limination of left atrial appendage potentials duringadiofrequency ablation near the right superior pulmonary veinichael Kuhne, MD,* Siew Yen Ho, PhD,† Fred Morady, MD,* Aman Chugh, MD*
rom the *Division of Cardiology, University of Michigan Health System, Ann Arbor, Michigan, and †Imperial College
ondon, London, England.
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Isolation of the left atrial appendage (LAA) during cath-ter ablation of atrial fibrillation (AF) has been reportedreviously.1 In the prior study, circumferential isolation ofhe LAA was performed to eliminate multiple foci thatriggered atrial tachycardia after isolation of the pulmonaryeins (PV). However, apparent isolation of the LAA duringadiofrequency ablation near the right superior PV has noteen reported.
ase report 42-year-old man with a history of chronic AF and con-estive heart failure (ejection fraction 10%, LA diameter 5.8m) was referred for catheter ablation. He had previouslyndergone a successful ablation procedure for spontaneousitral isthmus-dependent flutter approximately 18 months
go. During follow-up, persistent AF developed requiringreatment with amiodarone, which was discontinued be-ause of thyrotoxicosis.
He presented to the electrophysiology laboratory in AFfter a transesophageal echocardiography failed to show aAA thrombus. Radiofrequency energy was delivered using 3.5-mm irrigated-tip ablation catheter (Thermocool, Bio-ense-Webster, Diamond Bar, California). The followingblation steps were performed: antral isolation of the PVs,blation of complex electrograms2 along the inferior LA,eptum, anterior base of the LAA, and in the coronary sinusCS). The AF cycle length lengthened and transthoracicardioversion was performed. Because of easily inducibleypical flutter, ablation at the cavotricuspid isthmus waserformed, which terminated the tachycardia, and bidirec-ional block was achieved.
Overnight, atrial tachycardia developed with 1:1 atrio-entricular conduction at a cycle length of 250 ms associ-ted with severe symptoms and hypotension. The patientnderwent a second procedure 48 hours after the initial AFrocedure. He presented to the electrophysiology laboratory
EYWORDS Atrial fibrillation; Left atrial appendage; Bachmann bundleHeart Rhythm 2008;5:475–478)
ddress reprint requests and correspondence: Dr. Aman Chugh, Divi-ion of Cardiology, University of Michigan Health System, 1500 Eastedical Center Drive, Ann Arbor, Michigan 48109. E-mail address:
gain in AF. The mean LA pressure was 30 mm Hg. The AFycle length was approximately 190 ms. Mapping with aing catheter (Lasso, Biosense-Webster) showed recoveryf conduction in the right superior PV. The ring catheteras placed in the LAA. A roof line was performed. Abla-
ion of complex electrograms was also performed. A singleesion at a site with a fractionated electrogram (Figure 1A)ear the anterior aspect of the right superior PV eliminatedhe LAA electrograms shortly after initiation of energyelivery (Figures 1B, 2, and 3).
Catheter ablation at the inferoposterior LA guided bydentification of fractionated electrograms terminated AF,iving way to the clinical tachycardia at a cycle length of50 ms. Another atrial tachycardia also developed at a cycleength of 220 ms. Both of these tachycardias were mappedo the posterior aspect of the right superior PV, whereadiofrequency ablation yielded sinus rhythm.
During sinus rhythm, a markedly delayed electrogram, oc-urring after ventricular activation, was recorded in the LAAFigure 4A). Pacing from the LAA at a cycle length of 600 msesulted in 1:1 atrial capture (Figure 4B). All PVs were docu-ented to be isolated, and conduction block across the roof
nd the mitral isthmus from the prior procedure was verified.he patient was discharged from the hospital in sinus rhythmithout antiarrhythmic medications. Approximately 4 weeks
fter discharge, the patient underwent implantation of dual-hamber pacemaker for symptomatic sinus node dysfunction.n echocardiogram performed at that time showed that the
jection fraction had improved to 45%.
iscussionntentional electrical disconnection of the LAA has beenescribed in a patient with multiple foci from the LAA thatere responsible for atrial arrhythmias after PV isolation.1
n that case report, 25 minutes of radiofrequency energyere required to circumferentially isolate the LAA. Weescribe a case of apparent isolation of the LAA during aingle application of radiofrequency energy near the ante-ior aspect of the right superior PV.
It may seem difficult to explain how ablation at a particularite eliminated conduction into a structure �5 cm away. How-ver, such a finding can be explained by the presence ofyocardial connections that link the anterosuperior left atrium
o the LAA. It is well known that the Bachmann bundle is
ocated in close proximity to the site where ablation waserformed. However, it may be less well appreciated that theachmann bundle is not an insulated or isolated muscle bun-
igure 1 A: The electrogram recorded by the ablation catheter before raf RF energy delivery at a site with a fractionated electrogram anterior to totentials recorded by the catheter in the left atrial appendage (LAA) are entirelso shown are electrocardiographic lead V1, bipolar electrograms recorded
igure 2 An electroanatomical map in an anteroposterior view showinghe site (solid black arrow) where ablation led to elimination of left atrialppendage (LAA) potentials. The dashed arrow shows the location of theatheter in the LAA, which is located 5.4 cm away from the ablation site.he white arrow refers to the site where ablation terminated atrial fibril-
ation. The red tags represent sites where radiofrequency energy waselivered. Note the numerous areas of scar (gray tags). RS � right supe-
ior; RI � right inferior; LS � left superior. c
le. It has direct connections with other muscle bundles thatake up the myoarchitecture of the atria.3–5 The original de-
cription by Papez3 referred to the left anterior and left poste-ior crests that arise from the septal raphe. Papez used the termeptal raphe to designate the area that he considered to be like
uency (RF) energy delivery shows continuous electrical activity. B: Effectsuperior pulmonary vein (RSPV). Shortly after commencing ablation, the
nated (asterisk). The dashed arrow refers to a far-field ventricular electrogram.blation (Abld and Ablp), and coronary sinus (CSd and CSp) catheters.
igure 3 A 3-dimensional computed tomographic (CT) image of the lefttrium obtained before the ablation procedure (AP view with cranialngulation). The relevant points have been imported from the electroana-omical map to the CT image. The pink tag refers to the site where ablationliminated conduction into the left atrial appendage (LAA) (white tag). For
diofreqhe right
larity, the size of the tags has been enlarged. MV � mitral valve.
