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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3734_Библиотеки_им_академика_М_И_Перельмана
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Management ofChronic Descending
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Thoracic andThoracoabdominal
Dissection andAneurysm - Stent Grafting,
Debranching
RolandAssi andWilsonY.Szeto
Introduction
In the late 1990’s, sentinel reports demonstrated the safety and feasibility of endovascular stent-grafting for the management of acute type B aortic dissection
(ATBAD) [1, 2]. Over the following decade, endovascular repair replaced open surgery as the treatment of choice of complicated acute type B aortic dissection due to
the superior perioperative survival [3–7]. Medical management remains the treatment of choice for uncomplicated ATBAD. However, in certain uncomplicated
ATBAD cases, endovascular repair in addition to optimal medical therapy (OMT)
might have a role to improve long-term survival and favor late aortic reverse remodeling by achieving early false lumen thrombosis [8, 9].
In chronic type B aortic dissection (CTBAD), OMT is the mainstay of therapy
for non-aneurysmal and asymptomatic cases. Open surgical repair is indicated for
aneurysms that reach operative threshold or in the presence of symptoms or complications. OMT includes blood pressure control and anti-impulse therapy with beta
blocking agents, the use of statins to stabilize the endothelial layer, and smoking
cessation among other cardiovascular risk prole interventions. The endovascular
treatment of chronic type B aortic dissection (CTBAD) continues, however, to present challenges to the surgeon. Conceptually, the treatment strategy is centered
around the principle of coverage of entry tears and all degenerative aortic segments.
Technically, this concept translates into difculty nding distal landing zones, complexity of reperfusing visceral branches originating from the false lumen, and the
R. Assi
Division of Cardiac Surgery, Department of Surgery, Yale University, New Haven, CT, USA
e-mail: roland.assi@yale.edu
W. Y. Szeto (
Division of Cardiovascular Surgery, Department of Surgery, University of Pennsylvania,
Philadelphia, PA, USA
e-mail: wilson.szeto@pennmedicine.upenn.edu
J. S. Coselli et al. (eds.), Aortic Dissection and Acute Aortic Syndromes,
https://doi.org/10.1007/978-3-030-66668-2_29
*)
409© Springer Nature Switzerland AG 2021
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stiffness of the intimal ap that precludes re-expansion of the true lumen. In the
remainder of this chapter we explore the technical success, challenges and outcomes of endovascular repair of CTBAD.
R. Assi and W. Y. Szeto
Goals ofTherapy andDening CTBAD Disease Spectrum
Based on data from the International Registry of Acute Aortic Dissection (IRAD), 1
out of 4 patients with ATBAD surviving to hospital discharge were deceased at
3years (data from 1996 to 2003) [10]. Risk factors for adverse outcomes were nontreatment specic and included female gender, a history of prior aortic aneurysm, a
history of atherosclerosis, in-hospital renal failure, pleural effusion on chest radiograph, and in-hospital hypotension/shock. The primary therapeutic goal is to alter
the natural history of CTBAD and improve long term survival. In ATBAD, TEVAR
is a safe and technically successful in the vast majority of cases; it is now considered
the standard of care. But what about TEVAR in the chronic phase?
The role of TEVAR in CTBAD remains somewhat controversial.
“Chronic” is not well dened. It appears that most studies consider any dissection older than 2weeks as chronic. This would include a wide variety of dissected
aortas in various stages of remodeling. The intimal ap in a dissected aorta of
2weeks is much more exible than a thickened calcied septum of many years. A
relatively recent dissection in an aneurysmal aorta behaves very differently from an
old dissected aorta that degenerated into a large complex aneurysm.
