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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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Due to the relative rarity of more proximal aortic injuries, they will not be exten-
sively discussed in this chapter. In the near future, endovascular options for treating
these proximal injuries will be available. Currently, however, options are limited to
open reconstruction (often using cardiopulmonary bypass) or off-label uses of commercially available endovascular devices.
B. L. Tjaden and A. L. Estrera
Diagnosis: Grading
BTAI are commonly classied on a grading scale ranging from I-IV.This grading
system was rst proposed by Azizzadeh et al. in 2009 [18] and, subsequently,
adopted in the 2011 Society for Vascular Surgery (SVS) clinical practice guidelines
[19]. Grade I injuries consist of an intimal ap. Grade II injuries are dened as
intramural hematoma (IMH), though we also include formal “double-barrel”
dissection in this category. Grade III injuries are pseudoaneurysms, identied by a
contour abnormality of the outer wall of the aorta. Grade IV injuries include total
aortic transections or ruptures. (Fig.2).
This grading system is not simply a framework for the academic discussion of
these injuries—it has been shown to correlate with real-world outcomes.
Furthermore, stratication by grades can help to determine when and if intervention
is needed [20, 21].
Management: Decision Making
Evaluation and management of a patient with a BTAI almost never occurs in isolation. The traumatic forces required to injure the thoracic aorta are so strong that
polytrauma is the rule, rather than the exception. Therefore, the management of
each patient with BTAI must be individualized, taking into account the competing
priorities of other injuries.
The SVS has issued guidelines for the management of BTAI [19], though it
should be noted that the evidence in support of these guidelines is limited and, as
such, this document provides only Grade 2 (weak) “suggestions,” not
“recommendations.”
In summary, the SVS suggests that Grade I injuries should be managed nonop-
eratively with serial imaging. For injuries Grade II-IV, urgent/emergent thoracic
endovascular repair (TEVAR) is suggested with several specic technical considerations: general anesthesia, no routine spinal drainage, open femoral exposure, routine low dose heparinization, and selective revascularization of the left subclavian
artery (LSA) [19].
Further discussion of the specics of medical management, as well as endovas-
cular and open surgery, will follow in the subsequent sections.
Blunt Traumatic Aortic Injury: Etiology, Diagnosis, andManagement
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CLASSIFICAT ION OF
TRAUMATIC AORTIC INJURY
213
GRADE I
Intimal Tear
Intima
Media
Adventitia
GRADE III
Pseudoaneurysm
Fig. 2 Grading system for blunt traumatic aortic injuries
GRADE II
Intramural Hematoma
GRADE IV
Rupture
Management: Medical
For nearly two decades, nonoperative management of BTAI with intimal disruption
alone (GI) has been considered the standard of care. Until recently, however, this
principle has been supported by relatively little data. In 2001, Malhotra etal. wrote
that that “[GI] injuries heal spontaneously and, hence, may be managed
nonoperatively.” [22] This conclusion was based on only 6 patients who underwent
surveillance scanning after nonoperative management, in which 3 developed small
pseudoaneurysms. The series reported by Azizzadeh et al. from Houston
demonstrated no deaths in 10 patients with GI injury who were managed medically
[18]. In a later publication from the same institution, follow-up CTA performed
4–6weeks after injury demonstrated complete aortic healing in 5 patients with GI
injuries who were managed nonoperatively [15].
Recently, larger series have proven the safety of nonoperative management.
Osgood etal. published a series of 46 GI BTAI [23]. They found only a 5% rate of
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injury progression, no need for intervention based on injury progression, and no
deaths in this group. Other authors reported 91% of GI injuries resolved or remained
stable over interval follow up [20]. A large institutional review of BTAI over a
15-year period demonstrated a 0% rate of injury progression and 0% aortic-related
mortality for GI injuries that were managed medically [24].
Several of these more modern publications have also demonstrated a fairly
benign natural history of GII aortic injuries [23–25]. We examined our institutional
experience with medical management of GI and GII injuries and found no signicant
differences in outcomes for patients with either grade of injury when managed
medically—other than a more rapid rate of injury resolution in GI injuries [21]. A
2017 survey carried out by the Aortic Trauma Foundation revealed that surgeons are
equally divided as to whether or not medical therapy or TEVAR is best for GII
injuries [26].
