2. Basics of AVNRT
Most common form of SVT treated by ablation and
accounts for 25% of all cases presenting to EP labs1
More common in females than males
Otherwise healthy individuals
Usually adolescent to mid-30's, but can occur at any
age, including infancy
A reentrant tachycardia which utilizes distinct atrial
inputs into the AVN that make up a large portion of the
circuit which makes it possible to ablate the arrhythmia
without damaging the AVN
1. Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology.
2
ReMEDICA Publishing. London, 2002, pg. 71.
3. AVNRT Circuit
Patients with AVNRT have a Dual Pathway Physiology
In 1/3 of patients with a slow pathway, it is not relevant for normal
conduction.
3
4. Slow and Fast Pathways
Slow Pathway
– Perinodal tissue possessing conduction
properties of slow depolarization and
relatively rapid repolarization inferiorly and
posteriorly close to the Csos (Posteroseptal
region)
Fast Pathway
– Perinodal tissue possessing the conduction
properties of relatively rapid depolarization
and relatively slow repolarization located
anteriorly and superiorly to Koch’s triangle
(Anteroseptal region)
4
5. Rightward and Leftward Posterior Extensions of the
Compact AVN
Anterior Compact
Inoue,S, Becker,AE. Extension AV Node
Posterior extensions
of the human Posterior
compact Extension
atrioventricular
node: a neglected
anatomic feature of
potential clinical
significance.
Circulation.
1998;97:188-193.
A B
A. The compact part of the AV node (with rightward and leftward posterior
extensions) is superimposed on the RAO view of the AV septal junction. The
rightward posterior extension runs in close proximity to the annular attachment of
the septal tricuspid valve leaflet and extends to the level of the CSos.
B. Posterior extension types in a series of 21 random hearts. None had a blunt-
ending of the posterior end of the compact node; 1 a leftward extension only; 7 a
rightward extension only; and 13 both rightward and leftward extensions. Dotted
5 line = Compact AVN/His bundle transition site.
6. Rightward and Leftward Posterior Extensions of the Compact
AVN
Image showing the histology
of the AV node and its
posterior extensions. A. The
compact AV node (arrows)
resting on the slope of the
muscular AV septum. B. A
section close to the opening
of the CSos, showing the
leftward (L) and rightward
extensions (R) (circled). C
and D. Magnifications
images of the leftward and
rightward extensions
(arrows), respectively.
Inoue,S, Becker,AE. Posterior extensions of the
human compact atrioventricular node: a
6 neglected anatomic feature of potential clinical
significance. Circulation. 1998;97:188-193.
7. Types of AVNRT
Three Main Types
– Typical (common; slow-fast) AVNRT: antegrade slow,
retrograde fast (88%)*
– Atypical AVNRT (uncommon; fast-slow or slow-slow)
Fast-slow AVNRT: antegrade fast, retrograde slow (10%)*
Slow slow AVNRT: antegrade certain slow fibers, retrograde other
slow fibers (2%)*
7
*Kuck KH, Cappato R. Catheter Ablation in the Year 2000. Current Opinion in Cardiology 2000;15:29-40.
8. Atypical Slow-Fast AVNRT with a
Posterior Exit
The atria are activated via
the posterior septum rather
than the anterior septum
– Earliest activation is via the
proximal CS electrodes
This is still called common
AVNRT, but it has a
posteriorly located fast
pathway
In the figure the VA interval
is very short, but the earliest
atrial activation is recorded
in the proximal CS
Francis Murgatroyd and Andrew Krahn. Handbook of cardiac
Electrophysiology. ReMEDICA Publishing. London, 2002, pg. 83
8
9. AVNRT ECG Recognition
Regular or irregular because of varying conduction through
the AV node.
Rate: 170-250 bpm
Conduction ratio: usually 1:1, uncommonly 2:1
Typical:
– The retrograde P wave is seen within, or in close proximity to the
terminal portion of the QRS complex (Short RP)
– Pseudo s wave
– Presence of a notch in lead aVL is a sensitive and specific predictor
of a diagnosis of AVNRT*
Atypical:
– The retrograde P wave occurs late, within or following the T wave
(Long RP).
