Key result
In an in silico model, bipolar electrogram amplitudes were significantly reduced when catheter orientation changed from parallel to perpendicular relative to the wave direction (1.77 to 0.79 mV, p<0.001).
Why the study?
Although bipolar electrograms are commonly used for catheter mapping and ablation of cardiac arrhythmias, their accuracy and reproducibility have not been evaluated.
Do catheter orientation, contact angle, conduction velocity, scar size, and catheter type influence bipolar electrogram morphology in an in silico model of atrial fibrillation?
Do catheter orientation, contact angle, conduction velocity, scar size, and catheter type influence bipolar electrogram morphology in an in silico model of atrial fibrillation?
Answers are grounded in this paper and cite their sources.
Multiple factors including catheter orientation, contact angle, conduction velocity, and catheter design significantly influence bipolar electrogram morphology, suggesting that universal voltage cut-off values may not be appropriate for substrate mapping.
Although bipolar electrograms (Bi-egms) are commonly used for catheter mapping and ablation of cardiac arrhythmias, the accuracy and reproducibility of Bi-egms have not been evaluated. We aimed to clarify the influence of the catheter orientation (CO), catheter contact angle (CA), local conduction velocity (CV), scar size, and catheter type on the Bi-egm morphology using an in silico 3-dimensional realistic model of atrial fibrillation. We constructed a 3-dimensional, realistic, in silico left atrial model with activation wave propagation including bipolar catheter models. Bi-egms were obtained by computing the extracellular potentials from the distal and proximal electrodes. The amplitude and width were measured on virtual Bi-egms obtained under different conditions created by changing the CO according to the wave direction, catheter-atrial wall CA, local CV, size of the non-conductive area, and catheter type. Bipolar voltages were also compared between virtual and clinically acquired Bi-egms. Bi-egm amplitudes were lower for a perpendicular than parallel CO relative to the wave direction (p<0.001), lower for a 90° than 0° CA (p<0.001), and lower for a CV of 0.13m/s than 0.48m/s (p<0.001). Larger sized non-conductive areas were associated with a decreased bipolar amplitude (p<0.001) and increased bipolar width (p<0.001). Among three commercially available catheters (Orion, Pentaray, and Thermocool), those with more narrowly spaced and smaller electrodes produced higher voltages on the virtual Bi-egms (p<0.001). Multiple factors including the CO, CA, CV, and catheter design significantly influence the Bi-egm morphology. Universal voltage cut-off values may not be appropriate for bipolar voltage-guided substrate mapping.
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Hwang et al. (2019) studied Atrial fibrillation (in silico model). Perpendicular catheter orientation (90°) vs. Parallel catheter orientation (0°) was evaluated on Bipolar electrogram amplitude (p=<0.001). In an in silico model, bipolar electrogram amplitudes were significantly reduced when catheter orientation changed from parallel to perpendicular relative to the wave direction (1.77 to 0.79 mV, p<0.001).
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