For the late chronic dissecting aneurysms of the aorta, the technical challenges
are related to the characteristics of the degenerated aorta. The stiffness of the intimal
ap may preclude true lumen expansion and create a very narrow space for wire and
catheter navigation. The presence of multiple distal re-entry tears makes it difcult
to achieve complete coverage and creates channels for retrograde lling of the false
lumen. In addition, the deployment of a stent-graft in a small true lumen against a
rigid dissecting ap may create new tears, known as stent-induced new entry tears
(SINE), which could be devastating. Another challenge is encountered when one or
more visceral branches are originating from the false lumen. Rapid or progressive
occlusion of the false lumen by the stent-graft would result in new end-organ malperfusion. Pre-operative planning for TEVAR in a chronically dissected aorta requires
careful consideration of the above-mentioned technical barriers.
TEVAR Feasibility
With the understanding that CTBAD includes a wide spectrum of progressive aortic
pathology, we now have growing body of data on the feasibility of TEVAR in
CTBAD from clinical trials and real-world experience.
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In a meta-analysis of 17 reports of 567 patients (mostly retrospective cohorts)
who underwent TEVAR for CTBAD between 1994 and 2009, technical success
rate was 89.9% (range 77.6–100%) with a re-intervention rate ranging between 0
and 60%. The data was very variable in between studies and most likely represented early experience with TEVAR for CTBAD. The type and brand of stentgrafts used were also variable. It is remarkable, however, that perioperative stroke
and spinal cord injury were only 0.82% (range 0–6.7%) and 0.43% (range 0–2.8%),
respectively [11].
In a prospective comparative study of TEVAR (208 patients) vs OMT (95
patients) from 4 centers in China between 2007 and 2010, technical success rate
was 100% and there was no index hospitalization mortality in either groups. The
rate of type I endoleak was 12%, paraplegia 0.9% and retrograde type A dissection
0.9% [12].
In a report from the Vascular Quality Initiative Registry, 125 patients underwent
TEVAR for CTBAD between 2010 and 2015. Technical success rate was 98.4%,
in-hospital mortality was 2.4%, stroke 0.8% and spinal cord ischemia 2.4% [13].
In the widely cited European INSTEAD trial randomizing 140 CTBAD patients
to elective TEVAR with OMT vs OMT only between 2003 and 2005, technical success was 95.7% and there was no operative mortality. Stroke was 1.5% and spinal
cord injury 2.9% [14].
Other studies from smaller series reported technical success between 96% and
100%, operative mortality between 0% and 5%, stroke rate between 0% and 1.3%,
and no spinal cord injury [15, 16].
Based on the data above, it is reasonable to conclude that in selected patients
with CTBAD, TEVAR is feasible and can be accomplished with high success rate
and acceptable operative morbidity and mortality.
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Effect onLate Aortic Reverse Remodeling and Survival Benet
The effect on aortic reverse remodeling and late survival is difcult to assess due
in part to the lack of large databases with long term follow-up and the variable
denition of aortic reverse remodeling. In general, the desired TEVAR effect is the
sustainable reduction of the total aortic size with preferential true lumen perfusion,
eliminating the risk of rupture or malperfusion. This is usually accomplished by
completely eliminating blood ow through the false lumen whether it is origination from intimal primary and re-entry tears or from false lumen branches (type II
endoleak). To achieve this goal, the initial approach is usually a descending thoracic
aorta (DTA) stent-graft to cover all primary tears, with the hope of inducing reverse
remodeling in the stented aorta and the downstream visceral aorta. Multiple reinterventions and distal stent-graft extensions may be required and lifelong surveillance is mandatory. Conceptually, the assumption is that aortic reverse remodeling
would translate into late survival benet.
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In the INSTEAD trial, there was no survival benet at 2years with TEVAR
despite signicant rate of complete false lumen thrombosis (91.3%) and larger true
lumen compared to the OMT group [14]. The survival advantage was however demonstrated in the follow-up INSTEAD-XL trial. At 5years, all end-points were superior in the TEVAR group compared with the OMT group. All-cause mortality was
11.1% vs 19.3%, aorta-specic mortality was 6.9% vs 19.3%, and progression was
27% vs 46.1%. An important nding was that survival and reverse remodeling were
associated with stent graft induced false lumen thrombosis in 90.6% of cases [9].