*Utility of the aVL lead in the electrocardiographic diagnosis of atrioventricular node
9
reentrant tachycardia. Dar ́ıo Di Toro, et al. Europace (2009) 11, 944–948
10. Typical AVNRT
Short RP
RP
Pseudo S Waves
10
http://en.wikipedia.org/wiki/ File:AV_nodal_reentrant_tachycardia.png
11. Typical AVNRT
Pseudo S Waves
Notch in aVL
Notch
in aVL
Utility of the aVL lead in the electrocardiographic diagnosis of atrioventricular node
11
reentrant tachycardia. Dar ́ıo Di Toro, et al. Europace (2009) 11, 944–948
13. Requirements for AVNRT
Three main requirements for AVNRT to occur:
- Fast and slow pathways
- Difference in refractory periods
- Slow pathway has a short refractory period
- Fast pathway has a long refractory period
- Block must occur in one pathway
13
14. Requirements for AVNRT
Three main requirements for AVNRT to occur:
- Fast and slow pathways
- Difference in refractory periods
- Slow pathway has a short refractory period
- Fast pathway has a long refractory period
- Block must occur in one pathway
Slow Pathway (SP)
SP ERP
Fast Pathway (FP)
FP ERP
14
15. Requirements for AVNRT
Three main requirements for AVNRT to occur:
- Fast and slow pathways
- Difference in refractory periods
- Slow pathway has a short refractory period
- Fast pathway has a long refractory period
- Block must occur in one pathway
Slow Pathway (SP)
SP ERP
Fast Pathway (FP)
FP ERP
15
16. Requirements for AVNRT
Induction of AVNRT
- Block must occur in the fast pathway and conduction is
down the slow pathway
Atrium
Inverted P Wave
Fast
Pathway
Slow
Pathway AV
Node
Ventricle
Fast premature atrial beat
Left
Bundle
Branch
Right Bundle
Branch
16 1.Zipes & Jalife, Cardiac Electrophysiology:
From Cell to Bedside, 2nd ed., 1995, p. 1199
19. S2 Through Slow Pathway
AH Jump occurs when for a 10msec decrement in the S1S2
interval you get > 50msec increase in the AH interval
19
20. PR Longer Than RP (Indicative of Slow Pathway)
PR Interval
RP Interval
A V V
Long PR interval indicates slow pathway conduction
Short RP interval indicates fast pathway conduction
20
21. AVN Conduction Curve
Zhu DWX, Maloney JD. Radiofrequency catheter ablative therapy for atrioventricular nodal reentrant tachycardia. In Singer I:
Interventional Electrophysiology. Williams & Wilkins, Baltimore, 1997, pp 310.
21
23. “Dual Pathway” Physiology
Dual AV nodal physiology - a “jump” in the A-H interval of greater than, or equal to, 50
msec in response to a 10 msec decrement in the S1S2 interval; during atrial extra-
stimulus testing as the extra-stimulus is introduced (decremented).
“JUMP”
23
25. Conduction Curve Indicative of Multiple Slow Pathways
Zhu DWX, Maloney JD. Radiofrequency catheter ablative therapy for atrioventricular nodal reentrant tachycardia.
In Singer I: Interventional Electrophysiology. Williams & Wilkins, Baltimore, 1997, pp 290.
25
26. Dual AV Nodal Physiology
Antegrade dual pathways are demonstrable in 75% of AVNRT
patients2 and AVNRT may occur in the presence of continuous
AV nodal conduction curves.3–5
But antegrade dual pathways can be demonstrated in subjects
without tachycardia as well.6–10
In patients with the fast–slow variety of AVNRT, antegrade
conduction curves are usually continuous.11-12
Retrograde stimulation curves may exhibit an H-A jump if the
fast pathway retrograde refractory period is longer than the
slow pathway’s.
