Download Site-Specific Transseptal Puncture for Emerging Structural Heart

Imaging
Site-Specific Transseptal
Puncture for Emerging
Structural Heart
Interventions
Imaging-assisted techniques for accurate access.
By Michael J. Rinaldi, MD, FACC, FSCAI; Markus Scherer, MD, FACC, FSCCT;
William Downey, MD, FACC, FSCAI; and Geoffrey Rose, MD, FACC, FASE
T
ransseptal catheterization is an established
interventional technique that was originally
developed for hemodynamic evaluation of the
left heart. Its use was then expanded to provide
access for balloon mitral valvuloplasty (BMV).1 Although
the most common use of transseptal catheterization
during the past decade has been in the electrophysiology lab for atrial fibrillation ablation procedures, newer
technologies that address a variety of unmet structural
heart needs have led to a resurgence in the use of this
technique in the interventional cardiology lab.
Historically, transseptal catheterization was performed
using fluoroscopic guidance. The primary goal was simply to safely traverse the septum, preferably through the
fossa ovalis, but with the development of a variety of
structural heart interventions, the need has emerged for
a site-specific approach to transseptal access. Intracardiac
echocardiography (ICE) and transesophageal echocardiography (TEE) have become integral in this procedure,
extending standard fluoroscopic approaches by providing a greater degree of anatomic orientation. In this
article, we review the specific imaging guidance that is
afforded by these modalities. We also provide CT image
references for the anatomic relationships of intracardiac
structures.
TEE FOR PROCEDURAL GUIDANCE
The esophagus lies adjacent to the posterior surface
of the left atrium (LA). The proximity of the TEE imag-
ing probe to the LA, intra-atrial septum (IAS), mitral
valve (MV), and left atrial appendage (LAA) thus renders TEE ideal for guiding structural heart interventions.
Simultaneous cross-sectional plane (x-plane) and threedimensional (3D) imaging provides real-time, comprehensive anatomical assessment, allowing performance of the
procedure with greater precision and safety.
SPATIAL ANATOMY
In patients with normal segmental anatomy, the right
atrium (RA) is anterior, and the LA is posterior. The
IAS lies in an oblique/off-axis coronal plane, with variable curvature depending on atrial size, pressure, and
tissue redundancy (Figure 1). In reference to the body,
the plane of the IAS is typically oriented left to right,
but for the purposes of guiding cardiac interventions,
describing its relationship to other cardiac structures
is more relevant. By convention, the plane of the IAS
is defined by two dimensions: anterior-posterior and
superior-inferior. The superior vena cava (SVC) and
inferior vena cava (IVC) lie adjacent to the superiorposterior and inferior-posterior aspects of the atrial
septum, respectively. The aortic valve/root is adjacent
to the anterior-superior portion of the atrial septum.
Various TEE imaging maneuvers will display IAS anatomy in detail. The standard bicaval view lays out the
superior and inferior aspects of the more posterior portion of the septum and is typically obtained with the
multiplane sector angled at 100° to 120°. A basal shortMarch/April 2014 cardiac interventions Today 25
Imaging
A
B
C
D
Figure 1. CT as a reference to show anatomic landmarks seen on TEE. Axial CT: four-chamber view in a patient with a prosthetic
mitral paravalvular defect (A; arrow). Note left-right and anterior-posterior septal orientation. A more posterior transseptal
access will increase catheter distance to the MV. Oblique plane CT: bicaval view (B). Derived from solid line of crosshair in panel A.
Equivalent to a TEE multiplane angle view of 90° with the probe rotated clockwise toward the posterior atrial septum. Coronal CT:
aortic valve and root level (C). Atrial septum and LA (not in image) are posterior to the RA. A solid line in crosshair to derive 30° TEE
multiplane view is demonstrated in panel D, which shows oblique plane CT, basal short-axis aortic valve level. TEE 30° equivalent
view is derived from panel C. The aortic valve is a landmark for the more anterosuperior portion of the adjacent atrial septum.
axis view at the aortic valve level will demonstrate
anterosuperior and inferoposterior septal landmarks
and is typically obtained with the multiplane sector
angled at 30° to 60°. Seeing both views simultaneously
may also be achieved using the x-plane feature with a
3D TEE probe (Figure 2).
TRANSSEPTAL PUNCTURE FOR
PERCUTANEOUS MV REPAIR USING
MITRACLIP
MitraClip (Abbott Vascular, Santa Clara, CA) is now
approved in the United States for percutaneous repair of
symptomatic, severe degenerative mitral insufficiency in
patients who are at high surgical risk.2,3 Precision in transseptal puncture is critical for procedural success. Three
views are used to guide puncture for appropriate steerable guiding catheter placement: bicaval, short-axis at
the base (SAX-B), and four-chamber views. X-plane can
be used to simultaneously show the bicaval and shortaxis views as the imager and implanter become more
comfortable with the technique.
