My new 2015 AF Symposium report is of special interest for patients with persistent Atrial Fibrillation.
Dr. Sebastian Knecht from CHU Brugmann, Brussels, Belgium presented preliminary findings from the AFACART clinical trial testing the effectiveness of ‘Panoramic Electrographic Non-Invasive Mapping’, specifically the CardioInsight—ECVUE System, as compared to conventional mapping and ablation procedures.
In the clinical trial, patients with persistent A-Fib receive an ablation using the ECVUE mapping/ablation system, then there is a 12-month follow-up period.
In an important change to standard ablation procedures, Dr. Knecht described the first step in the ECGI/ECVUE ablation process as ablation of A-Fib drivers (rotors and foci). This is in contrast to the ‘step-wise’ approach that begins with ablation of the openings of the pulmonary veins.
To read more, see my 2015 AF Symposium article, AFACART Clinical Trial: Preliminary Results of the CardioInsight—ECVUE System in Multiple Centers.
The past week or so has been a hair-pulling experience for Patti and me. Our web server service went down and our website along with it for four hours. (Apologies to all.) A software upgrade lead to lost files. So, we had to restore many of our blog posts.
During this time, you may have missed some of our best blog posts, so I encourage you to browse the A-Fib News blog page (and click the ‘earlier’ post arrow as the bottom) to see posts you may have missed.
Share the Goodness. If you enjoy a post, why not click and share it with your network? As always, email me with comments..
Visit Steve’s A-Fib blog often. Share the goodness. Share your favorites posts.
Persistent A-Fib: Insights into Finding Additional Drivers May Shorten Ablation Procedures with Fewer Lesions
By Steve s. Ryan, PhD, July 2015
Dr. Pierre Jais of the French Bordeaux/LIRYC group gave a presentation on “The Spectrum of Atrial Tachycardias Following Ablation of Drivers in Persistent AF.”
He described a study of the ablation of 50 persistent A-Fib patients using ECGI to map and ablate A-Fib signal drivers.
A-Fib was terminated in 79% of patients, with 10% returned to sinus rhythm and the remaining 69% in tachycardias (but with no A-Fib).
For those still in arrhythmia, ECGI was used to map, analyze and diagnose the locations of the arrhythmias signals, and additional ablation lesions were performed. Identified were 25 macro-reentry circuits and 14 focal/localized-reentry circuits.
The reentry circuits found by ECGI were:
• common atrial flutter in 14 patients
• perimitral flutter in 9 patients
• roof dependent flutter in 2 patients
Dr. Jais showed many slides and videos of how ECGI mapped and analyzed where these arrhythmias were coming from and how they were ablated.
Dr. Jais’ Conclusions
Dr. Jais stated that the study data revealed, “the focal/localized-reentry were adjacent to drivers at 0.9cm from the core of driver with low voltage (0.5 mV)”.
To clarify, this means that the drivers of the remaining arrhythmias were located very close (adjacent) to the drivers previously mapped by ECGI.
Therefore, when ECGI locates an area of rotors and drivers, it is highly likely this is where the source of additional arrhythmias will most likely be found. This insight reduces or eliminates the need (and time) to search other areas of the heart thereby shortening procedure length and decreasing the number of lesions needed.
ECGI mapping and ablating is changing our understanding of and our techniques for ablating persistent A-Fib. If a patient has continued arrhythmias after the initial ablation, ECGI often can re-map and identify where the remaining arrhythmias are coming from, usually very near previously identified driver locations. This is a valuable insight for doctors doing ablations.
For patients, it may mean a shorter procedure time with fewer burns needed to eliminate the sources of A-Fib signals.
Last updated: Thursday, August 6, 2015
ECGI is changing everything. Instead of potentials and CFAEs, EPs will focus on ablating drivers (rotors and foci). Prof. Michel Haïssaguerre of the French Bordeaux group/LIRYC gave a presentation on the changing world of catheter ablation using Non-Invasive Electrocardiographic Imaging, or ECGI (from CardioInsight), a radically new and innovative mapping and ablation system.
The system automatically detects rotors and foci and computes them into a “Cumulative Map” or movie. These driver regions are ranked, based on statistical prevalence. They are displayed in statistical density maps which define the ablation road map.
Ablation using ECGI results in a dramatic decrease of RF burns needed to produce A-Fib ‘termination’.
