Correlation between the ventricular electrogram amplitude in sinus rhythm and in ventricular fibrillation.

Area of Science:

• Cardiology
• Biomedical Engineering

Background:

• Implantable defibrillators require accurate sensing of ventricular fibrillation for effective therapy.
• Assessing the safety margin for sensing ventricular fibrillation is crucial for device performance.

Purpose of the Study:

• To investigate if ventricular electrogram amplitude in sinus rhythm can predict amplitude during ventricular fibrillation.
• To evaluate this prediction as a proxy for the safety margin in sensing ventricular fibrillation.

Main Methods:

• Compared peak-to-peak epicardial ventricular electrogram amplitude in sinus rhythm and ventricular fibrillation in 12 patients.
• Recorded electrograms using an integrated bipolar lead, filtered at 10-50 Hz.
• Induced ventricular fibrillation via alternating current before defibrillator shock.

Main Results:

• A significant positive correlation (R=0.7, P<0.001) was found between sinus rhythm and ventricular fibrillation electrogram amplitudes.
• Mean amplitude in sinus rhythm was 15.3 ± 5.4 mV; in ventricular fibrillation, it was 8.3 ± 3.6 mV.
• Individual amplitude decrease during ventricular fibrillation varied widely (ratio 0.29-1.05), averaging a 0.55 ± 0.20 reduction.

Conclusions:

• Ventricular electrogram amplitude in sinus rhythm is a significant predictor of amplitude during ventricular fibrillation.
• This relationship can serve as an initial estimation of the safety margin for ventricular fibrillation sensing.
• Anticipate potential fourfold decreases in electrogram amplitude during ventricular fibrillation.