What is the significance of Q waves in diagnosing prior MI?

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Multiple Choice

What is the significance of Q waves in diagnosing prior MI?

Q waves signify prior myocardial infarction and scar. When heart muscle has undergone necrosis and healing, the affected tissue becomes nonconductive scar, which alters the direction of ventricular depolarization and produces a downward deflection in the leads overlying that region. Pathologic Q waves—typically wider than 0.04 seconds and deeper than about a quarter of the following R wave—tend to persist, providing evidence of a completed infarction with permanent scar in that territory. While small Q waves can be seen as normal variants in some healthy individuals (including many young athletes), persistent, clearly defined Q waves in the expected leads point to a past MI with scar rather than a normal finding.

Q waves signify prior myocardial infarction and scar. When heart muscle has undergone necrosis and healing, the affected tissue becomes nonconductive scar, which alters the direction of ventricular depolarization and produces a downward deflection in the leads overlying that region. Pathologic Q waves—typically wider than 0.04 seconds and deeper than about a quarter of the following R wave—tend to persist, providing evidence of a completed infarction with permanent scar in that territory. While small Q waves can be seen as normal variants in some healthy individuals (including many young athletes), persistent, clearly defined Q waves in the expected leads point to a past MI with scar rather than a normal finding.

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