Dr. Haïssaguerre showed slides where he ablated driver regions which then transformed rapid complex A-Fib signals into slower organized signals.
A-Fib Patient Story #79
By Dr. Carlo Romero, The Philippines, February 2015
I am a 49-year-old male from the Philippines. I was diagnosed with A-Fib in 2007 at age 42. It happened after I was dehydrated playing golf. The A-Fib resolved by itself after a few hours. But after a few months, I had another attack. When I went to the ER, an ECG documented the AFIB. I was not given any medication but was advised to stay away from triggers which I did. I even stayed away from cigarettes, drinking, chocolates, food with monosodium glutamate.
After Three Years, Severe Pain Triggers A-Fib—Amiodarone Works, But Thyroid Problems
I did not have any attacks for a year, but my thyroid hormones were becoming abnormal due to the amiodarone.
A-Fib Attacks Become More Frequent—Decides To Go To Bordeaux
At this time I was already doing research about what other options were available, because I know that in time, the medications will stop working. In 2010, I was already in touch with Steve Ryan and had already heard of ablation. I had written several big centers and inquired about ablation procedures and cost. I wrote emails to Bordeaux and to the secretary of Dr. Natale. But since the attacks were few and far between, I decided to stick to medication which controlled the symptoms.
It was a choice between having the ablation in San Francisco or the Bordeaux group…The cost made me decide on Bordeaux, because it cost half that of San Francisco.
Arriving at Bordeaux Hospital
In August 2014, I wrote Bordeaux emails, and they made me answer a questionnaire to determine my status. I sent my reply and was told I would be a good candidate. I was given an ablation date Nov 3, 2014, more than 2 mos. from the time I inquired. I was instructed to do some blood tests and a TEE 2-3 weeks prior to my ablation and to settle the payment for the procedure 1 month before the ablation date. I complied with all of these requirements, got a medical visa from the French Embassy, plane ticket, hotel booking and was all set. I arrived in Bordeaux on Oct 29, 2014. Since we still had time, we first went to Lourdes, France and then back to Bordeaux the next day.
Nov 3, 2014, Monday, I was told to be at the Hospital at 8am. To be sure that we didn’t get lost, we took a cab which cost around 45 euros coming from the center of Bordeaux near the opera house. Admission was a breeze, and I made sure we had internet which you can get in the Admitting section (ask them about it because the nurses are not familiar with it). I made sure of the internet connection to be able to use the app I downloaded which helps me to communicate in French. (Translate App) When you type in English, the app will translate it to French.
I was attached to a holter monitor whose signals were transmitted to the nurse’s station. The first day was spent getting X-rays, lab exams, preparation and shaving of the groin area. They also started injecting heparin. I was told to stop amiodarone 5 days prior to ablation. But since I learned from Steve Ryan that amiodarone has a long half-life, we asked Dr. Jais thru email if the instruction was right. He was able to correct it to 10 days prior to ablation and pradaxa 48 hours prior to ablation.
Ablation with ECGI
The next day, I received IV fluids and was brought down to the CT scan area. I laid down on a bed and was given a vest which I learned later was an ECGI. It’s the new procedure which, according to Dr Haissaguerre, is not yet in use in the US. But they have found it very useful and promising.
His explanation is that it is like an ECG. But instead of 12 leads, it has 252 leads (attached in the vest) The ECGI vest represents the future of the mapping procedure, and according to him will shorten the OR time since they can map out the heart prior to the procedure. (For a further explanation of how the ECGI mapping system works, see “How ECGI [Non-Invasive Electrocardiographic Imaging] Works.”)
I think I was the 2nd case that day since I was brought down at the theatre at 1 pm. I did not see Dr Haissaguerre at that time nor prior to the procedure which made me a little bit anxious. But I was assured by his assistant that He will be doing the ablation. The assistant doctor asked me if it was ok that he start with the insertion of the catheter and that Dr Haissaguerre will be the one doing the ablation later, to which I agreed.
I must have dozed off. Because when I became aware again, I heard that we were about to be finished. Although during the ablation there were instances where I felt my heart going very fast, then they would later massage my neck area. And then after a while, there were two more cycles like that. I was told later that, since I was not in A-Fib, they had to induce me several times. My procedure took almost 4 hours.
