Blunt
trauma to the thoracic aorta: mechanisms involved, diagnosis and management
(Portuguese
PDF version)
Roberto
Chiesa1, Marcelo Ruettimann Liberato de Moura1,
Carla Lucci1, Renata Castellano1,
Efrem Civilini1, Germano Melissano1,
Yamume Tshomba1
1.
Department of Vascular Surgery, Università Vita-Salute, IRCCS San
Raffaele, Milan, Italy.
Correspondence:
Prof. Roberto Chiesa
Department of Vascular Surgery
IRCCS H. San Raffaele
Via Olgettina, 60 - 20132, Milano
Italia
E-mail: chiesa.roberto@hsr.it
ABSTRACT
Traumatic
rupture of the thoracic aorta is a life threatening situation, and
may be secondary to several mechanisms; mainly penetrating or iatrogenic
lesions and blunt trauma. Although penetrating mechanisms predominate,
the number of patients with aortic disruption due to blunt trauma
has continued to increase. This paper shows an overview focusing
on the pathogenesis, diagnosis, timing and type of treatment regarding
traumatic injuries of the thoracic aorta; it also reports the experience
of one single center that deals with these lesions.
The major difficulty in the evaluation data on blunt aortic injury
is that retrospective reviews often group together patients with
all types of aortic lesions, comparing outcomes for injuries in
different locations, with diverse methods of repair and different
surgeons and/or institutions.
Key
words: trauma, thoracic aorta, treatment.
Palavras-chave: trauma, aorta torácica, tratamento.
J
Vasc Br 2003;2(3):197-209
Aortic
injuries may be secondary to several mechanisms; mainly penetrating
or iatrogenic lesions and blunt trauma.1-3
In a recent large autopsy study, Dosios et al.4
showed that all penetrating trauma victims died before reaching the
hospital, whereas 5.5% of the blunt trauma victims were admitted to
hospital alive; therefore surgeons will generally face blunt thoracic
aortic traumas.
Blunt aortic injury occurs as the result of motor vehicle accidents,
falls, and crush injuries and it may account for 10 to 15% of deaths
caused by vehicular crashes.5
It is estimated that between 70 and 90% of patients sustaining this
injury die at the scene from free aortic rupture. The 10 to 20% of patients
with thoracic aorta injuries who survive long enough to reach the hospital
have a dismal prognosis: it has been estimated that approximately 30%
of them will succumb within six hours, 40 to 50% within 24 hours and
90% within four months, unless expedient and proper diagnostic and therapeutic
measures are undertaken.6
Pate et al. found that associated injuries were present in more than
90% of patients with aortic transection, and 24% of them required a
major operation before aortic repair.7
The major complications of survivors diagnosed and treated are related
to associated injuries and spinal cord ischemia after surgical treatment.
The characteristics of thoracic aorta injuries have made it difficult
for single centers to accumulate large series of patients. Most studies
are retrospective, performed on relatively small populations8-10
or done over long time periods11-12 or
concentrated on one particular method of treatment.13-16
Thus, many questions and controversies persist with regard to the optimal
methods of diagnosis and treatment of this pathology.
PATHOGENESIS
Mechanisms
of trauma
Over 90% of thoracic great-vessel injuries are caused by penetrating
trauma.1
Penetrating injuries include complete or partial transections and arteriovenous
fistulae.
Most penetrating lesions are located at the ascending aorta and arch
branches, with a very poor prognosis, which renders them rare in the
clinical setting.4
Although penetrating mechanisms predominate, the number of patients
with aortic disruption due to blunt trauma has continued to increase.17
Aortic rupture in blunt trauma results most commonly from sudden high
speed deceleration and less frequently from chest compression (Figure
1).
 Figure
1- Common mechanism of aortic injury: a high-speed frontal deceleration
collision.
