Cardiac Rhythm Management
Articles Articles 2016 August


DOI: 10.19102/icrm.2016.070804


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Dear Readers,

Contact force sensing is a relatively new technology and represents a major breakthrough in the field of catheter ablation. Two force sensing catheter systems are available in the US and other parts of the world. They have both been shown, in large multinational clinical studies such as SMART AF and TOCCASTAR, to improve the outcome of ablation for atrial fibrillation (AF) when optimal force is used. Most of the early studies in the field of contact force sensing aimed at defining the basic parameters of this technology such as optimal contact force for ablation, optimal force time integral (FTI), as well as defining high forces that increased the risk of perforation. More recently, there appears to be a trend focusing on defining skills and techniques that help achieve optimal contact force and increase the chance of success. One such article is published in this issue of the Journal by Boles et al. The authors aimed to assess the dynamic range for contact force (CFdf) in order to achieve effective lesions according to anatomic variables. The CFdf was defined as the difference between the highest and lowest recorded contact force for each RF application. They found that the greater the dynamic range, the less likely the lesion would reach 400 g/s FTI and the longer the duration of the application is required. The findings of this study are important and confirmed our belief regarding the importance of achieving stable catheter position during energy delivery. The authors also found that the dynamic range of contact force is dependent on the location of ablation in the heart.

There are techniques that can be used to reduce force variation and improve the quality of the ablation lesion. At our center we rely on three practices to achieve optimal contact force:

  1. Steerable sheath: All ablations for AF at our center are performed using a steerable sheath. Data from the TOCCASTAR study presented at the scientific meeting of the Heart Rhythm Society demonstrated the value of this tool for improving catheter stability and achieving optimal contact force.
  2. Pacing: At our center pacing is performed at 100 bpm during ablation for AF. For patients presenting in AF, ventricular pacing is performed to regularize cardiac motion and improve catheter stability. We also pace the atria in patients presenting in sinus bradycardia in order to reduce the stroke volume and reduce catheter motion.
  3. High frequency jet ventilation (HFJV): In contrast to conventional ventilation, HFJV eliminates chest movement and allows a significantly more stable catheter position. It requires close collaboration with a skilled anesthesia team.

These techniques are relatively easy to adopt and maximize the value of contact force sensing. It is important to recognize that improving catheter stability may result in deeper lesion formation, and hence the need to reduce the power, duration, and contact force when ablating near the esophagus on the posterior left atrial wall.

As always, I hope that you find this issue of the Journal beneficial to you and your practice.

Warm regards,

Moussa Mansour, MD, FHRS, FACC
The Journal of Innovations in Cardiac Rhythm Management
Director, Cardiac Electrophysiology Laboratory
Director, Atrial Fibrillation Program
Massachusetts General Hospital Boston, MA