After the Ablation—Time With Dr. Haissagguerre
Wednesday, when I woke up, I had a fever of about 39 degrees and had a difficult time breathing. The nurses upon instruction from the doctor gave me paracetamol which lowered the fever, but I was still in pain if I breathed. I was really worried at that time and kept on reminding the nurses to ask the doctor when will they see me so I can talk with them about these symptoms.
That night, a young doctor came to my room with a portable 2d echo and, after examination, concluded I had fluid around my heart and that the fever and the difficulty of breathing were related to that. I was given an anti-inflammatory which relieved the symptoms in 2 days. At this time my abdomen was black and blue due to the round-the-clock injection of heparin. Towards the evening , I was allowed to start with soup and yogurt and later solid foods if I could tolerate them.
Thursday, the fever and the difficulty of breathing diminished. The nurses also advised me to start pradaxa after my last dose of heparin. I was allowed to sit up already and go to the bathroom. In the afternoon, Dr Haissaguerre was able to visit me which was the first time I met him face-to-face. My wife told me that he visited a few hours after my procedure, but I was mostly asleep at that time. He had an aura of confidence in him that made me feel that I was talking to a very knowledgeable person. He explained that I had 3 problematic areas. 1 in the atrial septum and 2 near the pulmonary veins. He added that since I was not in A-Fib, they had to induce it with isoproterenol.
Dr Haissaguerre stayed in the room for almost an hour explaining to us what was done and what to expect in the future. I asked him how many international patients they have. He informed that they accept only 2 international patients per week.
Dr Haissaguerre stayed in the room for almost an hour explaining to us what was done and what to expect in the future. I asked him how many international patients they have. He informed that they accept only 2 international patients per week. And I was told that I was the first Filipino patient he had. I was also able to meet for the first time Laurence Bayle, the secretary of the doctors with whom I was in contact most of the time. Sometimes it would take a day or two for my emails to be answered, sometimes a week. But despite that, I was able to arrange and carry out my ablation. Probably the volume of the inquiries made it impossible for them to answer immediately.
Discharge—Questions For Dr. Haissaguerre
The next day, Friday, I was told that I would be discharged. I was given all the instructions. While waiting for our Dr Haissaguerre to meet us prior to discharge, we were able to go around the hospital and outside it. From what I understand, it’s a big hospital building which caters solely for heart patients. We were sent to the admitting section to settle our accounts, but we were told that we would have no additional payments, as everything is included in the package.
When Dr. Haissaguerre arrived to see us in the afternoon, I informed him about skipped beats which bothered me post op. He told me that it was normal for an ablated heart to skip beats especially since I had a pericardial effusion, but that they will go away in time. (the skipped beats slowly went away in a month’s time).
I went back to the hospital in November 10, 2014 for my final check-up prior to being allowed to go home. The next few days, we opted to go to Paris and spent some vacation time just in case there was still a need to see Dr. Haissaguerre prior to our flight back home to the Philippines.
The whole “healing journey” was very memorable. I cannot believe that I really went out of country just to have the procedure, but everything went as planned. A lot of anxious moments and hesitancy, but I made it through. A few hitches here and there, but nothing that couldn’t be handled.
In this age of the Internet, we as patients have the power to learn more about our disease and act accordingly. We can opt to just live with it which is not really a bad choice as a lot of A-Fib patients have done successfully. Or we can be proactive about it. Of course the ablation procedure is not 100% curative nor 100% safe, But I made my decision based on my goal that I still wanted to practice my profession as a doctor. I owe it to my patients to try to heal myself by the best possible means so that I can render the best medical service to them.
I am now exactly 100 days post ablation. I’m still on anticoagulants, but am A-Fib free. In the last conversation I had with Dr Haissaguerre, I asked him if there are things that I am prohibited to do or food that I am not allowed to eat, and he told me no prohibitions.
“Live a Normal life” and that’s what I plan to do.
Because Dr. Carlo had been in A-Fib for some time, his ablation probably was more challenging. It took four hours which was longer than usual considering that the mapping had been done already by the ECGI system. He had a minor pericardial effusion which is often unavoidable in more extensive ablations.
The ablation Dr. Carlo had represents a radical, transformative change in ablation therapy and may alter the way ablations are done. Normal catheter ablation for A-Fib usually starts with isolating the pulmonary vein openings. But Dr. Haissaguerre instead started with the atrial septum area as indicated by the ECGI system. Only later did he go to the pulmonary vein areas. ECGI will certainly change the way catheter ablations are performed.
