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A Heart attack occurs when the blood flow going to a portion of the heart muscle is cut down to a critical level which kills that part of the heart muscle. The correct term for a heart attack is an acute myocardial infarction. The symptoms are usually worse than with angina and may occur at rest. The symptoms are usually prolonged lasting at least 30 minutes, often associated with nausea and vomiting, shortness of breath and severe sweating. These symptoms can occur in a patient with known angina or out of the blue in somebody who has never had any symptoms before. Heart attacks can be fatal but the good news is that most people who survive to get to hospital and receive treatment will in fact survive their heart attack. Death from heart attacks usually occurs because the heart rhythm becomes unstable and the muscle pump of the heart stops beating and goes in to a chaotic electrical activity called ventricular fibrillation. When this happens the heart cannot pump any blood around the body and so loss of consciousness occurs. The Paramedics in the ambulance will be able to recognise this and administer an electrical shock straight away to restart the heart rhythm.
In patients who get to hospital the treatment is to administer prompt pain relief and oxygen and to try and open the blocked artery as quickly as possible. An aspirin tablet will be administered to the patient as soon as possible, but if the heart beat trace or electrocardiogram shows evidence of classical changes of the heart attack, then one of two treatment strategies in 2005 will be employed. In most cases the patient will be given clot busting agents intravenously, which break up the clot and allow the blood to get down the artery into the heart muscle. This is known as “thrombolytic therapy”. The figure opposite shows an angiogram from a patient while the artery is blocked and after the clot busting drug is administered. (figure 4)
Most people make a good recovery from the heart attack and if they are not known to have heart disease before, they should be placed on all the correct medication to try and prevent reoccurrence. This will include aspirin, one of the Statins to lower cholesterol and often other medications such as beta blockers or ACE inhibitors.
A new strategy to treat heart attack patents is to actually try and reopen the artery mechanically without using clot busting drugs. This will necessitate the patient being taken straight to one of the cardiac angiography laboratories (see angiography below) and a small wire and balloon and a stent are used to squash the clot out of the way and re-establish flow. The latest research shows that patients who undergo this treatment known as “primary angioplasty” have better opening rates of the artery than those produced by clot dissolving drugs and patients are less likely to need another intervention at a later date.
All these strategies are designed to restore the blood flow back to as high as possible down the blocked artery and keep as much heart muscle alive as possible. The more heart muscle we can save the better the outlook for the future.
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Figure 4: Three pictures from an angiogram in a patient who had a heart attack, before and after giving clot buster treatment. Frame A shows the totally blocked right coronary artery (arrowed). Frame B is the same artery 30 minutes after the drug. The arrows show the site of the blockage and the blood clot. Frame C is 90 minutes after the drug. The artery is completely open but the arrow shows the tight narrowing in the artery that remains after the clot has gone.
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