26
See references in notes
27. Two for One Phenomenon
Rarely the AV nodal tissue
has time to recover
between the conduction of
the slow and fast
pathways and a single
atrial impulse can result in
two His and ventricular
depolarizations, one from
the fast pathway
conduction and the other
from the slow pathway
conduction
Conduction travels down
the fast and slow
pathways simultaneously
giving rise to a normal A-
H-V response via the fast
pathway and an echo
response (H-V only) via
the slow pathway.
27
Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology. ReMEDICA Publishing. London, 2002, pg. 71.
28. Two for One Phenomenon
Normally
conduction
blocks in the
slow
pathway due
to retrograde
conduction
from the fast
pathway
Slow
pathway Fast
Fast Slow pathway
with very
Pathway Pathway recovers
slow
conduction
28
29. AV Nodal Echo Beats
An atrial
premature beat
travels down the
slow pathway and
then retrograde up
the fast pathway
resulting in an
atrial echo beat
almost
simultaneous with
the ventricular
beat.
29
30. Retrograde Dual AV Nodal Pathways
Retrograde dual AV nodal pathways
A jump in the retrograde VA interval may occur if
conduction in the fast pathway occurs during ventricular
pacing or a PVC, allowing conduction up the slow pathway
to the atrium.
An atypical ventricular echo beat can occur via the fast
pathway.
An H-A interval prolongation will occur.
Block in the His-Purkinje system
A VA jump can occur due to an infra-His delay where block
occur in the His-Purkinje system below the AVN and this is
the most common cause of VA block.
The H-A interval will be normal, but the VA prolonged
(prolonged V-H).
30
Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology. ReMEDICA Publishing. London, 2002, pg. 78-79
31. Retrograde Dual AV Nodal Pathways
A B
Figure A: Retrograde conduction is via the SP resulting in a retrograde jump with
earliest atrial activation at PCS. By the time the retrograde beat reaches the atrium the
FP is no longer refractory and an atypical ventricular echo beat (V’) occurs.
Figure B: Note the V2-H2 interval prolongs and not the H2-A2 showing jump was in
31
the His-Purkinje system not the AVN.
Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology. ReMEDICA Publishing. London, 2002, pg. 78-79
32. Typical AVNRT
In typical AVNRT,
antegrade conduction
is down the slow
pathway and
retrograde up the fast
pathway.
The earliest atrial
activation is recorded
in the anteroseptal
region (HIS) where the
fast pathway is located.
Also since conduction
to the ventricle is down
the slow pathway, the
AH interval will be
prolonged.
32
33. Criteria for Typical AVNRT
Typical AV Nodal Reentry
– Retrograde atrial activation caudocephalic with
electrogram in the AV Junction (His) earliest
(VA = 42-70 msec)
– Retrograde P wave within the QRS with
distortion of terminal portion of the QRS. Atrium,
His bundle, and ventricle not required
– Vagal manuevers slow and then terminate SVT
– During ablation junctional rhythm arising from
the posterior extension of the AV node occurs
with retrograde atrial conduction via the fast
pathway*
Clinical Cardiac Electrophysiology: techniques and interpretations,2nd. Ed..Lea and Febiger, 1993.page224
*Fujiki A et al. Europace 2008;10:982-987
33
36. Atypical AVNRT
In atypical AVNRT
antegrade
conduction is down
the fast pathway
and retrograde up
the slow pathway
Earliest atrial
activation would
be recorded in the
posteroseptal
region (proximal
CS) where the slow
pathway is located.
Since conduction to
the ventricle is
down the fast
pathway, the AH
interval will be
36
normal.
37. Atypical AVNRT
Atypical AVNRT is dependent on the same perinodal reentrant
circuit as typical AVNRT
– Antegrade conduction is via the fast pathway
– Retrograde conduction occurs over a slow pathway.
Atypical, or uncommon, AVNRT induction is dependent on a
critical HA interval during slow pathway conduction.
