Europace (2008) 10, 1004–1005
doi:10.1093/europace/eun163
SHORT COMMUNICATION
Anatomically left-sided septal slow pathway ablation
in dextrocardia and situs inversus totalis
Demosthenes G. Katritsis1* and John Papagiannis2
1
Department of Cardiology, Athens Euroclinic, 9 Athanassiadou Street, Athens 11521, Greece; and 2Department of Pediatric
Cardiology, Mitera Hospital, Athens, Greece
Received 26 April 2008; accepted after revision 22 May 2008; online publish-ahead-of-print 12 June 2008
KEYWORDS
Atrioventricular nodal
re-entrant tachycardia;
Dextrocardia;
Situs inversus;
Ablation
We present a case of typical (slow–fast) atrioventricular nodal re-entrant tachycardia in a patient with
complete situs inversus in whom catheter ablation of the slow pathway was accomplished from the
right-sided anatomically left ventricle with considerable ease.
Catheter ablation of atrioventricular nodal re-entrant tachycardia (AVNRT) in the setting of congenital heart disease is
potentially very challenging, especially when associated
with deviations from the usual situs solitus arrangement of
atria and viscera. There have been reports of successful
slow pathway ablation in patients with dextrocardia and
situs inversus but usually at the expense of prolonged procedure and fluoroscopy times.1–3
A 29-year-old lady with chronic renal failure and
dextrocardia and complete situs inversus was referred
for evaluation of paroxysmal narrow-complex tachycardia.
Electrophysiological testing was undertaken and revealed
dual AV nodal physiology and typical (slow–fast) AVNRT.
A conventional ablation catheter, a D-curve with a 4 mm
tip and 2.5 mm interelectrode spacing (Cordis-Webster,
Diamond Bar, CA, USA), was introduced through the right
femoral vein, and mapping of the slow pathway in the
posterior area of the left-sided (anatomically right)
septum was commenced. Despite recording of suitable
electrograms (Figure 1), delivery of radiofrequency
current (preset at 608C and 45 W) failed to produce nodal
activity and tachycardia remained inducible. Having
completed 30 min of fluoroscopy time with attempts at
posterior and mid-septal sites and inside the coronary
sinus ostium, it was decided to approach the slow pathway from the arterial side. A second ablation catheter was
* Corresponding author. Tel: þ30 210 6416600; fax: þ30 210 6416661.
introduced in the anatomically left ventricle through the
right femoral artery, and the right side (anatomically left)
of the septum was mapped for stable recording of a His
bundle electrogram. From this position, the catheter tip
was directed towards the ostium of the coronary sinus at
the posterior aspect of the septum (Figure 2). This is the
anatomic position of the left posterior extension of the AV
node.4,5 Two deliveries of a radiofrequency current for 60 s
resulted in immediate nodal rhythm with 1:1 retrograde
conduction. After these applications, AVNRT was not
inducible despite maximal doses of isoproterenol. The AH
interval remained unchanged and there was no evidence
of slow pathway conduction.
We have recently provided evidence in support of the
notion that the right and left inferior nodal extensions of
the human AV node and the atrio-nodal inputs they facilitate may provide the anatomic substrate of the slow
pathway.4,5 Our studies have indicated the presence of
an atrio-nodal connection that is operating on the left
side of the septum and corresponds to the leftward atrial
inferior extension of the AV node. These observations
provide the rationale for the well-documented feasibility
of left-sided ablation of AVNRT. Dextrocardia in the
context of complete situs inversus presents an anatomic
challenge, and the left-sided approach may be of particular help by means of providing an accessible target for slow
pathway ablation.
Conflict of interest: none declared.
E-mail address: [email protected]
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2008.
For permissions please email: [email protected].
AVNRT ablation in situs inversus
1005
Figure 1 (A) Despite recording of suitable signals and appropriate anatomic position of the anatomically right (R Abl) ablation catheter on
the left side of the septum, no nodal beats or rhythm could be obtained with radiofrequency current delivery. (B) Recording of a His bundle
electrogram by the anatomically left (L Abl) ablation catheter on the right side of the septum. (C ) By advancing the anatomically left ablation
catheter on the right side of the septum posteriorly and towards the CS ostium, the anatomic area of the left posterior extension of the
AV node is negotiated. At this point, nodal rhythm was immediately obtained by radiofrequency current delivery, and following two
current deliveries, the AVNRT was no longer inducible. I, II: ECG leads taken in a mirror-image position; His: His bundle electrogram; CS:
coronary sinus.
Figure 2 Position of catheters in the right (RAO) and left anterior oblique (LAO) projections. The site of successful slow pathway ablation (L
Abl) is at the posterior, anatomically left septum towards the ostium of the coronary sinus. Abbreviations as in Figure 1.
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