Boston AF Symposium, January 11-13, 2007
The annual international Boston A-Fib Symposium is one of the most important conferences on A-Fib in the world. It brings together researchers and doctors who share the latest information. But if you haven’t read and understood most of A-Fib.com, it may be difficult reading.
The overall tone or mood of the 2007 Boston A-Fib Symposium seemed to be one of confidence in a maturing field—that this Symposium was more about fine tuning rather than major changes.
Was a definitive method found to avoid the rare complication atrio-esophageal fistula (where the ablation catheter unintentionally burns a hole through the back of the heart and into the esophagus)? No. But every major center seemed aware of this possible complication and was taking steps to prevent it, such as:
1. Limiting ablation time at the back of the heart to 15 seconds.
2. Using an esophageal temperature probe and stopping the particular ablation whenever there is a rise in esophageal temperature.
3. Using an Echocardiogram to locate the exact position of the esophagus relative to the heart, and then not ablating in areas near the esophagus.
4. Using an irrigated tip catheter at low wattage in the back of the heart.
5. Using a Cryo catheter in the back of the heart (Cryo [freezing] catheters seems to cause less tissue damage).
But because atrio-esophageal fistula is such a rare complication (approximately one case out of 1000 ablations), it may be some time before a particular method of avoiding atrio-esophageal fistula is proven better and more effective than others.
(See below/Marchlinski: Preventing Atrial Esophageal Fistula)
Though “silent” A-Fib especially in “cured” A-Fib patients was still a concern, being A-Fib symptom free was recognized as a major improvement in quality of life and overall health from both a patient’s and doctor’s perspective. (In this author’s opinion, doctors should be proud of the great number of their patients who are now A-Fib symptom free. Successful catheter ablation for A-Fib is one of the great medical breakthroughs of our time. One doctor commented on how fewer patients he sees who are in Persistent A-Fib, because so many have been “cured” before they get to that point.)
Silent A-Fib episodes after successful catheter ablation seem to be more often of short duration. Are these silent A-Fib episodes as dangerous in terms of causing a stroke as in symptomatic A-Fib? Intuitively patients feel more healthy and less prone to stroke when they are A-Fib symptom free, though this has yet to be proven scientifically.
New Research and Medical Developments in A-Fib
Autonomic Ganglionated Plexi sites on the outside of the heart may be very important in generating A-Fib signals, according to Dr. Jackman. It may be possible by ablating only these seven Ganglionated Plexi areas to eliminate A-Fib signals and symptoms. However, this hypothesis is years away from being clinically tested and proven. (See Jackman Autonomic Ganglionated Plexi.)
Randomized clinical trials of the CryoAblation balloon catheter have begun in the US. (The 2006 Boston A-Fib Symposium featured a live demo of a Cryo balloon catheter ablation at Massachusetts General.) (To this author, Cryo [freezing] ablation seems to be significantly safer for patients than standard RF ablation. [See 2006 Boston AF: Ablation Catheters that Use Cryo.] However, Cryo ablations currently take more time to perform than RF ablations. The Cryo balloon catheter will likely allow a doctor to perform a Cryo ablation and isolation of the Pulmonary Vein openings more easily and much faster than current methods. The Cryo balloon catheter may become a major improvement in the treatment of A-Fib. It has already been approved in Europe, with close to 100% success rate in isolating the PVs, and 75-80% success in keeping patients free of A-Fib without anti-arrhythmic drugs.)
The A-Fib medical community seemed somewhat in awe of the French Bordeaux group’s recently reported 95% success rate in curing Persistent A-Fib. (The French seem to have definitely raised the bar for curing A-Fib. Their methods and success rates will probably soon become standard operating procedure for many centers in the US.) Dr. Jaïs reported on recent A-Fib developments in Bordeaux to be summarized later.
Current catheter ablation procedures, particularly the more complicated ones, are not being adequately covered by insurance and government programs. This is a concern for patients who may eventually be excluded from ablation treatment because insurance companies won’t reimburse adequately for complicated catheter ablation procedures. More lobbying needs to be done to improve current reimbursement rates.
The medication ranolazine (brand name Renexa), recently approved by the FDA for chronic angina (chest pain associated with lack of blood to the heart), may help suppress A-Fib by blocking sodium channels in the atrium. (Ranolazine may become an effective antiarrhythmic medication because it is atrial-selective—it affects only the atria and not the ventricles. However, the data on Ranolazine is ALL experimental and there are NO DATA in humans at this time. So, the potential benefit of ranolazine in A-Fib is intriguing but speculative at this point.)
