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Cardiology Teaching Package

A Beginners Guide to Normal Heart Function, Sinus Rhythm & Common Cardiac Arrhythmias

Definition of Myocardial Infarction

Prior to 2001, 2 categories existed:

  1. Acute myocardial infarction (AMI)
  2. Unstable angina, subdivided into high and low risk

Now Myocardial infarction is defined if the following criteria are satisfied:

And at least one of the following:

Q waves can occur naturally on an ECG where they appear as a small downward deflection following the P wave, no more than 2 small squares in depth. Pathological Q waves are greater than 2 small squares in depth. They are often followed by a reduced R wave and are indicators of myocardial tissue death.

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