Other
mechanisms involved in blunt aortic injuries might include compression
of the vessels between bony structures, such as sternum and spine, and
profound intraluminal hypertension during a severe traumatic event.18-20
Lesion
topography
The typical point of injury is located in the most proximal descending
aorta, at the site of insertion of ligamentum arteriosum, just distal
to the origin of the left subclavian artery (Figure 2).6
At this point, a highly mobile region of the aorta is placed between
two fixed segments: the aortic arch is anchored with the neck vessels
including the left subclavian artery, and the descending thoracic aorta
is fixed to the thorax by the ligamentum arteriosum and by the intercostal
vessels. The mobile part of the aorta, which is the distal part of the
arch and the most proximal part of the descending, is only loosely fixed
to the chest wall by the parietal pleura. With abrupt thorax deceleration
the fixed portions decelerate with the chest, but the loosely fixed
part continues to move forward until they finally decelerate: aortic
rupture occurs at the interface between these two parts.21
Figure
2 - Principal location of thoracic aortic lesions.
Total
rupture or transection apply to the full thickness separation of the
aorta, which can be partial or circumferential. On the other hand, injury
or partial rupture refers to lesions without a complete wall disruption.
True traumatic dissection, which involves a longitudinal separation
of the media along the length of the aorta, has rarely been reported.22
DIAGNOSIS
Each clinical
situation, depending on patient's general status, must be individually
judged searching for the best diagnostic studies.
Anamnesis
Although an accurate history and physical examination are necessary,
clinical signs and symptoms are often lacking in these patients. A high
index of suspicion is the cornerstone for timely diagnosis of thoracic
aorta injuries. Aortic injury must be suspected in any patient with
high-energy trauma to the chest.
Clinical
findings
Aortic trauma is often obscured by the presence of other serious injuries.21
Nevertheless, if the diagnosis is made, it can overshadow the presence
of other severe and more lethal lesions. Head trauma, massive abdominal
hemorrhage, extensive burns and respiratory distress mandate the delaying
treatment of traumatic aortic injuries. On the other hand, the radiological
finding of an expanding mediastinal area, increasing hemothorax and/or
anuria, gives priority to the treatment of a thoracic aortic lesion.
The clinical signs can be as unspecific as interscapular or thoracic
pain, which can happen with aortic adventitia distension. However, patients
can rarely present more specific syndromes like an aortic "pseudocoarctation",
coursing with superior member hypertension and reduced or absent femoral
pulses.23 Intimal flaps or dissections can
cause ischemic complications, and finally if a total rupture is present,
bleeding into the mediastinum and pleura will cause hemodynamic instability,
worsening pain and death in the majority of cases.
Imaging
studies
The diagnostic practice depends on patient's conditions on hospital
admission. The kind of aortic and associated lesions influence the outcome
and diagnostic protocol, according to the patient's hemodynamic status.
Chest
radiograph
The first step is to obtain a chest radiograph, as initial radiological
evaluation, in every high-speed trauma patient with suspected blunt
traumatic aortic injury. There are several radiological findings reported
for traumatic aortic rupture. Many studies have shown that the widened
mediastinum on chest radiographs is present in more than 90% of thoracic
aortic injuries.24 (Figure 3). Other frequent
signs are irregularity or blurring of the aortic knob contour, presence
of a left apical cap and a tracheal displacement.25
With a 90% sensitivity, a 25% specificity, and a 95% negative predictive
value, the chest radiography is a valuable screening tool for mediastinal
hemorrhage, but is worth little as far as definitive diagnosis is concerned.26
It is important to obtain serial follow-up chest films in patients with
a high clinical suspicion for aortic lesion, because radiographic abnormalities
may be absent on initial evaluation.
Figure
3 - Chest radiograph showing a widening mediastinum and left lung contusion.
Spiral
computer tomography (SCT)
Spiral computer tomography is currently considered not only as a screening
method to select patients for thoracic aortography, but also as a definitive
diagnostic procedure, since it recognizes aortic injuries and rupture
(Figure 4). Comparing it to aortography, it is less invasive, faster
to obtain, more readily available and less expensive.27
Figure
4 - SCT demonstrates: thoracic aortic injury at the descending part
with vessel wall irregularity and left hemothorax.
