Inappropriate Subcutaneous Implantable Cardioverter-defibrillator Shocks-A Rare Case of Triple Counting

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.