Atrial flutter is a reentrant tachycardia involving the right atrium. There are two main types - typical atrial flutter which revolves counterclockwise around the tricuspid annulus, and reverse typical atrial flutter which revolves clockwise. Catheter ablation aims to create a continuous linear lesion across the cavotricuspid isthmus to block conduction and terminate the arrhythmia. Successful ablation is confirmed by the inability to induce flutter and demonstration of bidirectional conduction block across the ablation line.

1. Atrial Flutter
馬偕紀念醫院 心臟內科 李應湘 醫師
1

2. Atrial Flutter
A macro-reentrant atrial arrhythmia that is
very regular with rates typically between
240 and 350 bpm1. There are several
recognized variations of atrial flutter.
1. Schamroth, L. The Disorders of Cardiac Rhythm. Oxford, UK, Blackwell Ltd, 1971, p 49.
2

3. Proposed Classification of Atrial Flutter
 A NASPE position paper proposed an open
classification
– Typical AFL (CCW)
– Reverse Typical AFL (CW)
Saoudi, N, Cosio, F, Waldo, A, et. al. JCE Vol. 12, No. 7, pp.852-866, July, 2001
3

4. Cardiac Anatomy
TA
ER/EV
ISTHMUS
Netter, F. Clinical Symposia. Novartis Pharmaceuticals Corporation, Summit, NJ, 1997.
Atrial Flutter is a reentrant tachycardia in which the reentrant
circuit is contained in the right atrium. The isthmus is formed by
the IVC and Eustachian ridge/valve (ER/EV) on one side and the
TA on the other. Conduction during fast rates cannot transverse
the ER/EV.
4

5. Atrial Flutter
5

6. Typical Atrial Flutter (CCW)
 In typical AF the reentrant circuit revolves around
6 the tricuspid annulus in a counterclockwise pattern

7. Reverse Typical Atrial Flutter (CW)
 In reverse typical the reentrant circuit revolves
7
around the tricuspid annulus in a clockwise pattern.

8. Electrogram Recognition
 Rate
 P wave morphology
 12 Lead
 On the surface ECG it may often be very
difficult to see the flutter waves. This may
be overcome with vagal maneuvers or
Adenosine administration.
8

9. P wave Morphology con’t
Adenosine
9

10. Electrogram Recognition
 Isthmus dependent Typical Atrial Flutter
(CCW)
– Atrial rhythm: regular and very stable (240-340
bpm)
– P wave:Characteristic sawtooth pattern with a
negative deflection in, II and III, and/or aVf
(inferior axis) and positive in V1 (but may be
negative or biphasic). Leads I and aVL show
low-voltage deflections
– Ventricular rate: usually 2:1 in both typical and
reverse typical aflutter (higher degrees of AV
block can occur in patients with AV nodal block
disease or increased vagal tone)
10

11. Typical Atrial Flutter
Sawtooth pattern
3:1 A-V Block
11

12. Electrogram : Reverse Typical AFL
 On the surface ECG typical atrial flutter
looks similar to reverse typical flutter,
however in Reverse Typical Aflutter
(CW), the p-waves appear to be mostly
positive in the inferior leads (II, III, aVf).
 P waves display an superior axis.
 Wide, negative deflections in V1 (may be
most specific diagnostic sign)
 May demonstrate atypical p -wave
morphologies
12

13. Reverse Typical Atrial Flutter
13

14. Catheter Positions
Catheter position varies from lab to lab
 Quadripolar at the His (to define septum/HBE)
 Multipolar in the CS (to define CS ostium, and
perform septal pacing)
 Multipole (Duo-Decapolar™) at the RA (to
define activation anterior/lateral to CT and isthmus). This
may eliminate the HRA and CS catheters
 Quadripolar at the RVA (safety pacing) optional
 Exploring/Rove (mapping/RFA)
14

15. Catheter Positions
15

16. Isthmus Mapping Catheters
16

17. Typical Atrial Flutter
Typical AFL Reverse Typical AFL  A 20 pole catheter
placed around the TA
with the distal pair of
electrodes near the
posterior free wall and
proximal pair, the
anterior septum, reveals
counterclockwise
activation around the TA
in typical AF, and
clockwise in reverse
typical AF.
17

18. Pre Ablation Methods and Strategies
 Induction
– Conduction barriers
– Diagnosis
 Mapping
 Entrainment
 Pacing maneuvers
 Strategy
– Pacing maneuvers in SR
 Base line measurements (Pre and post
comparison)
18

