firm stability throughout the length of the
catheter. We find this feature allows for flutter
ablation without use of a longer stabilizing
sheath, which enhances our procedure efficiency.
When approaching a common arrhythmia, it is
useful to have consistency of maneuverability or
“feel” to the catheters used during the ablation.
The toolset used in this case employed a single
type of Blazer® Catheter steering platform. The
benefits of bidirectional steering and curve-lock
features are discussed elsewhere, but the fact
that the steering platforms used to manipulate
the different catheters are uniform allows for a
better consistency of manual manipulation.
Electrophysiology
Technique Spotlight
An Anatomic Case Discussion of CTI-Dependent
Flutter Ablation: Utility of a Duodecapolar Catheter
and an 8mm-tip Ablation Catheter
Conclusion
There are several potential anatomic barriers to
rapid and safe ablation of typical atrial flutter.
The bidirectional steering in the Blazer Dx20 Duodecapolar Catheter, coupled with the
stability found in the Blazer Prime XP Catheter
for ablation, provide useful tools to overcome
these obstacles.
Venkata Bavikati, MD and Michael Lloyd, MD, FACC
Department of Cardiac Electrophysiology
Emory University Hospital, Atlanta, GA
Case Description
A 51-year-old male with chronic lymphocytic
leukemia presented to an outside facility with
sudden-onset sustained palpitations. An electrocardiogram was obtained and it revealed
atrial flutter with rapid ventricular response
(Figure 1). He recalled a similar incident about
5 years prior that was treated with chemical cardioversion. An echocardiogram showed stage I
diastolic dysfunction, but an otherwise structurally normal heart. Myocardial perfusion imaging
was also normal. His CHADS2 score for thromboembolic risk was 1 for a history of hypertension. However, the presence of his underlying
chronic hematologic malignancy rendered his
true risk for thromboembolism uncertain. He
was placed on diltiazem drip and heparin. Electrophysiologic consultation was obtained. After
discussion with his primary care physician and
hematologist, ablation was recommended given
his likelihood for recurrence and the anticipation
of chemotherapy in the upcoming year. He was
transferred to our facility.
* Boston Scientific provided compensation to the author for preparation of this article and reviewed
and edited the content of this article.
* This case study involves use of the Blazer® Dx-20 Bidirectional Duodecapolar Diagnostic Catheter and
Blazer Prime® XP Temperature Ablation Catheter in a single case. Results in other cases may vary.
www.bostonscientific-international.com
Address for Correspondence
Michael S. Lloyd, MD, FACC
Assistant Professor
Assistant Program Director, Electrophysiology Fellowship
Emory University Hospital Department of Cardiac Electrophysiology
1364 Clifton Rd. NE Suite F424
Atlanta, GA 30322
Phone: 404-712-4070
Email: [email protected]
Description of Procedure
Individual symptoms, situations, and circumstances may vary. Patients should consult a physician or qualified health provider
regarding their medical condition and appropriate medical treatment. The information provided is not intended to be used for
medical diagnosis or treatment or as a substitute for professional medical advice. This information is to be used in conjunction
with other resource material, which may include the applicable patient handbook, Boston Scientific device physician’s manual
and any implant accessories instructions for use.
All cited trademarks are the property of their respective owners. CAUTION: The law restricts these devices to sale by or on the order of a physician. Indications, contraindications, warnings and instructions for
use can be found in the product labelling supplied with each device. Information for the use only in countries with applicable health authority product registrations.
PSST 6563 Printed in Germany by medicalvision.
© 2011 Boston Scientific Corporation
or its affiliates. All rights reserved.
DINEP2162EA
In a fasting state, after ruling out thrombus in
the left atrial appendage by transesophageal
echocardiography, central venous access was
obtained via the right femoral vein. A diagnostic
quadripolar catheter was advanced to the high
right atrium and a Blazer® Dx-20 Bidirectional
I
II
III
aVR
aVR
aVR
V1
V2
V3
V4
V5
V6
Figure 1
12-lead ECG of the patient’s clinical arrhythmia
(obtained in the electrophysiology laboratory).
Duodecapolar Diagnostic Catheter (model M004
20SL21020, 7F(2.33 mm), 2-10-2 mm interelectrode
spacing, Boston Scientific) was advanced to
the high right atrium. Unidirectional curl and
subsequent torque was applied to the catheter to
position it against the tricuspid annulus within the
Eustachian recess in front of the Eustachian ridge.
The tip of the Blazer Dx-20 Catheter was now near
the coronary sinus ostium. The coronary sinus
ostium had a Thebesian valve coming from the
floor of the Eustachian recess that deflected the
catheter upward and out of the ostium when the
catheter was advanced. This was overcome by
“backsteering” (steering the curve in the opposite
direction) of the bidirectional catheter to first get
I
II
aVL
aVF
HRA
ABL d
ABL
HALO 1
HALO 2
HALO 3
HALO 4
HALO 5
HALO 6
HALO 7
HALO 8
Panel A
Panel B
HALO 9
HALO 10
Panel A
Stim 1
Figure 2
Left anterior oblique (A) and right anterior oblique (B) views of catheter placement. Arrow in panel A indicates region of Thebesian valve. (High right atrial catheter
removed, white arrow: very subtle upward “hump” at region of Thebesian valve)
I
II
aVL
aVF
HRA
above the valve and then displace it downward
with the reverse curve, to allow coronary sinus
access. This displaced valve is suggested by a
very subtle upward “hump” midway along the
catheter at the CS ostium (Figure 2). The curvelock feature of this catheter was then used to
ensure stability for the duration of the ablation.
