ST Elevation Myocardial Infarction Overview
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| Myocardial infarction Classification and external resources | |
| ICD-10 | I21.-I22. |
|---|---|
| ICD-9 | 410 |
| DiseasesDB | 8664 |
| MedlinePlus | 000195 |
| eMedicine | med/1567 emerg/327 ped/2520 |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-525-6884
Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2] Phone:617-525-7431
Keywords and synonyms: AMI, STEMI, heart attack, MI, myocardial infarct, acute MI, coronary, coronary thrombosis
Overview
Acute myocardial infarction (AMI or MI), more commonly known as a heart attack, is a medical condition that occurs when the blood supply to a part of the heart muscle or myocardium is interrupted. The resulting ischemia or oxygen shortage causes damage and / or irreversible death (necrosis) of the myocardium (heart muscle). It is a medical emergency, and the leading cause of death for both men and women worldwide, particularly in developed countries.[1] The term myocardial infarction is derived from myocardium (the heart muscle) and infarction (tissue death due to oxygen starvation). The phrase "heart attack" is sometimes used incorrectly to describe sudden cardiac death, which may or may not be the result of acute myocardial infarction.
There are two types of acute MI: ST elevation myocardial infarction (STEMI), the topic of this chapter and non ST elevation MI (NSTEMI) which is discussed in another chapter of WikiDoc. ST elevation myocardial infarction refers to an electrocardiographic pattern in which the ST segments are elevated reflecting complete epicardial vessel occlusion. Once the vessel is opened by percutaneous coronary angioplasty, the ST segments can remain elevated due to absence of perfusion or flow into the myocardium itself. At this point in the evolution of the ST elevation MI, the epicardial artery is open, but the capillary network is occluded due to swelling, embolization, and / or vasospasm.
Non ST elevation myocardial infarction refers to a disease state in which the epicardial artery is open, but there is inadequate blood flow to the myocardium which results in an electrocardiographic pattern of ST segment depression. Inadequate blood flow to the muscle may be due to embolization of material downstream into the myocardium or a restriction of blood flow due to severe narrowing of the epicardial artery.[1] [1] [1] [1]
Risk Factors for ST Elevation Myocardial Infarction
Important risk factors are a previous history of vascular disease such as atherosclerotic coronary heart disease and/or angina, a previous heart attack or stroke, advanced age, smoking, the abuse of certain illicit drugs such as cocaine, high LDL ("Low-density lipoprotein") and low HDL ("High density lipoprotein"), diabetes, high blood pressure, obesity and family history of coronary artery disease.[1]
Triggers of ST elevation myocardial infarction can include psychological stress and excess exertion.
Symptoms of ST Elevation Myocardial Infarction
One third of patients who experience ST Segment Elevation Myocardial Infarction (STEMI) will die within 24 hours of the onset of ischemia, and many of the survivors will suffer significant morbidity. Morbidity and mortality from STEMI can be reduced significantly if patients and bystanders recognize symptoms early, activate the EMS, and thereby shorten the time to definitive treatment.
Classical symptoms of acute myocardial infarction include chest pain (which in some patients may radiate to the left arm), shortness of breath, nausea, vomiting, palpitations, sweating, and anxiety or a feeling of impending doom.
Many patients will state that there was no chest pain, but rather a sense of chest discomfort that they may describe as a squeezing sensation or a sense of chest heaviness or fullness.
Patients frequently feel suddenly ill. Women may experience different symptoms from men. Common associated symptoms of MI in women include shortness of breath, weakness, and fatigue.
Serial electrocardiographic studies have shown that approximately one third of all myocardial infarctions (the appearance of new pathologic q waves) are silent, without chest pain or other symptoms.
Diagnostic Studies in ST Elevation Myocardial Infarction
The primary diagnostic tests include the electrocardiogram (ECG, EKG), a chest X-ray and blood tests to detect elevated creatine kinase or troponin levels (these are chemical markers released by damaged tissues, especially the myocardium).
Treatment of ST Elevation Myocardial Infarction
Immediate treatment for suspected acute myocardial infarction includes oxygen, aspirin, nitroglycerin (also known as glyceryl trinitrate) and pain relief, using an analgesic agent such morphine sulfate.
Further treatment may include either medications to break down blood clots that block the blood flow to the heart, or mechanically restoring the flow by dilatation or bypass surgery of the blocked coronary artery. Coronary care unit admission allows rapid and safe treatment of complications such as ventricular tachycardia or ventricular fibrillation.
Prognosis
Despite advances in modern pharmacotherapy and device-based therapy, the short term mortality remains high in modern registry series (15%-20%).
See also
- acute coronary syndrome
- angina
- Cardiac arrest
- coronary thrombosis
- Hibernating myocardium
- Stunned myocardium
- Ventricular remodeling
References
External links
- Risk Assessment Tool for Estimating Your 10-year Risk of Having a Heart Attack - based on information of the Framingham Heart Study, from the United States National Heart, Lung and Blood Institute
- Heart Attack - overview of resources from MedlinePlus.
- Heart Attack Warning Signals from the Heart and Stroke Foundation of Canada
- Regional PCI for STEMI Resource Center - Evidence based online resource center for the development of regional PCI networks for acute STEMI
- STEMI Systems - Articles, profiles, and reviews of the latest publications involved in STEMI care. Quarterly newsletter.
- American College of Cardiology (ACC) Door to Balloon (D2B) Initiative.
- American Heart Association's Heart Attack web site - Information and resources for preventing, recognizing and treating heart attack.
- The MD TV: Comments on Hot Topics, State of the Art Presentations in Cardiovascular Medicine, Expert Reviews on Cardiovascular Research
- Clinical Trial Results: An up to dated resource of Cardiovascular Research
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
