What are the key ECG features of ventricular fibrillation?

• A. Chaotic, irregular waveform with no recognizable P waves, QRS, or T waves; requires immediate defibrillation.
• B. Regular, organized rhythm with identifiable P waves.
• C. Wide QRS tachycardia with visible P waves.
• D. Normal sinus rhythm.

Answer: (A)

Ventricular fibrillation is a life-threatening, chaotic electrical disturbance. On the ECG, the activity is irregular and disorganized, with no recognizable P waves, QRS complexes, or T waves. The ventricles are quivering rather than contracting effectively, so there is no coordinated pumping of blood. This lack of output makes immediate defibrillation essential toreset the electrical activity and allow a normal rhythm to restart.

This contrasts with a normal sinus rhythm, which shows a regular rhythm with identifiable P waves before each QRS complex, and with ventricular tachycardia, which presents as a wide, often somewhat organized rhythm that can still show a more defined QRS pattern (and may or may not have visible P waves).