The bicaval view is used to follow the transseptal
dilator as it moves down the septum from the SVC
toward the IVC (Figure 3A). The position is confirmed
by the typical tenting of the septum caused by the dilator. Simultaneously, clockwise torque is applied, which
moves the dilator from anterior to posterior away from
the aorta. This can be confirmed and adjusted by switching to the SAX-B view (Figure 3B). Stored torque in the
catheter due to contact with the septum is compensated
for by moving the catheter slightly inferiorly as posterior
torque is applied. Therefore, it is best to start applying
posterior torque while the dilator is somewhat superior
to the desired position. Posterior orientation is essential
to achieve adequate height above the MV annulus.
26 cardiac interventions Today March/April 2014
LA
LA
SVC
IVC
RA
RA
Ao
Figure 2. X-plane TEE image of dilator across the septum
in correct position as demonstrated in bicaval and SAX-B
views.
When a posterior and slightly superior position has
been established, the echocardiographer then acquires
the four-chamber view to measure height above the MV
(Figure 3C). This view is adjusted to show tenting of the
septum in the same view as the MV annulus. A measurement is then taken by drawing a line perpendicular to
the valve plane from the point of tenting, and then a
second line, 90° to the first, is extended down from that
point to the valve. In order to have adequate height for
the procedure, this line should be 3.5 to 4 cm from the
valve annulus. Adequate height above the valve ensures
that the MitraClip system has room to create a straight
downward trajectory to the apex of the ventricle with a
minimum of manipulations.
It is critical that this posterior position is achieved. An
improper guide position can make the procedure difficult, if not impossible, to perform. An approach that is
Imaging
A
LA
LA
needle
SVC
RA
SVC
RA
B
LA
LA
needle
RA
Ao
RA
C
Ao
LA
height
RA
RA
height
MV
(Simulator images courtesy of Abbott Vascular.)
LA
Figure 3. TEE views to guide transseptal puncture for MitraClip percutaneous MV repair. Bicaval views demonstrated from a simulator and corresponding TEE view (A). SAX-B views demonstrated from a simulator and corresponding TEE view (B). Four-chamber
views demonstrated from a simulator and corresponding TEE view with measurement to the valve annulus overlaid (C).
too anterior (or even a midfossa stick) brings the guide
closer to the valve plane, leaving inadequate distance to
the valve. A puncture that is too superior delivers the
guide closer to the aorta, placing the guide too anterior
relative to the MV plane. When an acceptable position is
confirmed, the echocardiographer returns to the SAX-B
view. Transseptal puncture is executed in this view to
ensure that the location is held as the implanter crosses
into the LA (Figure 2).
A recent report on the use of MitraClip to treat noncentral jets suggests a tailored approach to the transseptal puncture that is specific to the location of the
jet. The authors illustrate that lateral jets may be better
approached with a slightly lower puncture to compensate for the height gained by the deeper position of the
system.4
TRANSSEPTAL PUNCTURE FOR LAA
OCCLUSION
A number of techniques have been developed for
percutaneous closure of the LAA for stroke prevention.5 These include implants such as the Watchman
device (Boston Scientific Corporation, Natick, MA), the
Amplatzer plug (St. Jude Medical, Inc., St. Paul, MN), and
the WaveCrest occluder (Coherex Medical, Salt Lake
City, UT), as well as the Lariat suture (SentreHEART,
Inc., Redwood City, CA) ligation technique. As with
other structural heart interventions, site-specific transseptal puncture is critical for a successful procedure.
The main axis of the LAA is anteriorly oriented, and
the plane of the LAA ostium is perpendicular to that
axis. Successful coaxial device deployment depends
on the ability to position the delivery sheath with as
March/April 2014 cardiac interventions Today 27
Imaging
A
B
LA
LAA
LAA
Figure 4. Views of Watchman double-curve sheath coaxially oriented with the longest axis of the LAA, allowing maximum
delivery depth, by fluoroscopy (A) and TEE (B).
much depth as possible into the LAA (Figure 4). This is
most reliably accomplished with a posterior-to-anterior
trajectory of the sheath. Thus, a transseptal puncture
that is posterior and mid to slightly inferior in position
provides the most favorable sheath orientation. Too
superior a puncture can lead to a sheath orientation
that is not coaxial with the LAA long axis or obstruction to the LAA ostium by the tissue that separates the
left upper pulmonary vein from the LAA (“coumadin
ridge”). Too anterior a puncture places the sheath out
of the plane of the LAA.
TRANSSEPTAL PUNCTURE FOR
PERCUTANEOUS CLOSURE OF MITRAL
PARAVALVULAR LEAKS
Percutaneous closure of paravalvular leaks with
Amplatzer plugs has become an effective procedure,
particularly for patients at high risk for reoperation.6
As for MitraClip, the position of the transseptal puncture for repair of mitral paravalvular leak requires
forethought in order to achieve the optimal position
to approach the defect. For defects away from the
septum, the location of the puncture is less critical.
However, for medial defects near the IAS, a posterior
and slightly superior puncture provides the appropriate
working height within the LA (Figure 5). TEE guidance
is critical.
