Achieving sub-millimetric bipolar resolution while retaining the clinical eye: the first bifocal clinical mapping array
Y Abderrahman, S Masse, K De Silva, T Subha, J Asta, G Mokhtar-Sasani, P Lai, B Ebrahimi, C Rousu, D Sheppard, S Basu, K NanthakumarAbstract
Introduction
Clinicians often make heuristic mapping impressions of slow conduction and block at an apparent bipolar resolution of 2-4mm, while yearning for sub-millimetric resolution. Manufacturing considerations, such as the labor-intensive production of ring/cylindrical electrodes, have limited the number of electrodes on existing mapping arrays and thus resolution, compromising recording characteristics, and driving post-hoc conciliatory arguments on optimal resolution rather than true clinical validation. Smaller disc electrodes, with tighter resolution compared to ring/cylindrical electrodes, would be beneficial for sensing local activity, however their deployment has been hampered by impedance issues.
Objective
We sought to evaluate the performance of the novel Multidimensional (Multi-D) mapping array, which contains both 0.1mm and 2mm industry-standard bipoles and is comprised of ultra-small disc electrodes, against a current state-of-the-art mapping array with a 2mm bipolar resolution.
Methods
Five swine hearts were studied on a unique Langendorff setup adapted for ex-vivo CARTO studies. A hybrid two-spline array combining Multi-D ultra-small disc electrodes and the current state-of-the-art ring electrodes was custom-built to enable co-localized electrogram (EGM) recordings for a direct comparison between the two. With the hybrid two-spline array deployed at different sites on the endocardial surface of the left ventricular free wall, EGMs were recorded under different pacing protocols. Unipolar and bipolar EGMs from the two arrays were compared for maximum absolute dV/dt, peak-to-peak voltage (Vpp) and EGM complex width.
Results
Both unipolar and bipolar EGMs were successfully recorded from the Multi-D and state-of-the-art splines throughout all the experiments. In the unipolar configuration, Multi-D displayed lower Vpp (5.13 mV vs. 5.69 mV, p < 0.05) but a higher maximum absolute dV/dt (0.73 mV/ms vs. 0.53 mV/ms, p < 0.05). When comparing the 0.1mm Multi-D and 2mm industry-standard bipoles, Multi-D showed a much lower Vpp (1.15 mV vs. 3.38 mV, p < 0.05), consistent with the smaller electrical field. Across both unipolar and bipolar comparisons, Multi-D generally showed a trend of smaller EGM complex widths.
Conclusion
Multi-D, featuring ultra-small disc electrodes arranged with sub-millimetric resolution while retaining 2mm clinical resolution, produced unipolar and bipolar EGMs that appear more localized than those obtained from a current state-of-the-art device. The dual-resolution configuration leads to augmented mapping akin to a bifocal view with high-fidelity signals, without the limitation of a single bipolar resolution from a cumbersome ring-electrode array construction. These preliminary results highlight the potential of Multi-D for high-fidelity, multi-scale mapping; however, additional studies are needed to validate these findings and fully assess the implications of the difference in EGM complex width.