Author’s note: This author was impressed by the willingness of A-Fib doctors to confront, discuss and learn from their most difficult and/or least successful cases. For example, in the live case demo a patient was chosen who had had two previous ablations to isolate the Pulmonary Vein openings, and in whom all four pulmonary vein openings were again generating A-Fib signals into the heart. Another doctor presented a talk on his center’s patients who needed a third and fourth ablation procedure to cure their A-Fib. Doctors share both their successes and their failures in order to help Symposium participants improve their A-Fib patient care.
The 2007 Boston A-Fib Symposium was an extra 1/2 day longer in order to devote more time to the Basic Science of A-Fib (such as chemical currents, nerve structure, and physical mechanisms of the heart during A-Fib), and to surgical operations to cure A-Fib.
Two ablation demonstrations live via satellite were presented. The first from Massachusetts General featured a patient who had had two previous catheter ablations but whose Pulmonary Vein openings were reconducting again. The second case was from Germany and featured a demo of the Stereotaxis remote catheter ablation system. (The excitement generated when a patient’s A-Fib is stopped is similar to a goal or touchdown in a soccer or football game.)
Participants in the 2007 Boston A-Fib Symposium were given an update/summary of the 2006 Boston A-Fib Symposium by Drs. David Keane, Vivek Reddy and Jeremy Ruskin.
Update on Mechanisms and Therapy for A-Fib from the 11th Annual Boston A-Fib Symposium 2006.
(This update was written by doctors for doctors and may be somewhat difficult for patients to read. However, it is an excellent summary not only of the main points of the 2006 Symposium but of all the issues of concern to A-Fib patients today.)
Dr. Francis Marchlinski of the University of Pennsylvania, Philadelphia, PA gave a presentation on “Third and Fourth PV Isolation/Ablation Procedures: Outcomes and Insights.”
One of the major concerns of both A-Fib doctors and patients is the occasional reoccurrence of A-Fib after an apparently successful Pulmonary Vein Ablation (Isolation) procedure. Dr. Marchlinski studied patients who needed not only a second but sometimes a third and even a fourth ablation procedure to cure their A-Fib.
At the Un. of Pennsylvania, 887 A-Fib patients received basically the same ablation treatment: Proximal or Antral PV Isolation along with Ablation of Non-PV (Pulmonary Vein) Triggers. Some patients were Paroxysmal, others were Persistent/Permanent (35%). Some patients needed a second ablation procedure which achieved a 87% success rate; 34 patients (4%) needed a third ablation procedure, and 4 (1%) needed a fourth. Two patients were never cured. (One had Mitral Valve Replacement and Maze surgery and still had recurrent A-Fib; another had two more ablation procedures at another institution and still had recurrent A-Fib.)
Dr. Marchlinski identified the following characteristics of A-Fib patients most likely to need a 3rd or 4th ablation.
- Larger left atrium
- More non-PV triggers
- Heart disease or significant hypertension
(By identifying these characteristics, patients more at risk of needing additional procedures can be identified. Further research may produce additional treatments to prevent them from needing repeat ablations.)
Dr. Marchlinski found that most patients needed repeat procedures because of regrowth or reconnection in the Pulmonary Veins. Of the patients undergoing 3rd and 4th ablation procedures, 65% had all four PVs partially or completely reconnected.
Answering a question from the audience Dr. Marchlinski explained that during ablation both Entrance and Exit block were verified in 100% of patients, that the reoccurrence of A-Fib probably wasn’t due to missed ablation spots.
Someone asked if there was a greater risk of complications during a second ablation procedure than during the first. According to Dr. Marchlinski, the complication rate for a second ablation is the same as for a first one.
Author’s Note: This study is very encouraging for A-Fib patients. The success rate for Pulmonary Vein Ablation procedures is often listed as 70-85%. But, when including those who had a 3rd and 4th procedure, the Un .of Pennsylvania achieved a near perfect cure rate.
Also, Dr. Marchlinski has identified the main reason why patients need repeat ablation procedures—reconduction or regrowth of ablated areas in the Pulmonary Veins. Further research may now be focused on eliminating this reconduction/regrowth.
Dr. Marchlinski’s study indicates that, if you choose to have a PVA(I) procedure, you may need a second procedure to be cured (approximately 26% chance). And there is a 5% chance you may need a 3rd or 4th procedure. This need for multiple procedures is most likely not due to a failed initial procedure, but because of spontaneous regrowth/reconnection of the ablated area.)
