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CHAPTER 2 Equipment required for aorticendografting 21
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Fig. 2.13 Inter V Ensnare device.
Fig. 2.14 Nestor (Cook) embolization coils used for arterial
and venous embolization.
Endograft selection
The following statements can be made about
thecurrent devices: No device is perfect. There is
no good quality scientific evidence that any one
device is better than the others. The majority of
devices are chosen on the basis of personal
preference and experience. The nitinol stent-grafts
are magnetic resonance compatible so that the risk
of irradiation can be reduced for the follow-up
examinations.
In general, devices are oversized by 10–20% for
aneurysms and slightly less for acute dissection
(e.g. 5–10%). When selecting a device diameter for
use in dissections, the caliber of the aorta just
proximal to the dissection should be used. This will
generally be the diameter of the mid-aortic arch. In
acute dissections, a device length should be chosen
to cover the main entry tear. In chronic dissection,
devices should extend from just proximal to the
entry tear to the diaphragm (Figs2.11 and 2.12).
Accessory tools
A variety of other tools may also be useful in
thoracic aortic endografting procedures. Snares,
such as the EV3 Gooseneck (EV3, Plymouth, MN)
and Inter V Ensnare device (INTER-V, Gainesville,
FL) (Fig. 2.13) are intended for use in thoracic
endografting procedures to retrieve and manipulate foreign objects and are useful when establishing brachio-femoral guide wire access to assist with
delivery of the thoracic stent in cases of severely
tortuous aortas. Embolization coils (Fig.2.14) may
also be needed to treat a type II endoleak by coiling
the origin of the left subclavian artery or to deposit
the coils in the sac. Peripheral vascular stents and
covered stents may be important tools when
addressing iliac artery stenoses to help with delivery
of the sheath and thoracic endoprosthesis.
Reference
1 Endovascular supplies 2010.
3
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CHAPTER 3
Advanced computed tomography
imaging, workstations,
andplanning tools
Paolo Perini1, Pascal Rheaume2 & Stéphan Haulon
1
Vascular Surgery, Hôpital Cardiologique, CHRU de Lille, France
2
Vascular Surgery, Hopital St-Francois D’Assise, Quebec City, Canada
Multidetector row computed tomography (MDCT)
has now replaced the old “gold standard” intraarterial digital subtraction angiography (DSA)
for assessing abdominal, thoracic, and cranial
vasculature. MDCT raw data is captured in
two-dimensional transverse sections; therefore to
generate an angiographic display, a 3D workstation
is required. To depict vascular anatomy on the
workstation, specific anatomic projections must be
created using one or more of the visualization
techniques. The image projections must display
the vascular region of interest in the correct
viewing planes without being obscured by other
vascular territories or non-cardiovascular structures. Furthermore, the resultant images must be
rendered with the correct window, level, and
lighting settings to accurately depict normal
anatomy and pathology. The volumetric data
acquired enable the acquisition of views from any
angle and perspective. MDCT has a superior diagnostic accuracy in comparison with intra-arterial
DSA in characterizing the neck of the abdominal
aortic aneurysm (AAA), identifying accessory renal
arteries, and characterizing renal arterial stenoses.
The implantation of an infrarenal endoprosthesis is a relatively simple procedure, requiring
preoperative length and diameter measurements
1
and accurate longitudinal device placement.
However, designing and implanting a device which
will accommodate the aortic branches is more
complex: inappropriate orientation of the visceral
branches will preclude successful endovascular
repair. Essential information needed for preoperative
assessment of aortic aneurysms includes the relationship of the aneurysm to the aortic branches, the
degree of iliac arterial involvement with the aneurysm, the presence of other coexisting iliac arterial or
aortic aneurysms, the presence of supernumerary or
aberrant aortic branches, and the presence of coexistent iliac arterial occlusive disease.
On currently available 3D workstations, there are
four principal visualization techniques: multiplanar
(axial, sagittal, coronal, oblique) reconstruction
(MPR), curved planar reformation (CPR), maximum
intensity projection (MIP), and 3D volume rendering (VR) (Fig. 3.1). Automated and semiautomated vessel analysis tools are integrated to run
these techniques. The generation of a center line of
flow image allows the visualization of a tortuous
aorta as if it were straightened or stretched out and
aids greatly in the design of the endoprosthesis, particularly in accurately measuring the correct length
of the graft between key anatomic targets such as
branch locations and vessel bifurcations (Fig.3.2).
Endovascular and Hybrid Therapies for Structural Heart and Aortic Disease, First Edition.
Edited by Jacques Kpodonu and Raoul Bonan.
© 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd.
22
CHAPTER 3 Advanced CT imaging, workstations, and planning tools 23
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(a)
Fig. 3.1 (a) MIP and (b) 3D-VR reconstructions of a descending thoracic aortic aneurysm. From Atlas of Advanced
Endoaortic Surgery. Copyright Springer.
