Spatial temperature reconstructions in myocardial tissues undergoing radiofrequency ablations by performing high-resolved temperature measurements.

<bold>Background: </bold>Radiofrequency (RF) lesion creation is related to the heat propagation induced by RF application on tissues. Thermocouple embedded in the RF antenna are not able to predict deep tissue temperature at various level.<bold>Objectives: </bold>This study aims to investigate the influence of power delivered on radiofrequency catheter ablation (RFCA) effects by means of high resolved 2D temperature maps.<bold>Methods: </bold>Three trials of four ablations (12 applications) were executed on each specimen of healthy excised swine myocardium in different application points at four RF power values (30 W, 40 W, 50 W, and 60 W) for a fixed treatment time. All the data provided by the fiber Bragg gratings (FBGs) were analyzed. Temperature variations (ΔT) in time recorded in the 28 sites of measurements were reported. Also, temperature maps showing the ΔT spatial distribution reached within the tissue at the end of the RFCA were produced and displayed, together with the representation of the lethal isotherm. Moreover, the time of achievement of the lethal isotherm at different tissue depths (from 1 to 8 mm) was evaluated for the four power settings.<bold>Results: </bold>Temperature trends reported comparable profiles across the different power settings. ΔT values and ΔT rising times showed dependence on the sensors' proximity to the RF energy source and on the set RF power. Temperature maps confirmed that heat propagation occurs preferentially along the width of the tissue than in the depth. Also, for the adjusted treatment time, no power setting guarantees lesions thicker than 6 mm.<bold>Conclusions: </bold>ΔT maximal values and ΔT rising time strongly depends on the proximity of the tissues to RF energy source, as well as on the RF power setting. A plateau is reached in lesion size, regardless of the power setting. A first correlation between lesion size, power setting, and time to achieve lethal isotherms has been established. [ABSTRACT FROM AUTHOR]