In the Chinese multicenter comparative study, survival at 2 and 4years did not
differ between the TEVAR and OMT groups; however, freedom from aorta-related
death at 2 and 4years was higher in the TEVAR vs OMT groups (91.6% and 88.1%
vs 82.8% and 73.8%). Reverse remodeling of the thoracic aorta occurred in 88.7%
in the TEVAR group compared to only 11.8% in the OMT group. This effect was
not seen in the untreated abdominal aorta; the aorta continued to increase in diameter similarly in both groups (1mm/year), likely caused by distal re-entry sites [12].
In a study from the University of Pennsylvania that included 48 patients who
underwent TEVAR for CTBAD between 2005 and 2015, 60.4% of patients failed to
show regression of aortic size of the DTA at 1year. Predictors of poor late aortic
reverse remodeling included increasing number of visceral vessels off the false
lumen, maximum preoperative aortic size, and location of the primary tear on the
greater curve [17].
Other studies reported variable degrees of aortic reverse remodeling in the short
and mid-terms. In general, the true lumen tends to expand in most cases while the
false lumen regresses depending on the presence of distal re-entry tears [18–20].
Distal re-entry tears are probably underdiagnosed because they are not easily detectable on traditional early arterial phase CT angiograms; delayed-phase imaging is
required to conrm that no entry tear is left behind [21, 22].
In summary, TEVAR is successful in inducing reverse aortic remodeling at a
much higher rate than OMT, particularly when false lumen ow is completely interrupted. Late survival data is not available for large numbers of patients, but conceptually it appears that at least aorta-related deaths could be prevented when reverse
aortic remodeling is sustained.
R. Assi and W. Y. Szeto
Perioperative Management
a. Preoperative evaluation
Evaluation of patients with CTBAD includes a complete cardiovascular and
neurologic examination and routine blood tests to check organ function, particularly renal. Echocardiography is generally helpful and any myocardial functional
abnormalities should be evaluated with a stress test and coronary catheterization
when indicated. Signicant rapid hemodynamic changes may occur during the
procedure and may induce myocardial demand ischemia. Another important element is a focused family history to rule out hereditary aortopathies. The most
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important diagnostic test is a CT angiogram with early and delayed arterial
phases to determine aortic anatomy and suitability for TEVAR.
b. Spinal cord injury (SCI) prevention
The role of spinal cord drainage and avoidance of perioperative hypotension
has been demonstrated repeatedly in large studies of open thoracoabdominal aortic repair [23, 24]. Practices vary widely between centers, but in general the same
considerations apply to TEVAR.Spinal cord drainage perioperatively is recommended whenever large segments of the aorta are covered, particularly when a
collateral circuit is compromised (left subclavian artery, intercostal arteries, lumbar arteries and internal iliac arteries). Open or endovascular reconstruction of
the left subclavian artery or the internal iliac arteries is desirable whenever coverage is anticipated [25–31].
c. Stroke prevention
In most cases, access to the aortic arch and ascending aorta with stiff wires is
required to provide a stable endovascular platform for stent-grafting of the thoracoabdominal aorta. Very meticulous wire and catheter manipulation and avoiding repetitive wire exchanges in the aortic arch are critical, particularly in the
presence of arch calcications. For complex TEVAR, stroke rate may be as high
as 20%. Other important considerations for stroke prevention include: the use of
heparin for ACT >250 seconds, cardiac output reduction during stent-graft
deployment, ICU surveillance postoperatively and the use of general anesthesia
for proximal aortic interventions [32].
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Treatment Strategies
Different approaches to the endovascular treatment of CTBAD have been described.
a. TEVAR for DTAA, with or without coverage of the left subclavian artery.
Coverage of the thoracic aorta from the left subclavian artery to the celiac
artery is the most common surgical modality of treatment for type B aortic dissection. Since most common primary tears originate from the proximal DTA,
coverage would restore true lumen perfusion and induce false lumen thrombosis.
