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Accurate Diagnosis and Efficient Workflow in AF Therapy

HOW DO THERAPIES BENEFIT FROM CONTACT FORCE IN COMPLEX AF PROCEDURES?

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How do therapies benefit from contact force in complex AF procedures?

Experimental in-vitro and in-vivo data has shown that catheter electrode-tissue contact force is a major determinant of lesion diameter and depth. Contact force-sensing catheters now allow direct measurement of contact force, improving the efficacy and safety of procedures.2

Direct measurement of contact force

In the past, surrogate markers of contact were used: tactile feeling, baseline impedance, impedance drop during ablation, catheter tip temperature (for non-irrigated ablation), and electrogram attenuation during ablation.2 The recognized importance of contact force led to the early adoption of steerable sheaths to maintain better contact force during atrial fibrillation ablation in many centers, and now to the advent of contact force-sensing catheters.

At a glance: the advantages of controlling contact force2

  • Contact force catheters provide real-time feedback of the force applied between the catheter tip and the myocardium.
  • Use of contact force catheters during ablation of atrial fibrillation has led to less acute pulmonary vein reconnection and fewer gaps in the circumferential isolation lines and has significantly improved outcome after atrial fibrillation ablation. 
  • Radiofrequency ablation lesion volume is proportional to applied contact force.
  • In the ventricle, improved contact force correlates with higher recorded unipolar and bipolar voltages and a larger number of recorded late potentials. 

PVI ablation with a contact force-sensing catheter

A prospective, non-randomized, multi-center study evaluated the safety and performance of the AlCath Force, a unique GoldTip force-sensing catheter, combined with the Qubic Force device for visualization of the contact force in pulmonary vein isolation (PVI) and cavo-tricuspid isthmus (CTI) ablations. The results of the study indicate that the AlCath Force catheter together with the Qubic Force device is safe and effective for contact force guided RF ablation.  
Acute procedural success, defined as bi-directional block across the CTI and entrance and exit block in all pulmonary veins, could be obtained in all cases. The target contact force used in the study was 20 gram (g) in the majority of cases with a range of 20-40 g. The recommended power setting was 30 W and the force-time integral (FTI) was 450 gram-seconds. The mean total skin-to-skin procedure time for all procedures was 130±48 min (156±37 min for PVI only and 107±48 min for CTI only). Mean fluoroscopy time was 28±20 min for all procedures (26±15 min for PVI procedures and 31±24 min for CTI procedures). Performance of the force measurement was rated adequate or better in 100% of cases and no procedure- or device-related serious adverse events were reported.

Further advantages of contact force catheters

The use of specific force-sensing catheters can potentially improve the outcomes of AF ablations. Additionally, contact force catheters could also offer an advantage for centers training electrophysiology fellows. Since the real-time contact force measurements allow instantaneous feedback for electrophysiologists in training, this can help them safely to improve catheter ablation skils.2

With the support of contact force data also seems to lead to a significant reduction in procedure times were shown/noted.1,[i] One randomized trial reported procedure times of 59,6 min in the contact-force group and 96,16 min in the non-contact force group.7 Similar results were shown by a German research group with a reduction of procedure times in the contact-force group (232±151 min vs. 269±57 min, p < 0.01) and a significant reduction in fluoroscopy time (29±14 min vs. 47±27 min, p < 0.01).1

A number of contact force sensing catheters with different force sensing technology have been introduced. The AlCath Force catheter combines a robust three-dimensional single optical fiber sensor technology with the ‘look and feel’ of a conventional irrigated ablation catheter.

AlCath Force is a steerable, irrigated, quadripolar catheter with an integrated force sensor. It is built on the well-established AlCath Flux eXtra Gold catheter with X-shaped irrigated GoldTip electrodes to maximize the natural cooling effect of the blood for safe and effective lesion creation. Gold has been used in RF ablation for more than a decade and there is a significant body of literature that suggests RF ablation using a gold tip delivers faster lesions, safely reducing ablation times and procedure times, since gold has superior thermal properties compared to platinum-iridium resulting in lower catheter tip temperatures while ablating due to the better convective cooling properties and highly efficient ablation tip irrigation design.

The AlCath Force has optical sensors based on established Fiber Bragg Grating technology, which reflect a particular wavelength that depends on the acting force. With several of these sensors integrated on a single optical fiber it can measure force in all three dimensions.

More details about AlCath Force:

  • 3.5mm irrigated GoldTip electrode
  • Innovative tip-cooling design
  • Isolated force sensor with temperature compensation
  • Ultra-thin gold ring electrodes
  • Full Circle deflection

Sources

  1. January CT et al. 2019 AHA/ACC/HRS Focused Update of the 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.J Am Coll Cardiol. 2019;74(1):104-132.
  2. Hindricks G et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS): The Task Force for the diagnosis and management of atrial fibrillation of the European Society of Cardiology (ESC) Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC. European Heart Journal, Volume 42, Issue 5, 1 February 2021, Pages 373–498.
  3. Hoffmayer KS, Gerstenfeld EP. Contact force-sensing catheters. Curr Opin Cardiol. 2015;30(1):74-80.
  4. Sattler S. Die Anwendung von Anpressdruck-Kathetern bei Vorhofflimmerablationen geht nicht mit einem verbesserten klinischen Outcome einher. Deutsche Gesellschaft für Kardiologie –Herz und Kreislaufforschung e.V., Pressetext DGK 04/2015. https://dgk.org/daten/Sattler-Anpressdruck-Katheter-Text.pdf (last access: February 1 2021).
  5. Gerstenfeld EP. Contact force-sensing catheters: evolution or revolution in catheter ablation technology? Circ Arrhythm Electrophysiol 2014; 7:5–6.
  6. Healy SG et al. Initial experience with a novel contact force sensing system - Results of BIOCONCEPT AlCath Force study, EP Europace, Volume 19, Issue suppl_3, June 2017, Page iii279; P1408.
  7. Kimura M, Sasaki S, Owada S, et al. Comparison of lesion formation between contact force-guided and nonguided circumferential pulmonary vein isolation: a prospective, randomized study. Heart Rhythm 2014; 11:984–991.

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