Some direct
signs of aortic lesions at SCT are intimal flap, intramural hematoma
or dissection, aortic wall or contour irregularity, pseudoaneurysm and
pseudo-coarctation.28 The presence of a
hemomediastinum is well characterized by a SCT and represents an important
indirect sign of aortic trauma. The use of 2D and 3D reconstructions
on SCT aortography creates images very close to those obtained by conventional
aortography,29 providing the surgeon with
important anatomic information. A normal mediastinum and a regular aorta
seen on SCT1 have been considered a sign
of 99.9% of negative predictive value for aortic lesions.
A total body study can also provide important information regarding
associate lesions.
Angiography
Aortography is traditionally considered the "gold standard"
imaging study to detect aortic injury, to define its location and extent.
It also provides important information about the vascular anatomy that
can influence the operative strategy. The demonstration of an irregular
or discontinued contour of the aortic lumen represents the aortographic
diagnosis of blunt traumatic aortic injuries. Intimal flap, aortic dissection,
posttraumatic coarctation, or luminal outpouching relating to a pseudoaneurysm
are other aortographic patterns caused by blunt traumatic aortic lesions.
Thoracic aortography can detect blunt traumatic aortic injuries with
a sensitivity and specificity of 95 to 99% and 94 to 100%, respectively.31-33
False negative examinations relate to incomplete series, inadequate
injections or projections. False positives often relate to prominent
ductus diverticulum or from ulcerated atheromas.
Transesophageal
echography (TEE)
Transesophageal echography (TEE) combined with color Doppler flow mapping
can accurately demonstrate isthmic lesions34-36
(Figure 5). This diagnostic method can be rapidly and simultaneously
realized with other procedures like mechanical ventilation or laparotomy.
TEE may be very useful for unstable patients, since it is not possible
to perform other time consuming studies in such cases.
Figure
5 - TEE showing a post isthmic aortic pseudoaneurysm with a clear large
neck and high velocity flow inside.(TL: true lumen; PA: pseudoaneurysm)
Magnetic
resonance angiography (MR-A)
The results of magnetic resonance angiography MR-A) are comparable to
those of SCT and conventional aortography. Nevertheless, MR has several
limitations as the time spent completing the exam and the inaccessibility
of the patient during examination, which exclude its routine use in
urgent cases.26
Intravascular
ultrasound (IVUS)
Intravascular ultrasound (IVUS) imaging has been described as a complementary
method for clarifying slight focal aortic abnormalities not visible
with thoracic aortography. Its use is until now limited and mainly associated
with endovascular procedures.37
Diagnostic practice for traumatic aortic injury is based on mechanism
of injury, chest radiography and SCT scan or aortography; all of these
modalities have limitations and thus must be considered in concert.
TREATMENT
Timing
The treatment of patients who survive to reach the hospital remains
controversial. The original strategy of immediate aortic repair38
has been challenged by recent reports of successful delayed repair.39
Although traumatic rupture of the thoracic aorta has traditionally been
considered a surgical emergency, there is a patient population for whom
non-operative management may be appropriate.
Indications for urgent operative repair include hemodynamic instability,
increasing hemorrhage from the chest tubes, and radiographic evidence
of an expanding hematoma.
Delayed repair may be considered in selected hemodynamically stable
patients, who may not necessarily benefit from immediate repair, including
patients with severe head injuries, risk factors for infections (major
burns, sepsis, heavily contaminated wounds), severe multisystem trauma
with poor physiologic reserve.
The basis for non-operative management is that maintaining the systolic
blood pressure below 120 mmHg or mean arterial pressure below 80 mmHg
significantly reduces the risk of rupture.