Retrograde atrial activation sequence caudocephalic with
earliest activation at the CSos
Retrograde P wave with long R-P interval
Atrium, His bundle, and ventricle not required; vagal manuevers
slow and then terminate SVT, always in the retrograde slow
pathway
During ablation junctional rhythm occurs without retrograde
atrial conduction via the fast pathway suggesting atypical
AVNRT is not a simple reversal of the typical slow–fast type*
37
*Fujiki A et al. Europace 2008;10:982-987
39. Slow Slow AVNRT
In Slow Slow AVNRT,
antegrade conduction
is down some slow
pathway fibers and
retrograde up other
slow pathway fibers.
Earliest atrial activation
is recorded in the
posteroseptal region
(CSos) where the slow
pathway is located.
Since conduction to the
ventricle and back to the
atrium is via slow
pathways, both the AH
& HA intervals may be
prolonged (not always).
39
40. Slow-Slow AVNRT
Slow–fast AVNRT (slow-slow) has long VA intervals and the
earliest retrograde atrial activation near the CSos.1,2
Posterior fast pathways have been reported in up to 6% of
patients with AVNRT3,4 and care must be taken to avoid
causing AV block when ablating at the site of the slow
pathway.
In true clinical practice, the junctional rhythm induced by the
slow pathway ablation does not show any VA conduction.
After successful retrograde slow pathway ablation,
antegrade slow pathway conduction remains in patients with
slow–slow AVNRT*
40
*Fujiki A et al. Europace 2008;10:982-987
41. Slow-Slow AVNRT
HA = 150ms AH = 270ms
V A VA
41
Fujiki A et al. Europace 2008;10:982-987
42. Summary of AVNRT Types
Katritsis D G , Camm A J Europace 2006;8:29-36 Fujiki A et al. Europace 2008;10:982-987
42
44. Catheter Positions
High right atrium near the sinus node (HRA)
Just across the tricuspid valve against
septum for His bundle recording (HBE)
Right ventricular apex (RVA)
Coronary sinus (CS)
Mapping/Ablation catheter
44
49. Differential Diagnosis
PVC when His bundle is refractory
Para-Hisian Pacing
Adenosine Administration
A-V Wenckebach periodicity or
Dissociation
V-A Wenckebach periodicity or
dissociation
49
50. PVCs on the His
Performed during tachycardia
Pace RV when AV node is refractory
Look for retrograde atrial conduction
V-A conduction while the AV Node is
refractory is diagnostic of an accessory
pathway not AVNRT
50
55. ParaHisian Pacing: Retrograde Conduction via the Normal
Conduction System during His Capture
Atrium
AV
Ventricle
Node
☼ Left Spike-A Interval
Bundle
Branch
Right
Bundle
Branch
Retrograde conduction traveling from the His to the atrium quickly via the normal
conduction system during His capture resulting in a short Spike-A Interval.
55
56. Parahisian Pacing: Retrograde Conduction via the Normal Conduction
System during loss of His Capture
Atrium
AV
Node Ventricle
☼ Left
Bundle
Spike-A Interval
Branch
Right
Bundle
Branch
Retrograde – Conduction travels from the His region through the ventricle to the
Purkinje fibers then up the bundle branches, His and finally to the atrium. Thus,
the Spike-A interval is long.
56
57. Parahisian Pacing: Retrograde Conduction via an Accessory Pathway and
Normal Conduction System during His Capture
Atrium
AV
Node Ventricle
☼ Left
Bundle
Spike-A Interval
Branch
Right
Bundle
Branch
Retrograde – Conduction travels from the His region to the atrium via the normal
conduction system and simultaneously through the ventricle to atrium via the
accessory pathway very quickly resulting in a short Spike-A interval.
57
58. Para-Hisian Pacing: Retrograde Conduction via an Accessory Pathway
during loss of His Capture
Atrium
AV
Node Ventricle
☼ Left
Bundle
Spike-A Interval
Branch
Right
Bundle
Branch
Retrograde conduction travels from the ventricle to the atrium via the accessory
pathway and normal conduction system, but the accessory pathway conduction
is faster resulting in a short Spike-A Interval.
