infarction

infarction,

blockage of blood circulation to a localized area or organ of the body resulting in tissue death. Infarctions commonly occur in the spleenspleen,
soft, purplish-red organ that lies under the diaphragm on the left side of the abdominal cavity. The spleen acts as a filter against foreign organisms that infect the bloodstream, and also filters out old red blood cells from the bloodstream and decomposes them.
..... Click the link for more information. , kidney, lungslungs,
elastic organs used for breathing in vertebrate animals, excluding most fish, which use gills, and a few amphibian species that respire through the skin. The word is sometimes applied to the respiratory apparatus of lower animals.
..... Click the link for more information. , brainbrain,
the supervisory center of the nervous system in all vertebrates. It also serves as the site of emotions, memory, self-awareness, and thought. Anatomy and Function
..... Click the link for more information. , and heartheart,
muscular organ that pumps blood to all parts of the body. The rhythmic beating of the heart is a ceaseless activity, lasting from before birth to the end of life. Anatomy and Function

The human heart is a pear-shaped structure about the size of a fist.
..... Click the link for more information. . The acute emergency known as myocardial infarction or heart attack is usually caused by a blockage in one of the coronary arteries that supply blood to the heart muscle. The blockage typically occurs when a blood clot (see thrombosisthrombosis
, obstruction of an artery or vein by a blood clot (thrombus). Arterial thrombosis is generally more serious because the supply of oxygen and nutrition to an area of the body is halted.
..... Click the link for more information. ) lodges in an area already narrowed by arteriosclerosisarteriosclerosis
, general term for a condition characterized by thickening, hardening, and loss of elasticity of the walls of the blood vessels. These changes are frequently accompanied by accumulations inside the vessel walls of lipids, e.g.
..... Click the link for more information. ; other causes are vasospasms in the arterial walls or viral infection of the heart. Symptoms include a crushing pain in the chest radiated to either arm (more commonly the left arm), the jaw, and the neck. The pain may be experienced, particularly in women, as pain in the shoulder or stomach, instead of the chest, and in some cases there are no symptoms at all. The seriousness of the infarction is dependent upon the amount of heart muscle affected, how long the area is deprived of blood, and whether it affects the natural pacemaker of the heart, setting off arrhythmiasarrhythmia
, disturbance in the rate or rhythm of the heartbeat. Various arrhythmias can be symptoms of serious heart disorders; however, they are usually of no medical significance except in the presence of additional symptoms.
..... Click the link for more information. such as ventricular fibrillation. Death of heart muscle tissue and heart failure may result (see congestive heart failurecongestive heart failure,
inability of the heart to expel sufficient blood to keep pace with the metabolic demands of the body. In the healthy individual the heart can tolerate large increases of workload for a considerable length of time.
..... Click the link for more information. ); damage to other vital organs, including the brain, may occur if the heart is unable to pump necessary oxygen and blood to them. Confirmation of myocardial infarction is made by electrocardiographyelectrocardiography
, science of recording and interpreting the electrical activity that precedes and is a measure of the action of heart muscles. Since 1887, when Augustus Waller demonstrated the possibility of measuring such action, physicians and physiologists have recorded
..... Click the link for more information. and measurement of elevations of white blood cells and certain enzymes. Treatment of acute myocardial infarction may include first aid in the form of cardiopulmonary resuscitationcardiopulmonary resuscitation
(CPR), emergency procedure used to treat victims of cardiac and respiratory arrest. CPR can be done in a hospital with drugs and special equipment or as a first-aid technique.
..... Click the link for more information. (CPR), an emergency balloon angioplastyangioplasty
, any surgical repair of a blood vessel, especially balloon angioplasty or percutaneous transluminal coronary angioplasty, a treatment of coronary artery disease.
..... Click the link for more information. , or the administration of beta-blockersbeta-blocker
or beta-adrenergic blocking agent
, drug that reduces the symptoms connected with hypertension, cardiac arrhythmias, angina pectoris, migraine headaches, and other disorders related to the sympathetic nervous system.
..... Click the link for more information. and thrombolytic drugsthrombolytic drug
or clot-dissolving drug,
substance, such as streptokinase or tissue plasminogen activator (tPA), that causes the breakdown of blood clots (see thrombosis) that obstruct the flow of blood through the vessels.
..... Click the link for more information. (clot-dissolving drugs), such as tissue plasminogen activator. The healing of an infarction occurs through replacement of the dead tissue by scar tissue.

