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Catheter Ablation
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Catheter Ablation

Have been bothered by A-Fib now for several years.  Started with Dig and worked way up the med ladder to Betapace which has worked very well for the past three years.  However, recently reg dose of 120 mgs twice daily is no longer controlling the condition.  Doseage increased to 160, if no positive result an ablation is being suggested.  I am told Amiodarone might do the trick, but MD's seem to feel not the way to go.
Have tried to obtain information re ablation but there does not seem to be to much available.  Any first hand comments would be appreciated.
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238668 tn?1232735930
Dear Ed,
Afib ablation is still a new procedure so there is still not a lot written about it out there.  In certain well selected individuals I think it is a good procedure to try.  It is only successful in about 60% of people over the long run.  I'm sure these numbers will improve as new technology comes along.  I've attached a paper that gives quite a bit of information about afib ablation and a review of the medical literature.  It's somewhat technical but you may find it helpful.

Christopher R. Cole,M.D. Andrea Natale, M.D.
Cleveland Clinic Foundation,  Cleveland, Ohio, USA

   Over the past 5 years there has been a paradigm shift in the treatment of atrial fibrillation (AF).  Advances in the understanding of the initiating triggers of AF and in ablation technique have changed the treatment of AF from one of chronic control to acute cure.   The question of the ability to cure AF has been answered; what remains to be answered is what technique is best suited to achieve this end.  
There are currently 3 main approaches to AF ablation: atrial linear lesions to interrupt AF wavelet propagation, focal ablation of foci that trigger AF, and circumferential ablation of the pulmonary vein ostium to achieve electrical isolation of triggering foci.  We will explore the advantages and disadvantages of each of these 3 techniques and discuss potential future directions of AF ablation.

The magnitude of the problem of AF is well known.   By age 65 upwards of 5% of the population have had an episode of AF and over a third of hospitalizations for arrhythmias are due to AF.   It is a major cause of morbidity, with over 200,000 strokes a year attributed to AF.  In the United States the cost to treat AF is $3.6 billion annually of which $400 million is for drugs alone (1, 2).

Until recently, pharmacotherapy with antiarrhythmic drugs or rate control agents with anticoagulation was the only treatment option for patients with AF.   Although better than placebo at maintaining sinus rhythm (3) antiarrhythmic drugs are relatively ineffective over the long run.  The retention rate for SR at 6 months after cardioversion is only 60% in patients on antiarrhythmic therapy (4).  In addition, antiarrhythmic drugs confer a small but added pro-arrhythmic risk to the patient, particularly those with structural heart disease.  For these reasons investigators have been looking for better treatment options for AF including ablation.

Overview of the Approaches to Atrial Fibrillation Ablation
As the understanding of the mechanisms of arrhythmias progresses, so does the ability to treat arrhythmias with catheter-based interventions (5). As we have seen in the past few years, each change in the mechanistic understanding of AF corresponded to advancement in the treatment options.

The hypothesis of a critical mass needed to sustain atrial fibrillation (6, 7) and the multiple wavelet theory of atrial fibrillation (8-10) led to the development of the surgical maze procedure (11, 12).   By making multiple linear scars in the atrium, the  atrial chambers are compartmentalized in smaller regions unable to sustain AF. This technique, although successful, requires general anesthesia and open heart surgery.  These important limitations have fueled interest in the development of catheter-based ablation procedures.

The idea that atrial fibrillation could be triggered from a rapidly firing single focus was first suggested by Scherf in the 1940's (13). However, it was not until recently that this idea was more fully explored.  It is now believed that in addition to the substrate needed for multiple wavelets, AF is triggered by a rapidly firing focus in the majority, if not all, cases.  The recognition of this mechanism is based on the pioneering work of  Haissaguerre et. al. (14, 15) who first demonstrated that atrial ectopic beats within the pulmonary veins are responsible for the initiation of spontaneous paroxysms of AF.  This finding paved the way to different catheter-based treatment approaches.  Focal ablation of the ectopic focus was initially considered.  However, since detailed mapping and ablation within the pulmonary veins is technically challenging and carries the risks of pulmonary vein stenosis, circumferential lesions to electrically isolate the pulmonary vein from the atrium has been considered more recently.