58
59. Para-Hisian pacing-
Retro AVN conduction; no BPT
Narrow QRS Wide QRS
Variable
Stim -A
His and V V capture
capture only
59 Zipes & Jalife, Cardiac Electrophysiology:
From Cell to Bedside, 2nd ed,. 1995, p. 623
60. Para-Hisian pacing-
Retro conduction through BPT
Narrow QRS Wide QRS
Fixed Stim - A
V capture
His and V
only
capture
60 Zipes & Jalife, Cardiac Electrophysiology:
From Cell to Bedside, 2nd ed,. 1995, p. 623
61. Pharmacological block
Block AV node conduction with adenosine or
verapamil
– Continued V-A conduction is diagnostic of an
accessory pathway during ventricular pacing
Adenosine can break some non-AVRT
tachycardias
There is no difference in incidence of
tachycardia termination at the AV node in AVRT
versus AVNRT after giving adenosine*
However with AVRT there may be an increase in
the VA interval but not with typical AVNRT, so
this can be used to differentiate between them*
Adenosine does not work in every patient
*Glatter et al. Electrophysiologic Effects of Adenosine in Patients With Supraventricular Tachycardia.
61 Circulation.1999;99:1034-1040
62. Adenosine Blocks AV Conduction: Retrograde Conduction via an
Accessory Pathway Results in an “A” Wave
Atrium
AV
Node Ventricle
Left Retrograde “A”
Bundle
Branch
☼ Right
Bundle
Branch
Retrograde “A” = Accessory Pathway
62
63. Adenosine Blocks AV Conduction: No Retrograde Conduction Means No
Accessory Pathway and No “A” Wave Results
Atrium
AV
Node Ventricle
No Retrograde “A”
Left
Bundle
Branch
Right
Bundle
☼
Branch
No Retrograde “A” = No Accessory Pathway
63
64. Wenckebach Periodicity or Dissociation
If A-V or VA Wenckebach periodicity or
dissociation occurs, it may rule out AVRT
A-V or V-A Wenckebach periodicity or
dissociation can occur during AVNRT
64
65. Differential Diagnoses
– Absence of an AV accessory pathway is
confirmed when:
Ventricular pre-excitation is absent during sinus rhythm (SR) and
atrial pacing
The ventriculo-atrial (VA) interval during the tachycardia is not
lengthened by the occurrence of bundle branch block
The tachycardia is not reset by ventricular extrastimuli delivered
when the His bundle is refractory
Para-Hisian pacing2 during SR exhibited an exclusive retrograde
AV nodal conduction pattern
The VA interval during pacing from the RV apex is shorter than
that during pacing from the RV base.
1.Josephson ME: Supraventricular tachycardias. Clinical Cardiac Electrophysiology. Techniques and Interpretations. Third
edition. Philadelphia: Lippincott Williams & Wilkins, 2002, pp. 168-271.
65
2.Knight BP, Zivin A, Souza J, Flemming M, Pelosi F, Goyal R, Man C, Strickberger SA, Morady F: A technique for the rapid
diagnosis of atrial tachycardia in the electrophysiology laboratory. J Am Coll Cardiol. 1999;33:775-81.
66. Differential Diagnoses
– Atrial tachycardia is excluded when:
A “V-A-V sequence” (not a “V-A-A-V sequence”) is
observed upon cessation of ventricular pacing
associated with 1:1 VA conduction during the
tachycardia2
The tachycardia is reproducibly terminated with
ventricular extrastimuli not reaching the atrium.
Heidbuchel H, Jackman WM: Characterization of subforms of AV nodal reentrant tachycardia.
66
Europace. 2004;6:316-29
67. VAAV Response
The response to ventricular pacing with 1:1 VA conduction during an SVT in a
patient with AT. The electrogram response upon cessation of ventricular pacing is
an atrial-atrial-ventricle (A-A-V).