(b)
Fig. 3.2 Practical steps for the generation of a “stretched”
aorta using a center line technique: a center line of ow
(green line on the left image) is generated by the
workstation. Before a stretched reconstruction is obtained
Three-dimensional workstations are now
intuitive and “user-friendly” in order to be accessible to cardiovascular surgeons and not only to
experienced radiologists. Reliable default VR and
MIP templates and quick access to advanced segmentation algorithms that automatically edit and
grow vessel territories are essential (Fig.3.3).
(right image), the center line can be modied by adding,
retrieving, or moving the numerous dots of the line
(middle image). From Atlas of Advanced Endoaortic
Surgery. Copyright Springer.
Vessel caliber, patency, tortuosity, and burden of
calcium and thrombus are important vascular features to assess preoperatively (Fig.3.4). Diameters,
lengths, and angles are often necessary dimensions
to measure (Fig. 3.5). Although much of this
imaging information can be visualized on conventional axial images, 3D-VR, multiplanar, and
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(a)
Fig. 3.3 3D-VR of a juxtarenal abdominal aortic aneurysm treated with a fenestrated endograft before (a) and after (b)
running the “bone removal” algorithm. From Atlas of Advanced Endoaortic Surgery. Copyright Springer.
(b)
Fig. 3.4 CPR of a renal artery used for planning a
fenestrated endograft depicting a severe stenosis at the
origin of the vessel. From Atlas of Advanced Endoaortic
Surgery. Copyright Springer.
curved planar reconstructions provide quick and
clear visualization of the complex relationships of
anatomy and pathology (Fig.3.6). The combined
use of the various visualization techniques is
critical in surgical planning.
The advantage of VR is the accurate spatial perception through a complete 3D angiographic overview. Care however must be taken in interpreting
these reformatted images; for example, a critical
Fig. 3.5 Sagittal MPR showing the superior mesenteric artery
and its angle with the aorta. The catheterization of this vessel
via a femoral approach during fenestrated endovascular aortic
repair (EVAR) is anticipated to be challenging (angle of the
target vessel to the aortic wall <60°). From Atlas of Advanced
Endoaortic Surgery. Copyright Springer.
stenosis may appear like a complete occlusion. It
is important to correlate 3D findings with the
corresponding two-dimensional images in order to
CHAPTER 3 Advanced CT imaging, workstations, and planning tools 25
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(a) (b)
Fig. 3.6 (a) 3D-VR and (b) stretched CPR of an infrarenal
aortic aneurysm associated with a right common iliac
aneurysm. The combination of the various visualization
avoid such pitfalls. With MPR, a two-dimensional
analysis through the original dataset is performed
in axial, coronal, sagittal, or oblique orientations.
Analysis of the vessel wall and the flow lumen with
accurate display of stenosis, occlusions, and calcification can be performed. The only disadvantage
is the limited spatial display. MIP is also a
two-dimensional analysis option for an angiographic overview, but semi-automated or complete
manual editing is required to remove structural
overlay. It can be useful to depict small caliber vessels and poorly enhanced vessels. Its accuracy is,
however, limited in calcified vessels. Confirmation
of stenosis and vessel caliber measurements should
always be done with orthogonal MPR. As vessels
curve in and out of the planes, standard MPRs
cannot display an entire vascular territory and
flow lumen in one image. To obtain a complete
longitudinal vessel display, the solution is to
techniques is vital to properly size and plan the endograft.
From Atlas of Advanced Endoaortic Surgery. Copyright
Springer.
generate a longitudinal cross-section using either
two-dimensional or rotating CPR techniques.
The measurements required for accurate
planning of branched and fenestrated endografts
are complex and beyond the scope of what can be
achieved accurately with standard two-dimensional
axial images and table positions to measure aortic
lengths and the relative positions of visceral
arteries. Indeed, there is significant potential for
error when trying to measure aortic lengths using a
combination of coronal and sagittal images of the
angulated aorta. The evolution of modern workstations has consigned these difficulties to history
with rapid generation of accurate 3D images now
feasible in real time (Figs3.7 and 3.8). It is likely
that some of the ongoing improvements in clinical
outcomes that are continuously being reported in
the endovascular literature are in part attributable
to more accurate graft design with consequent
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Fig. 3.7 Various phases of the planning of a fenestrated
endograft using a workstation. On the upper left the
3D-VR is generated. The center line is drawn in green, and
is used to generate the stretched CPR on the right of the
screen. The two-dimensional image on the lower left is
the reconstruction perpendicular to the center lumen line.
It is used to precisely assess the diameter of the aorta.
From Atlas of Advanced Endoaortic Surgery. Copyright
Springer.
CHAPTER 3 Advanced CT imaging, workstations, and planning tools 27
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(a)
Fig.3.8 (a) A meticulous analysis of the preoperative CT
scan on the workstation was mandatory to design an
endograft that perfectly matched the aortic anatomy.
(b)Postoperative 3D-VR of a type II thoraco-abdominal
benefits in terms of improved target vessel perfusion rates, less graft migration/endoleak, and
shorter procedure times. Clearly in striving to
(b)
aneurysm treated with a four-branch endograft. The
length and diameter of the sealing zone in each target
vessel has also been evaluated. From Atlas of Advanced
Endoaortic Surgery. Copyright Springer.
improve clinical outcomes it is incumbent on all
endovascular surgeons to become comfortable with
this remarkable technology.