This is accomplished relatively easily in the acute and subacute settings. In
CTBAD, distal re-entry tears originating in the abdominal aorta are common,
precluding false lumen thrombosis. In this sense, DTA TEVAR is best suited for
the treatment of CTBAD limited to the thoracic aorta (DeBakey type IIIA)
(Fig.1). Even then, treatment failure may still occur despite full coverage of the
dissected aorta. Failure of distal reverse aortic remodeling has been linked to a
large size aorta at the level of the distal landing zone and failure to extend the
repair to the level of the celiac trunk [17, 33].
A key technical aspect of TEVAR for CTBAD is sizing of the stent-graft. In
ATBAD stent-grafts are generally oversized 10% to the total aortic size at the
proximal landing zone. The optimal sizing for CTBAD is not well known. Stent-
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Proximal
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Fig. 1 TEVAR extending from the left subclavian artery to the celiac artery with coverage of a
large proximal intimal tear
R. Assi and W. Y. Szeto
stent
Pre-TEVAR
Chronic type B
aortic dissection
Fig. 2 Stent-graft induced new entry tear (SINE). Note the improvement in the true to false lumen
size ratio immediately after TEVAR (left 2 panels). Note the late occurrence of SINE followed by
true lumen compression and false lumen expansion (right 2 panels)
TEVAR SINE Delayed progress
False lumen expension (thoracic)
Tr ue luman compression (abdominal)
induced new entry tears (SINE) is a TEVAR-related complication that is associated with increased morbidity, re-interventions, conversion to open surgery and
lack of reverse remodeling (Fig.2). It could be lethal in cases of retrograde type
A dissection and may require urgent open intervention. The occurrence of
stent- induced new entry tears (SINE) in CTBAD has been linked to oversizing,
however, the pathological mechanism is far more complex and is most likely
related to the biomechanical properties of the stent-graft used versus the pathologic aorta. Hereditary aorthopathies are also a risk factor. Other factors such as
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ballooning and the use non-tapered stent-grafts may play a role. In fact, SINE
can still occur even in the absence of oversizing [34–36]. In general, 10% oversizing based on the total aortic diameter—not the compressed true lumen—is
considered safe.
b. Fenestrated or branched TEVAR/EVAR (F/BEVAR) for dissecting thoraco-
abdominal aortic aneurysms (TAAA)
Early experience with F/BEVAR showed that the approach is technically successful in selected cases. These techniques offer elegant total endovascular solutions for complex TAAA dissecting aneurysms. In general, for visceral branches
taking off at a right angle and when the stent-graft is against the aortic wall,
fenestration is preferred. For larger aortic diameters, especially when the visceral
branch take-off is at a steep angle, a branched graft is preferred (Fig.3).
In an early series of 6 patients, technical success was achieved in all patients,
with no operative mortality or paraplegia. Most patients, however, required reinterventions for endoleaks or stent occlusion [37].
A more recent study from physician-sponsored investigational device exemption databases showed similar technical success and early outcomes of F/BEVAR
for post-dissection TAAA compared to degenerative TAAA [38]. Endoleaks,
however were frequent and more prevalent in the post-dissection TAAA F/
BEVAR (76% vs 43%).
Verhoeven et al. reported the long-term outcomes of the largest European
series of endovascular TAAA repair using fenestrated and branched stent grafts
(166 patients between 2004–2013). The series included 9% emergent operation
for contained rupture or symptoms and 65% were refused open surgery earlier.
11% were aneurysms secondary to chronic type B dissection. 47% had prior
open or endovascular aortic procedures. Technical success was 95% and operative mortality was 9%. SCI was 9% (permanent paraplegia in 1.2%). Survival at
1, 2 and 5years was 83%, 78%, and 66.6%, respectively. Reintervention rate was
24% mostly by endovascular means. Freedom from reintervention at 1 and
3years was 88.3% and 78.4% [39].
In patients with marginal proximal landing zones, experience with branched
aortic arch TEVAR in conjunction with TAAA repair is growing and contemporary series have shown promising results. These techniques offer elegant endovascular solutions, particularly to patients with high risk for open proximal
thoracic aortic repair [40, 41] (Fig.4).
