Q: What is the danger of synchronized cardioversion in the presence of hyperkalemia?


Answer:

Cardioversion in "synchronized" form reads the EKG so the shock occurs on an R wave. When you synchronize cardiovert someone, it may take few seconds until the defibrillator senses an R wave and delivers the shock. Sometimes it takes 3 or 4 QRS complexes to do this.

If the patient has severe hyperkalemia, sometimes the defibrillator may sense tall, peaked T waves as QRS complexes. If you deliver a cardioversion shock that is sync'd on the T wave, you may induce ventricular fibrillation.