New Reports by Drs. Haissaguerre, Wilber, Reddy & Valderrabano
I’ve been rather prolific with my summaries of key presentations from the recent 2016 AF Symposium (January, Orlando, FL). Four new reports have been posted at 2016 AF Symposium: My Summary Reports Written for A-Fib Patients.
You might want to start with two presentations by the A-Fib research pioneer1, Dr. Michel Haissaguerre of Central Hospital, Bordeaux, France (he cured my A-Fib in 1998):
Then move on to the very HOT topic of Rotors, and two difficult cases of ablation with LAA closure:
• Rotors! Rotors! Rotors! Good News for Patients with Persistent A-Fib. presented by Dr. David Wilber of Loyola University Medical Center, Chicago, IL
• Two Challenging, Difficult Catheter Ablation Cases with LAA Closure by Dr. Vivek Reddy, Mount Sinai Hospital, New York, NY and Dr. Migel Valderrabano, Houston Methodist Hospital, Houston, TX
More Reports to Come
You can see a list of my first six reports at 2016 AF Symposium: My Summary Reports Written for A-Fib Patients.
For an introduction to the 2016 AF Symposium, don’t miss my brief Overview.
I expect to write 15 – 20 additional reports in the coming months. So visit the reports list often. Just use the left menu tab “2016 AF Symposium Reports” (found on every page) to go to my growing list of reports.
- Pioneer in the Ablation of A-Fib: In 1997, a major breakthrough came to AF ablation as Dr. Michel Haïssaguerre and his researchers observed that a vast majority of A-Fib was initiated by triggers from a focal source in the Pulmonary Veins (PV) and ablation of the focal source in the PV eliminated Parosysmal A-Fib.↵
7. “How dangerous is the fluoroscopy radiation during an ablation? I know I need a Pulmonary Vein Ablation (Isolation) procedure to stop my A-Fib. A-Fib destroys my life. I can’t work or exercise, and live in fear of the next attack. Antiarrhythmic meds cause me bad side effects. But I’m worried about being exposed to radiation during the ablation.”
Back in 2003, exposure to radioactivity during an ablation was a legitimate concern; a typical A-Fib ablation resulted in around 50 minutes of fluoroscopy time.
Today, many centers use much less or no fluoroscopy at all. Instead many use 3D non-fluoroscopy (no radiation) imaging techniques such as Intracardiac Echocardiography (ICE) and/or Magnetic Resonant Imaging (MRI). Check with your A-Fib center as to how much radiation their typical A-Fib ablation patient is exposed to, then compare it to the following points of reference to determine if you should be concerned.
|TYPE OF RADIATION EXPOSURE||AMOUNT (mSv units)|
|Average Background Radiation/year||2.4 mSv|
|Chest X-Ray Radiation||0.02-0.2 mSv|
|Full-mouth Dental X-Ray||0.03-0.2 mSv|
|Spinal X-Ray Radiation||1.5 mSv|
|Heart CT Scan Radiation (100-600 Chest X-rays)||12.0 mSv|
|25.5 min. fluoroscopy during an A-Fib Ablation||15.2 mSv|
But bear in mind, even a one hour-long exposure to fluoroscopy is a relatively small risk compared to the risks of being in A-Fib, taking anti-arrhythmic meds, and/or Maze surgery.
Protecting Yourself from Radiation Damage
You can take safeguards before and after your ablation to help protect yourself from radiation damage. Since much of the cancer-causing damage from ionizing radiation is from hydroxyl free radicals, it’s recommended to take antioxidant supplements to neutralize them. A typical plan is to take the following natural supplements every six hours for at least 24 hours before and after your radiation exposure. These are available without a prescription from health food stores. But check with your doctor before taking any supplements.
1. Vitamin C 1000 mg
2. Lipoic Acid 400 mg
3. N-Acetyl Cysteine 200 mg
4. Melatonin 3 mg
Dr. Leo Galland, MD of the Foundation for Integrated Medicine suggests two additional supplements to reduce the risks of radiation exposure:
• Egb 761 (Tebonin), a Ginkgo extract to be taken a week after being exposed to imaging radiation, 120 mg daily. “Reduced the damaging effects of radiation on chromosomes—and the benefits persisted for several months after workers stopped taking it.”
