1. Catheter Ablation in the Treatment of Atrial Fibrillation

2. Atrial Fibrillation First described in 1903 by Hering
Most common sustained arrhythmia
The irregularity and inequality of heart rhythm associated with atrial fibrillation was first described by Dr. Hering in 1903.
Atrial fibrillation is by far the most common sustained arrhythmia diagnosed and treated by physicians. It may be either paroxysmal or chronic. Paroxysms may be brief or lengthy, frequent or infrequent; they may be benign or result in marked symptoms. 1

3. Atrial fibrillation accounts for 1/3 of all patient discharges with arrhythmia as principal diagnosis
6% PSVT
6% PVCs
18% Unspecified
4% Atrial Flutter
9% SSS
34% Atrial Fibrillation
8% Conduction Disease
10% VT
3% SCD
2% VF
Baily D. J Am Coll Cardiol. 1992;19(3):41A.

4. Atrial Fibrillation What is Atrial Fibrillation?
Chaotic circular impulses in the atria
Several reentrant circuits moving simultaneously
Atrial rates
300 to 600 beats per minute
Ventricular rates regulated by the AV node
Irregularly irregular due to partial depolarization of AV node
Results in loss of AV synchrony
20% to 30% decrease in cardiac output

5. Incidence and Prevalence
Prevalence increases with age
4.8 % in the age group
Increases to
8.8% in the age group
During the next 7-8 years, the number of people over the age of 80 is expected to quadruple

6. Atrial Fibrillation Demographics by Age
U.S. population x 1000
Population with AF x 1000
30,000
20,000
10,000
Population with atrial fibrillation
500
400
300
200
100
U.S. population
<5
5- 9
10- 14
15- 19
20- 24
25- 29
30- 34
35- 39
40- 44
45- 49
50- 54
55- 59
60- 64
65- 69
70- 74
75- 79
80- 84
85- 89
90- 94
>95
Age, yr
Adapted from Feinberg WM. Arch Intern Med. 1995;155:

7. Stages of Atrial Fibrillation
Paroxysmal
Persistent
Permanent

8. Stages of Atrial Fibrillation
Paroxysmal (23% of AF population)
Self limiting
Spontaneous conversion to sinus rhythm within 24 hrs after onset is common
Once the duration exceeds 24 hrs, the likelihood of conversion decreases
After one week of persistent arrhythmia, spontaneous conversion is rare
30% of these patients develop “Persistent” AF

9. Stages of Atrial Fibrillation
Persistent (38% of AF population)
Requires intervention to restore normal rhythm
Cardioversion
Electrical or Chemical (drugs)
Can lead to electrophysical and structural changes in the myocardium (remodeling) that can lead to “Permanent” AF
AF with duration of greater than 7 days rarely spontaneously converts

10. Stages of Atrial Fibrillation
Permanent (39% of AF population)
Unable to convert Electrical or Chemical (drugs)

11. Mechanisms of AF
Theories of the mechanism of AF involve 2 main processes:
- Enhanced automaticity in one or several rapidly depolarizing foci
- Reentry involving one or more circuits

12. Mechanisms Contributing to AF

13. Mechanisms of AF
Rapidly firing atrial foci, located in one or several pulmonary veins (PVs), can initiate AF in susceptible patients
Foci also can occur in RA and infrequently in the superior vena cava or coronary sinus

14. Pulmonary Vein Myocardial Sleeves

15. Factors Involved in the Pathogenesis of AF
Studies in man have shown that increased inhomogeneity of refractory periods and conduction velocity is present in AF patients.
Structural changes in atrial tissue may be one of the underlying factors for dispersion of refractoriness in AF.
Other factors involved in the induction or maintenance of AF include premature beats, the interaction with the autonomic nervous system, atrial stretch, anisotropic conduction, and the aging process, vein of Marshall……….

