Atrial fibrillation catheter ablation
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2] Vendhan Ramanujam M.B.B.S [3]
Overview
In patients with atrial fibrillation where rate control drugs are ineffective and it is not possible to restore sinus rhythm using cardioversion, non-pharmacological alternatives are available. One of the techniques used is called as catheter ablation, where the bundle of cells that pace the heart in the atrioventricular node, are destroyed using radiofrequency energy source, the dominant energy source for catheter ablation. Cryoablation has more recently been developed as a tool for AF ablation procedures.[1] Balloon-based ultrasound ablation and laser based ablation systems have also been developed for AF ablation.[2] [3] [4][5] Other energy sources and tools are in various stages of development and/or clinical investigation.
Indications for Catheter and Surgical Ablation
Ablation of atrial fibrillation is recommended when the primary indication is the presence of symptomatic AF, which is refractory or intolerant to at least one class I or III antiarrhythmic medication. The indications are stratified as class I, class IIa, class IIb, and class III indications.[6]
Class I Indications
In symptomatic paroxysmal AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, catheter ablation is recommended.
Class IIa Indications
- In symptomatic persistent AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, catheter ablation is reasonable.
- In symptomatic paroxysmal AF patients, prior to initiation of antiarrhythmic drug therapy with either class I or III antiarrhythmic agent, catheter ablation is reasonable.
- In patients who are undergoing surgery for other indications with symptomatic paroxysmal AF, refractory or intolerant to at least one class I or III antiarrhythmic medication, surgical ablation is reasonable.
- In patients who are undergoing surgery for other indications with symptomatic persistent AF, refractory or intolerant to at least one class I or III antiarrhythmic medication, surgical ablation is reasonable.
- In patients who are undergoing surgery for other indications with symptomatic longstanding persistent AF, refractory or intolerant to at least one class I or III antiarrhythmic medication, surgical ablation is reasonable.
- In patients who are undergoing surgery for other indications with symptomatic paroxysmal AF prior to initiation of antiarrhythmic drug therapy with either class I or III antiarrhythmic agent, surgical ablation is reasonable.
- In patients who are undergoing surgery for other indications with symptomatic persistent AF prior to initiation of antiarrhythmic drug therapy with either class I or III antiarrhythmic agent, surgical ablation is reasonable.
Class IIb Indications
- In symptomatic longstanding persistent AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, catheter ablation may be considered.
- In patients with symptomatic persistent AF prior to initiation of antiarrhythmic drug therapy with a class I or III antiarrhythmic medication, catheter ablation may be considered.
- In patients with symptomatic longstanding persistent AF prior to initiation of antiarrhythmic drug therapy with a class I or III antiarrhythmic medication, catheter ablation may be considered.
- In patients who are undergoing surgery for other indications with symptomatic longstanding persistent AF prior to initiation of antiarrhythmic drug therapy with a class I or III antiarrhythmic agent, surgical ablation may be considered.
- In symptomatic paroxysmal AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, stand alone surgical ablation may be considered if they have not failed catheter ablation but prefer a surgical approach.
- In symptomatic paroxysmal AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, stand alone surgical ablation may be considered if they have failed one or more attempts at catheter ablation.
- In symptomatic persistent AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, stand alone surgical ablation may be considered if they have not failed catheter ablation but prefer a surgical approach.
- In symptomatic persistent AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, stand alone surgical ablation may be considered if they have failed one or more attempts at catheter ablation.
- In symptomatic longstanding persistent AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, stand alone surgical ablation may be considered if they have not failed catheter ablation but prefer a surgical approach.
- In symptomatic longstanding persistent AF patients who are either refractory or intolerant to at least one class I or III antiarrhythmic medication, stand alone surgical ablation may be considered if they have failed one or more attempts at catheter ablation.
Class III Indications
In symptomatic paroxysmal or persistent or longstanding persistent AF patients, prior to initiation of antiarrhythmic drug therapy with a class I or III antiarrhythmic agent, stand alone surgical ablation is not recommended.
Recommendations Regarding Catheter Ablation Technique
- The cornerstone for most AF ablation procedures are ablation strategies that target the pulmonary veins and/or pulmonary vein antrum.
- While targeting the pulmonary veins, electrical isolation should be the goal.
