Temperature-Controlled Cooled-Tip Radiofrequency Ablation in Left Ventricular Myocardium Avoidance of Steam Pop During Ablation

Abstract

SummarySteam pop and intramural charring have been reported during cooled-tip radiofrequency catheter ablation (RFCA). We studied the feasibility of temperature-controlled cooled-tip RFCA in the canine heart.An internally cooled ablation catheter was inserted into the left ventricle. A custom-made radiofrequency (RF) generator capable of controlling the tip-temperature at the preset level by slow increases in the power was used. Temperature-controlled cooled-tip RF applications were performed at a target temperature of 40°C for 90 seconds. Acute study: Intramyocardial temperature was measured at the ablation site in 10 dogs by inserting a fluoroptic probe. Chronic study: Lesion depth and volume were measured in 5 dogs after 3 weeks of survival. In the acute study, no pop or abrupt impedance rise was observed. Maximum intramyocardial temperature was 72.4 ± 14.4°C at 2-4 mm above the endocardium. No coagulum formation, craters, or intramural charring were observed. Maximum lesion depth was 6.7 ± 1.5 mm, and lesion volume was 404 ± 219 mm 3 . In the chronic study, maximum lesion depth was 5.9 ± 1.1 mm, and lesion volume was 281 ± 210 mm 3 . Temperature controlled RFCA is feasible with a cooled-tip catheter and an RF generator that slowly increases the RF power until the preset catheter-tip temperature is reached. (Int Heart J 2010; 51: 193-198)

Impedance decrement indexes for avoiding steam‐pop during bipolar radiofrequency ablation: An experimental study using a dual‐bath preparation

“…However, once higher temperature-rise develops inside the myocardium with limited cooling effects, steam-pop-induced myocardial disruption can occur in some cases. [12][13][14] To avoid this complication, TID around 20 ohm has been used in UNIP ablation. 6,7 However, in several studies, 9,15 these indexes were reported to be insufficient to prevent the occurrence of steam-pop.…”

Radiofrequency cardiac ablation with catheters placed on opposing sides of the ventricular wall: Computer modelling comparing bipolar and unipolar modes

“…The models considered two internally cooled catheter tip electrodes (7Fr diameter, 4 mm catheter tip), similar to those used in RF cardiac ablation [3,4,18,19]. Although open-irrigated catheters are commonly used for VFW ablation [6], they have been associated with problems of fluid accumulation in the epicardial space (due to saline irrigation) necessitating frequent aspirations before each lesion [20].…”

“…We modeled an internally-cooled catheter, and although these catheters are used for clinical RF ablation of cardiac tissue [3,4,18,19], other types of catheters, such as non-irrigated and open-irrigated catheters, are also employed for this type of intervention. The conclusions reached in this study could therefore be different when using other catheter designs.…”

Epicardial Ablation With Irrigated Electrodes

“…Furthermore, we have previously reported that steam pop could be prevented by slowly increasing the RF power automatically to the preset temperature to 40°C. 30 Thus, monitoring catheter-tip temperature and changes in impedance might be useful for preventing steam pop. However, the upper limit of the catheter-tip temperature and lower limit of the decrease in impedance should be determined individually for each ablation system.…”