While the specics of medical management for low-grade BTAI have varied
slightly in the literature, the general approach has been very similar. The infusion of
intravenous beta blockade and/or vasodilators is initiated in order to reduce the
systolic blood pressure (SBP) and heart rate (HR). The rationale for this approach is
that by minimizing the mechanical forces on the disrupted intima, the risk of injury
propagation can be minimized and the odds of healing/aortic remodeling can be
maximized. Our institutional practice is to begin with an infusion of labetalol (with
nicardipine as the second-line agent), titrated to a goal of SBP 100–120 and HR
60–90 [21]. In addition, we often recommend 81 mg of aspirin daily until
conrmation of injury resolution, though this practice is more variable and is
dependent on other injuries.
It should be noted that in patients with concomitant brain injuries, anti-impulse
therapy may be contraindicated: the need for permissive hypertension required to
optimally perfuse the injured brain may preclude the relative hypotension required
for aortic protection. In this case, a joint decision should be made with the trauma
and neurosurgical teams in order to agree on acceptable hemodynamic parameters.
Rarely, this may require repair of a low-grade aortic injury in order to allow for
increased blood pressure.
Interval imaging is needed for patients undergoing medical management of GI or
GII aortic injuries, as some injuries can progress to higher grades of injury with
time. It is our practice to obtain a repeat CTA after 7–10days, with further imaging
surveillance at 1-, 6-, and 12-month intervals thereafter if the lesion persists [21].
B. L. Tjaden and A. L. Estrera
Management: Surgical: Endovascular Rationale, Changing
Practice Patterns
Historically, there has been little question that higher grades of aortic injuries (GIII/
GIV) benet from repair to reduce the risk of death. However, in the pre-endovascular
era, open repair of BTAI was plagued by high rates of complications and mortalities.
25
20
10
Open Repair
TEVAR Medical Management Only
15
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215
A meta-analysis of open repairs reported paraplegia rates of 9.9% and mortality
rates of 21.3% [27]. Even in more modern series, open repair was associated with a
17% mortality rate [28].
TEVAR for BTAI has been associated with signicantly decreased morbidity
and mortality when compared to open repair, with some centers reporting paraplegia
rates and operative mortality rates of 0% [28, 29]. In addition, the overall rate of
major complications and length of stay is shorter with TEVAR [30].
In light of these benets, it should come as no surprise that TEVAR has rapidly
supplanted open repair in the treatment of BTAI [30–32]. The utilization of TEVAR
in the treatment of BTAI at a large volume center is illustrated in the gure from
Fortuna etal.’s 2016 publication (Fig.3) [24].
Management: Surgical: Endovascular,
Technical Considerations
The SVS clinical practice guidelines provide suggestions in regard to technical
steps for TEVAR to treat BTAI, as described above. Our institutional practice varies
slightly from this document, and is described below.
1. Timing of Repair
(a) For GIII injuries (or particularly large/ominous GII injuries), we generally
perform TEVAR within 48hours.
(b) For GIV injuries, we generally perform TEVAR within 24hours.
5
0
Fig. 3 Utilization of open repair vs. thoracic endovascular aortic repair (TEVAR) at a largevolume center over a 15-year period. This illustrates a dramatic reduction in the number of open
repairs with the advent of endovascular options
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
1999
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B. L. Tjaden and A. L. Estrera
2. Preoperative Considerations
(a) Preoperative lumbar drains are not placed. This is because only a short seg-
ment of aortic coverage is usually required [7], allowing for the use of a
single, 10-cm device in most cases—and the risk of spinal paraplegia is very
low in historical cohorts of trauma patients treated with TEVAR without
drainage [19].
(b) Decisions regarding intraoperative heparinization are made before the oper-
ation in conjunction with our trauma surgery and neurosurgery colleagues.