19. Atrial Flutter Induction
 Induction methods for flutter include:
– Extrastimulas testing
– Atrial burst pacing
– Isoproterenol
 Induction or termination using rapid atrial
pacing may also induce atrial fibrillation
(due to short cycle lengths)
19

20. Intracardiac Electrogram
Recognition – CCW Mapping
Sequential activation around the right atrium
20

21. Intracardiac Electrogram
Recognition – CW Mapping
Sequential activation around the right atrium
21

22. Conduction Barriers in AFL
22

23. Concealed Entrainment
PPI :Post pacing interval FCL: Flutter cycle length
Post pacing intervals PPI=TCL
23 15. Lesh et al. JCE Vol.7,No 4, April
1996

24. Entrainment Mapping
24 Olgin et al. J of Cardiovasc Electrophysiology Vol.7,No.11,Nov 96

25. Double Potential
 Crista terminalis is an important anatomical
and functional barrier in atrial flutter
 Atriotomy sites and the eustachian ridge are
25 examples of fixed lines of block

26. Double Potentials
26

27. Management of Typical and Reverse
Typical AFL
 Medication
– Control the ventricular response
– Convert to sinus rhythm
 Anticoagulation
 Atrial overdrive pacing
 Cardioversion
 AV node ablation
 Isthmus RF ablation
27

28. AV Node Ablation
 In some situations medical therapy and
ablation attempts are unsuccessful. In
circumstances it may be necessary to
ablate the AV node and implant a
permanent pacemaker.
28

29. Goal of RF Ablation of Atrial Flutter
 The goal of RF ablation is the elimination
of conduction within the critical zone of the
reentrant circuit necessary to sustain atrial
flutter.
 Tachycardia may be terminated by one
lesion point along the Isthmus however this
method is associated with a high
recurrence rate
 In any of the targeted ablation areas, the
key to success is a contiguous, transmural
lesion from one anatomic barrier to another
29

30. Ablation Methods and Strategies
 Methods
– Point by point
– Drag (Linear lesion)
 Strategy
– During SR
 No acute end point
– During SR with CS pacing
 Shift in activation
– During tachycardia
 Termination of tachycardia
30

31. Orientation During RF Ablation
 Atrial flutter ablation is
anatomically guided along with
electrogram verification of the LAO
location between the:
– Tricuspid annulus (TA) and
CSos (septal isthmus: 5
o'clock )
– TA and inferior vena cava
(IVC) (posterior isthmus: 6
o'clock)
– TA and IVC (lateral isthmus
7 o'clock)
 No matter whether it is typical or
reverse typical AF, the ablation
sites are always either the septal
or posterior isthmuses. However,
ablation can be performed
anywhere along the isthmus, from
the entrance to the exit of the
31isthmus.

32. Ablation Sites
TV
CS
Long distance IVC Short distance
but more ４：３0 but many
smooth septal isthmus valleys
7：00
lateral isthmus 6：00
posterior isthmus
LAO
32
Nakagawa. H., et al., “Role of the Tricuspid Annulus and the Eustachian Valve/Ridge on Atrial Flutter: Relevance to Catheter Ablation of the
Septal Isthmus and a New Technique for Rapid Identification of Ablation Success.” Circulation. 1996;94:407-424.

33. Ablation Challenges: Variability of
Trabeculated Isthmus
 Blood pool
 Non-uniformity of the Posterior Isthmus
– highly variable trabeculated patterns
found inferior to the Cs ostium as well
as at the inferior rim of the Cs ostium
within the “flutter isthmus”
 Eustachian valve and ridge
5. Nakagawa. H., et al., “Role of the Tricuspid Annulus and the Eustachian
Waki, K. et.al. JCE Vol 11. No 1 January 2000 pg 92 Valve/Ridge on Atrial Flutter: Relevance to Catheter Ablation of the Septal
Isthmus and a New Technique for Rapid Identification of Ablation Success.” .
33 Circulation. 1996;94:407-424.

34. RAMPTM Sheath for Access to the sub-
Eustachian recess
34

35. Catheter Position: Septal Isthmus
35

36. Catheter Positions: Posterior Isthmus
RAO
LAO
36

37. Catheter ablation of the Posterior Isthmus
RAO LAO
ablation catheter ablation catheter
SVC
SVC
CSo
IVC
37
IVC

38. Ablation technique
 Catheter
– Normally an 8mm tip ablation catheters is used, but for
very thick or problematic isthmuses, an irrigated ablation
catheter can be used.
– Some doctors may even use a 4mm tip, but it will be a
longer procedure and recurrence may be higher
 Electrogram criteria
– Initial lesion point should show big V small A.
– Electrogram should be evaluated after each point
ablation. (Point by point ablation)
– Observe for a decrease in the electrogram amplitude
and keep ablating spots with significant A waves
 Use pacing maneuvers to assess the creation of
complete isthmus conduction block
38