16. Mechanisms contributing to AF

17. Atrial Fibrillation: Clinical Problems
Embolism and stroke (presumably due to LA clot)
Acute hospitalization with onset of symptoms
Anticoagulation, especially in older patients (> 75 yr.)
Congestive heart failure
Loss of AV synchrony
Loss of atrial “kick”
Rate-related cardiomyopathy due to rapid and irregular ventricular response
Rate-related atrial myopathy and dilatation
Chronic symptoms and reduced sense of well-being

18. Therapeutic Approaches to Atrial Fibrillation
Anticoagulation
Antiarrhythmic suppression
Control of ventricular response
Pharmacologic
Catheter modification/ablation of AV node
Curative procedures
Catheter ablation
Surgery (maze)

20. Antiarrhythmic Therapy for Atrial Fibrillation
Advantages
High efficacy for some patients, at least initially (< 50% of all patients)
Low initial cost
Noninvasive
Disadvantages
High recurrence rate
High long-term cost
Non-curative
Adverse effects
Potential proarrhythmia

21. Antiarrhythmic Suppression
Drugs
Conversion of AF
Class 1A (decrease conduction velocity, increase refractory periods of cardiac tissue, suppress automaticity)
Quinidine
Procainamide
Class III (decrease conduction velocity, increase refractory periods of cardiac tissue, suppress automaticity)
Amiodarone
Sotalol
Ibutilide (Corvert)
Dofetilide

22. Antiarrhythmic Suppression
Drugs
Maintenance of normal rhythm
Class 1A
Class III
Class 1C (decrease conduction velocity)
Flecainide
Propafenone
Drug choice depends upon patient’s underlying heart disease

23. Nonpharmacological Approaches to Atrial Fibrillation
Pacemaker therapy
2. Ablation
3. Surgery

24. RF Ablation Techniques
Focal ablation of PV (Pulmonary vein) triggers
Segmental PV isolation
Wide Area Circumferential Ablation
Ablation of Fractionated Complex Electrograms
Targeted ablation of ganglionated autonomic plexi in the epicardial fat pads

25. Focal Ablation of Triggers

26. Focal Ablation of Atrial Fibrillation
95% of foci are located within a pulmonary vein ( PV).
Focal sources of AF may be found in the RA, LA, coronary sinus, superior vena cava or vein of Marshall.
Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339:659–66.
Chen SA, et. al: Initiation of atrial fibrillation by ectopic beats originating from the pulmonary veins: Electrophysiologic characteristics, pharmacologic responses, and effects of radiofrequency ablation. Circulation 1999;100:

27. Pulmonary Vein Spike Discharges

28. Pulmonary Vein Spike Discharges

29. Initiation of AF by PV Discharges

30. PV Potentials
PV potentials

31. PV Potentials

32. PV Potential on 6-10

33. PV potentials disappeared during radiofrequency current application

34. Loss of PV Potentials

35. Focal Ablation of Pulmonary Veins Complications
The most common complications associated with the focal ablation of the PVs are pericardial effusion (<4%), transient ischemic episodes (<2%) and symptomatic PV stenosis <2%).
Asymptomatic PV stenosis may occur at as many as 40% of sites at which focal ablation is performed.
Symptomatic PV stenosis seems to be infrequent if the number of radiofrequency applications delivered within PV is kept to a minimum.

36. PV Stenosis

37. PV Stenosis

38. Multi-slice CT Endocardial View

39. PV Stenting

40. Tamponade: Intra-cardiac echo
The incidence of perforation during ablation of the left atrium is relatively low

41. Segmental PV Isolation

42. Segmental PV Isolation
Limitations associated with focal ablation have prompted the development of other techniques for eliminating the PV arrhythmias.
Anatomically PV isolation has significant advantages over focal ablation.

43. Lasso or Spiral Catheters

44. Dissociation of the PV potential after successful isolation

45. Segmental Ostial Pulmonary Vein Isolation
The initial experience with segmental ostial ablation of PVs guided by PV potentials is encouraging, with a long-term success rate of 90% in patients with paroxysmal AF
Minimal risk of PV stenosis when the power of radiofrequency energy applications is limited to 30 W.

46. Wide Area Circumferential Ablation

47. Circumferential Ablation
It is an anatomic approach in which circumferential lines of block are created using 3D maps ( Carto, NavX..) around the ostia of PVs for isolation of PVs from LA.
Additional linear lesion from LIPV to mitral annulus for preventing LA incisional tachycardia ( 2%).
Additional linear lesions (posterior, roof, right isthmus….) may be created deepening on operator’s preference.
Pappone C, et al. Atrial electroanatomic remodeling after circumferential radiofrequency pulmonary vein ablation: efficacy of an anatomic approach in a large cohort of patients with atrial fibrillation. Circulation 2001;104:2539–2544.

