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-30s, 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.
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
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
Rightward and Leftward Posterior Extensions of the Compact AVN Anterior CompactInoue,S, Becker,AE. Extension AV NodePosterior extensionsof the human Posteriorcompact Extensionatrioventricularnode: a neglectedanatomic feature ofpotential clinicalsignificance.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.
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: a6 neglected anatomic feature of potential clinical significance. Circulation. 1998;97:188-193.
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.
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 CSFrancis Murgatroyd and Andrew Krahn. Handbook of cardiacElectrophysiology. ReMEDICA Publishing. London, 2002, pg. 83 8
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 9reentrant tachycardia. Dar ́ıo Di Toro, et al. Europace (2009) 11, 944–948
Typical AVNRT Short RP RP Pseudo S Waves10 http://en.wikipedia.org/wiki/ File:AV_nodal_reentrant_tachycardia.png
Typical AVNRT Pseudo S Waves Notch in aVLNotchin 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
Atypical (Fast-Slow) AVNRT EGM Long RP R P A V A12 Fujiki A et al. Europace 2008;10:982-987
Requirements for AVNRTThree 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 pathway13
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 ERP14
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 ERP15
Requirements for AVNRTInduction 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 Branch16 1.Zipes & Jalife, Cardiac Electrophysiology: From Cell to Bedside, 2nd ed., 1995, p. 1199
Sinus Rhythm with Dominant Fast Pathway Conduction17
S2 Through Slow PathwayAH Jump occurs when for a 10msec decrement in the S1S2interval you get > 50msec increase in the AH interval19
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 conduction20
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
AVN Conduction Curve con’t Zhu DWX, Maloney JD. Radiofrequency catheter ablative therapy for atrioventricular nodal reentrant tachycardia. In Singer I: Interventional Electrophysiology. Williams & Wilkins, Baltimore, 1997, pp 310.22
“Dual Pathway” PhysiologyDual AV nodal physiology - a “jump” in the A-H interval of greater than, or equal to, 50msec 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
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
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
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. 27Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology. ReMEDICA Publishing. London, 2002, pg. 71.
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 slowconduction28
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
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). 30Francis Murgatroyd and Andrew Krahn. Handbook of cardiac Electrophysiology. ReMEDICA Publishing. London, 2002, pg. 78-79
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
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
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;10:982-98733
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 be36 normal.
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
Atypical (Fast-Slow) AVNRT EGM Long RP R P A V A38 Fujiki A et al. Europace 2008;10:982-987
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
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
Slow-Slow AVNRT HA = 150ms AH = 270ms V A VA41 Fujiki A et al. Europace 2008;10:982-987
Summary of AVNRT TypesKatritsis D G , Camm A J Europace 2006;8:29-36 Fujiki A et al. Europace 2008;10:982-987 42
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 catheter44
Differential Diagnosis PVC when His bundle is refractory Para-Hisian Pacing Adenosine Administration A-V Wenckebach periodicity or Dissociation V-A Wenckebach periodicity or dissociation49
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 AVNRT50
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
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
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
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
Para-Hisian pacing- Retro AVN conduction; no BPTNarrow QRS Wide QRS Variable Stim -AHis and V V capturecapture only59 Zipes & Jalife, Cardiac Electrophysiology: From Cell to Bedside, 2nd ed,. 1995, p. 623
Para-Hisian pacing- Retro conduction through BPT Narrow QRS Wide QRS Fixed Stim - A V captureHis and V onlycapture 60 Zipes & Jalife, Cardiac Electrophysiology: From Cell to Bedside, 2nd ed,. 1995, p. 623
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
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
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 Pathway63
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 AVNRT64
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. 168-271.652.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.
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
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
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.
VAV ResponseThe 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
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
Triangle of Koch Tendon of TodaroZipes :catheterablation ofarrhythmiasSelectivetranscathetermodification oftheatriovetricularnode 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
Radiographic Positioning LAO RAO His His CS RV CS RV ABL ABL76
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. Aktar77
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
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
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.).
Junctional Rhythm during RF applicationThe peri-AV nodal region is highly innervated by the autonomic nervous system andmay be stimulated during the AVNRT RF ablation, generating junctional tachycardia. Italso may be due to the effects of the local release of norepinephrine causing an abruptrise and fall in the rate. Junctional rhythm may result from heat injury to the slowpathway. 83 Fujiki A et al. Europace 2008;10:982-987
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 atrium84 Fujiki A et al. Europace 2008;10:982-987
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
Post RF Stimulation No slow pathway conduction AVN ERP No His or V86
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 SP87
AVN conduction curveZhu DWX, Maloney JD. Radiofrequency catheter ablative therapy for atrioventricular nodal reentrant tachycardia. In Singer I: Interventional Electrophysiology. Williams & Wilkins, Baltimore, 1997, pp 310.88
AVN Wenkebach Post RF Ablation89 If the FP ERP is too long, you can get Wenkebach while at rest
Lower Common Pathway90Hein Heidbüchel. Characterization of subforms of AV nodal reentrant tachycardia.Europace.Volume 6, Issue4P.p. 316-329
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 sameof 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 (stippledsame CL as SVT, the AH = 380 msec or area) in SVT, the HA = 20 ms and during60 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.
Potential Complications 3rd degree AV block – Rare when targeting slow pathway – 10% when targeting fast pathway Other EP study related complications92
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
Posterior Fast Pathway InputLow siteLow 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
Conclusions Easy to diagnose Easy to treat High success rate with RFA95