Failure of Ventricular Fibrillation Sensing During Subcutaneous Implantable Defibrillator Testing: A Twitchy Situation.

Oversensing of extra-cardiac noise may inhibit delivery of subcutaneous cardiac implantable defibrillator (S-ICD) therapy. We report a case of diaphragmatic tetany resulting in the inhibition of S-ICD therapy at the time of defibrillator testing without the use of muscle relaxants. Clinicians should be aware of this phenomenon.