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CHAPTER 4
Technique of thoracic endografting
for thoracic aneurysm using the
approved Gore TAG device
Jacques Kpodonu
University of California Irvine,
Cardiovascular Hybrid Interventions, Hoag Heart and Vascular Institute, Newport Beach, CA, USA
The technique of thoracic endografting for the
treatment of thoracic aortic aneurysm [1] using
a Gore TAG device (W.L. Gore & Associates,
Flagstaff, AZ) (Fig.4.1) is preferably performed in
ahybrid operating room (Fig.4.2) or an endovascular suite provided the patient is an adequate
candidate for endovascular repair. The procedure
isperformed under general anesthesia with spinal
drainage selected for patients who have had a
previous open surgical repair of an abdominal
aortic aneurysm or patients considered high risk
for paraplegia.
Percutaneous retrograde access of the common
femoral artery is obtained in one groin and open
retrograde cannulation of the contralateral
common femoral artery performed with an 18
gauge needle (Fig. 4.3). An 0.035 inch soft-tip
angled glide wire (Medi-tech/Boston Scientific,
Natick, MA) is passed into the distal thoracic aorta
(Fig. 4.4). A 9 Fr sheath is usually placed in the
open common femoral artery and, similarly, 5 Fr
sheath placed in the percutaneously accessed
common femoral artery under fluoroscopic visualization. A dose of 5000 units of heparin is given to
keep the activated clotted time at greater than 200
seconds. A 5 Fr pigtail catheter is advanced through
the percutaneous sheath into the ascending thoracic
aorta for an ascending and arch angiogram which is
saved as a road map picture (Fig.4.5). The fluoroscopic C-arm is positioned in a left anterior oblique
angle and an oblique thoracic arch aortogram is
performed to visualize the arch vessels and the
descending thoracic aortic aneurysm (Fig.4.6).
Intravascular ultrasound (IVUS) (Fig.4.7) can
be performed to provide more information on
the proximal and distal neck diameter, length
of thoracic aorta involved with the aneurysm,
presence or absence of thrombus in the neck, and
any other pathology that may have been missed on
the angiogram or preoperative computed tomography (CT) angiogram of the thoracic aorta (see
Fig.4.1). The 5 Fr pigtail catether is exchanged for
an extra stiff 260 cm double curve Lunderquist wire
(Cook Medical, Bloomington, IN). The 9 Fr groin
sheath in the open cannulated femoral artery is
exchanged for an appropriate-sized device sheath
which is advanced to the distal thoracic aorta
(Fig.4.8). The endograft is subsequently advanced
through the device sheath and positioned into the
thoracic aorta to exclude the thoracic aneurysm
(Fig.4.9). Prior to deployment, the proximal and
distal landing zones identified are marked on
Endovascular and Hybrid Therapies for Structural Heart and Aortic Disease, First Edition.
Edited by Jacques Kpodonu and Raoul Bonan.
© 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd.
28
CHAPTER 4 Thoracic endografting for thoracic aneurysm using the Gore TAG device 29
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Fig. 4.1 Reconstructed 3D CT scan of the chest
demonstrating a thoracic aortic aneurysm.
angiographic road map. At the time of deployment
of the endoluminal graft, a systolic blood pressure
of 90 mmHg is achieved to decrease the “windsock”
effect in the thoracic aorta. We have not felt the
need for adenosine-induced asystole. The device is
deployed (Fig.4.10a) and a Gore tri-lobe balloon
(Fig. 4.10b) is used to perform post-deployment
balloon angioplasty to both the proximal and distal
segments of the graft for good fixation and any
areas of overlap if more than one graft is deployed.
A completion angiogram is then performed to confirm exclusion of the aneurysm and to determine if
any endoleak is present (Fig.4.11).
All wires and sheaths are removed from the
right common femoral artery with the incision
closed in a transverse fashion (Fig.4.12). A 6 Fr
angioseal vascular closure device (St. Jude
Medical, St. Paul, MN) is deployed to the common
femoral artery that was percutaneously accessed
(Fig.4.13). At the end of the procedure confirmation of the presence of bilateral peripheral pulses
is performed, the patient is extubated prior to
leaving the operating room, and is transferred to
the recovery room. The blood pressure is kept elevated using a pressor agent if needed to keep the
mean arterial pressure greater than 90 mmHg. A
postoperative CT scan of the chest (Fig.4.14) is
Fig. 4.2 A hybrid room with a xed imaging system used for the endovascular management of thoracic aortic aneurysms.
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Fig. 4.3 Open retrograde cannulation of the right groin
with an introducer sheath and a retrograde percutaneous
access of the left common femoral artery using an 18
gauge needle.
Fig. 4.5 Advancement of a pigtail angiographic catheter
up the aortic arch for a thoracic aortogram.
Fig. 4.4 Advancement of a glide wire up the aortic arch.
Fig. 4.6 Thoracic aortogram performed with an
angiographic pigtail catheter.
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