Successful ablation of a right epicardial accessory pathway via
the right ventricular diverticulum in a patient with
Wolff-Parkinson-White syndrome
Zhijun Zhang
MD1 *, Changsheng Ma MD2, Xuewen Li
MD1, Lijuan Qu MD1, Bingye Zhao
MD1, and Rong Bai MD3
1Department of Cardiology, Shanxi Bethune Hospital,
Shanxi Academy of Medical Sciences,
Tongji Shanxi Hospital, Third Hospital of Shanxi Medical University,
Taiyuan, 030032, China 2Cardiovascular Division,
Beijing Anzhen Hospital, Capital Medical University, Beijing,
100029, China
3Banner University Medical Center, Phoenix,
The University of Arizona College of Medicine, Phoenix AZ, USA
* Correspondence: Zhijun Zhang MD, Department of Cardiology, Shanxi
Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi
Hospital, Third Hospital of Shanxi Medical University, Taiyuan, 030032,
China E-mail: zzj5431@163.comDisclosures: None
Funding: None
Abstract
Introduction: We describe one rare case of successful ablation of a
right epicardial accessory pathway (AP) via the right ventricular
diverticulum in a patient with Wolff-Parkinson-White syndrome.
Methods: A 42-year-old woman being referred to the hospital for a
catheter ablation of a Wolf-Parkinson White syndrome. Earliest
activation was shown to be present in the region of the tricuspid
annulus. However, ablation had no effect on the AP.
Results: We decided to do a selected angiography, in which a big
diverticulum near to the right tricuspid annulus was shown to be
present. Ablation in this region successfully repressed the AP without
any recurrences within a follow-up period of 12 months.
Conclustion: The ventricular diverticulum mediated AP is a novel variant
of pre-excitation. It can serve as an anatomical substrate of
supraventricular tachycardia, and can be ablated endocardially using an
irrigation tip catheter within the diverticulum.
Keywords: Arrhythmias, Ventricular diverticulum, Supraventricular
tachycardia (SVT), Epicardial accessory pathway, Wolff-Parkinson-White
syndrome, Catheter ablation,
Introduction
Accessory pathway (AP) is an anomalous muscular connection between
atrium and ventricle that bypasses the atrioventricular node.
Radiofrequency catheter ablation (RFCA) of AP-mediated supraventricular
tachycardia is recommended as first-line therapy with an overall success
rate exceeding 92% 1. RFCA of right-sided AP
continues to be challenging1, resulting in lower
success rates and higher recurrence rates. Atypical configuration of AP
or cardiac structural abnormalities result in a lower initial success
rate and a higher recurrence rate2. In a previous
study, 8% of prolonged or failed ablation of AP was due to the presence
of epicardial AP. We describe one rare case of successful ablation of a
right epicardial accessory pathway via the right ventricular
diverticulum in a patient with Wolff-Parkinson-White syndrome. Informed
consent was obtained from the patient for publication of this case
report and any accompanying images.
Case Report
A 42-year-old women with type B Wolff-Parkinson-White syndrome and
documented recurrent episodes of narrow QRS complex AVRT (Figure 1A) was
referred for catheter ablation. The earliest antegrade ventricular and
retrograde atrial activation were distributed over a relatively wide
range at the 7 to 8 o’clock position of the tricuspid annulus (TA).
Initial RF ablation had no effect on antegrade and retrograde accessory
pathway (AP) conduction with irrigated ablation contact force catheter
(Thermocool SmartTouchTM). While maneuvering the
catheter in this region for further mapping, the catheter was positioned
into an orifice with impedance rising from 120-130Ω to 160-200Ω.
Selected angiography revealed the presence of a long diverticulum which
protruded from the right lateral side of TA of right atrium(RA)to
right ventricle (RV) (Figure1B and Supplementary material online,
Video1-3). Further catheter dislodgment with 5g force touch in the
middle cavity of the diverticulum suppressed AP function with impedance
of 150-160Ω. Local ventricular activation (MAP 1-2) precedes the QRS
onset by 37ms. Local mapping showed that the earliest ventricular
activation was recorded within the chamber
located lateral to the RV and far
away from the TA. An A:V ratio of about 1:10 was observed in the local
electrogram. There was no sign of AP conduction recurrence after
catheter mechanical block of pathway conduction. RF ablation (25 W with
30 mL/min flow) at this site within the ventricular diverticulum was
continued to 120 seconds, with the aid of a long sheath (Figure 1C).
When gently pulling back the catheter to the ostium of ventricular
diverticulum, the impedance decreased from 160-200 Ω to 120 Ω.
12-lead
ECG showed disappearance of delta wave after ablation (Figure 1A). After
a 30-minute waiting period, there was no sign of AP conduction
recurrence and no complications occurred. Then, contrast-enhanced CT of
RA and RV confirmed a pouch-like extension of cardiac muscles after
ablation (Figure 1D). During 12 months follow-up, the patient
experienced no tachycardia
recurrence.
Discussion The ventricular diverticulum mediated AP is a novel variant of
pre-excitation. Minois, D3 reported a case of left
ventricular diverticulum associated with two concealed atrioventricular
accessory pathways. This is the first report of a right epicardial
accessory pathway via the small right ventricular diverticulum in a
patient with type B Wolff-Parkinson-White syndrome.
In clinical practice, routine mapping of AP insertion is generally
performed along the edge of
mitral and tricuspid annuli. Right-sided APs with atrial insertion far
from TA were reported2, 4. In our case, the successful
RF target localized to the ventricular diverticulum side of right
ventricle far from the TA. It is an extremely rare condition for such a
lengthy ventricular diverticulum
musculature to transmit an electrical
impulse from RA to the right ventricle. Similar to the posterior septal
AP mediated by middle cardiac vein5, the connections
between ventricular diverticulum
musculature and ventricular myocardium are the anatomic basis of the
ventricular diverticulum mediated AP. The angiography and
electroanatomic mapping also showed that the small right ventricular
diverticulum located lateral to the RV far from TA.
Patients with prior failed ablation of AP may have APs with unique
anatomical substrates6, 7 such as small cardiac
vein8 or axillary ventricular9. It
is feasible to enlarge the range of electroanatomic mapping region to
identify atrial or ventricular insertion far from the annulus.
Interestingly, the serendipitous discovery of ventricular diverticulum
in this case was partially due to the sudden rise in impedance and
catheter dislodgment. Then, local mapping excluded a pouch-like
extension of cardiac muscles and angiography confirmed the opening of
the ventricular diverticulum. Thus, if the ventricular insertion is
found in a ventricular orifice far from TA and the local impedance is
above 160 Ω, a ventricular
diverticulum related AP should be considered.
Another distinctive characteristic of ventricular diverticulum related
AP is the vulnerability to RF energy. In this case, AP conduction block
was simply achieved by catheter-induced mechanical stress. With precise
activation mapping and cautious power delivery, endocardial catheter
ablation of ventricular diverticulum related AP with an irrigated
catheter appears to be effective and safe.
Conclusion The ventricular diverticulum mediated AP is a novel variant of
pre-excitation. This is the first report of a right epicardial accessory
pathway via the right ventricular diverticulum in a patient with type B
Wolff-Parkinson-White syndrome. The ventricular diverticulum
can serve as an anatomical substrate of supraventricular tachycardia,
and ventricular diverticulum-related AP can be identified and ablated
endocardially using an irrigation tip catheter within the diverticulum.