Relationship Between Catheter Forces, Lesion Characteristics, Popping, and Char Formation: Experience with Robotic Navigation System

Introduction: Popping, char and perforation are complications that can occur following catheter ablation. We measured the amount of grams (g) applied to the endocardium during ablation using a sensor incorporated in the long sheath of a robotic system. We evaluated the relationship between lesion formation, pressure, and the development of complications.
Methods: Using a robotic navigation system, lesions were placed in the left atrium (LA) at six settings, using a constant duration (40 seconds) and flow rate of either 17 cc/min or 30 cc/min with an open irrigated catheter (OIC). Evidence of complications was noted and lesion location recorded for later analysis at necropsy.
Results: Lesions using 30 Watts (W) were more likely to be transmural at higher (>40 g) than lower (<30 g) pressures (75% vs 25%, P < 0.001). Significantly higher number of lesions using >40 g of pressure demonstrated popping and crater formation as compared with lesions with 20–30 g of pressure (41% vs 15%, P = 0.008). A majority of lesions placed using higher power (45 W) with higher pressures (>40 g) were associated with char and crater formation (66.7%). No lesions using 10 g of pressure were transmural, regardless of the power. Lesions placed with a power setting less than 35 W were more likely to result in relative sparing of the endocardial surface than lesions at a power setting higher than 35 W (62% vs 33.3%, P = 0.02) regardless of the pressure.
Conclusions: When using an OIC, lower power settings (≤35 W) and lower/medium contact pressure were more likely to show a relative spared endocardial surface. Overall, contact pressure between 20 g and 30 g and a power setting of 40 W appeared to achieve transmurality by preserving safety.