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477Kuhne et al Elimination of Left Atrial Appendage Potentials
seam that knitted together the atria because most of the largeuscle bundles of both atria, including the Bachmann bundle,
rise from here. The raphe is bounded by the entrance of theuperior vena cava on the right, the orifice of the right superiorulmonary vein on the left, and the Bachmann bundle anteri-rly (Figure 5). The deep fibers of the left anterior and poste-ior crests arise from the raphe alongside the septoatrial bundle,hereas the superficial fibers are in continuity with the upperart of the Bachmann bundle. Leftward, the left atrial crests areontinuations of the Bachmann bundle that diverge at the basef the LAA, only to meet again posterolaterally, embracing thes of the appendage. It is plausible that the septal end of one ofhese bundles of fibers of the left atrial crests was interruptedith the ablation lesion.It is likely that the endocardial projections of the contin-
ations of the Bachmann bundle had been disrupted at leastartly by prior ablation. Circumferential antral ablationround the left-sided PVs along with ablation of complexlectrograms at the anterior base of the LAA likely lead tolowing of conduction into the LAA by disrupting the distalamifications of the posterior and anterior endocardial pro-ections, respectively. This is supported by the fact that theAA cycle length (approximately 250 ms) was longer than
hat of the CS (approximately 200 ms), and the LA prior toblation (Figure 1B).
Although the endocardial projections of the Bachmannundle were disrupted by ablation, the bundle itself was
igure 4 A: During sinus rhythm, the left atrial appendage (LAA) electrlso, note that the P wave in lead II lacks a terminal negative component, co
t a cycle length of 600 ms, there is 1:1 atrial capture. Also, the electrogro the pacing stimulus (dashed arrow), consistent with far-field LAA activ
robably largely intact. This is supported by the fact the o
waves in the inferior leads during sinus rhythm did nothow terminal negativity (Figure 4A), an electrocardio-raphic hallmark of injury to the Bachmann bundle.6 It isortuitous that the major route of interatrial conductionas still capable of providing synchronous activation of
he LA.It should also be noted that although the LAA seems to
e completely isolated during AF, there was conduction intohe appendage during sinus rhythm and out of the append-ge during pacing. These observations suggest that conduc-ion into the LAA is rate dependent. This may have importantmplications regarding the patient’s risk of thromboembolism.pecifically, although there is conduction into the LAAuring sinus rhythm, there may be rate-dependent conduc-ion block into the appendage during higher heart rates, forxample, during exercise. For this reason, we have recom-ended indefinite anticoagulation with warfarin to the pa-
ient.
linical implicationshe fact that the LAA may be disconnected remotely isoteworthy for several reasons. First, it is likely that inatients who require extensive ablation for chronic AF,onduction into the LAA may be compromised more fre-uently than realized. Because the LAA electrograms aresually not monitored during the ablation procedure, slow-ng of LAA conduction may occur unbeknownst to the
arrow) is significantly delayed and is recorded after ventricular activation.t with intact conduction over the Bachmann bundle. B: During LAA pacingorded by the ring catheter in the left superior pulmonary vein is advanced
ogram (nsistenam rec
perator. It may be reasonable to verify the integrity of LAA
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478 Heart Rhythm, Vol 5, No 3, March 2008
onduction during sinus rhythm after such procedures. It islso helpful to note that arrhythmias originating from theAA may be targeted without having to ablate around orirectly within the appendage because it may be very thin inertain individuals and prone to perforation.
eferences. Takahashi Y, Sanders P, Rotter M, et al. Disconnection of the left atrial
appendage for elimination of foci maintaining atrial fibrillation. J Cardiovasc
igure 5 A: Anterior view of a heart specimen dissected to show the subundles (arrows), that surround the left atrial appendage (LAA). The openown onto the septal raphe to show the muscle bundles going leftward andotched arrow marks the septopulmonary bundle. LS � left superior pulm
Electrophysiol 2005;16:917–919.
. Oral H, Chugh A, Good E, et al. Radiofrequency catheter ablation of chronic atrialfibrillation guided by complex electrograms. Circulation 2007;115:2606–2612.
. Papez J. Heart musculature of the atria. Am J Anat 1920;27:255–285.
. Ho S, Anderson R, Sanchez-Quintana D. Atrial Structure and fibres: Morpho-logical basis of atrial conduction. Cardiovasc Res 2002;54:325–336.
. Lemery R, Guiraudon G, Veinot JP. Anatomic description of Bachmann’sbundle and its relation to the atrial septum. Am J Cardiol 2003;91:1482–1485,A1488.
. Cosio FG, Martin-Penato A, Pastor A, et al. Atrial activation mapping insinus rhythm in the clinical electrophysiology laboratory: Observations dur-ing Bachmann’s bundle block. J Cardiovasc Electrophysiol 2004;15:524 –
al muscle bundles, including the Bachmann bundle (BB) and the divergingindicates the septal raphe. B: A view of the same heart as above lookingard (small arrows). The open arrow marks the septoatrial bundle, and thevein, RS � right superior pulmonary vein, SVC � superior vena cava.
