Multiple factors influence the morphology of the bipolar electrogram: An in silico modeling study

Area of Science:

• Cardiac Electrophysiology
• Computational Modeling
• Medical Device Engineering

Background:

• Bipolar electrograms (Bi-egms) are crucial for cardiac arrhythmia mapping and ablation.
• The accuracy and reproducibility of Bi-egms are not well-established.
• Factors influencing Bi-egm morphology require detailed investigation.

Purpose of the Study:

• To evaluate the impact of catheter orientation (CO), contact angle (CA), local conduction velocity (CV), scar size, and catheter type on Bi-egm morphology.
• To assess the reliability of Bi-egm measurements in atrial fibrillation using an in silico model.
• To determine if universal voltage cut-off values are appropriate for substrate mapping.

Main Methods:

• Development of a 3D realistic in silico left atrial model with activation wave propagation.
• Simulation of bipolar electrograms (Bi-egms) by computing extracellular potentials.
• Systematic variation of CO, CA, CV, scar size, and catheter type to analyze Bi-egm amplitude and width.
• Comparison of virtual Bi-egms with clinically acquired data.

Main Results:

• Bi-egm amplitudes decreased with perpendicular CO, 90° CA, and slower CV (0.13 m/s vs. 0.48 m/s).
• Larger non-conductive areas reduced Bi-egm amplitude and increased width.
• Catheters with narrower electrode spacing and smaller electrodes yielded higher voltages.
• Significant influence of CO, CA, CV, and catheter design on Bi-egm morphology was observed.

Conclusions:

• Catheter orientation, contact angle, conduction velocity, scar size, and catheter design critically influence bipolar electrogram morphology.
• Universal voltage cut-off values for bipolar voltage-guided substrate mapping may be inappropriate.
• In silico modeling provides valuable insights into factors affecting electrogram signal characteristics.