(c) Endografts are selected to achieve 5–10% oversizing relative to the native
aorta. Trauma patients tend to be young with fairly normal aortas, and the
average aortic diameter in BTAI cases is 24mm [7].
(d) When considering a BTAI patient for TEVAR, we are willing to accept
shorter proximal seal zones. Ideally, we would still like at least 1 cm of
healthy aorta proximal to the tear to achieve endograft wall apposition. This
is possible in the majority of cases (Fig.4), as the tear is, on average, 1.6cm
distal to the LSA [7]. However, we usually approach these cases with the
philosophy that any proximal seal zone is adequate—i.e., we will be satised
if the entry tear can be covered without the endograft slipping into the tear
itself. This is because, unlike aneurysmal disease, there is little concern for
impending aortic degeneration and loss of seal or xation.
(e) If the tear encroaches on the LSA and the ability to achieve seal distal to it is
questionable, care should be taken to preoperatively identify the absolute
contraindications to LSA coverage without revascularization. These include:
Fig. 4 Left: Initial angiogram of a Grade IV blunt thoracic injury (the same injury as pictured in
Fig. 1) demonstrating typical anatomy, with a generous potential seal-zone distal to the left
subclavian artery. Right: Completion angiogram showing exclusion of the injury without evidence
of endoleak
Blunt Traumatic Aortic Injury: Etiology, Diagnosis, andManagement
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a left vertebral artery that terminates in a posterior inferior cerebellar artery
(PICA); a previous coronary artery bypass using a left internal mammary
artery; an absent, atretic, or occluded right vertebral artery; or a functional
left arm hemodialysis access.
3. Intraoperative Specics
(a) A unilateral percutaneous approach is usually employed, with contralateral
access obtained, if needed. Percutaneous TEVAR for BTAI has been shown
to be feasible with very low rates of complications [33]. In our experience,
we found that the lack of calcic femoral disease in most young trauma
patients renders percutaneous access straightforward and safe in almost all
cases of BTAI.
• Ultrasound guidance is mandatory [34].
• After securing access with a 5 French (Fr) sheath, the arteriotomy is “preclosed” using two ProGlide® devices (Abbott, Abbott Park, IL). The femoral
artery is then plugged with an 8Fr sheath, which will facilitate diagnostic
angiography and/or IVUS.
• If heparinization is planned, it is initiated at the time of 8Fr sheath placement.
(b) A oppy guidewire and marker ush catheter are used for initial angiogra-
phy. A wire exchange for a stiff wire (e.g. a Lunderquist® wire [Cook
Medical, Bloomington, IN]) is performed.
(c) IVUS is used selectively. If adequate CT imaging is available to size the
endograft, then IVUS is not usually employed. However, if the aortic
diameter or the area requiring coverage is questionable, then IVUS is
performed.
(d) The endograft is delivered and positioned over the stiff wire. If the stiff wire
and/or device appear to displace the aorta relative to its initial angiographic
position, an additional angiogram should be obtained with the device in
place in order to ensure appropriate positioning. This can be performed
either via a “buddy” catheter through the ipsilateral groin, or through
contralateral femoral access.
(e) In the absence of absolute contraindications, coverage of the LSA will be
performed, if necessary, to exclude the injury. This has been shown to be
associated with low rates of complications in cases of BTAI [19, 35–37].
(f) After device deployment, completion angiography is performed.
Percutaneous hemostasis is achieved via the previously placed ProGlide®
devices and protamine administration. Rarely, adjunctive techniques for
hemostasis may be needed, such as creation of a Rummel-type tourniquet,
with or without topical thrombin [38]. (Fig.5)
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4. Postoperative Management
(a) Patients are cared for postoperatively in a critical care unit to be monitored
for extremity ischemia or neurologic decits.
(b) Anti-impulse therapy is discontinued after TEVAR.
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B. L. Tjaden and A. L. Estrera
Fig. 5 Illustration of the
ProGlide
tourniquet technique, an
effective adjunct for
achieving hemostasis after
percutaneous TEVAR
®
Rumel
(c) In the event of symptomatic and ongoing ischemia after LSA coverage (isch-
emic rest pain, claudication, spinal ischemia), left subclavian revascularization is performed via subclavian-to-carotid transposition or carotid-subclavian
bypass [19].