67
Knight et al. JACC Vol. 33, No. 3, 1999. Rapid Diagnosis of Atrial Tachycardia. March 1, 1999:775–81
68. VAAV Response
Note after stopping ventricular pacing the last paced V is followed by an
“entrained” A, then by a spontaneous tachycardia A and V. This V-A-A-
68 V response is diagnostic of AT.
Roberts-Thompson et al. Atrial Tachycardia: Mechanisms, Diagnosis, and Management. Curr Probl Cardiol 2005;30: 529-573.
69. VAV Response
The response to ventricular pacing with 1:1 VA conduction during tachycardia in a
patient with typical AVNRT. The electrogram response upon cessation of
ventricular pacing is an atrial-ventricle (A-V).
69
Knight et al. JACC Vol. 33, No. 3, 1999. Rapid Diagnosis of Atrial Tachycardia. March 1, 1999:775–81
70. Mapping and Ablation
Objective
Modify the slow pathway of the AV node in order
that it will no longer conduct
Slow Pathway Modification
Ablation catheter is positioned “anatomically” on
the tricuspid valve annulus posterior and inferior to
the His bundle at the level of the CS ostium. If
unsuccessful, the catheter is moved anterior and
superior in a stepwise fashion until successful.
70
71. Triangle of Koch
Tendon of Todaro
Zipes :catheter
ablation of
arrhythmias
Selective
transcatheter
modification of
the
atriovetricular
node
Membranous
Septum
His bundle/compact AVN are at the apex of Koch’s triangle
CS ostium forms the posterior portion of Koch’s triangle
Tricuspid annulus defines the third face of Koch’s triangle
71
http://www.rjmatthewsmd.com/Definitions/anatomy_ofthe_heart.htm
77. Catheter Mapping Techniques
Zipes: catheter ablation of
arrhythmias
Selective transcatheter
modification of the
atriovetricular node pg 176
S.Deshpande, M Jazayeri, A
dhala, Z Blanck, J. Sra, S.
Bremner, M. Aktar
77
78. Slow Pathway Potentials
In the region of the Triangle of Koch, potentials
separate from the local atrial potential and His potential
can be recorded. These are slow pathway (SP)
potentials.
Near the Csos the atrial potential may be sharp, but the
SP potential may have a low frequency and amplitude.
Moving slightly more anterior the SP potential may be
more discrete and the atrial potential will be less well
defined.
Moving even more anterior, neither an SP or His
potential can be recorded. This is the location of the
AVN.
Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology.
78
ReMEDICA Publishing. London, 2002, pg. 80
81. Junctional Rhythm During Ablation
During ablation, thermal injury to the slow pathway
may enhance the automaticity of the posterior
extension of the AV node and induce junctional
rhythm that conducts to the atrium through the
retrograde fast pathway
Junctional beats associated with VA block during
slow pathway ablation are suggested as a marker
of injury to the fast pathway, which could induce
AV block
Loss of VA conduction during slow pathway
ablation is not always associated with AV
conduction block.
81
Fujiki A et al. Europace 2008;10:982-987
82. AV Junctional Tissue
Schematic diagram summarizing the Fluorescent imaging of the AV
distribution of NF160, Cx43, Cx45, Cx40, junction showing the pacemaker
and HCN4 in the rabbit AV junction. TV area of AV Junctional Rhythm
indicates tricuspid valve; TT, tendon of marked by the blue oval. This
Todaro. The posterior nodal extension is shows AV Junctional Rhythm
the slow pathway and responsible for the breakthrough to the atrium by the
junctional rhythm pacemaker site. fast pathway exit.
Dobrzynski, H, Nikolski, VP, Sambelashvili, AT, Greener, ID, Yamamoto, M, Boyett, MR, Efimov, IR. Site of
82 Origin and Molecular Substrate of Atrioventricular Junctional Rhythm in the Rabbit Heart. Circulation
Circulation Research. 2003;93:1102 Research. 2003;93:1102.).
83. Junctional Rhythm during RF application
The peri-AV nodal region is highly innervated by the autonomic nervous system and
may be stimulated during the AVNRT RF ablation, generating junctional tachycardia. It
also may be due to the effects of the local release of norepinephrine causing an abrupt
rise and fall in the rate. Junctional rhythm may result from heat injury to the slow
pathway.
