"This book is incredibly complete and easy-to-understand for anybody. I certainly recommend it for patients who want to know more about atrial fibrillation than what they will learn from doctors...."

Pierre Jaïs, M.D. Professor of Cardiology, Haut-Lévêque Hospital, Bordeaux, France

"Dear Steve, I saw a patient this morning with your book [in hand] and highlights throughout. She loves it and finds it very useful to help her in dealing with atrial fibrillation."

Dr. Wilber Su Cavanaugh Heart Center, Phoenix, AZ

"Your book [Beat Your A-Fib] is the quintessential most important guide not only for the individual experiencing atrial fibrillation and his family, but also for primary physicians, and cardiologists."

Jane-Alexandra Krehbiel, nurse, blogger and author "Rational Preparedness: A Primer to Preparedness"


"Steve Ryan's summaries of the Boston A-Fib Symposium are terrific. Steve has the ability to synthesize and communicate accurately in clear and simple terms the essence of complex subjects. This is an exceptional skill and a great service to patients with atrial fibrillation."

Dr. Jeremy Ruskin of Mass. General Hospital and Harvard Medical School

"I love your [A-fib.com] website, Patti and Steve! An excellent resource for anybody seeking credible science on atrial fibrillation plus compelling real-life stories from others living with A-Fib. Congratulations…"

Carolyn Thomas, blogger and heart attack survivor; MyHeartSisters.org

"Steve, your website was so helpful. Thank you! After two ablations I am now A-fib free. You are a great help to a lot of people, keep up the good work."

Terry Traver, former A-Fib patient

"If you want to do some research on AF go to A-Fib.com by Steve Ryan, this site was a big help to me, and helped me be free of AF."

Roy Salmon Patient, A-Fib Free; pacemakerclub.com, Sept. 2013

2014 Boston AF Symposium

The New Era of Catheter Ablation Technology: Force Sensing Catheters

By Steve S. Ryan, PhD

Dr Moussa Mansour

Dr Moussa Mansour

Dr. Moussa Mansour of Massachusetts General Hospital gave a presentation entitled “Role of Force Sensing in Catheter Ablation for AF.” In particular, he referenced the Biosense Webster’s Thermocool SmartTouch irrigated tip ablation catheter with force sensing technology and the St. Jude Medical’s TactiCath (Endosense) contact-force sensing ablation catheter.

Note: The month following Dr. Mansour’s presentation at the Boston AF Symposium, the FDA approved the Biosense Webster’s Thermocool SmartTouch irrigated tip ablation catheter with force sensing technology (February 25, 2014). The main competing system, St. Jude Medical’s TactiCath (Endosense) contact-force sensing ablation catheter, was approved for use in Europe (July 22, 2014) and hopes to get FDA approval by the end of 2014.

Just the right amount of pressure

Doctors (and patients) are excited about force sensing catheters, because they allow doctors to apply just the right amount of pressure to make a good ablation lesion. Previous studies have shown that even experienced operators sometimes apply too little pressure which can result in incomplete lesions and gaps, or they sometimes apply too much pressure which can lead to overheating and can damage or even perforate the heart. Researchers found a wide variance in contact force applied by doctors, and even a variance of force by particular doctors within the same ablation procedure.

The clinical trial for the Biosense Webster SmartTouch SMART-AF demonstrated for the first time that the consistent and stable application of contact force on the heart wall positively impacts the efficacy of catheter ablation. According to Dr. Andrea Natale, “Consistent and stable application of contact force has a significant impact on patient outcomes…and represents a major advancement for the clinical community.”

How the ThermoCool SmartTouch works

BisenseWebster Smart Catheter illustrations

Biosense Webster’s Thermocool SmartTouch irrigated tip ablation catheter with force sensing technology

The basic mechanism of the SmartTouch is a magnet and precision spring near the catheter tip. When the catheter makes contact with heart tissue, it bends allowing small amounts of electrode movement. Sensors record the micro-movements of the spring and monitor the transmitter coil location which sends signals back about the location of the spring. Changes in catheter angle and contact force are calculated by the changes in the position of the sensors.

The ThermoCool SmartTouch is usually used in conjunction with the Biosense Webster CARTO 3 electroanatomic mapping and navigation system which displays the contact force readings in real-time. (Contact force is usually measured in grams.)

How the TactiCath Works

Not yet approved by the FDA, the St. Jude Medical’s TactiCath contact-force–sensing ablation catheter uses an optical fiber system with three fibers. When the catheter tip touches tissue, the optical fibers bend changing the wavelength of the fibers. Software translates this information into a measurement of how much pressure is being applied. A console also displays the angle of the catheter. (In the TOCCATA trial, contact force (CF) measurements below 10 grams usually failed, “Clinical failure is universally noted with an average CF below 10 grams.”)

