Introduction: Contrary to initial expectations, recent clinical data show that high-power, short-duration (HPSD) radiofrequency (RF) ablation can result in a similar oesophageal injury rate as traditional low-power, long-duration (LPLD) ablation. Existing methods to prevent oesophageal injury have yielded variable or uncertain results, and many can result in prolonged procedure time. An oesophageal cooling device currently available for whole-body temperature modulation and now being studied for the prevention of oesophageal injury during LPLD RF ablation as well as cryoablation may offer protection in HPSD ablation. We sought to measure the capability of this new oesophageal cooling device to protect from oesophageal injury under high-power conditions under an expected range of tissue electrical conductivity.
Methods: Using a mathematical model we developed of HPSD RF ablation in the left atrium, we measured the change in oesophageal lesion formation and the depth of lesions (measured as percent transmurality) with the oesophageal cooling device in place and operating at a temperature from 5°C to 37°C. Tissue parameters, including electrical conductivity, were set to average values obtained from existing literature, and energy settings were evaluated at 50 W for between 5 and 10 seconds, and at 90 W for a duration of 4 seconds.
Results: Oesophageal injury (as measured by percent transmurality) was higher at 50 W using 10 s duration than at 90 W of power with 4 s duration; however, both settings showed potential for oesophageal injury. The protective effect of the oesophageal cooling device was evident for both cases, with a greater effect when using 50 W for 10 s (Figure 1). At the coldest device settings, using a 5 min pre-cooling period also reduced the transmurality of the intended atrial lesions.
Conclusions: Oesophageal cooling with a commercially available device shows protective effects against thermal injury during RF ablation across a range of tissue electrical conductivity, using a variety of high-power settings. Adjusting the cooling power by adjusting the circulating water temperature in the device provides a mechanism to adjust the protective effects to match a range of operating conditions.
