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42 PA R T I Natural history and preoperative planning
thoracic aorta, however given its larger size; 2.0–
3.0 cm is generally thought to be sufficient. Some
experts rely upon a ratio calculation and target a fix-
ation length of 0.75 times the aortic diameter as a
minimal acceptable length. During patient selection
if inadequate neck length exists, the patient should
be evaluated for proximal and/or distal debranch-
ing techniques toaccomplishaneurysm exclusionor
traditional open repair. Some devices provide addi-
tional fixation without sacrificing branched arteries
with bare stent regions.
It is also crucial that the aortic walls be fairly par-
allel and free of significant calcification and throm-
bus. Implantation into funnel shaped necks is not
advised and alternative options including hybrid
procedures or open repair should be considered in
these patients. While isolated thoracic aortic lesions
can still meet these requirements, many thoracic
aortic processes involve the entire descending tho-
racic aorta and end at, or near, the crus of the di-
aphragm or in the visceral section. In these cases,
obtaining adequate distal fixation can be problem-
atic. The angle of the descending thoracic aorta also
plays a major role in the migration of thoracic stent
grafts, possibly causing a cephalad migration of the
caudal aspect of the device. It can also make precise
deployment rather difficult; many times it is nec-
essary to deploy an additional distal extension [7].
Implanting the device in a region where significant
angulation exists can jeopardize the durability of the
endovascular repair. Finally, most stent-graft dep-
loyment mechanisms are designed for precise prox-
imal placement with minimal or no control over the
distal attachment site or landing zone. Therefore ac-
curate deployment near the celiac artery becomes
more challenging. Given the aforementionedissues,
it is advisable to lengthen the distal neck by perform-
ing aortic debranching techniques in a small but not
insignificant number of patients.
While additional fixation can be obtained on the
proximal aspect of the aneurysm by either carotid
subclavian bypass or coverage of the left subclavian
artery, the visceral section of the aorta is less forgiv-
ing. While there are reports of celiac artery coverage
without incident, severe complications may arise
from either hepatic or splenic ischemia, resulting in
potential demise of the patient [8, 9]. It has been
our approach to routinely revascularize all celiac
arteries if coverage is planned unless certain con-
traindications exist [10]. These include prohibitive
abdominal surgical risks, diminutive hepatic or in-
flow vessels potentially jeopardizing collateral flow
or patients with documented celiac occlusion.
Neck angulation can also impose significant re-
strictions on proximal thoracic pathologies. Since
the arch of the aorta is fixed by the great vessels,
proximal aneurysms often induce an acute angle
change at or just distal to the left SCA. Passage
of some devices can be difficult in these situations
and are often associated with an increased risk of
stroke during endovascular exclusion. It is advis-
able in these patients to evaluate the extent of arch
atheroscleroticdisease and councilthe patientabout
potential stroke risks.
Aortic morphology
Tortuosity in other regions of the aorta can also
cause intent to treat failures. The thoracic aorta
is a complex three-dimensional (3D) structure,
which when dilated from aneurysmal disease can
pose many challenges for the interventionalist. One
should be familiar with the available devices and
their relative ability to traverse various thoracic
anatomies (flexibility). This becomes especially im-
portant when treating extensive regions of the
thoracic aorta. Each component implanted into
the thoracic aorta results in a relative compliance
change and potentially limits the insertion of the
next component. There have been instances when
exclusion of the aneurysm cannot be completed af-
ter the deployment of the initial device because sec-
ondary devices are not able to traverse the thoracic
aorta. One approach is to evaluate the radius of
curvature. In the cases where the aortic arch radius
is less than 25–35 mm endovascular repair may be
problematic. In addition, when the aortic angles ex-
ceed 75
◦
, the deliverability of the device often be-
comes extremely difficult or impossible.
Device position
During patient selection, the location of the prox-
imal implantation region of the device should be
determined. Adjustments to the ideal position of
the proximal seal are not only governed by the neck
location, but also the orientation and conformation
of the device and the sealing stents to the thoracic
aorta. In angled regions, especially in the arch, this
can alter the intendedimplantation site and result in
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CHAPTER 5 Natural history and preoperative planning 43
unanticipated coverage of branched vessels. When
preoperative evaluation predicts that this may oc-
cur, cerebral evaluation should be completed prior
toimplantation [11].This generallyincludes carotid
and subclavian artery duplex ultrasonography, as
well as CT and/or MRA of the great vessels, verte-
bral arteries and the Circle of Willis. As previously
described the left subclavian artery can be man-
aged expectantly without preprocedural revascular-
ization with few exceptions [11, 12]. These include
patients with aberrant or dominant left vertebral ar-
teries and LIMA bypass grafts. Whenmore proximal
implantation is desired,aortic archdebranching can
be performed. This can be accomplished with nu-
merous procedures that include carotid–subclavian
bypass or transposition, carotid–carotidbypass and
ascending arch to innominate and carotid bypass.