• The flavonoid Hesperidin, a type of antioxidant, 250 mg about one hour before testing. “In human tests…it reduced radiation-induced damage by about one third.”
Editor’s comment: The nuclear theory that any level of radiation is cumulatively damaging may not be valid (the “Linear No Threshold” theory). The levels of radiation received during a typical catheter ablation may not be dangerous, but may even be healthful. See
Thanks to Stephanie Fagan for this question.
¤ Macle, L et al. “Radiation Exposure During Radiofrequency Catheter Ablation for Atrial Fibrillation.” Pacing and Clinical Electrophysiology, March 28, 2003. Volume 26, Issue 1p2, Pages 288-291.
¤ Efstathopoulos et al. “Patient and staff radiation dosimetry during cardiac electrophysiology studies and catheter ablation procedures: a comprehensive analysis.” Europace (The European Society of Cardiology), 2006 8(6): 443-448; doi:10.1093/europace/eul041
¤ Galland, Leo. Guard Against Radiation Danger. Bottom Line/Health, May 2015, p. 9.
Return to FAQ Catheter Ablations
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
Cellular Remodeling and Mapping of A-Fib
Report by Dr. Steve S. Ryan, PhD
Dr. Sanjiv Narayan of the University of California, San Diego gave a presentation entitled “Cellular Remodeling and Spatial Mapping of Human AF.” Dr. Narayan is known for inventing the FIRM mapping/ablation system (Topera). (For a discussion of the FIRM system, see BAFS 2013: FIRM [Focal Impulse and Rotor Modulation] for Catheter Ablation of A-Fib by Dr. Narayan of UC San Diego).
Background: Understanding the Firm System. Because the FIRM system uses a proprietary, patented algorithm to identify A-Fib producing spots in the heart, it’s hard to understand and evaluate it. (In a private conversation with someone from Topera, this algorithm is a closely guarded secret like the secret recipe for Coca Cola.) If you’re the type of person who likes to look under the hood of your car and understand the mechanics of how it operates, the FIRM system may be very frustrating. (Continued below)1
SUSTAINING MECHANISMS, SUBSTRATES, CFAES
Dr. Narayan began his presentation by discussing Sustaining Mechanisms (Substrate, CFAEs). (CFAEs are Complex Fractionated Atrial Electrograms [an electrogram is a picture of the electrical activity of the heart as sensed by a pacemaker or catheter in the heart]. They are low voltage electrical signals with very short cycle lengths used to identify areas in the heart that need to be ablated.) (For an in-depth discussion of CAFEs, see BAFS 2011: Using CAFEs in Ablating Persistent A-Fib )
Dr. Narayan identified four different types of non-localized sustaining mechanisms―Collision, Block, Pivot Point and Slow Conduction (see graphic online). But these CFAEs have no discrete target. “Localized ablation can’t work.”
Whereas what Dr. Narayan described as Spatially Localized (”Drivers”) are identifiable A-Fib targets. When one ablates these “(true) sources,” A-Fib is eliminated.
But A-Fib remodeling often leads to ‘substrates’ (CFAEs) that are spatially localized.
ROLE OF PACS
Dr. Narayan discussed the role of PACs (Premature Atrial Contractions) in A-Fib remodeling (‘Substrate’, CFAEs). In describing the findings from his own studies of fibrosis and Stiles’ “Reduced Voltage areas”2, PACs trigger A-Fib. But they don’t in patients without A-Fib.
Advanced or cellular remodeling may be due to APD (Action Potential Duration) Oscillations at slow rates in a rotor pattern, and they enable PACs to trigger A-Fib. In mapping these signals, A-Fib is sustained by spatially reproducible rotors.
DR. NARAYAN’S CONCLUSIONS
• Remodeling is the “rosetta stone” linking basic science with clinical observations of A-Fib.
• Remodeling is spatially non-uniform and regional, that explains clinical observations, A-Fib ‘substrates’.
