What do Q waves on an ECG typically indicate?

Q waves on an ECG typically indicate previous myocardial infarction. When there is damage to the heart muscle, such as from an infarction, the electrical activity underneath that area can change. These changes can manifest as Q waves on the ECG.

In the context of a myocardial infarction, Q waves may appear days to weeks after the event, indicating that there has been significant heart muscle damage in that region. They are considered pathological if they are deep and wide, reflecting necrosis or scar tissue formation. The presence of Q waves is a marker that the heart has undergone significant injury in the past, which is critical for diagnosing individuals with a history of heart disease.

While other options address different cardiac issues, they do not relate specifically to the interpretation of Q waves in the context of past myocardial infarction, highlighting the importance of recognizing these waves as an indicator of prior cardiac events.