The risk of fatal rupture of the periaortic hematoma in hemodynamically
stable patients has been estimated to be 4,5% within the first 72 hours,
but it does not increase if conservative treatment is further continued.39
This might be related to the maintenance of aortic adventitia continuity
in patients who survive, and, hemorrhage is contained by the surrounding
mediastinal structures. These patients may develop chronic pseudoaneurysms.
Although a small risk of free rupture still remains, data supports the
concept that non-operative management of aortic lesions can be utilized
safely in selected cases. In some cases of smaller aortic tears, the
lesion may heal on its own.
The downside of the delayed repair is that due to the extensive scarring
at the site and around the injury, the surgical dissection of the aorta
is more difficult and tedious, unless an endovascular procedure could
not be performed.
Current indications for delaying the aortic repair in the hemodynamically
stable patient include: trauma to the central nervous system with coma,
respiratory failure from lung contusion, body surface burns, blunt cardiac
injury, tears of solid organs that will undergo non-operative management,
retroperitoneal hematoma, contaminated wounds, age 50 years or older,
medical comorbidities.22
Approach
Patient positioning and skin incision are important, as adequate exposure
is mandatory for proximal and distal control of great vessels (Figure
6). General exposure and skin preparation should include the anterior
neck, thorax, abdomen and a lower extremity. When a subclavian injury
is suspected, the ipsilateral arm should be prepared and draped in a
fashion that maintains free mobility of the shoulder.
Figure
6 - Most common approaches to the thoracic aorta: (A) Posterolateral
thoracotomy, with possible abdominal extension; (B) anterior thoracotomy,
with possible contra-lateral extension and/or sternotomy.
The left
posterolateral thoracotomy provides excellent exposure to virtually
all portions of the hemithorax.40
This approach may allow a transverse sternotomy in case of difficult
control of the proximal aorta. Associated phrenoceliotomy may be performed
to treat previous undiagnosed abdominal vascular and visceral injuries.
For hypotensive patients with undiagnosed injury, the best approach
to thoracic trauma surgery is the left anterior thoracotomy on fourth
intercostal space, with patient in supine position.
This is also the incision of choice for rapid access to the mediastinum
for open cardiac massage. When additional exposure is needed, an anterior
thoracotomy may be extended across the sternum in the midline; it is
also possible to extend the incision posteriorly, in order to have a
better control of proximal aorta.
A median sternotomy is preferred for injuries of the ascending aorta
and of the innominate and proximal carotid arteries. Extension into
the neck, along the anterior border of the right sternocleidomastoid
muscle, allows access to the proximal right subclavian artery, and to
the right vertebral artery.
A thoracosternotomy41 associates the anterolateral
thoracotomy through the third intercostal space to a median sternotomy.
This procedure permits a rapid access to the mediastinum, to have the
control of the proximal aorta and if it is necessary, to perform cardiopulmonary
bypass.
Techniques
of organ perfusion/repair
Debates regarding the optimal management of injury to the thoracic aorta
after trauma continue because of concerns about spinal cord ischemia
and the potential for paraplegia. Several methods for indirect assessment
of perfusion are available during thoracic and thoracoabdominal aortic
surgery, however in emergency situations, the operation needs to be
performed as expeditiously as possible without these techniques.
The technique of choice is indeed dictated by the urgency of the patient's
condition, availability of technical personnel and surgeon preference
at each hospital.
Clamp
and sew
The single clamp-and-sew method of repair has many strong advocates,
who point to its simplicity, the low paraplegia rate if cross clamp
times are short, and a low mortality rate as compared with approaches
that use heparin.16,24,42
Sweeney et al.43 reported a mortality rate
of 12% and a permanent paraplegia rate of 1.3% with a mean cross-clamp
time of 24 minutes. However, a cross-clamp time this brief cannot be
guaranteed9 and most surgical groups do
not meet this mark.44,45
Experimental data and clinical series have demonstrated that the occlusion
of the descending thoracic aorta for more than 30 minutes is associated
with the development of postoperative spinal cord ischemia. When the
clamping time reaches one hour there is a correlate risk of paraplegia
of approximately 40%.45-47
The average international cross-clamp time, as reported by Von Oppel
and co-workers, is 41 minutes.47
Even those who advocate the clamp-and-sew technique have patients with
paraplegia, because of unexpectedly long cross-clamp times. Most recently,
groups using this technique reported paraplegia rates ranging from 2
to 24% (Table 1).