Preclinical Testing of force sensing catheters

Dr. Mansour pointed out how the same lesion depth can be achieved by a 30W energy level at 30 g contact force as a 50W at 20g.

In another study where operators were blinded to the force they were using, lower force (below 400gs FTL (Force-Time Integral) resulted in over 20% reconnections vs. only 5% with a force of over 400gs FTL (EFFICAS I) (TactiCath contact force sensing catheter).1

In a study where the force information was visible to the operator, more PVs were durably isolated (EFFICAS II) (TactiCath)2.

In another study, low contact force (0-10 [g]) resulted in 100% recurrence after 12 months; 10-20 [g] had 47% recurrence; over 20 [g] had only 20% recurrence3

Clinical Trials of Force sensing catheters

In the SMART-AF trial of the ThermoCool SmartTouch catheter, if operators stayed within their pre-selected force range 80% or more, they had a much higher success rate. In general, operators remained in their preselected force ranges 73% of the time. Possible reasons for catheter instability include the beating of the patient’s heart and their breathing motion.

Using High Frequency Jet Ventilation (which slows down the beating heart and breathing motion), improved catheter stability and contact force (FTL) (Mansour et al. HRS 2012).

Dr. Mansour’s Conclusions

•  Higher contact force during ablation results in deeper lesions
•  Contact force greater than 20g is associated with an improved clinical outcome
•  Increased percent of time within operator-targeted force range is associated with improved clinical outcome
•  Jet ventilation and steerable sheath improve the ability to achieve the desired contact force.

Editor’s Comments:
Contact force sensing catheters is a major medical advancement that will change the way ablations are done. Ablation lesions will be more durable and consistent. Instances of tamponade will be significantly reduced or possibly eliminated entirely. Catheter ablation success rates will rise.
Though it’s been less than 12 months since the FDA approved Biosense Webster’s Thermocool SmartTouch contact force-sensing catheter, anecdotal reports of its success are very encouraging. Experienced operators who already have a high success rate, report a 10%+ improvement using contact force sensing catheters. I’m surprised at how many top echelon EPs are already using force sensing catheters.
For example, Dr. Hugh Calkins of Johns Hopkins wrote the author:
“We have quickly adopted force sensing catheters in all of our atrial fibrillation and VT ablation procedures.  The additional contact information provided with these catheters is invaluable in maximizing the safety and efficacy of radiofrequency ablation procedures.”
Unfortunately, because of the added cost and technology challenges, the low volume operators who need to use force sensing catheters the most, will probably be the last to adopt them. (See my report about low-volume operators: Catheter Ablation Complications: A 2014 In-depth Review and Comparison with Anticoagulation Drug Therapy)
As a patient, ask your EP if they use contact force-sensing catheters. If the answer is no, should you make an effort to find an EP who does use force sensing catheters? Absolutely! Force sensing catheters will improve ablation success and durability, and will reduce complications. Even if you have to travel, it’s certainly worth the effort to find an EP who uses contact force sensing catheters.
Jet ventilation is an improvement, but may not be a game changer that you want to hunt for.
I intend to research which EPs are using contact force sensing catheters and make a special “Steve’s List” of them under the Directory Doctors/Facilities page of A-Fib.com.
Additional references for this article
[[1]]Neuzil et al. AHA 2011 http://circ.ahajournals.org/cgi/content/meeting_abstract/124/21_MeetingAbstracts/A18101

Return to Reports: 2014 Boston AF Symposium

References    (↵ returns to text)
  1. Kautzner et al. HRS 2012)
  2. Reddy et al. Heart Rhythm 2012 http://www.pubfacts.com/detail/22820056/The-relationship-between-contact-force-and-clinical-outcome-during-radiofrequency-catheter-ablation.

Related Posts

Follow Us
facebook block 65 pix REVtwitter block 65 pixlinkedin block 65 pixpinterest.block 65 pix

A-Fib.com Mission Statement

Mug - Seek your cure - Beat Your A-Fib 200 pix wide at 300 resEncourage others
with A-Fib
click to order

A-Fib.com top rated by Healthline.com for the third year.
A-Fib.com top rated by Healthline.com for the third year. 2014  2015  2016

Support A-Fib.com. Every donation helps, even just $1.00

We Need You

Home | The A-Fib Coach | Help Support A-Fib.com | A-Fib News Archive | Tell Us What You think | Media Room | GuideStar Seal | HON certification | Disclosures | Terms of Use | Privacy Policy