A common issue in these cases is difficulty in puncturing a fibrotic septum that is scarred or patched from the
atriotomy done during the MV replacement. Some physicians use the back end of a coronary guidewire through
a transseptal needle or electrocautery to facilitate initial passage through the septum. We have found the
28 cardiac interventions Today March/April 2014
NRG radiofrequency transseptal needle (Baylis Medical
Company, Inc., Montreal, QC, Canada) to be invaluable
in these cases. This device is blunt, but allows the targeted administration of radiofrequency energy to the IAS,
safely burning a passage through the septum without the
pressure often required on the Brockenbrough needle in
these cases. Even after puncture is achieved, advancing
the sheath over the system can still sometimes be difficult in the fibrotic septum. In these cases, balloon septostomy over a 0.014-inch wire introduced into the LA
greatly facilitates passage. If difficulty is still encountered,
the balloon itself can be used as a dilator positioned
across the septum by deflating it while simultaneously
advancing the sheath.
TRANSSEPTAL PUNCTURE FOR OTHER
PROCEDURES
The TandemHeart percutaneous ventricular assist
device (CardiacAssist, Inc., Pittsburgh, PA) requires placement of a 24-F LA inflow cannula through a transseptal
puncture. Although the location of transseptal puncture
is less critical for this procedure, in our experience, a
fairly central transseptal catheter position allows more
room in the LA. This reduces the likelihood of “chatter”
through contact between the cannula and the LA wall
while still permitting enough catheter length across the
septum, reducing the chance that the cannula will inadvertently slip back into the RA.
BMV was the first indication for transseptal puncture
for the treatment of valvular heart disease worldwide
and remains the most common. Although countless
BMV procedures have been performed with fluoroscopic imaging alone, it is possible that the procedure
Imaging
sheath
RA
LA
MVR
Figure 5. Three-dimensional TEE view of Agilis steerable
sheath (St. Jude Medical, Inc.) across a high posterior transseptal puncture to facilitate access to the paravalvular defect
on the septal side of the mitral bioprosthesis.
could be performed with greater safety and efficiency
with use of adjuvant imaging to guide site-specific
transseptal puncture. As with MitraClip, a more posterior puncture would allow better height above the MV
and a more coaxial plane; this would facilitate transit
of the balloon across the valve. Although experienced
operators clearly can perform BMV without such
guidance, it is possible that, given the low volume of
BMV in developed countries, less-experienced operators might benefit from such a targeted transseptal
approach.
ICE GUIDANCE FOR TRANSSEPTAL
PUNCTURE
In cases when TEE is not used, ICE guidance can be
extremely useful in facilitating safe transseptal puncture.7
Operators primarily accustomed to TEE need to keep in
mind that they are looking from the RA to the LA, the
opposite view from TEE. The fossa ovalis is usually best
identified by moving to a long-axis view of the aortic
valve and then tilting the ICE catheter posteriorly. The
ICE catheter can then be manipulated slightly to find the
tenting. Puncture can then be completed under direct
visualization by ICE. Although ICE is an invaluable tool
and may be adequate to direct most left-sided electrophysiology procedures, it does not provide equivalent
visualization to TEE and cannot be used as a substitute
for TEE to guide most structural heart therapies.
CONCLUSION
Site-specific transseptal puncture is an essential
skill to guide many interventional structural heart
procedures. As with most interventional procedures,
proper guide position is the foundation upon which
the success of the procedure depends. Accomplishing
this requires not only an understanding of intracardiac
anatomy, but also seamless communication between
the echocardiographer and the interventionist in the
performance of the procedure. Although this technique
requires a high-level skill set from the echocardiographer, it is eminently acquirable by dedicated teams. n
Michael J. Rinaldi, MD, FACC, FSCAI, is Director,
Clinical Research, at the Sanger Heart & Vascular
Institute and Professor of Medicine, Carolinas HealthCare
System, Carolinas Medical Center in Charlotte, North
Carolina. He has disclosed that he is on the medical
advisory board for Abbott Vascular and Boston Scientific.
Dr. Rinaldi may be reached at (704) 446-2434; michael.
[email protected].
Markus Scherer, MD, FACC, FSCCT, is with the Sanger
Heart & Vascular Institute, Carolinas HealthCare System,
Carolinas Medical Center in Charlotte, North Carolina.
He stated that he has no financial interests related to
this article. Dr. Scherer may be reached at (704) 4462434; [email protected].
William Downey, MD, FACC, FSCAI, is Director,
Cardiac Catheterization Laboratories, at the Sanger
Heart & Vascular Institute and Associate Professor
of Medicine, Carolinas HealthCare System, Carolinas
Medical Center in Charlotte, North Carolina. He stated
that he has no financial interests related to this article.
Dr. Downey may be reached at (704) 446-2434; william.
[email protected].
Geoffrey Rose, MD, FACC, FASE, is Chief of Cardiology,
the Sanger Heart & Vascular Institute and Professor
of Medicine, Carolinas HealthCare System, Carolinas
Medical Center in Charlotte, North Carolina. He stated
that he has no financial interests related to this article.
Dr. Rose may be reached at (704) 446-2434; geoffrey.
[email protected].
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2011;364:1395-1406.
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Published March 20, 2013.
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