Mini-, Micro-, and Conventional Electrodes: An in Vivo Electrophysiology and Ex Vivo Histology Head-to-Head Comparison.

Objectives: This study sought to assess the relative effect of catheter, tissue, and catheter-tissue parameters, on the ability to determine the amount of viable myocardium in vivo.

Background: Although multiple variables impact bipolar voltages (BVs), electrode size, interelectrode spacing, and directional dependency are of particular interest with the development of catheters incorporating mini and microelectrodes.

Methods: Nine swine with early reperfusion myocardial infarctions were mapped using the QDot catheter and then remapped using a Pentaray catheter. All QDot points were matched with Pentaray points within 5 mm. The swine were sacrificed, and mapping data projected onto the heart. Transmural biopsies corresponding to mapping points were obtained, allowing a comparison of electrograms recorded by mini, micro-, and conventional electrodes with histology.

Results: The conventional BV of 2,322 QDot points was 1.9 ± 1.3 mV. The largest of the 3 microelectrode BVs (BV) average 4.8 ± 3.1 mV. The difference between the largest (BV) and smallest (BV) at a given location was 53.7 ± 18.1%. The relationships between both BV and BV and between the conventional BV and BV were positively related but with a significant spread in data, which was more pronounced for the latter. Pentaray points positively related to the BV with poor fit. On histology, increasing viable myocardium increased voltage, but both the slope coefficient and fit were best for BV.

Conclusions: Using histology, we could demonstrate that BV is superior to identify viable myocardium compared with BV and BV using the Pentaray catheter. The ability to simultaneously record 3 BVs with different orientations, for the same beat, with controllable contact and selecting BV for local BV may partially compensate for wave front direction.