Dr. Carlo Romero is a great example of a proactive A-Fib patient who educated himself about A-Fib, researched all his options, found the right doctor for him, and wouldn’t settle for less than the opportunity for a complete cure of his A-Fib.
If you find any errors on this page, email us. Y Last updated: Sunday, July 17, 2016
When I think about the field of atrial fibrillation in 2013, several thoughts come to mind. There were technical advancements, some new drug therapies, and additions to our understanding of Atrial Fibrillation (and a few accomplishments for our A-Fib.com website).
Heart Imaging And Mapping Systems
Perhaps the most important technical innovations in 2013 for A-Fib patients were the introduction of two new heart imaging and mapping systems. A third system, the Bioelectronic Catheter, represents a whole new technology with tremendous potential for A-Fib patients.
The ECGI System
The ECGI system, combined with a CT scan, produces a complete 3-D image of your heart along with identifying all the A-Fib-producing spots. Think of it as an ECG with 256 special high resolution electrodes rather than 12. It greatly reduces your ablation time and your radiation exposure.
A day before your ablation, you simply don a special vest with 256 electrodes covering your upper torso, and lay down. The 3-D image created is a road map of your heart with all the focal and rotor areas (A-Fib-producing spots) identified. During your ablation your EP simply ablates the “guilty” areas. Read more of my article…
The FIRM System
The FIRM system uses a different approach to mapping the heart and the A-Fib producing spots. It uses a basket catheter inside the heart to map large areas in a single pass and reveal the location of foci and rotors. Read more of my article…
Why are these two technologies important? ECGI allows your imaging & mapping to be performed the day prior to your ablation, rather than during your ablation. This shortens the length of your ablation procedure. In addition it reduces your radiation exposure and produces remarkably accurate 3D images of your heart and identifies where A-Fib signals are coming from. The FIRM system, though performed during an ablation rather than before it, may be a significant improvement over the Lasso catheter mapping system now in current use. Both systems may mark a new level of imaging/mapping for A-Fib.
Stretchable Electronics Meets the Balloon Catheter
The merging of living systems with electronic systems is called “bioelectronics”. Key is a flexible, pliable circuit made from organic materials—the carbon-based building blocks of life. Bioelectronics have entered the EP lab with a prototype of a ‘bioelectronic catheter’, the marriage of a pliable integrated circuit with a catheter balloon.
In a mapping application, the deflated bioelectronic balloon catheter is slipped into the heart, then pumped up. The inflated integrated circuit conforms to the heart’s grooves and makes contact with hard-to-reach tissue. It can map a hundred electrical signals simultaneously, across a wider area and in far greater detail than had been previously possible. And it’s being developed to function in reverse. For ablation applications, instead of detecting current, it can apply precise electrical burns. This is a potentially breakthrough technology that may well change the way catheter mapping and ablation are performed. (Thanks to David Holzman for calling our attention to this ground-breaking research article.)
This is a remarkable time in the history of A-Fib treatment. Three very different technologies are poised to radically improve the way A-Fib is detected, mapped and ablated. We’ll look back at 2013 as a watershed year for A-Fib patients.
Three New Anticoagulants
In 2013 we saw three new anticoagulants, a welcome development for A-Fib patients. Note: the new anticoagulants are very expensive compared to the proven anticoagulant warfarin.
How do they compare to warfarin?
Warfarin seems to have a slightly higher chance of producing intracranial bleeding.
In general stay away from Pradaxa. There are horrible ER reports of patients bleeding to death from even minor cuts, because there is no antidote or reversal agent. Read more about my Pradaxa warning…
Eliquis, in general, tested better than Xarelto in the clinical trials, but it’s so new we don’t have a lot of real-world data on it yet. And, as with Pradaxa, neither have antidotes or reversal agents.
In addition, there was what some consider a major problem with the clinical trials comparing the new anticoagulants to warfarin. ‘Compliance’ rates by warfarin users were poor (many either weren’t taking their warfarin or weren’t in the proper INR range). Did this skew the results?
And finally, unlike warfarin where effectiveness can be measured with INR levels, we don’t have any way to measure how effectively the new blood thinners actually anticoagulate blood. Read more of my article “Warfarin vs. Pradaxa and the Other New Anticoagulants“.
