Heart Attack [1]

What is a Heart Attack?
A heart attack (called a myocardial infarction) is the death of a portion of heart muscle in an area where there is sudden loss of blood supply.

What is a Heart Attack?
A Heart Attack (called a myocardial infarction) is the death of a portion of heart muscle in an area where there is sudden loss of blood supply.

  • Orderly movement (transmission) of electrical signals in the heart is important for the regular beating (pumping) of the heart.  
  • Death of the heart muscle often causes Chest pain and may cause electrical instability of the heart muscle tissue, resulting in a rapid and disorganised heartbeat (ventricular fibrillation).  
  • A heart undergoing ventricular fibrillation simply quivers, and cannot pump or deliver oxygenated blood to the brain.  
  • Permanent brain damage and death can occur unless oxygenated blood flow is quickly resumed.

How do you get a Heart Attack?
A heart attack is usually caused by a complete blockage of a coronary artery by a blood clot forming. This occurs when there is advanced coronary artery disease in which the blood vessel, containing fatty deposits, is damaged. This encourages a blood clot to form on the damaged surface inside the artery.

  • A coronary artery is an artery that supplies blood (along with essential nutrients) to the heart muscle.  
  • Chest pain or pressure is a common symptom of heart attack, but can also be a symptom of many other conditions.  
  • Cardiac chest pain is often vague, or dull, and may be described as a pressure or constricting band-like sensation, squeezing, heaviness, or other discomfort.

How serious is a Heart Attack?
A heart attack is potentially very serious. It can lead to a chronic disabling condition because it can cause heart failure, or it can lead to full recovery. In some, it is rapidly fatal mainly because if the heart’s rhythm is disturbed, permanent brain damage and death can occur unless blood flow is quickly resumed.

How long does a Heart Attack last?
A heart attack itself may last several minutes when the symptoms are present. However, because of the damage it causes and the way the heart tries to cope with it, in those people who survive a heart attack, the consequences last a lot longer. This may mean there is a risk of more abnormal heartbeats (arrhythmias) for several hours or days following. For some patients there can be further risk several months later because they may go on to develop heart failure or other problems. This is why special care and medicines are needed for a long time, to reduce the chances of this happening.

  • Following recovery from a heart attack there is damage to the heart muscle, which takes some time to repair.  
  • The repair to the heart muscle is not always complete and scarring is usually present.  
  • There is always a chance of a recurrence due to the continued presence of diseased coronary arteries that caused the heart attack.  
  • There is also the risk of heart failure developing over a period of weeks as the heart reacts to the injury it has sustained.  
  • For these reasons it is necessary for patients to be monitored carefully and to receive the appropriate treatment to reduce the risk of further disease progression and other heart attacks.

How is a Heart Attack treated?
Medical treatment is aimed to open the blocked artery and restore blood flow to the affected area of heart muscle (doctors call this reperfusion). Treatment is also aimed at preventing further damage and the chance of repeat heart attacks in the future.

  • Once the artery is open, the heart attack is generally halted and the patient becomes pain free.  
  • The patient is most likely to make a good recovery if reperfusion can be established in the first 4-6 hours of a heart attack.  
  • Anti-platelet medicines, for example Aspirin, reduce the tendency of platelets (a type of blood cell) in the blood to clump and clot. These medicines help to prevent the arteries from becoming blocked again.  
  • Nitroglycerin, a vasodilator (blood vessel dilator), widens the blood vessel by relaxing the muscular wall of the blood vessel.  
  • ACE (angiotensin converting enzyme) inhibitors, another type of vasodilator, improve the heart muscle healing process. They do this by blocking the production of a hormone (chemical signal carried in the blood) called angiotensin II.  
  • Beta-blocking agents interfere with the nerves controlling the heart by blocking the action of a chemical they release called noradrenaline. They also block a hormone (chemical carried in the blood) called adrenaline. This makes the heart beat more slowly and less forcibly, which decreases the amount of muscle damage and can help to prevent serious arrhythmias.

After a heart attack, many other recommendations may be made including changes in diet, lifestyle, stopping smoking and so on. The aim of these is to try to reduce the chance of having another heart attack. If specific conditions are discovered that have contributed to the heart attack, like High cholesterol or high blood pressure for example, then specific treatments might be needed for these.

  • Heart attack.

    Last Edited: 15 Aug. 2005

    Johns Hopkins patient information

    Last revised: December 4, 2012
    by Janet G. Derge, M.D.

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