Paraplegia risks
While it has been shown with open thoracoabdomi-
nal aneurysm repair that the length ofaorta replaced
is associated with an increased risk of paraplegia,
this has not been the experience with thoracic en-
dovascular procedures. Therefore, generous sealing
regions (3–5 cm) that exceed the IFU recommen-
dations are usually chosen for the patient to maxi-
mize the potential for long-term success. An asso-
ciation with paraplegia has been identified however
in those patients who have had prior abdominal
aortic aneurysm repairs. It appears that the risk is
increased approximately two-fold, from 4% to 8%
[6, 13]. In this cohort care should be taken when
planning the procedure. Preservation of left SCA
flow should be stressed because it provides an ex-
cellent collateral pathway in potentially preventing
spinal cord ischemia. Additionally, many surgeons
will insert a prophylactic spinal drainage catheter.
This practice has arisen from several anecdotal case
reports of resolution of spinal cord ischemic com-
plications after placement of a lumbar drain in pa-
tients.
Access issues
Access complications are often due to a combina-
tion of iliofemoral arterial calcification, tortuosity,
and stenosis that can be identified with preopera-
tive imaging. While the presence of any one of these
aspects can easily be overcome, their combination
can lead to access failure or vascular complications
during the procedure. Critical assessment of the il-
iac vessels should be undertaken with axial imaging
characterizing the caliber of access vessels (common
iliac, external iliac, and common femoral) and the
degree, location, extent, and circumferential nature
of calcium; and 3D reconstructions can map out
vessel tortuosity. Delivery catheter sizes are still rel-
atively large and have a size range of 22–25 Fr.
Approximately 15–20% of patients will require an
iliac or aortic conduit for successful device implan-
tation. While this can be tolerated in most patients
in the elective situation, it does add additional mor-
bidity to the procedure.When emergent conversion
from iliac rupture occurs, it imparts significant risks
to the patient. If any potential access issues are iden-
tified preoperatively, an elective conduit placement
should be planned.
Conclusion
Despite advancements in devices and technology
over the past decade, patient selection criteria have
remained relatively the same and are mainly gov-
erned by aortic neck characteristics both proximally
and distally. When compromises are made in either
of these two regions, patient outcomes are nega-
tively impacted. Detailed axial imaging with mul-
tiplanar reconstruction capabilities is crucial for
proper evaluation, planning and sizing for thoracic
endovascular procedures. In the future, branched
and fenestrated devices will allow for the treat-
ment of lesions involving either the great vessels
or the visceral section w ith less invasive meth-
ods compared to hybrid procedures performed
today.
References
1 Dake MD, Miller DC, Semba CP, Mitchell RS, Walker
PJ, Liddell RP. Transluminal placement of endovascu-
lar stent-grafts for the treatment of descending thoracic
aortic aneurysms. N Engl J Med 1994; 331(26): 1729–
1734.
2 Volodos NL, Karpovich IP, Shekhanin VE, Troian VI,
Iakovenko LF. A case of distant transfemoral endopros-
thesis of the thoracic artery using a self-fixing synthetic
prosthesis in traumatic aneurysm. Grudn Khir 1988;2(6):
84–86.
3 Saito N, Kimura T, Odashiro K et al. Feasibility of the In-
oue single-branched stent-graft implantation for thoracic
https://t.me/med1917
44 PA R T I Natural history and preoperative planning
aortic aneurysm ordissection involving the left subclavian
artery: Short- to medium-term results in 17 patients. J
Vasc Surg 2005; 41(2): 206–212; discussion 12.
4 Htay T,Fujiwara H, Sato M, TanakaM, Sasayama S, Inoue
K. Transcatheter Inoue endovascular graft for treatment
of canine aortic dissection. Heart Vessels 1996; 11(2): 80–
85.
5 Semba CP, Mitchell RS, Miller DC et al. Thoracic aortic
aneurysm repair with endovascular stent-grafts. Vasc Med
1997; 2(2): 98–103.
