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Published on: February 28, 2012
Inappropriate Subcutaneous Implantable Cardioverter-defibrillator Shocks-A Rare Case of Triple Counting
Sai Nikhila Ghanta1, Bader Alotaibi2, Hakan Paydak2
1Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
Insights
Subcutaneous implantable cardioverter-defibrillators (S-ICDs) offer an alternative to transvenous devices but can deliver inappropriate shocks. This case highlights S-ICD oversensing of P-, R-, and T-waves causing false therapy delivery.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Sudden cardiac death (SCD) from ventricular tachyarrhythmias is a global health concern.
- Transvenous implantable cardioverter-defibrillators (ICDs) reduce SCD mortality but pose risks like infection and lead complications.
- Subcutaneous ICDs (S-ICDs) provide an alternative, particularly for patients with infection risk or venous access issues.
Observation:
- This report details a rare case of inappropriate S-ICD therapy delivery.
- The patient experienced shocks due to oversensing of P-, R-, and T-waves during sinus rhythm.
- This phenomenon, termed triple counting, led to a false detection of ventricular tachyarrhythmia.
Findings:
- Oversensing of cardiac signals, specifically P-waves and T-waves, can trigger inappropriate S-ICD shocks.
- The triple counting of P-, R-, and T-waves is an unusual cause of S-ICD oversensing.
- Limited case reports exist documenting inappropriate shocks from P-wave and T-wave oversensing.
Implications:
- Pre-implantation screening is crucial for identifying patients at risk of S-ICD inappropriate shocks.
- Understanding S-ICD sensing algorithms is vital for optimizing device performance.
- Further research into S-ICD signal processing may reduce instances of inappropriate therapy.
Abstract:
Sudden cardiac death (SCD) caused by ventricular tachyarrhythmias is a significant contributor to cardiovascular deaths worldwide. Implantable cardioverter-defibrillators (ICDs) have shown efficacy in preventing and reducing mortality from SCD, but traditional transvenous ICDs have inherent challenges and drawbacks, such as lead fractures, lead-associated endocarditis, and lead failure. To address these issues, subcutaneous ICDs (S-ICDs) have been developed. S-ICDs lack pacing capacity but are a valid alternative for patients at high risk for infection or with difficult venous access. Pre-implantation screening can help prevent inappropriate device shocks. We present a case in which a patient received inappropriate S-ICD therapy, which was attributed to the triple counting of P-, R-, and T-waves in a patient with sinus rhythm. This is an unusual occurrence, and, to the best of our knowledge, there are only a limited number of case reports documenting inappropriate shocks due to the oversensing of P-waves and T-waves.
