Traces downloaded from the device. (Top) Noise leading up to the delivery of the first inappropriate shock. This was misinterpreted by the device as ventricular fibrillation, demonstrating the importance of electrogram review before deciding appropriateness of therapy. (Middle) Provocation testing by arm movement, shown here to cause significant noise in the primary and secondary vectors but not in the alternate vector. Hence, the alternate was the chosen vector going forward. (Bottom) Despite negative provocation testing, the Alternate vector could still be affected by enough noise to trigger an inappropriate shock.