Which of the following findings is a characteristic marker of infarction?

• A. Wide QRS complex
• B. Deep Q wave
• C. Prolonged PR interval
• D. U wave presence

Answer: (B)

The presence of a deep Q wave is a characteristic marker of infarction on an electrocardiogram (ECG). In the context of myocardial infarction, the Q wave evolves from the necrosis of cardiac tissue, indicating that there has been significant damage to the heart muscle. These deep Q waves reflect the loss of electrical activity in the area of the heart that has been affected by the infarction. Typically, this change occurs in the leads that face the region of the heart where the infarction has taken place, providing valuable information about the specific area affected.

The development of deep Q waves is usually associated with a significant and often permanent change in the myocardium, distinguishing it from transient ischemic changes. This is an important diagnostic criterion in differentiating between acute and chronic ischemic conditions on an ECG, as acute ischemia may show other changes (like ST elevation or T wave inversions) that can resolve, while deep Q waves are more indicative of a past myocardial infarction.

The other options do not specifically indicate infarction. A wide QRS complex may suggest a bundle branch block or ventricular hypertrophy but is not specific to infarction. A prolonged PR interval could indicate atrioventricular block, and the presence of U waves is