Keep in mind: ‘New’ doesn’t necessarily mean ‘better’ or ‘more effective’ for You.
High Blood Pressure with Your A-Fib? Is Renal Denervation a solution?
As many as 30% of people with A-Fib also have high blood pressure which can’t be lowered by meds, exercise, diet, etc. There was hope that Renal Denervation would help.
With Renal Denervation, an ablation catheter is threaded into the left and right arteries leading to the kidneys, then RF energy is applied to the nerves in the vascular walls of the arteries, hopefully reducing ‘Sympathetic Tone’, lowering high blood pressure and reducing A-Fib. For many people Renal Denervation seemed the only realistic hope of lowering their high blood pressure. However, the Medtronic Simplicity-3 trial indicated that renal denervation doesn’t work. Read more of this article… For 2014 news on this topic, read more…
A Study of Obesity and A-Fib: A-Fib Potentially Reversible
Obesity is a well known cause or trigger of A-Fib, probably because it puts extra pressure and stress on the Pulmonary Vein openings where most A-Fib starts.
In 2013 A research study report focused on obese patients with A-Fib. Those who lost a significant amount of weight also had 2.5 times less A-Fib episodes and reduced their left atrial area and intra-ventricular septal thickness.
Good news! Losing weight can potentially reverse some of the remodeling effects of A-Fib. Related article: Obesity in Young Women Doubles Chances of Developing A-Fib.
Obstructive Sleep Apnea and A-Fib
Obstructive Sleep Apnea (OSA) is another well recognized cause or trigger of A-Fib. Anyone with A-Fib should be tested for sleep apnea.
Earlier studies have shown approximately two-thirds (62%) of patients with paroxysmal or persistent A-Fib suffer from sleep apnea. In 2013, research reports showed that the worse one’s sleep apnea is, the worse A-Fib can become. In addition, sleep apnea often predicts A-Fib recurrence after catheter ablation.
Before an ablation, Dr. Sidney Peykar of the Cardiac Arrhythmia Institute in Florida, requires all his A-Fib patients be tested for sleep apnea. If they have sleep apnea, they must use CPAP therapy after their ablation procedure.
A-Fib.com: Our New Website’s First Year
The original A-Fib.com web site was created using the phased out software MS FrontPage. Thanks to a “no strings attached” grant from Medtronic, A-Fib.com was reinvented with a more up-to-date but familiar look, and features more functionality (built on an infra-structure using Joomla and WordPress). We can now grow the site and add features and functions as needed.
It involved a tremendous amount of work. A special thanks to Sharion Cox for building the new site and for technical support. My wife, Patti Ryan, designed the look and all graphics. (I can’t thank Patti enough; I’m so lucky!)
Update the Directory of Doctors & Facilities
Back when I started A-Fib.com in 2002, there were less than a dozen sites performing ablations for A-Fib. Today our Directory of Doctors and Facilities lists well over 1,000 centers in the US, plus many sites worldwide.
Increasingly, doctors were writing me asking why they weren’t included, or why their info was incorrect since they had moved, etc. To update our records and our service to A-Fib patients, starting in July 2013, we prepared and mailed letters to over 1,000 doctors/facilities. We asked each to update/verify their listing (and include a contact person for our use).
The response to our bulk mailing was great. The data input started in October and continued for several months (as time allowed). Recently, we cut over to the ‘new’ Directory menu and pages.
What’s Ahead for A-Fib.com in 2014
2014 Boston AFib Symposium Reports: Check out my new reports from the 2014 Boston A-Fib Symposium (BAFS) held January 9-11, 2014 in Orlando FL.
The first two reports are posted. Look for more reports soon. I usually end up with 12-15 reports in total.
Our a-Fib.com Directory of Doctors & Facilities: Work on updating our listings is still underway. We need to contact those who did not respond to our request for verification or updating of their listing. (Shall we write again or maybe make phone calls?)
Amazon Best Sellers list: Our book sales continue to grow. Did you know that our book ‘Beat Your A-Fib’ has been on Amazon’s Best Sellers list continually in two categories (Disorders & Diseases Reference and Heart Disease) since its debut in March 2012? Visit Amazon.com and read over 40 customer reviews.
