Download Anatomical Obstacles to Catheter Ablation for Atrioventricular Nodal

ECG & EP Cases
Anatomical Obstacles to
Catheter Ablation for
Atrioventricular Nodal
Reentrant Tachycardia
고려대학교 의과대학 내과학교실
노승영/박상원
Seung-Young Roh, MD / Sang Weon Park, MD, PhD
Division of Cardiology, Department of Internal Medicine, Korea University Medical Center, Seoul, Korea
Abstract
Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common forms of arrhythmia. The first
line of treatment is typically radiofrequency catheter ablation (RFCA), though the efficacy and safety of this
procedure can be limited by anatomic variations. We present two cases of patients with anatomic variations
undergoing RFCA for AVNRT. These variations were: first, a diverticulum in the right atrial (RA) septum, and
second, heart distortion caused by a tuberculosis-destroyed lung. Despite efforts to normalize the procedure,
both variations complicated the execution of RFCA.
Key Words: ■ atrioventricular nodal reentrant tachycardia ■ catheter ablation ■ diverticulum ■ complication
Introduction
Case 1
Radiofrequency catheter ablation (RFCA) is
A 22-year-old woman presented with par-
the first choice of treatment for symptomatic
oxysmal palpitation. Electrocardiography (ECG)
1
AVNRT. However, its use in patients with an-
revealed narrow QRS tachycardia with a pulse
atomic variations can be complicated. Here, we
rate of 160 beats/min during palpitation (Figure
present two cases of catheter ablation for AVN-
1). The patient’s blood pressure was 110/80 mmHg
RT in patients with anatomic variations: an RA
during tachycardia. QRS rhythm was regular and
septal diverticulum, and lung-disease-induced
pseudo R’ wave was observed in the precordial
heart distortion, respectively.
lead from V1 to V3. Sinus rhythm was restored
following rapid administration of intravenous
adenosine (6 mg). The patient had no history of
disease or operations. A transthoracic echocar-
Received: May 23, 2014
Revision Received: September 10, 2014
Accepted: September 14, 2014
Correspondence: Sang Weon Park MD, PhD, Department of Cardiology,
Korea University Anam Hospital, 73, Inchon-ro, Seongbuk-gu, Seoul 136705, Korea
Tel: +82-2-920-6394, Fax: +82-2-927-1478
E-mail: [email protected] Ko, MD, PhD, Division of Cardiology
diogram (TTE) showed normal left ventricular
ejection fraction (60%) and no structural abnormalities. For electrophysiological (EP) investigation, a 2-mm and a 4-mm quadripolar catheter
were used to record His and right ventricular (RV)
activity, respectively. Unfortunately, placement
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The Official Journal of Korean Heart Rhythm Society
ECG & EP Cases
Figure 1. ECG for Case 1. The patient presented with palpitations. The observed narrow QRS tachycardia was attributed to AVNRT following EP investigation. Pseudo R' was observed in precordial lead from V1 to V3 (arrows).
A
B
Figure 2. Right atrial angiogram for Case 1. A pouch-like structure with contractility was observed in the lower septum of the RA (indicated by dot line in A and arrows). It was not definitely separated in RAO view. (A) LAO view. (B) RAO view.
a, duodecapolar catheter for RA; b, quadripolar catheter for His; c, quadripolar catheter for RV; d, pigtail catheter for dye injection
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ECG & EP Cases
A
B
Figure 3. Coronary sinus angiogram by retrograde approach for Case 1. The pouch-like structure (indicated by arrows) in the right atrial
septum was not enhanced.
a, duodecapolar catheter for RA; b, quadripolar catheter for His; c, quadripolar catheter for RV; d, pigtail catheter for dye injection; e,
Judkins catheter for left coronary angiogram *, coronary sinus ostium
Figure 4. ECG for Case 2. The patient presented with palpitation. The observed narrow QRS tachycardia was attributed to AVNRT following EP investigation.
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ECG & EP Cases
A
B
Figure 5. (A) Chest radiography for Case 2. The right lung was destroyed by prior tuberculosis infection. (B) Chest computed tomography
for the same patient. The heart was rotated counter-clockwise and distorted by the destroyed lung.
RV, right ventricle; LV, left ventricle; RA, right atrium
of a duodecapolar catheter into the coronary si-
at the anterior margin of the CS to ablate the
nus (CS) failed as it could not be advanced into
slow pathway. The ablation catheter was found
the CS ostium. A right atrial (RA) angiogram was
to be unstable yet it was easily moved up and
performed for structural analysis (Figure 2). A
down at the margin of the septal diverticulum. As
pouch-like structure was observed in the lower
a result, successful RFCA was only achieved after
septum of the RA, near the CS ostium. As this
a considerable time interval.
structure exhibited contractility, it was diagnosed
as a diverticulum, rather than a septal aneurysm.