The resulting electrograms revealed an activation
pattern consistent with counterclockwise typical
flutter which was later confirmed by entrainment
at the cavotricuspid isthmus (Figure 3). The
electrogram amplitudes throughout the case
indicated good tissue contact of this catheter
along the entirety of its electrode span.
I
II
aVL
aVF
HRA
ABL d
ABL
HALO 1
An 8 mm-tip Blazer Prime® XP Temperature
Ablation Catheter (model M004P4500THK20,
7F(2.33 mm), 8 mm, large curve, Boston Scientific)
was positioned just behind the 6 o’clock
position of the tricuspid valve. Ablation was
performed in the temperature control mode
at 60°C and maximum power of 70W, with the
anticipation that power could be titrated to
100W if temperatures were not reached. Despite
significant respiratory excursion of the heart in
this patient, two linear sets of lesions resulted
in the termination of flutter and bidirectional
conduction block across the isthmus (Figure 4).
High-voltage electrograms were noted in the
vertical region behind the tricuspid valve along
the apical wall of the Eustachian recess and on
the front wall of the Eustachian ridge. These
were ablated using the maximum curve of the
Blazer Prime XP Catheter and laying the 8mm
ablation electrode against the vertically-oriented
tissue (Figure 5).
ABL d
ABL
HALO 1
HALO 2
HALO 3
HALO 4
HALO 5
Figure 6
HALO 6
Schematic of anatomic barriers to proper catheter position and ablation of typical atrial flutter. AVN: region of compact AV node, RA: right atrium, TVO: tricuspid
valve orifice, ThV: Thebesian valve, ER: Eustachian ridge, ERec: Eustachian Recess, Unlabeled arrows: Tall vertical ridges of potentially difficult-to-ablate tissue in
patients with deep recesses.
HALO 7
HALO 8
HALO 9
HALO 10
Panel B
Stim 1
Figure 4
Intracardiac electrograms supporting bidirectional conduction block across the cavotricuspid isthmus. Panel A was obtained during pacing within the coronary sinus
(white asterisk). Latest atrial activation is seen on Halo 5 (solid arrow) - which lies on the side opposite to the line of putative block. This supports medial-to-lateral
conduction block across the isthmus. Panel B was obtained during pacing just lateral to the site of putative block (white asterisk). The latest electrograms are seen on
electrodes just opposite the line of putative block (solid arrow).
HALO 2
HALO 3
HALO 4
Case Discussion Points
Typical cavotricuspid isthmus-dependent flutter
is often an easily ablated arrhythmia. However,
there are frequent anatomic obstacles that can
reduce the efficacy and efficiency of ablation.
HALO 5
HALO 6
HALO 7
HALO 8
HALO 9
HALO 10
Stim 1
Figure 3
Intracardiac electrograms of the arrhythmia. (Halo 10 indicates the proximal
most electrode pair and Halo 1 indicates the distal electrode pair of the
Blazer® Dx-20 Bidirectional Duodecapolar Diagnostic Catheter in the proximal
coronary sinus. “ABL D” and “ABL” are ablation electrograms at the His
bundle and “HRA” denotes the high right atrial catheter.)
This case represents two relatively common
anatomic barriers to proper catheter position for
flutter ablation. The first is a valve at the ostium
of the coronary sinus, or Thebesian valve (Figure
6). These valves deflect the tip of a duodecapolar
diagnostic catheter upward when attempts are
Figure 5
Full deflection of the Blazer Prime® XP Temperature Ablation Catheter
to achieve better contact and stability against vertically oriented
isthmus tissue. Region of a deep Eustachian recess with tall vertical
ridges depicted in white.
made to advance the catheter in the coronary
sinus. Thebesian valves are bypassed by a
superior approach to CS access, which can be
difficult from the femoral vein. Many institutions
use superior access points such as the internal
jugular vein to overcome this. We have found
that tools like the Blazer Dx-20 Catheter that offer
bidirectional deflection are particularly helpful
in these instances. The bidirectional steering
allows for upward deflection of the catheter tip
above the Thebesian valve, followed by reverse
or “backsteering” to divert the valve downward
and allow passage of the catheter tip in the body
of the CS. Bidirectional steering also enhances
maneuverability within the inferior vena cava.
Finally, the soft catheter tip reduces the potential
for trauma when advanced in the CS.
The use of a 20-electrode catheter like the one in
this case for atrial flutter is generally preferred
to another common strategy which requires
the use of a shorter multi-electrode catheter in
the CS body and a separate catheter along the
lateral right atrium. We favor this approach
because it involves one catheter (instead of two)
that has electrodes which span the entirety of
the isthmus, enabling a streamlined assessment
of electrograms within close proximity to the
lesion set.
A second obstacle to efficient isthmus ablation
involves a variation in cavotricuspid isthmus
anatomy. A commonly encountered anatomy is
that of a deep Eustachian recess which results
in more vertically oriented tissue to ablate
(Figure 6).
This tissue is often the reason for persistence of
flutter despite seemingly contiguous lesions. The
stability and steerability of the Blazer Prime XP
Catheter allow for laying the electrode up against
the vertical portion of the recess, as was done in
this case, and has been very useful in our
laboratory for isthmus ablation. This coupled
with the larger (8mm) electrode size, aids
significantly in good tissue contact, delivery
of contiguous lesions, and rapid termination
of atrial flutter during ablation. In addition,
an advantage of the Blazer Prime XP
Catheter over other earlier flutter catheters is a