PREVENTING ATRIAL ESOPHAGEAL FISTULA
Dr. Marchlinski also described his procedure for trying to prevent atrial esophageal fistula (unintentionally burning a hole through the heart into the esophagus). He uses Echo (Electrocardiograph) and CT/MR (Computed Tomography and Magnetic Resonant Imaging) in an online monitoring system to identify the location of the esophagus in relation to the back of the atrium. If the ablation catheter is near the esophagus, he uses shorter bursts of energy during ablation. “We don’t avoid (ablating near the esophagus) completely if it is required for isolation.”
Dr. David Kress of the Midwest Heart Surgery Institute in Milwaukee, Wisconsin discussed “Surgical Therapy for A-Fib: Selected Cases and Techniques.”
Many cardiac surgeons specialize in one kind of surgery. Dr. Kress described how he uses not just one type but rather an array of different surgical techniques (Radial Maze, Wolf Bipolar RF,Saltman Microwave, Box Lesion Ultrasound), as well as mapping and ablation techniques (ablation of Autonomic Ganglionated Plexi and CryoCath Catheters), depending on the different needs of his A-Fib patients.
For example, one patient with A-Fib also needed surgery to replace an Aortic Valve. Dr. Kress replaced the Aortic Valve, and in the same surgery he used both the Saltman Microwave box lesions and the Wolf Bipolar RF Clamp to isolate the Pulmonary Veins. He also mapped and ablated the Autonomic Ganglionated Plexi (a newer ablation technique that can be performed from outside the heart). According to Dr. Kress, mapping and ablation of Autonomic Ganglionated Plexi increases A-Fib surgery success by 10%.
During surgery on a 73-year-old man with Aortic Stenosis (swelling), he performed a Box Lesion Ultrasound operation, but A-Fib electrical activity continued. He then cut into the left atrium and ablated the remaining A-Fib signal sources with a CryoCath catheter.
In another example, a 49-year-old woman with A-Fib and Hypertrophic Cardiomyopathy also needed a new Mitral Valve. During her surgery Dr. Kress replaced her Mitral Valve, performed a Radial Maze operation and used a CryoCath catheter to make the Radial Maze connecting lesions (as an adjunct to the typical extensive cutting and sowing of the Radial Maze operation).
Author’s Note: Dr. Kress’ approach may represent the future of A-Fib surgery. Cardiac surgeons, instead of specializing in one type of surgery, may develop expertise in many different surgical and ablation techniques. In some centers surgeons and Electrophysiologists already work together to treat A-Fib patients.
REMOVING THE LEFT ATRIAL APPENDAGE
Almost all current surgical techniques include cutting out and/or stapling shut the Left Atrial Appendage. According to Dr. Kress, “Left Atrial Appendage removal is often the most important part of the (operation)…(because) the patient can stop taking Coumadin.” Coumadin can be stopped even if the patient is still in A-Fib. Sometimes after the Left Atrial Appendage operation, small Appendage pouches or sacs remain which could produce clots and stroke. But according to Dr. Kress’ experience, after 3-4 months these pouches or sacs generally fill in with fiber and become relatively smooth walled, thereby reducing the risk of stroke.
Someone from the audience asked, “Is removal of the Left Atrial Appendage a suitable substitute for Coumadin?” Dr. Kress thought so, but acknowledged there were no clinical studies demonstrating this.
Author’s comment: The author believes that Dr. Kress is correct, and that future studies will demonstrate that removal of the Left Atrial Appendage is indeed a substitute for Coumadin.
According to Dr. Kress, Microwave energy using the Flex-10 catheter is currently the most accepted method and has the best delivery system to position the catheter.
He warned that the Microwave catheter, if oriented improperly, can burn unintended areas.
According to Dr. Kress, all current Mini-Maze operations have the drawback of “unreliable transmurality” (the lesions or burns on the outside of the heart aren’t effective unless they penetrate through to the inside of the heart, but this doesn’t always happen).
Dr. Kress also warned that, “surgery on older and out-of-shape patients can have minor and major complications because they are under General Anesthesia.”
Dr. Ralph Damiano, Jr., of Barnes Jewish Hospital in St. Louis, MO talked about “Future Directions in A-Fib Surgery: Can We Make the Atria Fibrillation-Proof?”
Dr. Damiano described how and why the Maze operation for A-Fib is not as effective for certain groups of patients, and what he is doing to improve this. (The Maze operation was the first and one of the most effective treatments for A-Fib, though it involves open heart surgery and is a very invasive and physically traumatic experience.)
