Review Question - QID 216646

This patient who presents following a motor vehicle accident is found to be pulseless with a rhythm strip showing ventricular fibrillation, which is managed with cardiopulmonary resuscitation (CPR) and immediate defibrillation.

Ventricular fibrillation and pulseless ventricular tachycardia are 2 ventricular dysrhymias that may be seen in patients with cardiac arrest and are managed with defibrillation. Ventricular fibrillation is characterized by irregular waveforms on ECG with no identifiable P waves, QRS complexes, or T waves whereas ventricular tachycardia is characterized by broad, uniform QRS complexes. Per the Advanced Cardiovascular Life Support (ACLS) algorithm, if a patient is found to have ventricular fibrillation, immediate defibrillation is indicated. CPR is conducted following defibrillation, and the rhythm is re-assessed to determine the need for additional defibrillation in addition to the administration of epinephrine as the cornerstone of management. Amiodarone and lidocaine may also be administered in ventricular fibrillation pending the circumstances. The cardiac rhythm is continuously reassessed to determine the need for defibrillation until return of spontaneous circulation is achieved. Any reversible causes should be addressed, if applicable.

Ludhwani et al. note that ventricular fibrillation is caused by irregular electrical activity in the ventricles. It normally presents with a heart rate greater than 300/min. Early treatment including defibrillation and CPR is recommended as this condition has a high mortality if not addressed within minutes. Ludhawni et al. found that patients receiving prompt defibrillation have shown improved survival (39.3%) compared to patients in whom defibrillation was delayed by 2 minutes or more (22.2%).

Figure A is a rhythm strip tracing showing ventricular fibrillation, in which there are irregular waveforms of varying amplitude without identifiable P waves, QRS complexes, or T waves.

Incorrect Answers:
Answer 1: Amiodarone is used in patients with ventricular arrhythmias, but is not used until after several rounds of defibrillation and CPR are completed and would therefore not be the next best step in management. It would be the most appropriate initial step in management in a hemodynamically stable patient in ventricular tachycardia.

Answer 3: Epinephrine is used in patients with ventricular fibrillation, pulseless ventricular tachycardia, asystole, and pulseless electrical activity, but does not come before defibrillation per the ACLS algorithm.

Answer 4: Procainamide is an antiarrhythmic drug that may be used in patients who are stable with ventricular tachycardia or in patients with Wolf-Parkinson-White syndrome who have tachdysrhythmias.

Answer 5: Synchronized cardioversion is used in unstable patients who present with supraventricular tachycardia, atrial fibrillation, or atrial flutter. It is not used in pulseless patients.

Bullet Summary:
Defibrillation is the initial treatment for ventricular fibrillation and pulseless ventricular tachycardia.