Table
1- Literature results of TRTA* repair with clamp and sew technique
 |
|
Author |
Year |
n of patients |
Mortality (%) |
Paraplegia/Paraparesis (%)† |
|
|
Schmidt14 |
1992 |
32 |
5 (16) |
1 (3.7)† |
|
Maggisano39 |
1995 |
36 |
3 (8) |
1 (3.0)† |
|
Sweeney43 |
1997 |
71 |
9 (13) |
1 (2.0)† |
|
Fabian45 |
1997 |
73 |
11 (15) |
12 (16.4) |
|
Attar48 |
1999 |
54 |
12 (22) |
10 (24.0)† |
|
Jahromi49 |
2001 |
21 |
2 (10) |
3 (16.0)† |
|
*Related
to live patients.
† TRTA = trauma of the thoracic aorta.
This is
in contrast to the result of 0 to 7% achieved by those who use active
distal support.7,45,50
Active
distal circulatory support
Active distal circulatory support is very effective in reducing the
risk of paraplegia, particularly when long cross-clamp times are needed.
Simple aortic clamping is known to raise cerebrospinal fluid pressures,
which could exacerbate intracranial injuries. Unloading of the proximal
aorta with an active distal support system may minimize that rise.
The adjuncts for distal aortic perfusion reduce but do not eliminate
the risk of neurological deficits.49 Distal
support has another theoretical advantage over simple clamping: it provides
proximal cardiac unloading,51 which may
be helpful in elderly patients and in those with myocardial contusions.
The most common methods of distal circulatory support are complete (CPB)
and partial (PCPB) cardiopulmonary bypass, or left atrial to aortic
or femoral bypass (lkeft hear bypass, LHBP).
Cardiopulmonary
bypass
Cardiopulmonary bypass (CPB) has the ability to oxygenate, scavenge
shed blood and heat and cool as desired.7,44
However, the use of full anticoagulation in a multiply injured patient
may increase the risk of bleeding and death. For this reason, complete
cardiopulmonary bypass has largely fallen into disfavor. Patients with
thoracic aortic injuries at multiple levels who require extensive repair
are notable exceptions.52
Partial cardiopulmonary bypass (PCPB) with heparin-bonded circuits has
been validated as an attractive option in the setting of TRTA (trauma
of the thoracic aorta) as a means of avoiding the use of systemic heparinization.
Cannulation of the right atrium via the femoral vein is simple and provides
a clear, unobstructed field in which to work.52
As opposed to LHBP, it can provide adequate distal circulatory support
and safely heat, cool, oxygenate and transfuse as required. Improved
oxygenation may also be attained with PCPB in the presence of lung contusions.7
Some literature results are seen in Table 2.
Table
2- Literature results of TRTA repair using partial-(full) CPB technique
|
|
Author |
Year |
n of patients |
Mortality (%) |
Paraplegia/Paraparesis (%) |
|
|
Soyer50 |
1992 |
43 |
3 (7.0) |
0 |
|
Pate7 |
1995 |
88 |
6 (7.0) |
2 (2) |
|
Fabian45 |
1997 |
39 |
5 (12.8) |
3 (7.7) |
|
Fabian (full)45 |
1997 |
22 |
5 (22.7) |
1 (4.5) |
|
Gammie44 |
1998 |
10 |
1 (10.0) |
0 |
|
Attar48 |
1999 |
43 |
7 (16.0) |
0 |
|
Jamieson53 |
2002 |
42 |
5 (12.0) |
0 |
|
Left
heart bypass (LHBP)
LHBP, which is connected between the left atrium and distal aorta or
a femoral artery, can be used with little or no heparin because an oxygenator
is not required.