Patient Selection
As with any procedure one of the keys to success is proper patient selection.  In a patient who has planned open-heart surgery for another reason the surgical maze procedure may be the best approach.   If the patient has infrequent episodes of AF and infrequent APCs, a focal AF ablation may be difficult to perform.

While there are no hard age cutpoints, a younger individual with paroxysmal AF and no other serious health problems would be a more ideal candidate for ablation than an older individual with chronic AF and other major illnesses.  Generally a trial of at least 2 antiarrhythmic drugs is given before proceeding to ablation.  If the left atrium is greatly enlarged (>4.5cm) on transthoracic echocardiogram, ablation may be less likely to succeed. Currently patients with a low EF (<40%) are excluded from ablation procedures; As the field progresses, the exclusion criteria will probably change.  

Linear Lesions (Atrial Segmentation, Maze Procedure)
The first catheter-based approach to ablation of AF was designed to mimic the surgical maze procedure (11).   The catheter-based maze has been performed by using a variety of catheters to make linear lesions in the atrium and interrupt the propagation of the wavelets of AF (16-20).   Several different approaches have been used including epicardial linear lesions generated by hand-held probes (21), the creation of right sided only linear lesions (17, 20, 22, 23), both right and left sided linear lesions (16, 18, 19), and the use of different proprietary catheters (24). The use of three-dimensional electroanatomical mapping has been suggested to facilitate line placement and to insure continuity of the lesions as well (25, 26).  

In a pioneering work, Swartz created 3 right atrial linear lesions, 4 left atrial linear lesions and one septal linear lesion using standard 7F ablation catheters and specialized coaxial long sheaths (16).  All 30 of his patients required both right and left sided lesions for termination of fibrillation and there was an 80% success rate.  There were two strokes following left-sided ablation in his series.

Due to the stroke risk of left-sided ablation right-sided only ablation appeared more appealing (17, 20, 22, 23). Haissaguerre et. al. described the first successful right-sided ablation case report (17).  Using specially designed catheters with closely spaced ring electrodes the investigators made two geometric linear lesions in the right atrium with successful cure of AF.  

Natale et. al. performed  right-sided only linear ablations in 18 patients with a 22 month success rate of 50% (20).  Of those who remained in sinus rhythm, 5 subjects did not require medication and 4 subjects responded to antiarrhythmic drugs that were previously ineffective.   Garg had a similar success rate in a series of  12 patients (23). Interestingly, although right atrial lesions may decrease the atrial defibrillation thresholds they seem to create the substrate for more incessant arrhythmias.

Subsequently Haissaguerre et. al. explored the addition of left-sided linear lesions for patients who failed right-sided only lesions in a series of 45 patients (18).   Patients were divided into 3 groups of 15 subjects with a different right-sided ablation pattern used in each group.  Those who failed right-sided ablation only proceeded on to left-sided ablation.  The success rate of the right-sided only approach was low- only a success rate of 13% without drugs to 40% with medications.  The addition of left-sided linear lesions in 10 patients increased the success rate with medication to 60% and decreased the number of episodes of AF in 70% of the patients.  Complications included 3 sinus node dysfunctions and 1 case of hemopericardium.

Expanding on this work, Jais and colleagues used biatrial linear lesions in 44 patients (19).  Using two right-atrial lines (1 septal and 1 cavotricuspid) and 3-4 left-atrial lines they were able to achieve a success rate of 57% with medications.  There were improvements in an additional 27% of the patients and 16% were considered treatment failures.   There were 5 pericardial effusions and 1 each of a pulmonary embolism, inferior myocardial infarction and a reversible cerebral ischemic event.  An average of 2.7
Avatar n tn
Dear Sir

I have had Atrial Fibrillation for 4 years, and after 2 1/2 years of amiodarone, which worked well, have had hyperthyroidism and was in bad shape. This is caused by the iodine in amiodarone.After 6 bad months and hospitalisation, my thyroid has finally recovered.
I am now considering catheter ablation of the pulmanory focus, and likewise would appreciate any contacts with anyone who has had this treatment.

Best Regards
Avatar n tn
A most informative article.
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