Help A-Fib.com Become Self-sustaining: We plan to step up our efforts to make A-Fib.com a self-sustaining site. (Since 2002, Steve and Patti Ryan have personally funded A-Fib.com with an occassional reader’s donation.)
In our efforts toward sustainabiliy, several years ago we added a PayPal ‘Donate’ button (you don’t need a PayPal account to donate) and invited donations toward our onlline maintenance costs.
Our newest effort is our ‘A-Fib can be Cured! shop with T-shirts and more at Spreadshirt.com. With each shirt purchase $2 goes to support A-Fib.com. (We will roll out new designs every quarter or so).
Posted February 2014
Help A-Fib.com become self-sustaining! Help keep A-Fib.com independent and ad-free.
Will 2014 be the year you help support A-Fib.com?
Last updated: Wednesday, February 11, 2015
ECGI vs. FIRM: Direct Comparison, Phase/Waveform Mapping
Report by Dr. Steve S. Ryan, PhD
In a further discussion of the ECGI mapping and ablation system, Dr. Phillip Cuculich of the Washington University School of Medicine in St. Louis, MO gave a presentation entitled “Advances in and Limitations of Noninvasive Mapping of AF.” (For a detailed description and discussion of the ECGI system, see 2013 BAFS: Non-Invasive Electrocardiographic Imaging ECG (ECG).
Background: ECGI stands for Non-Invasive Electrocardiographic Imaging used at Yoram Rudy’s lab at Washington University in St. Louis to understand the mechanisms of heart rhythm disease. A similar system called Electrocardiographic Mapping (ECM/ecVUE) uses similar technology, but has been developed and tested for clinical use in Europe (http://www.cardioinsight.com) and has different goals. Each group works independently and has different ways to seek solutions.
The software used by the ECGI system to produce data and images from the multi-channel ECG mapping and CT scan is called CADIS.
POTENTIAL BENEFITS OF ECGI
Dr. Cuculich began by describing the potential benefits of ECGI:
• Save time: Locate the arrhythmia in a single beat
• Better Preparation: Understand and plan for the arrhythmia before an ablation
• Avoid Frustration: Map and ablate unstable, transient or complex arrhythmias
• Research Platform for Discovery: Identify and describe the mechanisms of arrhythmias
A-FIB PATTERNS OR SIGNALS AS REVEALED BY ECGI
After imaging patients with ECGI, A-Fib patterns are a combination of mechanisms:
• In simple A-Fib, Dr. Cuculich showed movies of left pulmonary vein focal sites with 1 to 2 wavelets and a left-to-right activation pattern
• In complex (Long-standing Persistent) A-Fib, he showed movies of four or more simultaneous wavelets, a high degree of wavelet curvature, and frequent wave breaks (no focal sites). The patterns tend to repeat and follow a preferred path.
FIRM AND ECGI COMPARISON
|Inside the heart||Outside the heart (body surface mapping)|
|Up to 64 contact electrodes to produce up to 64 electrograms||1000 reconstructed electrodes|
|QRST subtracted||No signal subtraction|
|70% rotor, 30% focal||Multiple wave fronts (1-4), 15% rotor|
|Stable beat-to-beat||Transient focal activity, transient rotational circuits|
(In the ECGI imaging/mapping system the number of points on the heart is changeable. But they have found 1000 to be a good number for reliable, detailed analysis.)
Dr. Cuculich compared ECGI data to recent invasive epicardial (inside-the-heart) mapping and body surface mapping (called “Phase Lock”). The data showed significant agreement between the imaging systems. Also, ECGI compares favorably to surgical maze mapping data.1
But compared to FIRM, the most common patterns of A-Fib Dr. Cuculich found were multiple wavelets, with pulmonary vein and non-pulmonary vein focal sites. Rotor activity was seen rarely.2
NO STANDARD DEFINITION OF “ROTOR”
There is no standard definition of a rotor. In Dr. Cuculich’s studies he used 2 rotations at the same spot as a “rotor.” This is perhaps why he found less rotors than in the FIRM system and in the CardioInsight system as described by Dr. Jais where they found 80% rotors. See: BAFS 2014 Jais, ECGi & Circular Catheter
Another major difference in ECGI and FIRM is that ECGI uses wavelet analysis (activation of the wavefront), while FIRM and CardioInsight uses phase mapping to describe the behavior of the arrhythmia. The main point of Dr. Cuculich’s presentation is that one must be very careful when applying phase techniques, as it can introduce rotor behavior into the imaging map. Dr. Cuculich’s group is studying whether this rotor behavior may be a true cause for the maintenance of A-Fib or just an artifact.