Case 2
A CS angiogram revealed no association between
the diverticulum and the CS (Figure 3). Attempts
A 71-year-old man with a tuberculosis-de-
to place the duodecapolar catheter in the CS were
stroyed lung presented with palpitation and dys-
impeded by the diverticulum. An EP study was
pnea. Electrocardiography (ECG) revealed nar-
subsequently performed using a duodecapo-
row-QRS tachycardia with a short RP interval
lar catheter positioned at the RA. Tachycardia
and a pulse rate of 170 beats/min during palpita-
was induced after an atrio-His (AH) jump, and
tion (Figure 4). The patient’s blood pressure was
atrioventricular and ventriculoatrial conduction
100/70 mmHg at the time of recording, and QRS
exhibited decremental properties. Clinical tachy-
rhythm was regular. Sinus rhythm was restored
cardia was attributed to slow-fast AVNRT after
following rapid administration of intravenous ad-
differential diagnostic maneuvers. A deflectable
enosine (6 mg). The patient had diabetes mel-
ablation catheter with a 4-mm tip was positioned
litus, hypertension, and a history of pulmonary
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A
B
C
D
Figure 6. Electrogram (A) and catheter position (B) for Case 2. Before ablation, the lowest point for detection of His potential (indicated by arrows) was identified using the ablation catheter (d). (C) Electrogram and (D) catheter position at the time of ablation.
Ablation was actually carried out at a lower point than that depicted in (B). His potential was not seen on the electrogram from the
ablation catheter.
a, duodecapolar catheter for right atrium and His; b, quadripolar catheter for His; c, quadripolar catheter for right ventricle
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The Official Journal of Korean Heart Rhythm Society
We have reported two complicated AVNRT
tricular ejection fraction (55%) and no structural
cases related to right heart anatomic abnormali-
abnormality. Chest radiography and chest com-
ties. In the first case, an RA septal diverticulum
puted tomography showed a severely distorted
compromised the positioning and stability of the
lung (Figure 5), and counter-clockwise rotation
catheter. Binder et al. analyzed 103 cases of con-
of the heart. In RA angiography, the RA exhibited
genital malformations of the RA and the CS.2 Of
erect morphology. An EP investigation was sub-
the 103 cases studied, 13 were associated with an
sequently performed using a 2-mm and a 4-mm
RA single diverticulum and these were predomi-
quadripolar catheter to record His and RV ac-
nantly asymptomatic. The presentation of symp-
tivity, respectively. A duodecapolar catheter was
toms such as supraventricular tachycardia was
positioned at the CS and the RA. Clinical tachy-
frequently induced by arrhythmia.
cardia was attributed to slow-fast AVNRT on the
We present the first reported case of a single
basis of EP investigation. Due to the high risk of
diverticulum in the RA septum. Previous studies
atrioventricular (AV) block, owing to the patient’s
have reported cases of RA diverticula predomi-
advanced age and distorted heart structure, the
nantly localized to the RA free wall or the CS.2-7
ablation focus was carefully considered. First,
The RA septal diverticulum described in this case
the lowest level for detection of His potential was
was separated from the CS, as demonstrated by
identified (Figure 6A, B). Next, a posterior ap-
the angiogram. Because the diverticulum exhib-
proach was taken, via the middle or posterior
ited contractility consistent with the heartbeat,
septal region near the CS ostium (Figure 6D). His
we ruled out the alternative diagnosis of septal
potential was not observed on the electrogram of
aneurysm, in which contractility would not be
the ablation catheter (Figure 6C). Energy deliv-
observed.8
ery resulted in successful induction of junctional
Acquired anatomic distortions can also inter-
rhythm, though ablation was immediately abort-
fere with RFCA for AVNRT. In the second case,
ed on observing ventriculoatrial (VA) conduction
safety was ensured by using numerous methods:
block some seconds later. A high degree of AV
(1) RA angiogram, (2) confirmation of the lowest
block with concurrent hypotension occurred. The
point for detection of His potential, (3) a poste-
AV block was initially sustained but eventually
rior approach near the CS ostium, and (4) vigilant
recovered after eight hours; the PR interval nor-
observation of VA conduction. A contemporary
malized after two weeks.
transient high degree AV block was nevertheless
ECG & EP Cases
tuberculosis. A TTE showed preserved left ven-
seen to occur.
Discussion
For effective and safe catheter ablation in patients with anatomic obstacles, an overview of
AVNRT is one of the most common tachyar-
the precise anatomy is critical. Angiograms and
rhythmias, and can be treated by catheter abla-
careful mapping can facilitate the identification of
tion. This can be hazardous when the slow path-
anatomic variants, and can confirm precise cath-
way is in close proximity to the normal conduction
eter positioning.
system. Thus, a clear understanding of cardiac
anatomy is essential before AVNRT ablation.
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ECG & EP Cases
Conclusion
We have reported two difficult AVNRT cases related to right heart anatomic variation: the first,
an RA septal aneurysm, and the second, heart
distortion due to tuberculosis-destroyed lung.
Anatomic obstacles can compromise successful
catheter ablation for AVNRT.
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