For many years Dr. Damiano used the Maze III (cut and sew) operation on patients with A-Fib who also had other heart problems which required surgery. In addition, he performed the Maze operation on A-Fib patients with no other heart problems (the Lone Maze). After years of follow-up, over 90% were free of A-Fib and off of Coumadin, though some still needed to take antiarrhythmic drugs. Five years ago he switched to using the Bi-Polar RF Clamp (to replace the cut and sew incisions with RF ablation lines), which he calls the Cox Maze IV operation. The RF clamp produces transmural conduction block, but is less apt to harm or damage the heart’s circulation system (the original Maze incisions sometimes did harm the heart’s circulatory system). He also uses a Uni-polar device to ablate areas of the heart which the Bi-Polar clamp can’t reach.
Dr. Damiano described the original Maze as a “salvage” operation at a time when it wasn’t possible to map the mechanisms of A-Fib. The placement of the cut and sew incisions was “empirically derived” (the incisions worked without knowing exactly what A-Fib mechanisms were affected). Even today the importance or effectiveness of each incision is unknown. The underlying theory of the Maze operation “Multiple Wavelet Macro-Reentrant Circuits” may be incorrect or inappropriate for many patients. (There can be multiple mechanisms responsible for A-Fib including focal drivers, single and multiple rotors, as well as reentrant circuits.) According to Dr. Damiano, “It is naive to think that one operation would fit all patients.”
PATIENTS WITH POOR MAZE OPERATION SUCCESS RATES
Even though his success rates for the Maze operation are high, there are some groups of A-Fib patients who don’t do well.
1. People who have been in A-Fib for over ten years. (This suggests that A-Fib over time may result in permanent remodeling which may not be reversible.)
2. People with very large left atriums (over 9 cm) have a poor success rate. (He cited studies relating to the “Critical Mass Theory” which found that as the size of the Left Atrium increases, the success rate for curing A-Fib decreases.1
3. People with shorter Effective Refractory Periods (ERP) and shorter A-Fib wavelength have poorer success rates.
Dr. Damiano indicated that the full Maze operation my be overkill for some A-Fib patients. For others (such as those mentioned above) it may not have the desired success rates. He suggested that surgeons in the future may not rely on a single operation approach, but may use mapping techniques to tailor operations to the needs of individual A-Fib patients.
Dr. Damiano described a pre-operative mapping technique called Body Surface Mapping that is completely non-invasive (the Prime ECG Electrocardiographic Body Surface Imaging by Heartscape Technologies, Inc.). Eleven easily-applied self-adhesive plastic strips containing 80 data collection points, or leads, cover the front and back of the body. This “jacket” of electrodes using CT and MRI techniques maps the structure of the heart and pinpoints where A-Fib signals originate. It’s similar to an ECG but with 80 leads instead of 12. It provides a 360 degree view of the heart’s electrical activity. The surgeon can use this mapping system to most effectively place the Maze ablation lines. (In simpler cases of A-Fib where A-Fib signals come from only one or two spots in the heart, less invasive procedures can be tailored to particular patients, thus avoiding the “overkill” and trauma of a Maze operation.)
(Author’s Note: The Body Surface Mapping system is currently not in clinical use but is in clinical trials for the detection of heart attacks. The clinical trial began Nov. 6, 2006 and is entitled “The Optimum Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction” [OCCULT-MI trial]
Dr. Damiano’s application of Body Surface Mapping to A-Fib may be a major innovation in the treatment of A-Fib. Body Surface Mapping may one day provide as much information as standard catheter mapping techniques without the need of inserting a mapping catheter into the heart.)
Dr. Fred Morady of the University of Michigan, Ann Arbor discussed “The Interpretation of the ECG Morphology During PACs, Atrial Tachycardia & Atrial Flutter.”
Dr. Morady showed how an ECG can not only reveal whether or not a patient has A-Fib, but also where an arrhythmia signal originates in the heart.
PULMONARY VEIN ARRHYTHMIA SITES
A negative or isoelectric (neither positive nor negative) P wave in lead I and a positive P wave in Lead V1 predicts almost 100% of the time that the arrhythmia comes from the Pulmonary Veins.2(The P wave is formed when the atria contract to pump blood into the Ventricles—see The EKG Signal).
A positive P wave in leads II and III indicates that the arrhythmia comes from the Superior Pulmonary Veins.
A negative or biphasic (both positive and negative) P wave in lead aVL suggests that the arrhythmia comes from the left rather than the right PVs.
Sometimes after surgery or ablation, a patient develops Atrial Flutter (Dr. Morady described instances where a full six years after surgery a patient developed Atrial Flutter). This Flutter often comes from either the Left Atrium or from the Cavotricuspid Isthmus in the Right Atrium. Negative or biphasic P waves in leads V1 through V6 suggests the Flutter may come from the Cavotricuspid Isthmus in the Right Atrium, whereas positive P waves in leads V1 through V6 indicate the Flutter may originate in the Left Atrium. (The usual suspect areas in the Left Atrium are the Coronary Sinus, Atrium Roof, and Mitral Isthmus, though the ECG currently does not help identify these signal areas.)