However, it has some limitations: LHBP systems do not incorporate a
heat exchanger and are dependent on adequate pulmonary function for
oxygenation. Cannulation of the left atrial appendage or pulmonary vein
can sometimes be difficult in the presence of an extensive mediastinal
hematoma; additionally, because of the risk of air embolization in these
closed systems, physicians are reluctant to rapidly infuse volume through
them.
Injuries to the aortic arch, innominate artery, or ascending aorta,
which represent a minority of aortic trauma cases, cannot be repaired
with LHBP. Full cardiopulmonary bypass or even profound hypothermic
circulatory arrest may be necessary. Furthermore, in patients who present
in extremis, necessitating immediate control of hemorrhage and restoration
of blood volume before repair, partial bypass may offer no advantage.
However, the majority of aortic transections occur at the isthmus and
patients who survive are usually hemodynamically stable, with the periaortic
hematoma contained in the mediastinum. These injuries can be complex
or close to the proximal cross-clamp, thus complicating and potentially
prolonging the repair. The adjuvant use of LHBP (Table 3) may help in
extending the critical window.
Table
3- Literature results of TRTA repair using LHBP technique
|
|
Author |
Year |
Number of Pts |
Mortality (%) |
Paraplegia/Paraparesis (%) |
|
|
Read61 |
1993 |
16 |
2 (13.0) |
0 |
|
Kipfer62 |
1994 |
10 |
0 |
0 |
|
Contino63 |
1994 |
24 |
5 (20.8) |
0 |
|
Fabian45 |
1997 |
69 |
10 (14.5) |
2 (2.9) |
|
Gammie44 |
1998 |
14 |
1 (7.0) |
0 |
|
Symbas64 |
2002 |
19 |
5 (26.0) |
0 |
|
|
Surgical
techniques
Injury usually originates in the medial side of the aorta at the level
of the ligamentum arteriosum.
The object of initial operative approach is to obtain the proximal and
distal control of the descending thoracic aorta.
Vascular clamps are applied to three locations: proximal aorta, distal
aorta and subclavian artery. The hematoma is entered, and back bleeding
from intercostal arteries is controlled. Care is taken to avoid indiscriminate
ligation of intercostal vessels: only those required for adequate repair
should be ligated.
During aortic reconstruction clamps should be moved as close as possible
to the site of injury, in order to reduce spinal cord ischemia, especially
with the clamp-sew technique.
Primary suture and graft interposition are the main strategies of aortic
repair after a traumatic lesion.
The first is usually the preferred choice because it is simple and fast.
This technique is adequate in cases of partial laceration, but also
in disruptions when aortic stumps are not too distant and severely damaged.
Frequently, in aortic trauma, adventitial layers are retracted and must
be carefully included in the aortic suture; during this phase, the esophagus
must be accurately separated from the posterior aortic wall. Teflon-felt
pledgets can be useful to strengthen a friable suture line. Finally,
the absence of a prosthetic graft decreases risk of infection.
Graft interposition has been used in more than 85% of the reported cases,11
and is advisable when more than 2 cm of vessel are injured. The aorta
is grafted with a straight Dacron® Vascular graft which is kept
as short as possible.
Complications
Significant postoperative complications related to the thoracic injury
can develop in these patients. Cardiac, renal, pulmonary and neurological
morbidities have been reported in literature with rates of up to 50%.59
The most common complications reported were: adult respiratory distress
syndrome and pneumonia (29.5%), severe systemic hypertension (20.5%),
coagulopathy, renal failure, serious cardiac arrhythmias, late tension
pneumothorax and thoracic wound infection.7
Paraplegia is the most devastating complication after repair of descending
aortic transection, since most of the patients who suffer blunt aortic
injury are young. The personal loss caused by paraplegia and the economic
impact on society are enormous.
