Q wave in ECG

[Vishal]

Hello, one of my patient had Q wave in III and avF but no Q wave in II.would this mean that if the Q's are only seen in III or aVF (no Q in II), it does not really indicate an old MI? Thank you

[Vishal]

Hey doctors, please reply. I am totally confused, and I am in dire need of ur help.

[Hero]

This is a nice question. I supposed Dr Juni is going to answer you, afterall she has an experience of teaching chinese students and doing PG in USA . But she didn't, may be she is busy searching "nepali porno sites" . OK lets not talk about her, xenoMED moderators will again warn me to read the rules and regulations. So lets come to the main point.

Q wave in II, III and AVF suggests an old inferior wall MI. But u need to find out whether this is a pathological Q wave or not. Generally a Q wave in lead III is "allowed" and is the least specific of all leads in diagnosing old MI and especially if it "normalizes" with deep inspiration. My teacher used to say that the Q wave in lead III and AVF should be greater than 50% of the subsequent R wave to be significant. I tell u, u must look the ECG carefully, if there is even a very small R wave it is not a Q wave. To answer ur question—Q wave in III and AVF is adequate to diagnose an old MI?? I was always taught that one Q wave = 30% accurate, 2 Q waves = 60% accurate, 3 Q waves = 90% accurate for old inferior wall MI. But they have to be “true Q” waves: no R wave at all, and at least 1mm deep and 1mm wide or half the height of the subsequent R wave. Depending on history and other risk factors, I suppose we should strongly consider stress testing in any patient of intermediate or high risk for CAD, even if a true Q is in only one lead. It would be harder to decide what to do with low risk patients. Shall we simply watch or order blood chemistry, echo or directly go for cath-lab (what we do here)? What u guys do there in Nepal in such cases?

[Vishal]

what a great explanation!thanks Hero