In the near future, branched thoracic endografts will be commercially available,
providing options for treatment of more proximal injuries (Fig.6) while still preserving ow into the arch vessels. The Gore Thoracic Branched Endograft (TBE)
(W.L.Gore & Associates, Flagstaff, AZ) is a single-branch thoracic endograft currently in clinical trials. It is based on the Conformable Thoracic Aortic Graft
(CTAG), and contains a single internal portal oriented in a caudal direction. We have
found that implantation of the TBE is expedited and simplied by rst obtaining
through-and-through (body oss) wire access through the groin and the left arm
(Fig.7). Prior to transfemoral delivery of the device, it is pre-cannulated with the
main body device loaded on a stiff aortic wire and the second through-and-through
wire through the portal. The main body device is delivered into the thoracic aorta
(with care taken to ensure no wire-wrap). (Fig.8) The main body is deployed, and a
purpose-built side branch endograft is then delivered transfemorally over this
second wire and positioned to bridge from the portal into the desired branch vessel
(Figs.9 and 10). At our institution, we have used this device on trial many times to
treat a variety of pathologies, and nd it well-suited to some trauma cases.
Management: Surgical—Open
Since the introduction of TEVAR, open surgical repair of BTAI has been supplanted
by endovascular repair. However, in rare circumstances, open repair might be
necessary. For example, a natural disaster or mass casualty incident could make it
difcult or impossible to obtain an appropriate thoracic endograft for endovascular
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Fig. 6 A reconstructed
parasagittal view of the
thoracic aorta
demonstrating a proximal
Grade III blunt thoracic
aortic injury encroaching
on the left subclavian
artery
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Fig. 7 From left: Fluoroscopic views of the descending thoracic aorta demonstrating the use of a
snare (delivered via the right groin) to capture a wire (delivered from the left arm), providing
through-and-through access to facilitate branched endograft placement
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Fig. 8 Fluoroscopic view
of the thoracic aorta
demonstrating the main
body of the thoracic
branched device being
positioned in the distal
arch/proximal descending
aorta. The through-andthrough wire exits the left
arm and right groin, and is
used to pre-cannulate the
portal of the device prior to
inserting it into the body
Fig. 9 Completion
angiogram after treatment
of the blunt thoracic aortic
injury using a thoracic
branched device
B. L. Tjaden and A. L. Estrera
treatment. Open repair of BTAI is challenging—and should ideally be undertaken
by surgeons experienced in open thoracic aortic repair.
Open repair should be performed using a dual-lumen endotracheal tube with
single-lung ventilation. The patient should be positioned in the right lateral decubitus
position in preparation for a left lateral thoracotomy. Partial left heart bypass is
initiated by cannulating the left inferior pulmonary vein for venous drainage and the
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Fig. 10 A selection of images from a CTA of the chest obtained 3 months after treatment of a
blunt thoracic aortic injury with a branched endograft. These images demonstrate excellent aortic
remodeling and no endoleak
left common femoral artery or distal thoracic aorta for arterial return. Once the
patient is heparinized and partial left heart bypass is initiated, proximal control is
obtained by clamping the aorta in zone 2, just proximal to the LSA, and using a
separate clamp on the proximal LSA. This is performed because the tear often
encroaches on the origin of the LSA.Distal control is easily obtained on the aorta
just proximal to the arterial in-ow cannulation site. The aorta is opened (Fig.11)
and the segment involved is replaced using an appropriately sized Dacron graft
(Fig.12). Chest tubes are placed prior to closure [39].
Surveillance
Patients treated for BTAI with open repair may not need dedicated thoracic imaging
in the future, unless there is concern for graft contamination or infection due to
other associated injuries within the chest. On the other hand, patients treated with
TEVAR require surveillance to identify potential endograft complications, such as
migration, kinking, or thrombosis. In general, we obtain a CTA of the chest
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