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Common causes of ischemia are: | Common causes of ischemia are: | ||
* Narrowing or obstruction of a coronary artery. | * Narrowing or obstruction of a coronary artery. | ||
* A fast | * A fast rhythm disturbance, causing a disbalance in supply and demand of energy. | ||
A short period of ischemia causes ''reversibele'' effects: The heartcells will be able to recover. When the ep[isode of ischemia lasts for a longer period of time, heartmuscle cells will die. This is called a '''heartattack''' or '''myocardial infarction'''. That is why it is critical to recognize ischemia on the ECG in an early stage. | A short period of ischemia causes ''reversibele'' effects: The heartcells will be able to recover. When the ep[isode of ischemia lasts for a longer period of time, heartmuscle cells will die. This is called a '''heartattack''' or '''myocardial infarction'''. That is why it is critical to recognize ischemia on the ECG in an early stage. | ||
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'''Signs and symptoms of myocardial ischemia:''' | '''Signs and symptoms of myocardial ischemia:''' | ||
* | * Crushing pain on the chest (angina pectoris), behind the sternum, often radiating to the lower jaw or the left arm | ||
* | * Fear of dying | ||
* | * Nausea | ||
* | * Shock (manifesting as paleness, low blood pressure, fast weak pulse) shock | ||
* | * Rhythm dysturbances (in particular increasing prevalnce of ventricluar ectopia, ventricular tachycardia, AV block) | ||
===Risk assessment of ischemia=== | ===Risk assessment of ischemia=== | ||
The narrowing of the coronary artery leading to a myocardial infarction, usually develops over several years. An increased risk of myocardial infraction can be estimated using [http://www.escardio.org/initiatives/prevention/prevention-tools/SCORE-Risk-Charts.htm SCORE system] which is developed by the European Society of cardiology (ESC). As shown in the figue, the most important risk factors for myocardial infrcation are: | |||
* | *Male sexe | ||
* | *Smoking | ||
* | *Hypertension | ||
* | *Diabetes Mellitus | ||
* | *Hypercholesterolemia | ||
An exercise test such as a bicycle or treadmilltest, may be usefull in detecting myocardial ischemia after exercise.<cite>accexercise</cite> In such a test, a continuous ECG registration is performed during exercise. The ST-segment, blood pressure asnd clinical status of the patient (i.e. chest complaints) are monitorered during and after the test. | |||
An excersize test is positive for myocardial ischemia when the following criteria are met: | |||
* | * Horizontal or downsloping ST-depression of = 1mm, 60 of 80ms na het J-punt | ||
* ST | * ST elevation of = 1.0 mm | ||
{{clr}} | {{clr}} | ||