6 Criado FJ, Clark NS, Barnatan MF. Stent graft repair in
the aortic arch and descending thoracic aorta: A 4-year
experience. J Vasc Surg 2002; 36(6): 1121–1128.
7 Ellozy SH, Carroccio A, Minor M et al. Challenges of en-
dovascular tube graft repair of thoracic aortic aneurysm:
Midterm follow-up and lessons learned. J Vasc Surg 2003;
38(4): 676–683.
8 Sunder-Plassmann L, Orend KH. Stentgrafting of the
thoracic aorta-complications. J Cardiovasc Surg (Torino)
2005; 46(2): 121–130.
9 Greenberg RK, O’Neill S, Walker E et al. Endovascular
repair of thoracic aortic lesions with the Zenith TX1
and TX2 thoracic grafts: Intermediate-termresults. J Vasc
Surg 2005; 41(4): 589–596.
10 Fulton JJ, Farber MA, Marston WA, Mendes R,
Mauro MA, Keagy BA. Endovascular stent-graft re-
pair of pararenal and type IV thoracoabdominal aortic
aneurysms with adjunctivevisceral reconstruction. J Vasc
Surg 2005; 41(2): 191–198.
11 Gorich J, Asquan Y, Seifarth H et al.Initial experience with
intentional stent-graft coverage of the subclavian artery
during endovascular thoracic aortic repairs. J Endovasc
Ther 2002; 9(Suppl) 2: II39–II43.
12 Tiesenhausen K, Hausegger KA, Oberwalder P et al.Left
subclavian artery management in endovascular repair of
thoracic aortic aneurysms and aortic dissections. J Card
Surg 2003; 18(5): 429–435.
13 Fattori R, Napoli G, Lovato L et al. Descending thoracic
aortic diseases: Stent-graft repair.Radiology 2003; 229(1):
176–183.
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6
CHAPTER 6
Noninvasive aortic imaging
modalities: CT, MRI, intravascular
ultrasound (IVUS),
and transesophageal
echocardiography (TEE)
Tae K. Song, & Rodney A. White
Noninvasive imaging modalities are the principal
methods used to determine which patients are can-
didates for thoracic aortic endovascular interventi-
on and allow for surveillance monitoring following
aortic endovascular procedures. Current modali-
ties being utilized include computed tomography
(CT), magnetic resonance imaging (MRI), trans-
esophageal echocardiography (TEE), and intravas-
cular ultrasound (IVUS). Each modality provides
information that is useful for preinterventional se-
lection of patients, deployment of endografts, and
assessment of long-term outcomes.
Preintervention CT and MRI are replacing con-
trast angiography as the primary imaging studies
for thoracoabdominal pathology in determining
patient candidacy for endovascular therapy. An-
giography can be particularly misleading regard-
ing adequacy of landing zone length and the dis-
tribution of thrombus at the fixation sites. In fact,
many interventionalists feel that contrast enhanced
CT scans (preferably centerline images with three-
dimensional (3D)reconstructions) arethe most ac-
curate method to determine aneurysm morphol-
ogy, aortic dissection characteristics, and adequacy
of fixation sitesfor endograft deployment inaortoil-
iac procedures. MRI provides similar information
as CT scans if high quality software is available.
IVUS and TEE are ultrasound-based imaging
modalities that are enhancing the 3D, real-time
imaging of aortic segments prior to, during, and
following endovascular therapy. These nonionizing
radiation imaging technologies supplement con-
ventionalangiographyand cinefluoroscopy.Appro-
priately employed in conjunction with preinterven-
tion CT images, IVUS interrogation can expedite
preprocedural planning and reduce fluoroscopic
and contrast requirements.
IVUS can also be used to determine aortic mor-
phology such as the presence of thrombus or cal-
cification. IVUS provides real-time observation of
endograft stent expansion and assessment of appo-
sition of endograft stents to the aortic wall before
the procedures are completed. In comparison, TEE
offers someof thesame advantages as IVUS but also
produces a unique perspective of cardiac function,
ascending and descending aortic anatomy.