- Electrical isolation requires, at a minimum, assessment and demonstration of entrance block into the pulmonary vein.
- Monitoring for pulmonary vein reconduction for 20 minutes following initial pulmonary vein isolation should be considered.
- Careful identification of the pulmonary vein ostia is mandatory to avoid ablation within the pulmonary veins.
- If a focal trigger is identified outside a pulmonary vein at the time of an AF ablation procedure, ablation of that focal trigger should be considered.
- If additional linear lesions are applied, operators should consider using mapping and pacing maneuvers to assess for line completeness.
- Ablation of the cavotricuspid isthmus is recommended in patients with a history of typical atrial flutter or inducible cavotricuspid isthmus dependent atrial flutter.
- If patients with long standing persistent AF are approached, operators should consider more extensive ablation based on linear lesions or complex fractionated electrograms.
- It is recommended that radiofrequency power be reduced when creating lesions along the posterior wall near the esophagus.
Radiofrequency Ablation
To control rate it is possible to destroy the bundle of cells connecting the upper and lower chambers of the heart - the atrioventricular node - which regulates heart rate, and to implant a pacemaker instead. A more complex technique, which avoids the need for a pacemaker, involves ablating groups of cells near the pulmonary veins where atrial fibrillation is thought to originate, or creating more extensive lesions in an attempt to prevent atrial fibrillation from establishing itself.[6]
Ablation is a newer technique and has shown some promise for cases of recurrent AF that are unresponsive to conventional treatments. Radiofrequency ablation (RFA) uses radiofrequency energy to destroy abnormal electrical pathways in heart tissue. The energy emitting probe (electrode) is placed into the heart through a catheter inserted into veins in the groin or neck. Electrodes that can detect electrical activity from inside the heart are also inserted, and the electrophysiologist uses these to map an area of the heart in order to locate the abnormal electrical activity before eliminating the responsible tissue.
Most AF ablations consist of isolating the electrical pathways from the pulmonary veins (PV),[7] which are located on the posterior wall of the left atrium. All other veins from the body (including neck and groin) lead to the right atrium, so in order to get to the left atrium the catheters must get across the atrial septum. This is done by piercing a small hole in the septal wall. This is called a transseptal approach. Once in the left atrium, the physician may perform Wide Area Circumferential Ablation (WACA) to electrically isolate the PVs from the left atrium.[8]
Some more recent approaches to ablating AF is to target sites that are particularly disorganized in both atria as well as in the coronary sinus (CS). These sites are termed complex fractionated atrial electrogram (CFAE) sites.[9] It is believed by some that the CFAE sites are the cause of AF, or a combination of the PVs and CFAE sites are to blame. New techniques include the use of cryoablation (tissue freezing using a coolant which flows through the catheter), microwave ablation, where tissue is ablated by the microwave energy cooking the adjacent tissue, and high intensity focused ultrasound (HIFU), which destroys tissue by heating. This is an area of active research, especially with respect to the RF ablation technique and emphasis on isolating the pulmonary veins that enter into the left atrium.
Efficacy and risks of catheter ablation of atrial fibrillation are areas of active debate. A worldwide survey of the outcomes of 8745 ablation procedures[10] demonstrated a 52% success rate (ranging from 14.5% to 76.5% among centers), with an additional 23.9% of patients becoming asymptomatic with addition of an antiarrhythmic medication. In 27.3% of patients, more than one procedure was required to attain these results. There was at least one major complication in 6% of patients. A thorough discussion of results of catheter ablation was published in 2007;[11]it notes that results are widely variable, due in part to differences in technique, follow-up, definitions of success, use of antiarrhythmic therapy, and in experience and technical proficiency.