See also coronary artery diseasecoronary artery disease,
condition that results when the coronary arteries are narrowed or occluded, most commonly by atherosclerotic deposits of fibrous and fatty tissue. Coronary artery disease is the most common underlying cause of cardiovascular disability and death.
..... Click the link for more information. .

infarction

[in′färk·shən] (medicine) Condition or process leading to the development of an infarct. infarct

infarction

[in-fark´ shun] 1. infarct.2. formation of an infarct.cardiac infarction myocardial infarction.cerebral infarction an ischemic condition of the brain, causing a persistent focal neurologic deficit in the area affected.myocardial infarction see myocardial infarction.pulmonary infarction localized necrosis of lung tissue caused by obstruction of the arterial blood supply, most often due to pulmonary embolism. Clinical manifestations range from the subclinical to pleuritic chest pain, dyspnea, hemoptysis, and tachycardia.

in·farc·tion

(in-fark'shŭn), 1. An area of tissue necrosis caused by impairment of arterial or venous blood supply due to mechanical factors (for example, emboli, thrombi) or to blood pressure alterations. 2. Synonym(s): infarct

infarction

(ĭn-färk′shən)n.1. The formation or development of an infarct.2. An infarct.

infarction

Medtalk Dying of tissue, necrosis

in·farc·tion

(in-fahrk'shŭn) 1. Sudden insufficiency of arterial or venous blood supply due to emboli, thrombi, vascular torsion, or pressure that produces a macroscopic area of necrosis; the heart, brain, spleen, kidney, intestine, lung, and testes are likely to be affected, as are tumors, especially of the ovary or uterus. 2. Synonym(s): infarct.

infarction

(in-fark'shon) [ infarct] Death of tissue from deprivation of its blood supply.

aborted myocardial infarction

Reperfusion of an occluded coronary artery before damage is done to the muscle that receives blood from that artery.

cardiac infarction

Myocardial infarction.

cerebral infarction

See: cerebral infarct

exercise-related myocardial infarction

A myocardial infarction whose symptoms begin within an hour of vigorous physical exercise.

lacunar infarction

A small stroke deep within the brain (as in the internal capsule, basal ganglia, thalamus, or pons) caused by damage to or a blockage of a tiny penetrating artery. Lacunar infarctions are associated with a kind of vascular damage caused by chronic high blood pressure called lipohyalinosis. They may be asymptomatic, showing up only on brain imaging, or may produce pure motor, pure sensory, ataxic, or mixed motor and sensory symptoms. Synonym: lacunar stroke

malignant cerebral artery infarction

A massive stroke involving the middle cerebral artery, in which swelling of the brain leads either to herniation and death or to additional strokes in other arteries.

MYOCARDIAL INFARCTION: Myocardial infarction as seen on an electrocardiogram

MYOCARDIAL INFARCTION

myocardial infarction

Abbreviation: MI
The loss of living heart muscle as a result of coronary artery occlusion. MI or its related syndromes (acute coronary syndrome or unstable angina) usually occurs when an atheromatous plaque in a coronary artery ruptures, and the resulting clot obstructs the injured blood vessel. Perfusion of the muscular tissue that lies downstream from the blocked artery is lost. If blood flow is not restored within a few hours, the heart muscle dies. Synonym: cardiac infarction

Acute MI affects 1.1 million people each year, and approx. 350,000 of them die. The probability of dying from MI is related to the patient's underlying health, whether arrhythmias such as ventricular fibrillation or ventricular tachycardia occur, and how rapidly the patient seeks medical attention and receives appropriate therapies (such as thrombolytic drugs, angioplasty, antiplatelet drugs, beta blockers, and intensive electrocardiographic monitoring). See: illustration; advanced cardiac life support; atherosclerosis; cardiac arrest; sudden death

Etiology

Proven risk factors for MI are tobacco use, diabetes mellitus, abnormally high cholesterol levels, high blood pressure, gender, advanced age, obesity, physical inactivity, chronic kidney disease, a family history of MI at an early age, and loss of albumin in the urine. Some research suggests that high C reactive protein levels, and other conditions may also lead to increased risk.

Symptoms

Classic symptoms of MI in men are a gradual onset of pain or pressure, felt most intensely in the center of the chest, radiating into the neck, jaw, shoulders, or arms, and lasting more than a half hour. Pain typically is dull or heavy rather than sharp or stabbing, and often is associated with difficult breathing, nausea, vomiting, and profuse sweating. Clinical presentations, however, vary considerably, and distinct presentations are seen in woman and the elderly, in whom, e.g., unexplained breathlessness is often the primary symptom. Many patients may mistake their symptoms for indigestion, intestinal gas, or muscular aches. About a third of all MIs are clinically silent, and almost half present with atypical symptoms. Often patients suffering MI have had angina pectoris for several weeks before and simply did not recognize it.