In general, F/BEVAR is feasible and safe in selected cases of CTBAD.Extensive
aortic coverage should be staged whenever possible. Most patients may require
multiple re-interventions for endoleaks or target vessel occlusion.
c. Hybrid procedures
A visceral hybrid approach for the treatment of complex post-dissection
TAAA may simplify the TEVAR approach and decrease the opportunity for
endoleaks by decreasing the stent-branch and stent-stent interface. Many
approaches may be utilized. In general, any large aortic branch may be chosen as
inow to bypass the visceral/renal vessels, which are then ligated at their origin.
The entire length of the aorta is then covered with a multiple overlapping TEVAR
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a bc d
e
R. Assi and W. Y. Szeto
f
h
g
Fig. 3 Endovascular treatment of complex dissecting TAAA with multiple re-entry tears (a, b). A
straight tubular graft was used for the treatment of DTA as a rst stage (c). Then a fenestrated stentgraft in the peri-visceral segment (d, e, f, g) and a branched stent-graft in the aorto-iliac segment
(h) were used to complete the repair
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Fig. 4 Aortic arch stent-grafting using a dual branch device. A Terumo Aortic dual branch platform was used (Left panel). The branches were deployed in the innominate artery and the left
carotid artery. Note the revascularization of the left subclavian artery using a carotid-subclavian
bypass graft (Middle panel). Postoperative CT angiogram (Right panel)
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stent-grafts [42]. The iliac arteries are most commonly used, but if pathologic,
the ascending aorta may be used as inow and the graft tunneled to the abdominal cavity through the anterior mediastinum.
Hybrid aortic arch approaches are particularly useful in young patients with
suboptimal proximal landing zones due to residual arch dissecting aneurysms
and who are t to undergo open proximal aortic repair. Aortic arch replacement
with a Dacron graft provides an excellent and stable proximal landing zone for
TEVAR and eliminates the risk of retrograde dissection (Fig.5). Multiple open
procedures have been described with or without cardiopulmonary bypass to
either replace the proximal aorta or debranch the aortic arch [43].
In general, when total or near-total thoraco-abdominal aortic coverage is
anticipated, data from experimental animal studies suggest reduced SCI when
the procedure is staged over time [44].
d. False lumen interventions
Interventions on the false lumen have been described during the index TEVAR
operation or later for persistent false lumen perfusion. The goal is to induce false
lumen thrombosis and improve the chances of reverse aortic remodeling. Multiple
techniques have been described including coil embolization, the candy-plug technique, cork in the bottleneck technique, deployment of detachable balloon, and
injection of thrombogenic solutions. Another solution for immediate false lumen
obliteration is the use of an oversized thoracic tubular endograft in conjunction
with controlled balloon fracture of the dissecting septum (the knickerbrocker
technique). This allows for the oversized TEVAR to reach the outer aortic wall
and occlude the false lumen. In general, false lumen obliteration is achieved successfully in most cases but the long-term effects are unknown [45–52] (Fig.6).
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Fig. 5 Staged hybrid
repair of complex
dissecting TAAA.Note the
proximal landing zone of
the stent-graft in a
prosthetic arch graft
R. Assi and W. Y. Szeto
Summary
Careful patient selection based on aortic anatomy is the most important factor for
TEVAR success in the treatment of CTBAD.The long-term durability is not well
known and lifelong imaging surveillance is necessary. Endovascular re- interventions
are common, particularly after complex repairs.
The best therapeutic effect of TEVAR is seen in the stented portion of the aorta, in
general the DTA.The downstream dissected aorta is not well treated by DTA TEVAR,
most likely due to distal lling channels. In general, the distal landing zone is key to
predicting downstream aortic remodeling. If the distal landing zone at the celiac artery is
not a healthy normal size aorta, poor distal aortic reverse remodeling should be expected.
With these limitations in mind, we recommend that older patients with CTBAD
who have suitable anatomy be considered for TEVAR as a rst-line therapy. For
younger patients with unfavorable anatomy, open surgery offers the most durable
solution. For younger patients with suitable anatomy, TEVAR is reasonable, usually
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