Computed tomogaphy
3D spiralCT imaging methods are dramatically im-
proving the utility of CT for interpreting the dis-
tribution of thoracoabdominal disease and for as-
sessing appropriate endovascular therapy. Images
can be reconstructed usingmaximum intensity pro-
jection (MIP), producing two-dimensional (2D)
images that can differentiate mural calcification
from intraluminal contrast. Alternatively, a shaded
45
Advanced Endovascular Therapy of Aortic Disease
Edited by Alan B. Lumsden, Peter H. Lin, Changyi Chen, Juan C. Parodi
Copyright © 2007 by Blackwell Publishing
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46 PA R T I Natural history and preoperative planning
surface display (SSD)-rendering technique may be
used, producing 3D images depicting the surface of
the contrast-enhanced structures. CT angiography
(CTA) then allows an infinite number of viewing
angles of the 3D reconstructed image.
CT has become the gold standard in preinter-
ventional planning of thoracoabdominal aortic an-
eurysms, thoracic aortic dissections, grafts, and
stents for endovascular therapy. CT offers precise
anatomic information needed for preplanning of
endovascular therapy. Thin cut CT slices of 2 to
3 mm can be converted into 3D reconstructions us-
ing specialized computer software (Medical MetRx
Solutions, West Lebanon, NH). Thus, CT allows
assessment of the cross-sectional morphology of
vascular structures with clear delineation of lumi-
nal and wall components (i.e. thrombus or calci-
fications), aortic dimensions (i.e. stent selection),
size of femoral access vessels, and involvement of
branch vessels [1]. With thoracic aortic dissections,
CT accurately determines the extent of dissection
flaps and which visceral vessels are supplied by the
true orfalse lumen (Fig. 6.1). This information may
be important when planning interventions such as
fenestration to alleviate the ischemic sequelae of a
thoracic dissection. CT is also sensitive (92%) and
specific (83%) for the detection of hemodynami-
cally significant renal artery stenosis [2]. CT accu-
rately delineates the splanchnic vessel anatomy, in-
cluding identifying accessoryrenal arteries, stenoses
involving mesenteric vessels, and collateral vessels
[3].
CT is helpful in monitoring the long-term func-
tion of devices and is the primary modality for es-
tablishment of long-term surveillance. Patients se-
lected for endovascular treatment are often enrolled
in follow-up surveillance programs with serial CT
scans obtained preoperatively and postoperatively
at 1 month,6 month, andyearly thereafter (Fig.6.2).
Serial CTscans can then help delineate the effects of
endovascular therapy on the natural history of tho-
racoabdominal pathology. CT will also detect com-
plications of endograft treatment such as stent frac-
ture, stent migration, thrombosis, and endoleaks.
Compared to digital subtraction angiography, CTA
is sensitive (86%) in detecting the presence of en-
doleaks, but demonstrates less specificity in differ-
entiating the type of endoleak [4].
Figure 6.1 Interactive 3D CT image of a
chronic descending aortic dissection
depicting a true and false lumen (f) with an
entry point distal to the left subclavian
artery and extending below the celiac axis
(celiac origin is derived from true lumen).
Corresponding axial images depict the 2D
findings found on conventional CT.
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CHAPTER 6 Noninvasive aortic imaging modalities 47
Figure 6.2 Composite interactive 3D CT images of complete regression over 7 months ofa7cmaneurysmal enlargement
of a chronic proximal descending aortic dissection following coverage of the proximal entry site with a single
130-mm-long Talent thoracic endograft.
Magnetic resonance imaging
The principle of “flow void,” where rapidly moving
protons fail to elicit a perceptible signal, forms the
basis for imaging blood vessels using MRI methods
(magnetic resonance angiography) essentially pro-
ducing a “luminogram” of the thoracic aorta [5].
More sophisticated techniques based on gradient-
echo (GRE) pulse sequences produce bright blood
images from 2D or 3D data sets that can be pro-
cessed for optimal viewing angles.
MRI is an important and noninvasive diagnos-
tic tool to screen patients for endovascular therapy.
MRI can also be used as an alternative method for
monitoring long-term outcomes following endo-
graft placement. A comparison of MRI to CT as the
sole preoperative imaging modality for endovascu-
lar therapy showed no differences in aborted proce-
dures, conversions to open procedures, or inability
to access vessels for deployment [6, 7].
MRI provides information regarding luminal di-
mensions, vessel wall, and the relation of pathology
to the arch vessels and paraaortic structures. Like
CT, MRI is effective for diagnosing aortic dissec-
tions, but MRI is more sensitive for demonstrat-
ing the dissection entry site and endpoint. On MRI
scans, intimal flapsare seenas linearstructuresof in-
termediate signal density, with blood flowing in the
adjacent lumens appearing as flow void or anoma-
lous intraluminal flowsignal. MRIis alsowell suited
to the evaluation of aortic aneurysmal disease de-
tecting the presence of a mural thrombus, outer di-
mensions of the aorta, size of the residual lumen,
and the relation of the aneurysm to major branch
vessels. Dynamic MR is developing as a powerful
method for evaluating intravascular 3D hemody-
namics andflow and is enhancing the assessment of
complicated aortic pathologies such as dissections.