References
- ↑ Sarabanda, AV.; Bunch, TJ.; Johnson, SB.; Mahapatra, S.; Milton, MA.; Leite, LR.; Bruce, GK.; Packer, DL. (2005). "Efficacy and safety of circumferential pulmonary vein isolation using a novel cryothermal balloon ablation system". J Am Coll Cardiol. 46 (10): 1902–12. doi:10.1016/j.jacc.2005.07.046. PMID 16286179. Unknown parameter
|month=ignored (help) - ↑ Meininger, GR.; Calkins, H.; Lickfett, L.; Lopath, P.; Fjield, T.; Pacheco, R.; Harhen, P.; Rodriguez, ER.; Berger, R. (2003). "Initial experience with a novel focused ultrasound ablation system for ring ablation outside the pulmonary vein". J Interv Card Electrophysiol. 8 (2): 141–8. PMID 12766506. Unknown parameter
|month=ignored (help) - ↑ Metzner, A.; Chun, KR.; Neven, K.; Fuernkranz, A.; Ouyang, F.; Antz, M.; Tilz, R.; Zerm, T.; Koektuerk, B. (2010). "Long-term clinical outcome following pulmonary vein isolation with high-intensity focused ultrasound balloon catheters in patients with paroxysmal atrial fibrillation". Europace. 12 (2): 188–93. doi:10.1093/europace/eup416. PMID 20089752. Unknown parameter
|month=ignored (help) - ↑ Neven, K.; Schmidt, B.; Metzner, A.; Otomo, K.; Nuyens, D.; De Potter, T.; Chun, KR.; Ouyang, F.; Kuck, KH. (2010). "Fatal end of a safety algorithm for pulmonary vein isolation with use of high-intensity focused ultrasound". Circ Arrhythm Electrophysiol. 3 (3): 260–5. doi:10.1161/CIRCEP.109.922930. PMID 20504943. Unknown parameter
|month=ignored (help) - ↑ Metzner, A.; Schmidt, B.; Fuernkranz, A.; Wissner, E.; Tilz, RR.; Chun, KR.; Neven, K.; Konstantinidou, M.; Rillig, A. (2011). "One-year clinical outcome after pulmonary vein isolation using the novel endoscopic ablation system in patients with paroxysmal atrial fibrillation". Heart Rhythm. 8 (7): 988–93. doi:10.1016/j.hrthm.2011.02.030. PMID 21354329. Unknown parameter
|month=ignored (help) - ↑ 6.0 6.1 Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Le Heuzey JY, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, Wann S, Smith SC, Jacobs AK, Adams CD, Anderson JL, Antman EM, Halperin JL, Hunt SA, Nishimura R, Ornato JP, Page RL, Riegel B, Priori SG, Blanc JJ, Budaj A, Camm AJ, Dean V, Deckers JW, Despres C, Dickstein K, Lekakis J, McGregor K, Metra M, Morais J, Osterspey A, Tamargo JL, Zamorano JL (2006). "ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society". Circulation. 114 (7): e257–354. doi:10.1161/CIRCULATIONAHA.106.177292. PMID 16908781. Retrieved 2013-01-07. Unknown parameter
|month=ignored (help) - ↑ "Miller Family Heart & Vascular Institute". Retrieved 2013-01-09.
- ↑ "Medscape Log In". Retrieved 2013-01-09.
- ↑ Nademanee K, McKenzie J, Kosar E, Schwab M, Sunsaneewitayakul B, Vasavakul T, Khunnawat C, Ngarmukos T. (2004). "A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate". J Am Coll Cardiol. 43 (11): 2044–53. doi:10.1016/j.jacc.2003.12.054. PMID 15172410.
- ↑ Cappato R, Calkins H, Chen SA, Davies W, Iesaka Y, Kalman J, Kim YH, Klein G, Packer D, Skanes A. (2005). "Worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation". Circulation. 111: 1100–1105. doi:10.1161/01.CIR.0000157153.30978.67. PMID 15723973.
- ↑ Calkins H, Brugada J, Packer DL, Cappato R, Chen SA, Crijns HJ, Damiano RJ Jr, Davies DW, Haines DE, Haissaguerre M, Iesaka Y, Jackman W, Jais P, Kottkamp H, Kuck KH, Lindsay BD, Marchlinski FE, McCarthy PM, Mont JL, Morady F, Nademanee K, Natale A, Pappone C, Prystowsky E, Raviele A, Ruskin JN, Shemin RJ. (2007). "HRS/EHRA/ECAS expert Consensus Statement on catheter and surgical ablation of atrial fibrillation: recommendations for personnel, policy, procedures and follow-up. A report of the Heart Rhythm Society (HRS) Task Force on catheter and surgical ablation of atrial fibrillation". Heart Rhythm. 4 (6): 816–61. PMID 17556213.