Lesion Dimensions During Temperature-Controlled Radiofrequency Catheter Ablation of Left Ventricular Porcine Myocardium

Abstract

Background-It is important to increase lesion size to improve the success rate for radiofrequency ablation of ischemic ventricular tachycardia. This study of radiofrequency ablation, with adjustment of power to approach a preset target temperature, ie, temperature-controlled ablation, explores the effect of catheter-tip length, ablation site, and convective cooling on lesion dimensions. Methods and Results-In vitro strips of porcine left ventricular myocardium during different levels of convective cooling and in vivo pig hearts at 2 or 3 left ventricular sites were ablated with 2-to 12-mm-tip catheters. We found increased lesion volume for increased catheter-tip length Յ8 mm in vitro (PϽ0.05) and 6 mm in vivo (PϽ0.0001), but no further increase was found for longer tips. For the 4-to 10-mm catheter tips, we found smaller lesion volume in low-flow areas (apex) than in high-flow areas (free wall and septum) (PϽ0.05). Increasing convective cooling of the catheter tip in vitro increased lesion volume (PϽ0.0005) for the 4-and 8-mm tips but not for the 12-mm tip as the generator reached maximum output. In contrast to power-controlled ablation, we found a negative correlation between tip temperature reached and lesion volume for applications in which maximum generator output was not achieved (PϽ0.0001), whereas delivered power and lesion volume correlated positively (PϽ0.0001). Conclusions-Lesion size differs in different left ventricular target sites, which is probably related to convective cooling, as illustrated in vitro. Longer electrode tips increase lesion size for tip lengths Յ6 to 8 mm. For temperature-controlled ablation, the tip temperature achieved is a poor predictor of lesion size. (Circulation. 1999;99:319-325.)

Near-infrared spectroscopy integrated catheter for characterization of myocardial tissues: preliminary demonstrations to radiofrequency ablation therapy for atrial fibrillation

“…Conventional catheters report indirect parameters, which may not necessarily correlate with successful lesion formation [13,14]. In previous works, catheter-based OCT has been used to directly visualize the myocardium surface [18].…”

“…However, a robust correlation between lesion depth and tissue impedance, or catheter tiptemperature, has yet to be observed [13,14]. As a result, operator skill and facility experience play a large role in treatment outcome [15].…”

Intramural Coronary Vasculature Prevents Transmural Radiofrequency Lesion Formation

“…Given the instantaneous heating of a larger volume of myocardium with simultaneous energy delivery, a smaller volume of preserved myocardium might be expected. 11 This may result from similar total energy deliveries to create simultaneous and sequential lesions. The protective effect of intramyocardial perfusion even at high flow rates can be overwhelmed by high energy deliveries and very high tissue temperatures.…”

Contact force and impedance decrease during ablation depends on catheter location and orientation: insights from pulmonary vein isolation using a contact force-sensing catheter

“…Catheter tip temperature has shown its potential to predict lesion formation [21]. With the introduction of the irrigated tip catheters and especially with the recently launched highly effectively cooled Bporous^catheters, however, this information is lost despite being the only direct measurement of the effective energy transfer for catheter ablation.…”