Novel Contact Force Sensor Incorporated in Irrigated Radiofrequency Ablation Catheter Predicts Lesion Size and Incidence of Steam Pop and Thrombus

Abstract

Background— An open-irrigated radiofrequency (RF) ablation catheter was developed to measure contact force (CF). Three optical fibers measure microdeformation of the catheter tip. The purpose of this study was to (1) validate the accuracy of CF sensor (CFS) (bench test); and (2) determine the relationship between CF and tissue temperatures, lesion size, steam pop, and thrombus during RF ablation using a canine thigh muscle preparation. Methods and Results— CFS measurements (total 1409) from 2 catheters in 3 angles (perpendicular, parallel, and 45°) were compared with a certified balance (range, 0 to 50 g). CFS measurements correlated highly (R2≥0.988; mean error, ≤1.0 g). In 10 anesthetized dogs, a skin cradle over the thigh muscle was superfused with heparinized blood at 37°C. A 7F catheter with 3.5-mm saline-irrigated electrode and CFS (Endosense) was held perpendicular to the muscle at CF of 2, 10, 20, 30, and 40 g. RF was delivered (n=100) for 60 seconds at 30 or 50 W (irrigation 17 or 30 mL/min). Tissue temperature (3 and 7 mm depths), lesion size, thrombus, and steam pop increased significantly with increasing CF at each RF power. Lesion size was greater with applications of lower power (30 W) and greater CF (30 to 40 g) than at high power (50 W) with lower CF (2 to 10 g). Conclusions— This novel ablation catheter, which accurately measures CF, confirmed CF is a major determinant of RF lesion size. Steam pop and thrombus incidence also increases with CF. CFS in an open-irrigated ablation catheter that may optimize the selection of RF power and application time to maximize lesion formation and reduce the risk of steam pop and thrombus

Steerable Versus Nonsteerable Sheath Technology in Atrial Fibrillation Ablation

“…Experimental data obtained with objective contact assessment technologies indicate a correlation between contact and lesion size. 18 The improved outcome observed in our study may therefore be in part interpreted as the clinical result of improved lesion formation and lesion maintenance. Other factors contributing to clinical outcome are likely to be related to the stability of the catheter position over longer ablation periods and the ability to reliably access different ablation target sites.…”

Novel miniature MRI-compatible fiber-optic force sensor for cardiac catheterization procedures

“…They make use of several sensing principles, such as strain-gauges [8], piezoresistivity [9], PVDF films [1] and fibre-optic technology [10], [11], [15]. However, only a small number of sensors were developed for the detection of contact forces between the catheter and tissue [12], [13].…”

Ablation of recurrent malignant idiopathic ventricular tachycardia: When proper diagnosis and success is a matter of contact

“…The difficulty of directly assessing the degree and quality of contact between the catheter tip and the target tissue has been demonstrated even in experienced operators 2. Moreover, preclinical research has shown that insufficient CF can result in ineffective lesion formation 5, 6, 7. Therefore, poorer clinical outcome can occur even if tactile feedback, fluoroscopy, and high‐amplitude electrograms appear to indicate good contact 2.…”