The goals of initial treatment are to minimize damage by restoring blood flow to the heart and to determine the amount of damage to heart tissue. It is critical to call for immediate medical attention if heart attack is suspected. Intensive research over the last 20 or more years has demonstrated that prompt treatment can decrease damage from a heart attack and increase the chance for survival.
The heart may develop irregular heart rhythms (arrhythmias) or stop beating (sudden cardiac arrest) during a heart attack. When the heart is unable to pump blood throughout the body, brain damage and death can occur within minutes.
Emergency medical personnel can quickly assess the situation and may perform an electrocardiogram (ECG) to measure electrical activity in the heart. If the patient is in cardiac arrest, or is experiencing an abnormal heart rhythm, a device called a defibrillator may be used to "shock" the heart into a normal rhythm.
Emergency medical personnel also can administer medications and begin treatments immediately that can help dissolve a blood clot and open a blocked coronary artery, restoring normal blood flow to the heart. If these therapies are initiated within 1 hour of the onset of symptoms, less irreparable damage may occur.
Even before emergency personnel arrive, cardiopulmonary resuscitation (CPR) can be performed if the patient has no pulse and a capable bystander is present. CPR is a combination of rescue breathing and chest compressions. Automated external defibrillators designed for CPR are available in some public places (e.g., airports, shopping malls, large office buildings). Defibrillators also are available without a prescription for home use.
Recent studies have shown that a procedure called cardiocerebral resuscitation may help improve outcomes for patients who suffer a heart attack outside of a hospital setting. In cardiocerebral resuscitation, emergency personal administer uninterrupted chest compressions for approximately 2 minutes (200 compressions), then perform regular CPR and use a defibrillator to administer an electrical shock, if necessary.
If the patient is still in cardiac arrest, the procedure is repeated as many as 3 times. Cardiocerebral resuscitation also involves administering epinephrine (drug that constricts blood vessels) as quickly as possible and with each cycle of 200 chest compressions.
Studies have shown that cooling the body temperature to between 89.6 °F and 93.2 °F may help to prevent brain damage in patients who survive cardiac arrest lasting more than a few minutes. This treatment, which is called mild therapeutic hypothermia, should be started as soon as possible after the patient is resuscitated and continued for 12–24 hours. Cooling blankets, ice packs, fanning, and intravenous (IV) solutions can be used to lower the patient's core body temperature.
Treatment may include the following:
Thrombolytic therapy
Heparin therapy
Aspirin
Beta-blockers
Nitroglycerin
IIb/IIIa Inhibitors
Primary percutaneous transluminal coronary angioplasty (PTCA)
Several new "clot-busting drugs," called thrombolytic agents, can help dissolve blood clots and prevent further heart damage. Although clot-busting drugs (e.g., r-PA, t-PA, tnk-PA, streptokinase) are most effective when administered within the first several hours of a heart attack, they are beneficial when administered within 12 hours following the onset of symptoms.
These medications are not used in all cases, and whether they are used or not is determined primarily by electrocardiogram results. Thrombolytic agents carry a small risk for causing excessive bleeding, which can cause stroke if it occurs in the brain; however, potential benefits usually outweigh the risk.
Heparin is a drug used to "thin" the blood to help prevent further blood clot formation. This drug may be particularly useful in patients who experience intermittent blood clot formation within a coronary artery.
The older form of heparin, called unfractionated heparin, usually is administered via a continuous intravenous (IV) infusion. Frequent blood tests are required during treatment to monitor how "thin" the blood is.
Newer forms of heparin, called low molecular weight heparins, usually are administered via injection in the abdomen twice a day. These medications include enoxaparin (Lovenox®), dalteparin (Fragmin®), and nadroparin (Fraxiparin®). Low molecular weight heparins require less frequent monitoring and several studies suggest that this form of the drug prevents recurrent heart attack and death more effectively than unfractionated heparin.
Taking an aspirin during a heart attack and each day following a heart attack can decrease the risk of dying from the condition by almost 25%. Blood clots primarily are composed of platelets (microscopic particles that circulate in the bloodstream) that "stick" to ruptured plaques and to each other. Aspirin makes platelets less "sticky," decreasing the risk for further blood clot formation.
Studies have shown that some patients are resistant to the effects of aspirin therapy. Regular blood tests may be performed to monitor the patient's response; the results of these tests can be used to adjust the aspirin dosage or change the medication.
These drugs slow the heart rate and decrease the strength of the heart's contractions, reducing strain on the heart and its oxygen requirement. Commonly used beta-blockers include metoprolol (Lopressor®, Toprol XL®) and atenolol (Atenolol®). These drugs usually are administered intravenously (through a vein) at first and then orally.
Studies have shown that taking beta-blockers during and after a heart attack decreases the risk for recurrent heart attack and death. Therefore, patients without contraindications to beta-blocker therapy often take these drugs indefinitely. Beta-blockers may cause erectile dysfunction.
Nitroglycerin is a chemical that opens up (dilates) arteries and veins and increases blood flow to the heart. During heart attack, nitroglycerin can be placed under the tongue, where it quickly dissolves and is absorbed into the bloodstream.
Nitroglycerin also can be administered via continuous intravenous (IV) infusion; applied to the skin in cream or patch form, where it is slowly absorbed; or administered as short- or long-acting nitrate pills. Isosorbide dinitrate (Isordil®) usually is taken 3 times a day and isosorbide mononitrate (Ismo®, Imdur®) is taken either twice (Ismo) or once daily (Imdur).
Because nitroglycerin dilates not only the coronary arteries, but also other blood vessels, it may cause severe headaches. In some cases, headaches are so severe that patients are unable to tolerate nitroglycerin therapy.
These drugs help to prevent platelets from sticking together and forming blood clots. They also help dissolve existing blood clots. Studies show that treatment with IIb/IIIa inhibitors can reduce the risk for recurrent heart attack or death. IIb/IIIa inhibitors include eptifibatide (Integrelin®), tirofiban (Aggrastat®), and abciximab (ReoPro®).
Primary percutaneous transluminal coronary angioplasty (PTCA)
In some cases, primary percutaneous transluminal coronary angioplasty (PTCA), or angioplasty, is performed to obtain images of the coronary arteries, identify the blockage, and determine the best course of treatment.
Coronary angioplasty is performed in a catheterization laboratory (cath lab), under sedation and a local anesthetic. An iodine-based dye or other contrast agent is injected to make the arteries and blockage(s) visible on a monitor. Physicians use a monitor as a guide during the procedure.
During coronary angioplasty, the coronary arteries are accessed through a small incision made in the femoral artery, located in the groin, or the brachial artery, located in the arm. In most cases, the femoral artery is used. A pencil-sized plastic sheath is inserted through the artery and flexible catheters are passed through the sheath to the blocked coronary artery. Then, a device such as an ultra-thin wire, tiny balloon, or a small metal spring-like device called a stent, is used to stretch open the blocked artery.
Although angioplasty is relatively safe, complications can occur, including the following:
Allergic reaction to iodine-based dye
Arrhythmias
Bleeding at the insertion site
Infection at the insertion site
Kidney failure
Ruptured artery (dissection)
Stroke
Allergic reactions to iodine-based dye range from hives to anaphylactic shock, which can involve hives, rash, swelling (edema), vascular collapse, shock, and respiratory distress. Anaphylactic shock is life threatening and requires immediate medical attention.
Rarely, an inflated angioplasty balloon can tear the blood vessel wall (dissection). If this occurs, emergency bypass surgery is performed.
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