In massive pulmonary embolism–related cardiac arrest, which rhythm is often observed initially?

• A. Ventricular fibrillation
• B. PEA
• C. Asystole
• D. Sinus tachycardia

Answer: (B)

Massive pulmonary embolism causes a sudden obstruction to blood flow, so the heart’s electrical activity can continue even though there is no effective circulation. This means you’ll often see organized electrical activity on the monitor but no palpable pulse or blood pressure—a pulseless electrical activity pattern. It’s a common arrest rhythm in this scenario because the problem is mechanical obstruction and RV failure, not a primary electrical disruption of the heart. By contrast, ventricular fibrillation or asystole are less characteristic of PE at the onset, and sinus tachycardia reflects pre-arrest compensatory activity rather than the arrest rhythm itself. Recognizing PEA directs you to CPR plus rapid evaluation for reversible causes like PE and to consider therapies such as thrombolysis or embolectomy when appropriate.