Increasingly, MRI is commonly used as an ad-
junct to ultrasound imaging for the assessment of
patients who are not suitable for radiologic con-
trast infusion due to renal insufficiency or con-
trast allergy. The incidence of anaphylactic reaction
to gadolinium is extremely low. MRI can also be
used to establish long-term surveillance outcomes
as the nitinol stent material is compatible with mag-
nets; however MRI does not allow assessment of
the stent lumen. Artifacts created by the presence
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48 PA R T I Natural history and preoperative planning
of intravascular steel coils [5] from previous em-
bolization vesselocclusion reduce imageresolution.
In contrast, the use of platinum intravascular coils
would allow for MRI compatibility.
More recently, application of MRI using faster
magnetic resonance gradients to allow for time-
resolved magnetic resonance angiography (TR-
MRA) has been employed not only to detect the
presence of endoleak, but also to characterize the
type of endoleak with much greater sensitivity than
CTA [8, 9]. The ability to characterize the type of
endoleak is important in directing the need for fu-
ture intervention for type I and type III endoleaks.
Currently, thegold standardfor detecting thetype of
endoleak is digitalsubtraction angiography. Haulon
etal. [9] suggestthe failure ofthe aneurysm to shrink
based on 6 month CTA surveillance should be fol-
lowed by a MRI with gadolinium to detect an en-
doleak with a high degree of sensitivity. Cine MRA
has also been used to correlate aneurysm pulsatil-
ity to differentiate between type I and type II en-
doleaks [10]. Type II endoleaks have not been as-
sociated with continued endotension [11] and are
often monitored with serial imaging.
MRI, however, is not suitable for all patients.
Exclusion from MRI scanning includes metal im-
plants, inability to hold one’s breath (i.e.ventilator-
dependent patients), and claustrophobia. MRI
shows a limited ability to determine the degree and
distribution of calcification within a vessel lumen
making assessment of the suitability of femoral ac-
cess vessels difficult. MRI does notaccurately detect
the presence of accessory renal vessels or the degree
of renal artery stenosis well.
Ultrasound imaging
Transesophageal echocardiography
The role of TEE during endovascular therapy is
evolving and is probably the least utilized noninva-
sive imaging modality. Primarily employed for the
assessment and treatment of thoracic aortic dissec-
tions, TEE provides a unique perspective of cardiac
function and ascending and descending thoracic
aortic anatomy. TEE allows precise localization of
entry sites and relationship to the brachiocephalic
artery, depicts the anatomical relationship of the
true and false lumens, and can detect endoleaks
[12]. Similar to IVUS, TEE can verify placement
of the guide wire within the true lumen prior to
endograft deployment and assess for stent appo-
sition following endograft deployment with color
flow Doppler. Because TEE does not interfere with
deployment, TEE can be used in real time to assess
successful exclusion of the false lumen (i.e. “smoke
phenomenon”) as well as to detect the presence of
endoleaks including a higher sensitivity in detecting
Type IV endoleaks [12, 13].
In contrast to IVUS, TEE requires general anes-
thesia and allows limited visualization of the trans-
verse aortic arch and abdominal aorta and its
branches. Similar to IVUS, the assessment of PTFE
stents with TEE will be less useful. With its higher
degree of sensitivity in detecting thoracic dissec-
tions and its utility in endograft deployment, the
role of TEE may continue to expand in the treat-
ment of aortic dissections.
Intravascular ultrasound
IVUS is particularly useful in the treatment of tho-
racoabdominal pathology [14]. For instance, IVUS
can establishaortic wall morphology,locate theori-
gins of branch vessels,size vessellumen dimensions,
and select proximal and distal landing zones for
endograft deployment [15]. In conjunction with
cinefluoroscopy, IVUS can be used to assess the
accuracy of endograft deployment, degree of de-
vice expansion, and stent apposition of the pros-
thesis to the vascular wall (Fig. 6.3). An advantage
of IVUS is the ability to map additional segments
of the aorta either proximal or distal to the endo-
graft in preparation for additional endograft stent
placement. IVUS is particularly useful when com-
bined with fluoroscopy to identify the origin of the
visceral vessels,thus enhancingprecise deployment.