ECGI—TOO MANY ELECTRODES?
In a conversation with the author, Dr. Cuculich brought up comments that perhaps ECGI/ECM uses too many electrodes to see stable rotors, that perhaps panoramic imaging with fewer electrodes could improve the identification of rotors. (ECGI has a much larger number of electrode points in the heart [usually 1000] compared to FIRM [64 max].) To test this hypothesis, he analyzed A-Fib using 64 spaced electrodes in each atrium vs. standard ECGI. It turned out that fewer electrodes did not help to visualize rotors.
PHASE MAPPING, WAVEFRONTS, WAVELET TRANSFORMATION, ACTIVATION PATTERNS
Dr. Cuculich introduced new concepts in the use of ECGI (at least to this author)—phase mapping and the importance of wavefronts or wavelet transformation in A-Fib signals. “ECGI uses wavelet transform looking at pure activation time.” He asked, “how does…phase mapping affect the result?” He related phase mapping to the CONFIRM concept of “phase lock” where a simple 12-lead ECG analysis can classify A-Fib mechanistically.3
Doctors (and we patients) are still struggling to understand what phase mapping and wavelet transformation actually mean. Dr. Cuculich’s studies of phase mapping techniques (Hilbert transform) in A-Fib show that phase mapping highlights and accentuates the curvature of a wavefront and thus indicates a rotor is present. According to Dr. Cuculich, phase mapping is highly dependent on the chosen cycle length. He concluded that “while published ECGI data used wavelet transform to identify activation patterns, phase mapping techniques (when performed carefully and correctly) may offer additive information.”
We’re grateful to Dr. Cuculich for his comparison of ECGI and FIRM which helps us understand both imaging system better. But it’s definitely disturbing that both systems vary so greatly. Why does the FIRM system find 70% rotors and ECGI only 15%? Why are FIRM’s A-Fib signals stable and ECGI’s transient? Why does the FIRM system not focus on wavefronts and wavelet transformation?
One way to resolve these discrepancies would be to use a standard Lasso mapping catheter to meticulously map every potential A-Fib-producing spot in an animal or human with Long-standing Persistent A-Fib (where one would expect to find multiple A-Fib producing spots in the heart). Then immediately use both the FIRM and ECGI system to map the same heart and compare the results.
Perhaps the single biggest new discovery in human A-Fib mapping is rotors. But there’s considerable debate about their definition and behavior. Dr. Cuculich found that rotors are relatively rare (15%), whereas the FIRM and CardioInsight studies indicate that 70-80% of A-Fib drivers are rotors.
Dr, Cuculich introduced new concepts, insights and vocabulary to our understanding of A-Fib, (some of which I’m still having trouble wrapping my head around). Are wavefronts and wavelet transformation important in themselves or are they part of the development of rotors? Phase mapping and wavelet transformation applied to A-Fib is a major innovation that may lead to a better understanding of how A-Fib signals activate in the heart. Besides making mapping and ablating A-Fib easier and more effective, ECGI with its detailed, high resolution capabilities may give us new insights into A-Fib.
- Lee, G. et al. Epicardial wave mapping in human long-lasting persistent atrial fibrillation: transient rotational circuits, complex wavefronts, and disorganized activity. European Heart Journal (2104) 35, 86-97. Last accessed May 13, 2013, URL:http://www.ncbi.nlm.nih.gov/pubmed/23935092 doi:10.1093/eurheartj/eht267↵
- Cuculich, PS et al. Noninvasive characterization of epicardial activation in humans with diverse atrial fibrillation patterns. Circulation. 2010 Oct 5; 122(14): 1365-72. Last accessed May 13, 2013, URL: http://tinyurl.com/okp4229↵
- Non-invasive identification of stable rotors and focal sources for human atrial fibrillation: mechanistic classification of atrial fibrillation from the electrocardiogram, Europace. February 28, 2013. Last accessed May 13, 2013, URL: http://tinyurl.com/njt9zd7; doi:10.1093/europace/eut038↵
2014 Boston AF Symposium
How ECGI (Non-Invasive Electrocardiographic Imaging) Works
Report by Dr. Steve S. Ryan, PhD
Dr. Michel Haissaguerre of the LIRYC Institute in Bordeaux, France gave a presentation entitled “Mechanistic Insights From Noninvasive Mapping of AF—Implications for Catheter Ablation.”