39. Fluoroscopic Orientation During RF Ablation
 Ablation of the isthmus in either the RAO or
LAO projection
 LAO projection allows identification of the
position in a “clockface” relative to the location
of the TVA (point to point)
 LAO projection allows visualization of the RF
catheter as it is withdrawn into the IVC
 RAO projection allows discrimination of the
Anterior (TVA), initial position, to Inferior (IVC),
final position, during creation of the lesion in the
isthmus
39

40. Further Considerations during AFL Ablation
 RF Power considerations
– With 4mm tip ablation catheters, 30-50 Watts will be
adequate, but 8mm tip catheters often require more than
50 Watts
 Anatomical considerations
– Convective effects of blood pooling and variable,
complex anatomy may require higher power applications
– Patient discomfort in region of IVC due to stimulation of
nerve plexus
40

41. Ablation End Point
 Termination of the clinical arrhythmia
– With this criteria alone there is a high
recurrence rate
 Inability to re-induce atrial flutter;
 Confirmation of Bi-Directional block.
– Pre and post timing
– Block indicated by a multipolar catheter
41

42. Termination During Ablation
42

43. CS Pacing Pre Ablation (in sinus rhythm)
43

44. LRA Pacing Pre Ablation (in sinus rhythm)
44

45. Bi-directional Block
 Proven by pacing both lateral and medial
to the ablation line
 Block is demonstrated by a linear
activation sequence at both sites
45

46. CS Pacing Post Ablation with Isthmus Block
46

47. CS Pacing During Ablation with the occurrence of
Isthmus Block
47

48. LRA Pacing Post Ablation with Isthmus Block
48

49. Summary of Complete
Bi-Directional Block
19-20
Ablation
CT
LLRA
1-2
CS Pre Post
19-20 19-20
CS
Pacing Site
1-2 1-2
19-20 19-20
LLRA
1-2 1-2
49

50. Other Methods to Confirm Bi-directional Block
 Vector Mapping with the BDB Catheter
 Searching for Gaps in the Blockline
 Differential Pacing
50

51. Vector Mapping with the BDB Catheter
BDB
Isthmus
ABL Catheter
51 Electrogram Polarity and Cavotricuspid Isthmus Block During Ablation of Typical Atrial Flutter.Tada,H. Oral, H. et al.
Journal of Cardiovascular Electrophysiology. Volume12, No. 4, April 2001. P.394.

52. Vector Mapping with the BDB Catheter
Vector mapping to confirm the blockline
52 (Electrogram Polarity and Cavotricuspid Isthmus Block During Ablation of Typical Atrial Flutter）

53. Searching for Gaps in the Blockline
When you pace on one side of the blockline and you will note
double potentials along the line where you have made a
complete line. However, where there is a gap as you slowly
move the catheter, you will note that the double potentials
disappear meaning that you are on the Gap. You might also
find fractionated potentials. You can also look for the sites with
large electrograms meaning they have not yet been ablated
and ablate at those site.
53

54. Searching for Gaps in the Blockline
<90 >110
ms ms
Tada et al.* reported that the interval separating the two
components of a double potential was useful to distinguish
complete (>110 ms) from incomplete isthmus block (<90 ms)
in patients undergoing radiofrequency ablation of typical atrial
flutter.
* Tada H et al. J Am Coll Cardiol 2001; 38:750-5
54

55. Differential Pacing to Confirm the Bloclline
<90 ms <90 ms
Eustachian Eustachian
Low Ridge Low Ridge
Lateral CS Lateral CS
right right
Atrium Atrium
Tricuspid Annulus Tricuspid Annulus
Pre-ablation – No Blockline
• CS pacing – measure the time it takes for the conduction impulse to
reach the catheter located at the LLRA.
• LLRA pacing - measure the time it takes for the conduction impulse to
reach the proximal electrodes of the CS catheter.
55

56. Differential Pacing to Confirm the Block line
>110 ms >110 ms
Eustachian Eustachian
Low Ridge Low Ridge
Lateral CS Lateral CS
right right
Atrium Atrium
Block line
Tricuspid Annulus Tricuspid Annulus
Post-ablation – Block line
• CS pacing – measure the time it takes for the conduction impulse to reach the
catheter located at the LLRA.
• LLRA pacing - measure the time it takes for the conduction impulse to reach the
proximal electrodes of the CS catheter.
• A 50% increase in the transisthmus conduction time from baseline is also
56 predictive of complete block.

57. THANK YOU
57