(Though related to Dr. Jaïs presentation, this summary is based on the Heart Rhythm Society’s DVD “Latest Atrial Fibrillation Techniques,” 2007.)
The French Bordeaux group now uses a five-step process to treat Chronic A-Fib.
1. They start by isolating the Pulmonary Vein openings. They also eliminate potentials at the base of the Left Atrial Appendage, but do not isolate or electrically disconnect the whole of the LAA which could possibly lead to clots forming in the LAA and A-Fib stroke. (“RSPV” stands for Right Superior Pulmonary Vein, “LSPV” Left Superior PV, “RIPV” Right Inferior PV, “LIPV” Left Inferior PV, “LAA” Left Atrial Appendage.)
(Ablating at the base of the LAA as part of the first step in treating A-Fib is a new approach and may become a very important first step in the ablation treatment of A-Fib.)
2. Next they make a roof line linear ablation linking the Right Superior Pulmonary Vein with the Left Superior Pulmonary vein opening to create complete electrical block.
3. They then work in the Inferior Left Atrium and the Coronary Sinus. They make an incomplete blocking line between the Right Inferior and Left Inferior PVs in order to slow down the rapid atrial electrical activity.
They treat the Coronary Sinus as though it were another heart structure or Left Atrium, rather than just another vein opening. They disconnect the CS from the Left Atrium and ablate potentials along the Mitral Annulus. They also slow down Coronary Sinus electrical activity by ablating both inside and outside the CS with a lower wattage power, usually 25 Watts. (Treating the Coronary Sinus as another Left Atrium is a new approach. Most current A-Fib ablation procedures tend to stay away from the Coronary Sinus because of the risk of Stenosis (swelling). The French Bordeaux group, by using a low wattage, irrigated tip catheter, ablates within the Coronary Sinus without damaging it.)
4. The fourth step is eliminating organized atrial activity in areas such as:
- Anterior Left Atrium & Left Atrial Appendage
- Posterior Left Atrium
- Superior Vena Cava
- Right Atrial Septum
5. The fifth step is to create a Mitral Isthmus blocking linear ablation line from the Mitral Annulus to the Left Inferior PV. The goal is to eliminate all potentials along this line.
In practice, even after these five steps, rapid atrial activity often remains. It has to be mapped, traced to its source and ablated. Often the top of the Left Atrial Appendage has to be ablated.
This whole procedure requires a great deal more time, effort, persistence, skill and experience than normal left ablation procedures. (Author’s note: The Bordeaux group also uses a Cavotricuspid Isthmus [CTI] line in the right atrium for A-Flutter.
(Please be advised that this five-step process for treating Chronic A-Fib is relatively new and isn’t available today at most A-Fib medical centers.)
Dr. Warren Jackman of the Un. of Oklahoma discussed “The Facilitation of A-Fib by Communication Between Autonomic Ganglionated Plexi.”
Dr. Jackman’s research identified a method of possibly eliminating A-Fib that is very different from any in use today.
According to Dr. Jackman there are seven areas of Autonomic Ganglionated Plexi (GP) on the outside surface of the heart that may trigger or maintain A-Fib. Most are located within epicardial fat pads (“epicardial” refers to the outside surface of the heart in contact with the Pericardium. This photo was taken from outside the heart during a Minimally Invasive Surgical Ablation of A-Fib.)
When stimulated, these GP areas can produce or trigger A-Fib at the Pulmonary Veins. In addition, the GP areas are interconnected, with the result that stimulating one GP can trigger A-Fib signals from a PV in a different area of the heart. The Autonomic Ganglionated Plexi areas consist of 10% Sympathetic Neurons, 10% Parasympathetic Neurons, and 80% Interconnected Neurons. (A Neuron is an electrically excitable cell in the nervous system that processes and transmits information.) There may be as many as 1000 neurons in a GP area.
Preliminary research on animals indicates that ablating the seven GP areas may stop the Pulmonary Veins from producing A-Fib signals.
Author’s Note: Surgeons performing the Maze and Mini-Maze operations report that ablating the Autonomic Ganglionated Plexi areas improves the success rate of their operations by 10%. [See Ablating Autonomic Ganglionated Plexi during surgery.] Surgeons doing these operations are able to ablate the GP areas since they normally access the heart from the outside; whereas Pulmonary Vein Ablation (Isolation) procedures usually stay inside the heart.
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Last updated: Wednesday, July 6, 2016