What are the characteristic EKG changes associated with a pulmonary embolus?

What are the characteristic EKG changes associated with a pulmonary embolus?

• A. Inverted T waves in leads V1-V4
• B. Large S wave in lead I, ST segment depression in lead II, and a Q wave in lead III
• C. Wide QRS complex in all leads
• D. Peaked T waves in all leads

Answer: (B)

The characteristic EKG changes associated with a pulmonary embolism often include the presence of a large S wave in lead I, ST segment depression in lead II, and a Q wave in lead III. This classic pattern is known as the S1Q3T3 pattern, which is specifically linked to acute pulmonary embolism.

The rationale behind this is that when a pulmonary embolism occurs, it can cause right heart strain due to increased pressure in the pulmonary arteries. Lead I shows a large S wave reflecting right ventricular overload, while lead III may show a Q wave indicating right heart strain and the changes in the ST segment of lead II are also reflective of the right ventricular stress response to the acute event. Therefore, this combination of findings effectively helps clinicians identify a possible pulmonary embolism in a patient based on EKG interpretation.

Understanding these changes is critical for timely diagnosis and treatment, as prompt recognition of a pulmonary embolism can significantly affect patient outcomes.