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

Abstract

Introduction Catheter‐tissue contact force is a determinant of radiofrequency (RF) ablation lesion effectiveness. However, ablation on a beating heart is subject to force variability, making it difficult to optimally deliver consistently durable and transmural lesions. This work evaluates improvements in contact force stability and lesion reproducibility by using a catheter contact‐force controller (CFC) during lesion delivery in vitro and in vivo. Methods and Results Using a sheath and force‐sensing catheter, an experienced operator attempted to maintain a constant force of 20 g at targets within the atria and left ventricle of a pig manually and using the CFC; the average force and contact‐force variation (CFV) achieved using each approach were compared. Ablation lesions (20 W, 30 seconds, 17 mL/min irrigation) were created in bovine tissue samples mounted on a platform programmed to reproduce clinically relevant motion. CFC‐assisted lesions were delivered to stationary and moving tissue with forces of 5 to 35 g. Mimicking manual intervention, lesions were also delivered to moving tissue while the CFC was disabled. Resultant lesion volumes were compared using two‐way analysis of variance. When using the CFC, the average force was within 1 g of the set level, with a CFV less than 5 g, during both in vitro and in vivo experiments. Reproducible and statistically identical (P = .82) lesion volumes proportional to the set force were achieved in both stationary and moving tissue when the CFC was used. Conclusions CFC assistance maintains constant force in vivo and removes effect of motion on lesion volume during RF lesion delivery.

Continuous ablation improves lesion maturation compared with intermittent ablation strategies

“…Finally, in-line contact force controllers may be used to fine-tune contact force with manual catheter manipulation. 16 Our results support the investigation of such strategies to maintain continuous energy delivery during RFA. The effect of intermittent ablation due to respiratory or cardiac motion may be less pronounced with high-power short duration ablation since volume creation is more rapid at higher power, although this may affect lesion dimensions.…”

“…Similarly, adherence of the catheter to tissue (for cryotherapy) 13 or catheter control techniques such as robotic guide catheters 14 and magnetic catheter manipulation 15 may be used to avoid interruption of ablation. Finally, in‐line contact force controllers may be used to fine‐tune contact force with manual catheter manipulation 16 . Our results support the investigation of such strategies to maintain continuous energy delivery during RFA.…”

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

“…However, with this, lesion homogeneity and transmurality is likely improved (Figure 5). This is supported by in vivo animal models demonstrating that as contact force variability is reduced, lesion homogeneity is increased 21 . These observed impedance changes are likely a consequence of the highly stable catheter motion produced by concurrent pacing and HFJV, and lend further support to the potential for combined pacing and HFJV to not only improve catheter stability but also improve outcomes.…”

Computer modeling of radiofrequency cardiac ablation including heartbeat-induced electrode displacement

“…Changes in the CF associated with systole-diastole heart movements are normally found during RFCA [20], and in fact in some ex vivo models electrode displacement has been mimicked by placing tissue samples on motorized motion-controlled platforms [21,22]. Our goal was to build an RFCA computer model including heartbeat-induced electrode displacement and to compare the computer results with those obtained from previous experiments based on a beating heart in similar conditions of energy and contact force.…”