Sanjiv Narayan, M.D., Professor of Medicine and Co-Director of Stanford Arrhythmia Center, in Palo Alto near San Francisco, California, talks about a technique that is pinpointing the exact source of the problem for AFib and improving the treatment odds.
Interview conducted by Ivanhoe Broadcast News in September 2016.
Tell me a little bit about the FIRM fibrillation and how it is a different procedure.
Dr. Narayan: Atrial fibrillation is the most common heart rhythm abnormality in the United States affecting several million people. Ablation is a common therapy for the condition, typically when medications have not worked well, which involves passing a catheter or flexible tube from one of the veins in the legs up in to the heart to ablate or cauterize hot spots in the heart. The standard approach involves cauterizing around the pulmonary veins which is an area of the left side of the heart where triggering beats can arise. The success rate of that procedure is not perfect and so our group worked on ways to improve that. FIRM targets hot spots outside the pulmonary veins which we believe are important for keeping the arrhythmia going – not just for triggering. By doing that we have actually been able to improve upon the success rates of the standard procedure by adding FIRM to it.
Why does it work?
Dr. Narayan: There’s been a lot of debate for thirty years on what atrial fibrillation is. It’s a disorganized disease when you look at it, and so people have initially assumed it was chaotic like the waves on an ocean on a stormy day. We found that in fact there are organizing centers that send waves spinning off, a bit like the eye of a storm. We found ways to identify them in patients during a case and cauterize or ablate them. In that way we believe that explains the benefits of the procedure.
Then is the FIRM part of the technique of identifying where the weak spots are or is it the cauterizing of them or is it both?
Dr. Narayan: We tend to talk about FIRM mapping which is identifying these driving sites or rotors and then the ablation we call FIRM guided ablation. Having found them we burn them. The actual ablation uses the same approach you would use for PV isolation and the way in which ablation is applied is very similar to a standard ablation.
How is the FIRM procedure able to find the spots more accurately?
Dr. Narayan: My work for the past fifteen years has focused on using computer methods and signal processing algorithms to develop software to sort out real heart signals with known properties from noise. If you think about the chaotic wave in the ocean there actually is some level of organization in them. It’s just hard to see. In the same way we started really fifteen years ago looking at ways that you could identify order or organization within these seemingly random patterns and we found that. We use a catheter which essentially is like a very floppy flexible basket which goes in to the heart, is FDA cleared, and then from those 64 or 128 simultaneous signals recorded for hundreds of seconds, we are able to extract regions of organization which are these drivers. That’s what we ablate.
That’s amazing.
Dr. Narayan: We’re very excited about it. It’s based on over thirty years of research by many key investigators, Dr. Pepe Jalife being one of the leading figures who showed in animals and computer simulations that rotors drive AFib. We were the first to show them in patients and use that to guide ablation.
What do you believe the improvement rate is using the FIRM?
Dr. Narayan: We’re seeing about a twenty percent improvement in success. None of these procedures including our own is perfect, unfortunately. However, what we have seen that is if you take a standard PVI ablation procedure often quoted with a success rate of fifty to sixty percent, we can add twenty percent to that. Now sometimes of course people will still recur, but when we take those people to the lab again we often find rotors in the same locations that were not fully eliminated, and can improve the expected success. There are many ongoing studies to find precisely what the step up in success is in different populations.
Does it add any time to the procedure?
Dr. Narayan: It does add extra time. It depends on the individual person and also experience with the technique but we’re finding it adds about an hour to a typical 3 hour case.
About Bob, how did you treat him, what were his symptoms and what was the outcome?
Dr. Narayan: Bob was a lovely gentleman who came to us with over a year of fatigue and tiredness, that stopped him from gardening which was one of his passions. It’s interesting that he didn’t have many common symptoms – many people have chest pain, he didn’t. Some people are extremely short of breath, he wasn’t. It was mostly fatigue and that’s actually a common symptoms. In fact Bob had had AFib for more than a year continuously and about a decade on and off. He had failed many cardio versions before – a procedure where an electrical shock is used to convert the rhythm to normal. He had failed four of those. He had used a couple of medications including the most powerful drug amiodarone, and had failed those. When he came to us we offered FIRM ablation and he agreed to have it. In the lab we found rotational drivers or rotors in the right side of the heart as well as the left. We saw numerous – 5-6 in total – which is common for somebody with that much atrial fibrillation. We systematically cauterized them followed by the standard approach and luckily he’s done very well.
How long has it been since his procedure?
Dr. Narayan: It’s been over a year and a half now.
His outlook is good then?
Dr. Narayan: Outlook is very good yes.
Anything else I haven’t asked you about the procedure that you think is important to include?
Dr. Narayan: I think the important thing is it’s a team effort. I think it’s very important for any kind of ablation to have an excellent team to evaluate the individual. At Stanford, my nurse Eve Zheng, and our nurse practitioners Angela Tsiperfal, Christine Tacklind and others help get a great sense of other conditions, such as high blood pressure, diabetes and so on. Core members of the team include Drs. Paul Wang, Mohan Vishwanathan and my other physician partners, and fellows such as Drs. Jay Nasir, David Ho, Tina Baykaner and Ron Jones. Together, we help to make sure people truly know what to expect before, during and after the procedure. Although this is not surgery – we don’t cut the chest, for instance- there are still things that people need to know about in terms of physical restrictions and some other things that after the procedure. I think because of that it’s very important to have a good team and I’m very lucky our team at Stanford is excellent.
Disclosure: Dr. Narayan is co-inventor on patents on this work licensed to Topera Inc., in which he has held equity. He is funded by grants from the National Institutes of Health for this work. His disclosures are listed fully on his Stanford University Website.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Angela Tsiperfal, MS, RN, ACNP-BC, CNS, CCDC
Lead Nurse Practitioner, Stanford Arrhythmia Service
650-723-7111
atsiperfal@stanfordhealthcare.org
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