inappropriate shock
An ICD shock delivered in response to misdetected rhythms that do not require defibrillation therapy.
Full Definition
Inappropriate shock refers to high-voltage therapy delivered by an implantable cardioverter-defibrillator when the device incorrectly interprets a non-life-threatening rhythm as ventricular fibrillation or ventricular tachycardia. Common causes include atrial fibrillation with rapid ventricular response, sinus tachycardia, lead fractures causing noise oversensing, or electromagnetic interference. These events are clinically significant because they cause patient distress, reduce quality of life, increase mortality risk, and deplete device battery. Prevention strategies include optimizing detection algorithms, programming longer detection times, utilizing discriminators to differentiate SVT from VT, and ensuring appropriate rate cutoffs for therapy zones.
Usage
Usage note: Distinguish from failed appropriate therapy; specify underlying cause when documenting.
In Context
- "The patient received an inappropriate shock during atrial fibrillation with rates of 180 bpm." — Emergency department visit note
- "Device interrogation revealed inappropriate shock delivery due to lead noise oversensing." — ICD malfunction report