Dr, Haissaguerre began by discussing the concept of voltage vs. noise in reading an ECG. High accuracy can be obtained with a EGM (electrogram signal) of >0.15mV. Body Filtering (ECGI) can miss small local A-Fib signals, but does not affect global patterns.
He found that when mapping Focal A-Fib signals from both inside and outside the heart, they may differ in location by 3.1mm. (This is a relatively small difference and isn’t enough to affect the overall accuracy of the mapping and ablation.)
How ECGI (Body Mapping) Works
He described how the ECGI system works. A patient lies down on his/her back and a technician places a vest-like device with 256 electrodes over his/her chest and stomach. These electrodes combine with rapid CT (Computed Tomography) scans to produce a very detailed 3D color map of the heart. (For a detailed description and discussion of the ECGI system, see 2013 BAFS: Non-Invasive Electrocardiographic Imaging [ECG])
The system automatically detects rotors and foci and computes them into a “Cumulative Map” or movie. These driver regions are ranked, based on statistical prevalence. Dr. Haissaguerre showed slides of these drivers originating from PVs in Paroxysmal A-Fib.
In persistent A-Fib he found multiple interplaying driver regions (median 4, 1 to 7) found in the Left Atrium, PVs and Right Atrium (“driver regions” include both focal sources and rotors). The rotors were temporally and spatially unstable. They were not sustained. Most had 2-3 rotations with a mean of 448ms. They required a statistical analysis of their core trajectory/density. Patients in Persistent Long-Lasting A-Fib for more than six months had the most driver regions and the least success in A-Fib termination after six months.
…ECGI ablation significantly reduced the amount of burns needed to terminate A-Fib.
Compared to the traditional Bordeaux step-wise ablation for persistent A-Fib, ECGI ablation significantly reduced the amount of burns needed to terminate A-Fib.
Dr. Haissaguerre uses a Multielectrode circular catheter not yet approved for use in the US. This catheter can more easily capture and isolate regional targets like rotors that do move a little.
Dr. Haissaguerre’s Conclusions
- Regional clusters of A-Fib drivers can be mapped non-invasively
- ECGI mapping before a procedure identifies critical regions to ablate. This reduces targeted atrial areas and RF delivery. The optimal timing is in the early months of persistent A-Fib.
- There is a need for appropriate ablation tools (such as circular or multielectrode catheters) as rotor targets are not so limited (they tend to move slightly).
Back in 2013 I predicted that “the ECGI system, barring unforeseen circumstances, will rapidly supersede all other mapping systems and will become the standard of care in the treatment of A-Fib patients.”
Not only does the ECGI system produce a complete, precise, 3D, color video of each spot in a patient’s heart producing A-Fib signals, but also an ECGI can be done by a technician before the procedure rather than by a doctor during an ablation. And the ECGI map is a better, more accurate, more complete map than an EP can produce by using a conventional mapping catheter inside the heart.
From a patient’s perspective, ECGI reduces both the time it takes to do an ablation and the number of burns a patient receives.
The only caveat that Dr. Haissaguerre found (which relate to all mapping strategies, not just to ECGI) is that rotors move slightly and are somewhat unstable. A computer has to be used to statistically analyze their core trajectory. But circular catheters can be used to contain and isolate them.
Addendum: April 2015
Jeffrey Patten asked, “I’ve heard that the new mapping and ablation vest system ECGI (CardioInsight), though very detailed with 256 electrodes, doesn’t directly map the septum area. Is that correct?”
It’s correct to say the ECGI does not directly map the septum area. But, that doesn’t mean the septal activity can’t be mapped with the ECGI.
I posed your question to the world-reknown cardiologist, Dr. Pierre Jais of the Bordeaux group. He explained that “the septal activity projects at the anterior and posterior attachments of the septum on both atria.” He added that mapping the septum with the ECGI system “…requires some experience, but is at the end easy.”
So don’t be reluctant to seek out the new mapping and ablation vest system ECGI (by CardioInsight). Just be sure you have a top-notch, experienced operator.
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Last updated: Wednesday, September 2, 2015