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Updated: Jul 16, 2026
16:40
A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Inappropriate ICD discharges due to "triple counting" during normal sinus rhythm.
Ejaz Khan1, Apostolos Voudouris, Stephen R Shorofsky
1Division of Cardiology, Department of Medicine, The University of Maryland School of Medicine, Baltimore, MD, USA.
Summary
Advanced renal failure and hyperkalemia can cause implantable cardioverter-defibrillator (ICD) malfunction. This case highlights how electrolyte abnormalities, specifically hyperkalemia, led to "triple counting" and inappropriate ICD shocks.
Area of Science:
- Cardiology
- Nephrology
- Electrophysiology
Background:
- Implantable cardioverter-defibrillators (ICDs) are crucial for managing life-threatening arrhythmias.
- Electrolyte imbalances, particularly hyperkalemia, can affect cardiac electrical activity.
Observation:
- A patient with advanced renal failure presented with multiple ICD shocks.
- Electrophysiology laboratory interrogation revealed significant hyperkalemia (serum potassium 7.6 mg/dL).
Findings:
- Intracardiac electrograms from the ICD showed "triple counting" during the QRS complex and T wave.
- This artifactual signal interpretation resulted in multiple inappropriate ICD shocks.
Implications:
- Hyperkalemia can distort intracardiac electrograms, leading to misinterpretation by ICDs.
- Prompt correction of electrolyte abnormalities is essential to prevent inappropriate ICD shocks in patients with renal failure.
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