What type of wave is diagnostic for myocardial infarction?

What type of wave is diagnostic for myocardial infarction?

• A. Peaked T waves
• B. Flat ST segments
• C. Significant Q waves
• D. U waves

Answer: (C)

Significant Q waves on an EKG are a key diagnostic indicator of myocardial infarction (MI). When myocardial tissue becomes ischemic or necrotic due to loss of blood supply, particularly in the case of a heart attack, it can result in the development of pathological Q waves. These Q waves are typically deeper and wider than normal, reflecting the presence of dead myocardial tissue.

The presence of significant Q waves usually indicates that the infarction is more than a few hours old, as it takes time for these waves to develop following an event of cardiac cell death. Thus, their identification on an EKG is critical for confirming the diagnosis of an MI and assessing its past occurrence.

In contrast, peaked T waves may indicate hyperkalemia or early ischemia but are not specific for MI, while flat ST segments generally indicate normal activity or can be seen in various conditions that do not pertain to infarction. U waves are associated with repolarization disorders, not directly with myocardial infarction.