What telemetry findings are typical of an implanted cardioverter-defibrillator (ICD) on rhythm strips?

• A. Steady rhythm with no spikes
• B. Sudden high-frequency spikes or shocks, possible pacing; assess need for device interrogation
• C. Regular QRS complexes with no spikes
• D. Only T-wave changes

Answer: (B)

ICD therapy is aimed at terminating dangerous ventricular rhythms, so telemetry from someone with an ICD typically shows abrupt, high-energy spikes that correspond to shocks. You may also see pacing spikes if the device is delivering anti-tachy pacing or post-shock pacing as it stabilizes the rhythm. After a shock, there can be a brief pause as the heart recovers. Because these spikes indicate device-delivered therapy, the appropriate next step is device interrogation to review stored events, confirm the therapy was appropriate, and check the device function, leads, and battery status. Other findings like a steady rhythm with no spikes or only T-wave changes do not reflect ICD-delivered therapy.