We still don’t understand how the FIRM system algorithms actually work. We can only speculate that the FIRM mapping system identifies Sustaining Mechanisms (Substrate, CFAEs) that produce rotors and filters out others that don’t. However, unless someone “leaks” the algorithms, we’ll probably never know and be able to compare and evaluate the FIRM system.
Dr. Narayan’s findings about PACs (Premature Atrial Contractions) is most important for A-Fib patients. Doctors tend to dismiss PACs because everyone gets them. But as many people with A-Fib know all too well, PACs often precede an A-Fib attack. Dr. Narayan’s studies show that PACs trigger A-Fib attacks, but they don’t in people without A-Fib. And PACs can be very disturbing, even if they don’t trigger A-Fib, particularly in people who’ve had a successful catheter ablation and are A-Fib free.
Can ablation techniques or meds be developed to eliminate PACs and thereby eliminate going into A-Fib? Should EPs ablate for PACs even without A-Fib? (I know of one EP who does ablate for PACs, even in the absence of A-Fib/Flutter.)
Many EPs map and ablate CAFEs (Sustained Mechanisms, Substrates) when trying to “cure” patients in Persistent A-Fib. But according to Dr. Narayan, ablating these areas is ineffective “Localized ablation can’t work,” because there is no discrete target as there is for areas producing rotors. (The ECGI system also seems to identify foci and rotors as compared to CFAEs.) For patients, Dr. Narayan’s observations may result in much less unnecessary burning and scarring of the heart during an ablation procedure.
Return to Index of Articles: AF Symposium: Steve’s Summary Reports
Last updated: Wednesday, September 2, 2015
- But here’s a possible way the FIRM system could possibly be evaluated. Take a standard Lasso mapping catheter or a system like ECGI and meticulously identify every possible A-Fib producing spot in, for example, an animal or human heart in long-term persistent A-Fib. Such a heart usually has many different A-Fib producing spots. Carefully mark the exact location of every foci, rotor, potential, CFAE or any spot producing possible A-Fib signals. Then immediately afterwards, use the FIRM mapping system on the same heart and compare the results. The FIRM system usually finds only one or two A-Fib signal sources in each atria. The FIRM algorithm probably filters out a lot of other A-Fib signal sources as noise. What does the FIRM system filter out? What does it select?
In the live satellite case presented at the 2014 Boston A-Fib Symposium in Orlando, the Bordeaux group using the ECGI system found many different foci and rotors in a patient in persistent A-Fib. But these were clustered in predominantly three areas. Would they show up in the FIRM system as only three foci/rotors?
Patent Law: The algorithms to analyze MRI slices, such as used by Dr. Marrouche, or the algorithms to map electrophysiology, such as used by Topera, have to be kept secret. Dr. Marrouche and Topera really have no choice. According to current US patent law (which I highly disagree with), you can’t enforce a patent on a medical technique. But you can for a surgical technique. For you legal types, the statute reads “35 USC 287(c) (1) With respect to a medical practitioner’s performance of a medical activity that constitutes an infringement under section 271(a) or (b) of this title, the provisions of sections 281 , 283 , 284 , and 285 of this title shall not apply against the medical practitioner or against a related health care entity with respect to such medical activity.” This law effectively makes any patent on a medical technique worthless. (Thanks to David Pressman, Patent Attorney for this important observation.)↵
- Stiles MK, John B, Wong CX, et al. Paroxysmal Lone Atrial Fibrillation Is Associated With an Abnormal Atrial Substrate: Characterizing the “Second Factor”. J Am Coll Cardiol. 2009;53(14):1182-1191. doi:10.1016/j.jacc.2008.11.054.↵
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 my article: BAFS 2013: Non-Evasive Electrocardiographic Imaging (ECGI)
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 on the FIRM System… 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 remarkable accurate 3D images of your heart and 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 abaltion applications, instead of detecting current it can apply precise electrical burns. This is a potentially breakthrough technology that may change the way catheter mapping and ablation are performed. (Thanks to David Holzman for calling our attention to this ground-breaking research article.)
What 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.
Return to Index of Articles: Research and Innovations
Last updated: Sunday, February 15, 2015