Diagnosis

A compatible history associated either with segment elevation (on a 12-lead electrocardiogram) or with elevated blood levels of cardiac muscle enzymes such as troponins or creatine kinase can establish the diagnosis. An ST-segment elevation of more than 1 mm above baseline in at least two contiguous precordial leads or two adjacent limb leads suggests myocardial injury. Myocardial infarctions with this presentation are known as ST-segment elevation MI (STEMI). This finding usually indicates significant muscle damage in the infarct area, a poorer prognosis, and a higher incidence of complications (arrhythmias, cardiogenic shock) than in a non-ST-segment elevation MI (NSTEMI). The differential diagnosis of chest pain must always be carefully considered because other serious illnesses, such as pulmonary embolism, pericarditis, aortic dissection, esophageal rupture, acute cholecystitis, esophagitis, or splenic rupture may mimic MI.

Treatment

Myocardial infarction is a medical emergency; diagnosis and treatment should not be delayed. People who experience symptoms suggestive of MI should be taught to call 911 immediately and chew and swallow aspirin. Oxygen is administered at 4 L/min as soon as it is available. History is gathered throughout the first few minutes after admission even as a 12-lead ECG is being done and blood taken for biomarkers. Cardiac troponins may not become elevated until 4 or more hr after symptoms begin. If the patient is hypotensive or in cardiogenic shock, right-sided ECG leads are assessed for a right ventricular (RV) infarct. An intravenous access is established along with continuous cardiac monitoring, and medications (which may include chewed aspirin [162 to 325 mg], heparins, or other medications to inhibit platelet aggregation, nitroglycerin [given SL, sprayed or IV], IV morphine, and beta-blockers) are administered as prescribed. Pain is assessed on a 1 to 10 intensity scale, and morphine 2 to 10 mg administered IV, with incremental doses of 2 to 8 mg every 5 to 15 min until relief is obtained. Beta-blockers (such as metoprolol or atenolol) decrease myocardial oxygen demand, helping to limit the amount of heart muscle damaged. An IV beta-blocker should be given if the patient is hypertensive or has a tachyarrhythmia as long as no contraindications exist. Patients with STEMI who arrive at the hospital within 6 hr of the onset of symptoms are treated with fibrinolytic therapy or percutaneous coronary intervention (PCI). The goal for administration of fibrinolytic therapy is 30 min postsymptom onset (door-to-needle); for PCI 90 min (door-to-balloon inflation). Absolute contraindications of fibrinolytic therapy include previous intracranial hemorrhage or ischemic stroke within 3 months ( intracranial malignancy), active bleeding, or bleeding disorders (except menses), significant closed head or facial trauma within 3 months (known structural cerebral vascular lesions), and suspected aortic dissection. Reperfusion is the immediate goal, usually best accomplished with balloon angioplasty and endovascular stent placement, although emergency coronary bypass surgery may be needed in cases when PCI fails. An angiotensin-converting enzyme (ACE) inhibitor is administered within 24 hr of a STEMI to suppress the renin-angiotensin-aldosterone system and prevent excess fluid retention. ACE inhibitors also prevent conversion of angiotensin I to angiotensin II (a potent vasoconstrictor), thus reducing afterload to help prevent heart failure.

In MI complicated by pulmonary edema, diuretics are administered, and dobutamine infusions may be necessary to increase cardiac output. Strict glucose control (maintaining blood sugars below 150 mg/dl, and preferably in the normal range) reduces mortality in acute MI. Hypotension and circulatory collapse frequently occur in patients with significant RV infarctions, and fluid challenge is administered to optimize RV preload. If this is unsuccessful, the patient with an RV infarct will require inotropic support, correction of bradycardia, and measures to achieve atrioventricular synchrony (cardioversion for atrial fibrillation, etc). In patients with ventricular arrhythmias, defibrillation, or cardioversion, lidocaine, vasopressin, or amiodarone infusions, or other drugs, may be necessary. Anemic patients (hematocrit less than 30 or those actively bleeding) benefit from blood (packed red cell) transfusions.

With contemporary care, about 95% of patients with acute MI who arrive at the hospital in time will survive. These patients are referred to nutrition therapists to learn how to use low-fat, low-cholesterol diets, and to cardiac rehabilitation programs for exercise training, tobacco cessation, and psychosocial support.

