EXERCISE 1. A patient in the emergency department presents with dyspnea at rest, distended jugular veins, and chest pain. You suspect an acute myocardial infarction and obtain a 12-lead ECG: ¹⁰

ECG Suggesting Acute Pulmonary Embolism

The pattern suggests acute pulmonary embolism. Diagnosis is confirmed by a spiral CT scan of the chest that shows a massive saddle PE in the right and left main pulmonary arteries.

 List the ECG criteria for pulmonary embolism that are seen in the ECG tracing above.

RATIONALE:

ÅQRSF 165°: aVF is the isoelectric lead, and lead I has a negative deflection. The axis is rotated 15° toward aVF because aVF is more positive than negative −180° − 15° = 165°. Negative deflections of lead II and aVR and positive deflections in lead aVL and III further confirm this evaluation of the cardiac axis.

Rationale Answer Infograph

The ECS suggests a complete RBBB because of the RSR pattern in leads V₁ through V₃.

• Presence of S_I Q_III inverted-T_III
• Inverted T waves in V₁–V₄ (see 12-lead ECG above)
• Clockwise rotation