Impact of Micro-, Mini- and Multi-Electrode Mapping on Ventricular Substrate Characterisation

Abstract

Accurate substrate characterisation may improve the evolving understanding and treatment of cardiac arrhythmias. During substrate-based ablation techniques, wide practice variations exist with mapping via dedicated multi-electrode catheter or conventional ablation catheters. Recently, newer ablation catheter technology with embedded mapping electrodes have been introduced. This article focuses on the general misconceptions of voltage mapping and more specific differences in unipolar and bipolar signal morphology, field of view, signal-to-noise ratio, mapping capabilities (density and resolution), catheter-specific voltage thresholds and impact of micro-, mini- and multi-electrodes for substrate mapping. Efficiency and cost-effectiveness of different catheter types are discussed. Increasing sampling density with smaller electrodes allows for higher resolution with a greater likelihood to record near-field electrical information. These advances may help to further improve our mechanistic understanding of the correlation between substrate and ventricular tachycardia, as well as macro-reentry arrhythmia in humans.

Local abnormal ventricular activity detection in scar‐related VT: Microelectrode versus conventional bipolar electrode

“…One could also speculate that under rare circumstances, the ME may miss the surviving bundle by a couple of millimeters while the larger detection from CBE records it. 16 This is strongly suggested by the result of RFCA described in Figure 3B, in which LAVA detected by ME disappeared while LAVA detected by CBE persisted. Another explanation might be that the larger electrodes may have a larger field of view in deeper substrates.…”

“…Theoretically, the opposite phenomenon, Type 3 detection, could occur. However, few papers have described this phenomenon in scar-related VT. 15,16 This study showed that 9.2% of LAVAs were detected by CBE without detecting the corresponding signals on ME.…”

Heterogeneous scar with functional block in ventricular tachycardia circuit: Visualization of moderate high-density mapping

“…All recorded voltages are subject to the size, spacing, and orientation of the recording electrodes relative to the wavefront. 14 The Advisor HD Grid consists of 4 parallel splines that are equally spaced 3 mm apart, each with 4 1-mm electrodes spaced 3 mm apart (4 × 4 electrode configuration). The catheter design allows for the simultaneous recording of bipolar electrograms in the orthogonal direction and within the same dimension.…”

Structure and function of the ventricular tachycardia isthmus

“…Yet, the definition of a normal left ventricular endocardial voltage in patients with postinfarct scar is still lacking (169). The values of bipolar electrogram cutoffs are also limited by activation wavefront direction (170), and there are significant voltage differences between diagonally orthogonal bipolar electrode pairs at any given recording site (171). High-density multi-electrode grid catheters can offer improvement because they enable simultaneous recordings from multiple orthogonal directions with the ability to select the largest voltage level in a small region (170,172) and can improve depiction of the diastolic pathway (173).…”

“…The values of bipolar electrogram cutoffs are also limited by activation wavefront direction (170), and there are significant voltage differences between diagonally orthogonal bipolar electrode pairs at any given recording site (171). High-density multi-electrode grid catheters can offer improvement because they enable simultaneous recordings from multiple orthogonal directions with the ability to select the largest voltage level in a small region (170,172) and can improve depiction of the diastolic pathway (173). Extensive substrate ablation of local abnormal ventricular activity (LAVA) evident during sinus rhythm or pacing is also utilized in targeting (164,174).…”