83
Fujiki A et al. Europace 2008;10:982-987
84. Junctional Rhythm during RF application
Tachycardia Circuits
Junctional Rhythm Mechanism during Ablation
Typical AVNRT Conducts Fast-Slow/Slow-Slow do not conduct to
to the atrium the atrium
84
Fujiki A et al. Europace 2008;10:982-987
85. RF Ablation Endpoints
Inability to reinduce tachycardia
Not favor
Loss of dual AVN physiology
Prolongation of AH interval
Complete heart block *
* Not a desirable endpoint for slow-pathway ablation.
85
87. Fast Pathway ERP Post Ablation
A significant shortening of the fast pathway
(FP) ERP (improved conduction) after
successful slow pathway (SP) ablation
often occurs, possibly due to:
– Increased sympathetic tone which can shorten
both the antegrade and retrograde FP ERPs
– Loss of the electronic interactions between the
FP and SP
87
88. AVN conduction curve
Zhu DWX, Maloney JD. Radiofrequency catheter ablative therapy for atrioventricular nodal reentrant tachycardia. In Singer I:
Interventional Electrophysiology. Williams & Wilkins, Baltimore, 1997, pp 310.
88
89. AVN Wenkebach Post RF Ablation
89 If the FP ERP is too long, you can get Wenkebach while at rest
90. Lower Common Pathway
90Hein Heidbüchel. Characterization of subforms of AV nodal reentrant tachycardia.Europace.Volume 6, Issue4P.p. 316-329
91. Upper and Lower Common Pathways
Upper Common Pathway (UCP) Lower Common Pathway (LCP)
Without a UCP the AH during SVT and Without an LCP the HA (dotted lines)
pacing is the same (350ms), with a UCP during SVT and pacing is the same
of AVN tissue between the AVN circuit (50ms) up the retrograde fast pathway,
and atrium (stippled area) in SVT, the AH with an LCP of AVN tissue between the
= 320 ms and during atrial pacing at the AVN circuit and His bundle (stippled
same CL as SVT, the AH = 380 msec or area) in SVT, the HA = 20 ms and during
60 msec more than SVT ventricular pacing at the same SVT CL,
the HA = 80 msec or 60 msec more than
SVT
91
Miller et al. Atrioventricular nodal reentrant tachycardia: studies on upper and lower 'common pathways‘.Circulation 75, No. 5, 930-940, 1987.
92. Potential Complications
3rd degree AV block
– Rare when targeting slow pathway
– 10% when targeting fast pathway
Other EP study related complications
92
93. Posterior Fast Pathway Input
The fast pathway retrograde input is usually located
anteriorly close to the His bundle, but rarely it may
be located in the posteroseptal RA, where the slow
pathway ablation is performed. Thus, occasionally
while ablating the slow pathway you could ablate the
retrograde fast pathway and affect the antegrade
fast pathway if the location of the antegrade and
retrograde fast pathways is anatomically similar.
Therefore, failure to recognize the presence of a
posterior fast pathway input may result in AV block.
93 Lee, Pi-Chang; Chen, Shih-Ann; Hwang, Betau. Current Opinion in Cardiology: March 2009 - Volume 24 - Issue 2 - p 105-112.
Atrioventricular node anatomy and physiology: implications for ablation of atrioventricular nodal reentrant tachycardia
94. Posterior Fast Pathway Input
Low site
Low site
The retrograde conduction route is very low so transient heart block can occur
To avoid the low retrograde conduction routes, RF energy (brown dots) is delivered
while viewing the precise geometry
94
Lee, Pi-Chang; Chen, Shih-Ann; Hwang, Betau. Current Opinion in Cardiology: March 2009 - Volume 24 - Issue 2 - p 105-112.
Atrioventricular node anatomy and physiology: implications for ablation of atrioventricular nodal reentrant tachycardia
95. Conclusions
Easy to diagnose
Easy to treat
High success rate with RFA
95
