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 (<or=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.