48. NavX Map

49. Anatomical Reconstruction of LA

51. Circumferential Ablation

52. Circumferential Ablation Carto Map

53. Circumferential Ablation

54. Circumferential Ablation

55. Circumferential Ablation

56. Magnetic Resonance Image
Electroanatomic Map

57. Circumferential Ablation
Effective in both paroxysmal and chronic AF (81%, 76%)
Bipolar amplitude < 0.1 mv inside and around the lesion may be acceptable for showing PV isolation.

58. Post Circumferential PV ablation
Bipolar amplitude < 0.1 mv inside the lesion

59. Mitral Isthmus Line
The addition of mitral isthmus line to the PV disconnection may allow a significant improvement of sinus rhythm maintenance rate, particularly in patients with persistent AF, without the risk for major complications.
J Cardiovasc Electrophysiol, Vol. 16, pp , November 2005

60. Complication rates following circumferential pulmonary vein ablation
Death 0%
Pericardial effusion 0.1%
Stroke 0.03%
Transient ischemic attack 0.2%
Tamponade 0.1%
Atrio-esophageal fistula 0.03%
Pulmonary vein stenosis 0%
Incisional left atrial tachycardia 6%
Phrenic nerve injury

61. Topographic Variability of the Esophageal Left Atrial Relation

62. CT reconstruction of the LA, the pulmonary veins, and the esophagus

63. Topographic Variability of the Esophageal Left Atrial Relation

65. Phrenic Nerve Injury

67. Ablation of Fractionated Electrograms
Hypothesis being that these are consistent sites where fibrillating wavefronts turn or split.
By ablating these areas the propagating random wavefronts are progressively restricted until the atria can no longer support AF.
Nademanee demonstrated 70% freedom from AF following a single procedure for permanent AF patients.
Nademanee K, et al. A new approach for catheter ablation of atrial fibrillation: mapping of the electrophysiologic substrate. J Am Coll Cardiol 2004;43:2044–53.

68. Segmental Ablation vs. Circumferential Ablation?
Is either of the two ablation strategies superior to the other?
Oral et al. showed that, during the 6 months following a single catheter procedure, Circumferential Ablation was associated with a significantly better outcome with no differences between the two ablation strategies in the complication rates.
Schmitt et al. reported opposite results to those of Oral et al.
The opposite results in the two studies were obtained because of the large variability in the success rate observed in patients undergoing Circumferential Ablation (88 vs. 47%) while the success rates in patients undergoing Segmental Ablation remained unchanged (67 vs. 71%).

69. Integrated Approach
Journal of Cardiovascular Electrophysiology Vol. 16, No. 12, Dec. 2005

70. Frequently Asked Question
Who is currently a candidate for AF ablation?

71. Patient selection criteria
Inclusion criteria
At least one monthly episode of persistent symptomatic AF or
At least one weekly episode of paroxysmal AF or
Permanent AF
And
At least one failed trial of antiarrhythmic drugs or
More than one antiarrhythmic drug to control symptoms
Exclusion criteria
NYHA functional class IV
Age > 80 years
Contraindications to anticoagulation
Presence of cardiac thrombus
Left atrial diameter ≥ 65 mm
Life expectancy < 1 year
Thyroid dysfunction
Recent updates
Patients with mitral and/or aortic metallic prosthetic valves are
not excluded
Previous repair of atrial septal defects is not an absolute contraindication

72. Frequently Asked Question
AF ablation for asymptomatic individuals?

73. Asymptomatic Patients
To date there is no evidence that treatment of AF by ablation improves mortality, although there are uncontrolled data suggesting that this may be the case.
Therefore, asymptomatic patients should not be offered curative ablation of AF, except in the case of those patients undergoing cardiac surgery who may benefit from surgical ablation of their AF as an adjunctive procedure.
There is also evidence that patients with heart failure have significant improvements in left ventricular function following successful catheter ablation of AF.

75. Conclusion
For many patients with a previously untreatable heart rhythm, ablation has dramatically improved their symptoms by restoring and maintaining sinus rhythm.
Preliminary randomized studies of catheter ablation of AF provide evidence that ablation (with or without concurrent anti-arrhythmic drug use) effectively improves maintenance of sinus rhythm when compared with current anti-arrhythmic drugs.
Although prognostic and quality of life data from long term randomized trials of catheter ablation for AF are still in preparation, the non-randomized data comparing ablation to continued medical treatment suggests a strong benefit from ablation.

76. Tehran Arrhythmia Center