Eliminating the effects of motion during radiofrequency lesion delivery using a novel contact‐force controller

Contact force sensors in minimally invasive catheters: current and future applications

INTRODUCTION

Advances in catheter design for minimally invasive surgery have brought about the incorporation of contact force (CF) sensors in catheters. Two main approaches to achieve CF sensing at the catheter end-effector consist of fiber optic or magnetic solutions. CF sensing feedback can be used to assist in ablation procedures, mapping cardiac regions, identifying tissue characteristics, and enhancing robotic catheter control.

AREAS COVERED

This review covers the technological and clinical aspects of CFS in catheters. Contact force and force-time integral thresholds for ablation procedures, procedural complications, and electroanatomical mapping strategies are discussed. Future applications of improving catheter control, minimizing complications, and enhancing mapping techniques through CF are examined.

EXPERT OPINION

Fiber optic CF catheters may be more desirable compared to magnetic modalities due to the lower cost, compactness, and higher accuracy. In ablation procedures, complications due to higher ablation duration, power, contact force, and force time can be reduced through practical experience and informed training for catheter operators. Future prospects consist of the incorporation of CF sensors with remote catheter systems to assist in catheter control. We propose that CF can also be used in machine learning decision-making algorithms to prevent complications or improve tissue characterization.

Continuous ablation improves lesion maturation compared with intermittent ablation strategies

BACKGROUND

Interrupted ablation is increasingly proposed as part of high-power short-duration radiofrequency ablation (RFA) strategies and may also result from loss of contact from respiratory patterns or cardiac motion. To study the extent that ablation interruption affects lesions.

METHODS

In ex vivo and in vivo experiments, lesion characteristics and tissue temperatures were compared between continuous (group 1) and interrupted (groups 2 and 3) RFA with equal total ablation duration and contact force. Extended duration ablation lesions were also characterized from 1 to 5 minutes.

RESULTS

In the ex vivo study, continuous RFA (group 1) produced larger total lesion volumes compared with each interrupted ablation lesion group (273.8 ± 36.5 vs 205.1 ± 34.2 vs 174.3 ± 32.3 mm³ , all P < .001). Peak temperatures for group 1 were higher at 3 and 5 mm than groups 2 and 3. In vivo, continuous ablation resulted in larger lesions, greater lesion depths, and higher tissue temperatures. Longer ablation durations created larger lesion volumes and increased lesion depths. However, after 3 minutes of ablation, the rate of lesion volume, and depth formation decreased.

CONCLUSIONS

Continuous RFA delivery resulted in larger and deeper lesions with higher tissue temperatures compared with interrupted ablation. This study may have implications for high-power short duration ablation strategies, motivates strategies to reduce variations in ablation delivery, and provides an upper limit for ablation duration beyond which power delivery has diminishing returns.

Rapid pacing and high-frequency jet ventilation additively improve catheter stability during atrial fibrillation ablation

INTRODUCTION

Catheter stability during atrial fibrillation ablation is associated with higher ablation success rates. Rapid cardiac pacing and high-frequency jet ventilation (HFJV) independently improve catheter stability. Simultaneous modulation of cardiac and respiratory motion has not been previously studied. The objective of this study was to determine the effect of simultaneous heart rate and respiratory rate modulation on catheter stability.

METHODS

Forty patients undergoing paroxysmal atrial fibrillation ablation received ablation lesions at 15 prespecified locations (12 left atria, 3 right atria). Patients were randomly assigned to undergo rapid atrial pacing for either the first or the second half of each lesion. Within each group, half of the patients received HFJV and the other half standard ventilation. Contact force and ablation data for all lesions were compared among the study groups. Standard deviation of contact force was the primary endpoint defined to examine contact force variability.

RESULTS

Lesions with no pacing and standard ventilation had the greatest contact force standard deviation (5.86 ± 3.08 g), compared to lesions with pacing and standard ventilation (5.45 ± 3.28 g; P < .01) or to lesions with no pacing and HFJV (4.92 ± 3.00 g; P < .01). Lesions with both pacing and HFJV had the greatest reduction in contact force standard deviation (4.35 ± 2.81 g; P < .01), confirming an additive benefit of each maneuver. Pacing and HFJV together was also associated with a reduction in the proportion of lesions with excessive maximum contact force (P < .001).

DISCUSSION

Rapid pacing and HFJV additively improve catheter stability. Simultaneous pacing with HFJV further improves catheter stability over pacing or HFJV alone to optimize ablation lesions.