Safety verification of a novel irrigation catheter with flexible tip of laser-cut kerfs and contact force sensor.

Abstract

The safety evaluation of TactiFlex, a novel contact-force sensing catheter with a flexible 4-mm tip irrigated through laser-cut kerfs, has been ongoing. This study aimed to verify the safety of this type of catheter. Study 1: Radiofrequency (RF) applications at a range of powers (30-50W), contact forces (10-20g), and durations (10-60 s) using perpendicular/parallel catheter orientation with half-normal (HNS) or normal saline irrigation were compared between TactiFlex (4-mm tip) and TactiCath (3.5-mm tip) with temperature-controlled mode in excised porcine hearts. Study 2: The relation between RF applications using TactiFlex and the incidence of steam-pops in the real clinical cases were examined. Study-1: 576 RF lesions were examined. TactiFlex demonstrated a significantly lower risk of steam-pops (5[1.7%] vs. 59[20.5%], p< .0001). Compared to 3.5-mm-tip catheter (TactiCath), 4-mm-tip catheter (TactiFlex) produced smaller lesion volume at perpendicular (193[98-554]mm3 vs. 263[139-436]mm3 , p< .0001), but relatively similar lesion volume at parallel contact (243[105-443]mm3 vs. 278[180-440]mm3 , p=.06). HNS-irrigation tended to increase the lesion volume in both catheters and to increase the incidence of steam-pops with TactiCath, but not with TactiFlex. The cut-off value of %impedance-drop ( =absolute impedance-drop/initial impedance) of 20% predicted steam-pops with a sensitivity=100% and specificity=89.6% in TactiFlex. Study-2: 5496 RF applications in 84 patients (51AFs/8ATs/3AVNRTs/4AVRTs/17PVCs/4VTs) using TactiFlex were analyzed. Four steam-pops (0.07%) in three patients with pericardial effusion were observed (%impedance-drop=24%/26%/29%/35%, respectively). The cut-off value of %impedance-drop=20%, derived from ex-vivo study, showed sensitivity=100% and specificity=90.1% in detecting steam-pops. TactiFlex reduced the risk of steam-pops than TactiCath. %impedance-drop≤20% may be reasonable for safely use with a sufficient safety margin. For 4-mm-tip catheter, parallel-contact may be recommended for larger lesion creation.