Pathologic Q Waves
Criteria for a previous myocardial infarction
Pathologic Q waves are a sign of absence of electrical activity. They can be thought of as an elecrical 'hole'. Myocardial infarction results in scar tissue that is electrically dead and therefore results in pathologic Q waves.
The precise criteria for pathologic Q waves have been debated. Here we present the latest definition as accepted by the ESC and ACC.[1]
- Definition of a pathologic Q wave
- Any Q wave in leads V1-V3
- Q wave > or = to 30ms (0.03s) in leads I, II, aVL, aVF, V4, V4, or V6 (the Q wave changes must be present in any two contiguous lead, and be > or = 1mm in depth).
Notes
- Absence of pathologic Q waves does not exclude a myocardial infarction!
- Lead III often shows Q waves, which are not pathologic as long as Q waves are absent in leads II and aVF (the contiguous leads)
For those interested: the Minnesota Code Classification System for Electrocardiographic Findings contains a very extensive definition of pathologic Q waves.
Referenties
- Alpert JS, Thygesen K, Antman E, and Bassand JP. Myocardial infarction redefined--a consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the redefinition of myocardial infarction. J Am Coll Cardiol. 2000 Sep;36(3):959-69. DOI:10.1016/s0735-1097(00)00804-4 |