Electrogram width parameter analysis in implantable cardioverter defibrillators: Influence of body position and...

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Devices

Background:

• The electrogram (EGM) width criterion is an algorithm in implantable cardioverter-defibrillators (ICDs) used to distinguish ventricular tachycardia from other arrhythmias.
• Its accuracy relies on optimal settings for slew and width thresholds, which may be influenced by patient body position and electrode configuration.

Purpose of the Study:

• To evaluate the stability of slew and width thresholds in supine versus orthostatic positions using tip-to-ventricular coil and can-to-ventricular coil configurations.
• To assess the time-dependent variations of these parameters at a 6-month follow-up.

Main Methods:

• Fifty-eight ICD recipients (Medtronic 7223cx and 7227cx) were studied.
• Thresholds were measured in supine and orthostatic positions, and at 1- and 6-month follow-ups.
• Tip-to-ventricular coil and can-to-ventricular coil configurations were analyzed.

Main Results:

• Body position changes caused significant threshold variations in 36% (tip-to-coil) and 44% (can-to-coil) of patients.
• Width threshold variation was significant (P < 0.02) with the can-to-coil configuration.
• Time-dependent variations were observed in 75% (can-to-coil) and 50% (tip-to-coil) of patients, with larger changes in the tip-to-coil group (P < 0.01).

Conclusions:

• EGM width parameters exhibit variability with body position and over time, particularly with the tip-to-coil configuration.
• The tip-to-coil configuration is less sensitive to body position but more prone to time-related variations.
• Findings suggest potential for optimizing ICD programming, though further investigation is needed to confirm improved discrimination specificity.