Cardiac Rhythm Management
Articles Articles 2014 September

Letter from the Editor in Chief

DOI: 10.19102/icrm.2014.050901

Moussa Mansour, MD, FHRS, FACC

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This issue of the Journal contains many interesting articles. I would like to discuss the article by Dr. Sohns and his colleagues entitled, “Catheter Contact Force: A Review of Emerging Techniques and Technologies in AF Ablation”. I chose this article because it refers to contact force sensing, an emerging technology that is expected to play a major role in ablation of atrial fibrillation.

In this elegant review, Dr. Sohns provides the rationale for the use of contact force sensing. He also describes the key features of the two recently developed contact force catheters, their mechanisms of force sensing, as well as data from clinical trials.

The two recently developed contact force catheters use different mechanisms of force sensing. One uses optical sensor technology while the other uses magnetic-based localization. Despite the difference in the mechanism of force sensing, the ability of each of these catheters to sense force accurately appears grossly similar. They are both very sensitive and can detect a small amount of force. The data from pre-clinical and clinical studies demonstrating the benefit of this technology are robust and convincing. Pre-clinical studies pointed to a potential role of force sensing in improving the safety of AF ablation. This was evidenced by the finding that higher contact force is associated with higher rates of mechanical perforation, steam pop, and esophageal injury. On the other hand, data from clinical studies demonstrated a beneficial role of force sensing in improving the efficacy of this procedure. In fact contact force sensing was shown to increase the rate of durability of PV isolation and the success rate of the procedure, as well as decrease the rate of repeat procedures.

At our own center, we have been using contact force sensing for more than 3 years, initially as part of clinical studies and more recently for regular atrial fibrillation ablation procedures. We find this technology very helpful. We aim for a force level between 10 and 40 grams. In order to maintain this range of force, we use a number of maneuvers and techniques. We find high frequency jet ventilation very helpful in ensuring catheter stability and achieving the desired level of force. We also use pacing to reduce catheter movement and obtain better force. We pace the atrium at 600 msec when the patient is in sinus bradycardia. When in AF, we pace the ventricle to regularize cardiac motion. We also rely heavily on the deflectable sheath which we find helpful in allowing us to achieve the desired force in difficult anatomical areas such as the ridge between the left superior PV and the left atrial appendage. When ablating in the posterior left atrial wall, we target a force just above 10 grams in order to reduce the risk of esophageal injury.

The multicenter clinical studies, SMART AF and TOCCASTAR, demonstrated that the success rate of AF ablation far exceeds 80% when optimal force is achieved. This success rate is excellent and represents a new standard in AF ablation. I believe, however, that this success rate can be further improved when force sensing is used in conjunction with other parameters of ablation, such as catheter location, power, lesion duration, and impedance drop. In this combination, force sensing may prove to be a tool that allows the assessment of lesion formation, which is the biggest unmet need in electrophysiology.

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