Patient care

Acute Care: On admission, all diagnostic and treatment procedures are explained briefly to reduce stress and anxiety. Continuous electrocardiographic monitoring is used to identify changes in heart rhythm, rate, and conduction. Location, radiation, quality, severity, and frequency of chest pain are documented and relieved with IV morphine. Bleeding is the most common complication of antiplatelet, anticoagulant, and fibrinolytic therapies. The complete blood count, prothrombin time, and activated partial thromboplastin time are monitored at daily intervals. IV sites are assessed for evidence of bleeding. Fluid balance and pulmonary status are closely monitored for signs of fluid retention and overload. Breath sounds are auscultated for crackles (which may resolve by having the patient cough when caused by atelectasis, or which may indicate pulmonary edema when they do not). Heart sounds are auscultated for S3 or S4 gallops or new heart murmurs. Patient care and other activities should be organized to allow for periods on uninterrupted rest. Stool softeners are prescribed to prevent straining during defecation, which can cause vagal stimulation and slow the heart rate. Antiembolism stockings help to prevent venostasis and deep vein thrombosis. Emotional support is provided to decrease stress and anxiety. Adjustment disorders and depression are often experienced by MI patients, and the patient and family are assisted to deal with these feelings. Stress tests, coronary angiography, cardiac imaging procedures, reperfusion techniques, and other interventions are explained. The patient receives assistance in coping with changes in health status and self-concept.

Ambulatory Care: Cardiac rehabilitation begins as soon as the patient is physiologically stable. The goal of cardiac rehabilitation is to have the patient establish a healthy lifestyle that minimizes the risk of another MI. Ambulation is slowly increased, and a low-level treadmill test may be ordered before discharge to determine exercise tolerance and the risk of future heart attacks. Patients are taught not only to measure their pulse but also to assess their response to exercise in terms of fatigue, ease of breathing, and perceived workload. Following discharge, exercise is slowly increased, first while being monitored closely by supervised cardiac rehabilitation, and then more independently. The patient also receives information about a low saturated fat, low cholesterol, low calorie diet, such as the DASH eating plan (Dietary Approaches to Stop Hypertension), resumption of sexual activity, work, and other activities. The patient is taught about desired and adverse affects of all medications: aspirin therapy is usually prescribed as ongoing antiplatelet therapy (with or without clopidogrel), but patients should be warned about the risk of bleeding and be advised to avoid products containing ibuprofen, which blocks aspirin’s antiplatelet effects. Smoking cessation is an important preventive for future MIs. High blood pressure, obesity, adverse cholesterol levels, and diabetes mellitus also should be carefully managed to help prevent future MIs. Alcohol intake should be limited to 1 drink daily (women), 2 drinks daily (men). Opportunities are created for patients and families to share feelings and receive realistic reassurance about common fears.

illustration

placental infarction

A localized necrotic area caused by abruption. See: abruptio placentae

pulmonary infarction

An infarction in the lung usually resulting from pulmonary embolism that may appear on x-rays as a wedge-shaped infiltrate near the pleura. Immediate therapy includes control of pain, oxygen administered continuously by mask, intravenous heparin (unless the patient has a known blood clotting defect), and treatment of shock or dysrhythmias, if present.

silent myocardial infarction

Unrecognized myocardial infarction. The patient may experience difficulty breathing, heartburn, nausea, arm pain, or other atypical symptoms.

infarction

The deprivation of a part of a tissue or organ of its blood supply so that a wedge-shaped area of dead tissue (an infarct) forms. Infarction of part of the heart muscle is the process underlying a heart attack.

Infarction

Death of tissue due to inadequate blood supply.Mentioned in: Electrical Stimulation of the Brain, Priapism

in·farc·tion

(in-fahrk'shŭn) Area of tissue necrosis caused by impaired arterial or venous blood supply due to mechanical factors (e.g., emboli, thrombi) or to blood pressure alterations.
Synonym(s): infarct.

infarction

infarction

in·farc·tion

infarction

in•farc•tion

infarction

infarction

infarction,

infarction

infarction

infarction

in·farc·tion

infarction

infarction

in·farc·tion

infarction

aborted myocardial infarction

cardiac infarction

cerebral infarction

exercise-related myocardial infarction

lacunar infarction

malignant cerebral artery infarction

myocardial infarction

Etiology

Symptoms

Diagnosis

Treatment

Patient care

placental infarction

pulmonary infarction

silent myocardial infarction

infarction

Infarction

in·farc·tion

infarction

Synonyms for infarction

noun localized necrosis resulting from obstruction of the blood supply

Synonyms

Related Words