Which statement about Q waves on telemetry is correct?

Which statement about Q waves on telemetry is correct?

• A. Q waves are always a normal variant with no clinical significance.
• B. Q waves measure the ST segment duration.
• C. Q waves are only seen with hyperkalemia.
• D. Pathologic Q waves may indicate prior myocardial infarction; correlate with history and other ECGs.

Answer: (D)

Q waves signal the start of ventricular depolarization, and their significance depends on size, duration, and placement. They are not automatically meaningless; a Q wave becomes abnormal (pathologic) when it is wide and deep in a pattern that suggests scar from myocardial damage. Specifically, a pathologic Q wave is typically wider than 0.04 seconds and deeper than about one-quarter of the following R wave in a given lead, often appearing in two or more contiguous leads. When such Q waves are present, they point to a prior myocardial infarction where heart muscle has scar tissue and no longer conducts normally. Because Q waves can sometimes be seen as a normal variant in some individuals, confirming prior infarction requires context. You should correlate with the patient’s history and compare with previous ECGs or serial tracings to determine if the Q waves reflect past MI rather than a benign finding. That’s why the statement linking pathologic Q waves to prior MI, with corroboration from history and other ECGs, is the best choice. Q waves do not measure the ST segment duration, and they are not specific to hyperkalemia, so those options aren’t correct.

Q waves signal the start of ventricular depolarization, and their significance depends on size, duration, and placement. They are not automatically meaningless; a Q wave becomes abnormal (pathologic) when it is wide and deep in a pattern that suggests scar from myocardial damage. Specifically, a pathologic Q wave is typically wider than 0.04 seconds and deeper than about one-quarter of the following R wave in a given lead, often appearing in two or more contiguous leads. When such Q waves are present, they point to a prior myocardial infarction where heart muscle has scar tissue and no longer conducts normally.

Because Q waves can sometimes be seen as a normal variant in some individuals, confirming prior infarction requires context. You should correlate with the patient’s history and compare with previous ECGs or serial tracings to determine if the Q waves reflect past MI rather than a benign finding. That’s why the statement linking pathologic Q waves to prior MI, with corroboration from history and other ECGs, is the best choice. Q waves do not measure the ST segment duration, and they are not specific to hyperkalemia, so those options aren’t correct.