Through the use of IVUS and pulsed fluoroscopy,
the amount of radiation exposure and potentially
nephrotoxic contrast use can be minimized signifi-
cantly. This reduced exposure and limited contrast
use may benefitthose withcontrast allergies or renal
insufficiency.
As an appealing alternative to contrast angiogra-
phy, IVUS can be used independently to investigate
pathologic lesions. Its ability to identify branch ves-
sels relative to a calibrated ruler placed beneath the
patient and anatomic landmarks has been used to
deploy endografts without the need for fluoroscopy
(Fig. 6.4).
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Figure 6.3 Postendograft deployment (a) image on fluoroscopy and corresponding IVUS image (b) demonstrating poor
apposition of the endograft to the aortic wall. The endograft underwent balloon dilatation with subsequent improved
apposition.
(a)
(b)
(c)
(d)
Figure 6.4 IVUS image depicting the typical sequence of aortic arch branch vessels (images a and b) of innominate artery,
left common carotid artery (CCA) and left subclavian artery (SCA). An entry site (tear) is demonstrated (image c) distal to
the left subclavian artery. An intimal flap separating the true (t) and false (f) lumen is shown by IVUS (image d).
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50 PA R T I Natural history and preoperative planning
Figure 6.5 Entry site (arrow) of an aortic
dissection is depicted by IVUS.
IVUS utilization requiresan understanding ofthe
principals of ultrasound interpretation in vascular
anatomy. The ultrasound signal may be attenuated
by calcification in the vessel wall, and may show
enhancement by prosthetic graft material. Analysis
of aortic wall morphology may show the presence
of thrombus, dissection flaps, and pulsatile flow
within the true and false arterial lumens in a dis-
sected artery.
Artifacts can be produced by wires and catheters
in the arterial lumen. Catheter designs that en-
able delivery of the ultrasound elements without
a monorail delivery wire eliminate wire artifact and
enhance 360
◦
views of the arterial anatomy. For
this reason, coaxial phased array systems that pro-
duce images utilizing electronically rotating signals
rather than mechanically rotating systems over ec-
centric wire delivery provide enhanced optimal res-
olution.
In our practice, IVUS is particularly useful in
the endograft treatment of aortic dissections [16].
IVUS can help identify entry and reentry tears in
aortic dissections (Fig. 6.5), identify the origin of
aortic and visceral branch vessels, and determine
the proximal fixation point relative to the brachio-
cephalic vessels. Selective endograft exclusionof the
false lumen can be aided by use of IVUS to care-
fully navigate a guide wire pathway within the true
lumen and assess for successful reperfusion of the
true lumen following endograft deployment. IVUS
may also help determine adequacy of stent length
coverage for false lumen exclusion by demonstrat-
ing the return of systolic pulsatile flow to the true
lumen as well as concomitant stagnation of flow
and thrombus development within the false lumen
(Fig. 6.6) [16]. The major drawback to the use of
IVUS is the need for invasive arterial access for
catheter placement.
Conclusion
There exist a number of noninvasive imaging
modalities that are currently available for use in
the treatment of thoracoabdominal pathology with
endovascular therapy. Each modality has particu-
lar advantages and will likely continue to evolve
as more experience with endografts is accumulated
and long-term outcomes are better understood.
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CHAPTER 6 Noninvasive aortic imaging modalities 51
Figure 6.6 IVUS images of aortic dissection preendograft deployment (a) and postendograft deployment (b)
demonstrating the dimensions of the true lumen (arrows) at the same aortic level. Real-time predeployment images show
pulsatile flow in the false lumen with severe compromised flow in the true lumen. The postprocedure IVUS image (b)
demonstrates enlargement of the true lumen with pulsatile flow in the true lumen and stagnation of flow in the false
lumen (f) following coverage of the proximal entry site.
Spiral CT remains the goldstandard for preoper-
ative assessment for patient selection and postoper-
ative surveillance. For instance, spiral CT is particu-
larly useful for choosing appropriate candidates for
complex reconstructive procedures such as endolu-
minal vascular prosthesis placement, where prein-
tervention assessment of the lesions, sizing of proxi-
mal and distalvessels, andidentification ofcollateral
beds is indispensable. Moreover, TEE and IVUS are
under-utilized modalities that may play an expand-
ing role in endovascular therapy given its applica-
bility within the operating room.
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https://t.me/med1917
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