PO-02-181 THE CHARACTERISTICS OF TEMPERATURE-CONTROLLED ABLATION: WHAT’S OLD IS NOW NEW

Abstract

More than 20 years ago, temperature was used to guide ablative intervention. This was subsequently replaced by power to drive intervention. Recently, temperature-guided ablation has been reintroduced into the ablation armament. But the anatomic and electrical characteristics of currently available temperature-controlled ablation is unclear. To verify the DiamondTemp temperature-controlled ablation system in the ventricle Both ventricles of canines (33.6kg [32.4-39.4]) were ablated using the open-irrigated temperature-controlled DiamondTemp ablation system controlling power to maintain temperature set-point and followed for one month. The temperature set points for the ablation were set at 50 and 60°C and the ablation duration was set at 30-90 sec. After ablation of the right and left ventricles, gadolinium and 8-10% triphenyl tetrazolium chloride were administered intravenously; postmortem delayed contrast-enhanced magnetic resonance (MR) imaging was performed on a 3 Tesla device, fixed with 10% formalin solution, and pathological examination was performed. 8 animals underwent evaluation of temperature-guided ablation with 65 lesions created. Lesions were well distributed throughout the myocardium. The lesion sites and number for the set temperature are as shown in the table. The power used to create these lesions is also as shown in the table. As can be seen, there is appreciable variability in actual power required to achieve and maintain a particular temperature set point. Power required to maintains the set point is 28.3±10.4(W) in set point 50°C and 42.1±8.7(W) in set point 60°C. Lesion size is also as noted in the table where the 50°C group produced smaller lesion than the 60°C group (p<0.001), the gross pathological lesion volumes were smaller than the MR lesion volumes (p<0.001) and the RV lesions tended to be smaller than the LV lesions due to LV wall thickness. (p=0.095). In looking at all lesions, the maximum depth was 8.1±2.1 mm, the depth at maximum width was 3.1±1.9mm and the maximum width at any site was 8.4±2.1mm. At a set point of 50°C, transmural lesions were seen in 12.9% in 50.0 (%) at a set point 60°C (p=0.001). These data demonstrate that in in situ deliveries, the biophysics of ablation using a temperature-controlled RF ablation system can be effective and accurate in safely creating lesions of required size. The lesion size with a set point of 60°C was more effective than the set point 50°C, with good control.