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Purpose: Although bipolar radiofrequency (RF) ablation (RFA) is broadly used to eliminate ventricular tachycardias in the interventricular septum wall, it can fail to create transmural lesions in thick ventricular walls. To solve this problem, we explored whether an RF-energised guidewire inserted into the ventricular wall would enhance bipolar RFA in the creation of transmural lesions through the ventricular wall. Methods: We built three-dimensional computational models including two irrigated electrodes placed on opposing sides of the interventricular septum and a metal guidewire inserted into the septum. Computer simulations were conducted to compare the temperature distributions obtained with two ablation modes: bipolar mode (RF power delivered between both irrigated electrode) and time-division multiplexing (TDM) technique, which consists of activating the bipolar mode for 90% of the time and applying RF power between the guidewire and both irrigated electrodes during the remaining time. Results: The TDM technique was the most suitable in terms of creating wider lesions through the entire ventricular wall, avoiding the hour-glass shape of thermal lesions associated with the bipolar mode. This was especially apparent in the case of thick walls (15 mm). Furthermore, the TDM technique was able to create transmural lesions even when the guidewire was displaced from the midplane of the wall. Conclusions: An RF-energised guidewire could enhance bipolar RFA by allowing transmural lesions to be made through thick ventricular walls. However, the safety of this new approach must be assessed in future pre-clinical studies, especially in terms of the risk of stenosis and its clinical impact. [ABSTRACT FROM AUTHOR]

Purpose: The thermal effect of the intramyocardial blood perfusion on the size of lesions created by radiofrequency cardiac ablation (RFCA) has not been adequately studied to date. Our objective was to assess the impact of including this phenomenon in RFCA computer modelling in terms of the thermal lesion depth created. Methods: A computer model was built and computer simulations were conducted to assess the effect of including the blood perfusion term in the bioheat equation. This term mimics the intramyocardial blood flow (i.e., blood perfusion) in the cardiac wall at the site at which the RFCA is being conducted and hence represents a heat removing mechanism. When considered, blood perfusion rates ranged from 609 to 1719 ml/min/kg. Two electrode design and modes were considered: a non-irrigated electrode with constant temperature mode and an irrigated electrode with constant power mode. Results: All the depths computed without including the blood perfusion term were larger than those that did include it, regardless of perfusion rate. The differences in lesion depth between ignoring and including blood perfusion increased over time; for a 60 s RFCA they were 0.45 and 1 mm for minimum and maximum perfusion rate, respectively. The differences were more or less independent of blood flow in the cardiac chamber, electrode type and ablation mode. Conclusions: The findings suggest that the heat-sink effect of blood perfusion should be taken into account in the case of ablations (>1 minute) such as those conducted in RFCA of the ventricular wall. [ABSTRACT FROM AUTHOR]