Guiding the e-field for advanced transmural mapping with novel modification to perpendicular electrode arrangement: advent of a new diagnostic catheter
S Masse, K De Silva, T Subha, Y Abderrahman, J Asta, P F H Lai, B Ebrahimi, L Botzer, D Sheppard, D Highsmith, C Rousu, G Malki, K Magtibay, K NanthakumarAbstract
Introduction
Recently we described a new type of electrode configuration termed perpendicular bipole (Perp_B) that provides a better local assessment without losing its unipolar characteristics (1). The perpendicular arrangement is created by combining a reference electrode located in the blood pool directly above the contact electrode. This electrode configuration can be considered as a local unipole for morphology analysis and to be impervious to direction bias. This arrangement might provide local information from the mapping surface (XY plane) but the effect of configuration parameters on the Perp_B to the field of view (FOV) through the myocardium (Z axis) has not been studied.
Objective
We present here our progression of implementing the Perp_B first as single pair arrangement and then as a mapping array prototype. Then we review options for manufacturing a clinically viable Perp_B array, while evaluating the effect of novel electrode design and isolation to the Perp_B FOV. We demonstrate from observations in lesion assessment to variation on electric field (E-Field) to demonstrate how this new construct may provide a tomographic view of the myocardium in a catheter.
Methods
Experimental studies were performed on isolated rabbit and swine heart preparation. 1) Perp_B were constructed from 2mm silver beads or available electrode arrays separated by air gap to allow blood to circulate between the electrodes. RF ablation lesions were created via the contact electrode while Perp_B amplitude was measured. 2) Isolated swine heart studies were performed with perpendicular arrangement with different spacing and isolation material on a novel diagnostic prototype while recording the egms on Carto. 3) Modelling studies were undertaken to understand the influence of insulation on E-field manipulation.
Results
Perp_bi could predict lesion assessment in thin tissue rabbit model as measured by amplitude reduction being linearly correlated to lesion delivery (59% Vpp reduction vs. 68% tissue depth, p=0.01). Modelling studies suggested a trend of increased amplitude in Perp_B amplitude as a result of inter-electrode insulation. This was confirmed in experimental studies Vpp of 2.02mV vs. 0.46mV (p<0.05) for insulator vs. non-insulator configurations, while combining more complexes, suggesting a dependence of perp_B FOV to inter-electrode configuration.
Conclusion
A perpendicular bipole without isolation provides local assessment, while isolation increased the FOV of the electrode by guiding the E-field to the mapping surface and functioning as a selective transmural unipole. Strategic isolation allows for potent bipole-like local clarity, while providing local unipole-like features that provides a window into the myocardium. Implementation of this strategy in catheter design will provide a unique tool for characterization of the effective depth view and window into the myocardium, while clarifying mechanisms of arrhythmia.Concepts of perpendicular bipoleEffect of insulator on perp_bi