Effect of respiration on catheter-tissue contact force during ablation of atrial arrhythmias

BACKGROUND Catheter-tissue contact is important for effective lesion creation. OBJECTIVE To assess the effect of respiration on contact force (CF) during atrial fibrillation and cavotricuspid isthmus (CTI)-dependent atrial flutter ablation. METHODS Patients undergoing CTI ablation alone (n = 15) and pulmonary vein (PV) isolation alone (n = 12) under general anesthesia were recruited. Lesions were delivered under ventilation (30 seconds) alternating with lesions delivered under apnea (30 seconds) at an adjacent anatomical site at CTI or PV antra. The average force (F-av), force-time integral (FTI), and force variability were measured in a region-specific manner by using a novel CF-sensing ablation catheter. Operators were blinded to CF data. RESULTS F-av and FTI were higher with apnea than with ventilation in all CTI and PV segments (P < .05), an effect attributed to drop in CF with each respiratory swing, resulting in greater force variability during ventilation (P < .05). Low FTI lesions (<500 g) were strongly associated with longer ablation time to achieve bidirectional CTI block (r(2) = .81; P < .001), left PVI (r(2) = .65; P = .009), and right PVI (r(2) = .41; P = .05). Sites with transient CTI block were associated with lower F-av and FTI than were sites with persistent CTI block (P < .05). Sites of acute PV reconnection were associated with lower F-av and FTI compared with non-reconnected sites (P < .001). CONCLUSIONS Catheter-tissue CF is critically influenced by respiration; greater CF is observed with ablation during apnea. Poor CF is implicated in longer ablation time to achieve CTI block or PV isolation and in acute reconnection.