricles, the lower chambers of the heart). Orderly transmission of electrical signals in the heart is important for the regular beating (and the efficient pumping) of the heart. A heart undergoingventricular fibrillationsimply quivers and can not pump or deliver oxygenated blood to thebrain. Permanent brain damage and death can occur unless oxygenated blood flow is restored within five minutes.
Many heart attack deaths are due to ventricular fibrillation that occurs before the victim can reach any medical assistance or the emergency room. These electrical disturbances of the heart can often be successfully treated with medications or other means by paramedics in the "field," or upon arrival to thehospital. Approximately 90-95% of heart attack victims who reach the hospital survive. The 5-10% who later die are those who have sufferedmajorheart muscle damage, or who suffer an "extension" or enlargement of their heart attack.
Early heart attack deaths can be avoided if a bystander startsCPR(cardiopulmonary resuscitation) within five minutes of theonsetof ventricular fibrillation. CPR involves breathing for the victim and applying externalchestcompressionto make the heart pump. When paramedics arrive, medications and/or electrical shock (cardioversion) to the heart can be administered to convert ventricular fibrillation to a normal heart rhythm. Therefore, prompt CPR and rapid paramedic response can improve the survival chances from a heart attack.
The treatment of a heart attack may include the prompt administration of drugs to dissolve and prevent blood clots; an angioplasty or intracoronary stenting to open an obstructed artery; and medications that open (dilate) blood vessels. Early reopening of a blocked coronary artery reduces the amount of heart muscle damage, lessens the size of the heart attack, and improvesprognosis. Patients suffering a heart attack are usually hospitalized for several days to detect heart rhythm disturbance, and observe forshortness of breathand chestpain.
A heart attack is also called a myocardial infarction or anMI. Myocardial refers to themyocardium, the heart muscle.Infarctionis tissue death due to a local lack ofoxygen.