The two central issues associated with prevention of paraplegia are
duration of cross-clamp and use of distal aortic perfusion.
Patients with acute aortic rupture are at a greater risk for paraplegia
during aortic repair than patients with chronic aneurysms or coarctation.
This increased risk is likely due to the lack of preformed collaterals,
along with the additional complication unique to trauma patients, including
pulmonary and cardiac contusions, shock, hypoxia and hyposmolality from
fluid overload.7
Late deaths, in fact, are most often due to multiple organ failure.60
As any major thoracic aortic surgery, these operations carry a high
risk of bleeding with coagulopathy and the need for massive transfusion;
acute renal failure, acute respiratory failure with the need for prolonged
mechanical ventilation.
Nevertheless, whatever the type of lesion and the surgical technique,
most deaths are secondary to associated lesions.
Endovascular
intervention
Despite advances in surgical and perioperative care, conventional surgery
for acute aortic rupture still carries a significant morbidity and mortality.
Thus, endovascular procedures may be an attractive option for treating
these kinds of lesions, and patients with other important comorbidities61
(Figures 7A and 7B).
Figures
7a - A less invasive technique: (A) isthmic injury with localized dissection
and (B) endovascular exclusion showed with CT scan.
Figures
7b - A less invasive technique: (A) isthmic injury with localized dissection
and (B) endovascular exclusion showed with CT scan.
Theoretical
advantages of stent-grafting are multiple: the absence of aortic cross-clamping
prevents rising of intracranial pressure in some situations as severe
head injury; patients with pulmonary contusions do not need one-lung
ventilation as used for conventional surgical repair.
Critical statements have pronounced a high risk of spinal cord ischemia
due to the exclusion of intercostal arteries during endovascular treatment.
Nevertheless, the placement of vascular stent grafts has not yet been
shown to increase the risk of paraplegia as compared to conventional
surgical intervention. The largest series of thoracic aortic diseases
electively treated with endoluminal grafts reported a paraplegia rate
of 3.6%.62 Up to 70% of traumatic aortic
injuries affect the isthmus segment. Thus, only a few branches to the
spinal cord might be excluded by the endoprosthesis.
Lachat et al.63 have reported significant
lower rates of morbidity and mortality for stent grafting of acute aortic
lesions demonstrating the benefits and advantages offered by this minimally
invasive technique. In their report patients were hemodynamically stable
to undergo contrast enhanced computed tomography (CT) and angiographic
evaluation to determine the suitability for stent grafting. TEE and
IVUS have been described by these and other authors as helpful associated
diagnostic studies.64 Early endovascular
treatment was considered in the management of stable non-bleeding lesions,
after recovery of associated life threatening injuries. The rupture
had to be contained, with a proximal neck of normal appearance with
length greater than 5 mm, and a diameter of 36 mm or less. Depending
on the associated lesions and the bleeding risk, no heparin at all or
a maximum dose of 5,000 IU was intravenously administrated and completely
reversed after stent graft delivery. Immediate technical success rate
was 100% as the aortic lesion could be excluded in all the cases; there
was one early death due to hemorrhagic shock in a patient with a semicircular
rupture who probably had an undetected incomplete proximal sealing.
Because most injuries occur at the aortic isthmus, much concern has
been raised regarding the placement of rigid devices in an angulated
aortic arch. As previously described, this can cause an inadequate seal
of thoracic aorta. However, this has been largely overcome with newer
and more flexible devices.
This new therapeutic strategy has few drawbacks worth describing. The
delivery systems caliber are actually of large diameter (18 Fr to 24
Fr), being difficult to introduce through small and spastic arteries
of young people or tortuous and calcified arteries of older people.
A further concern is the stock inventory of devices, which must be available
for emergency cases in different sizes and lengths.
Another topic of concern is the relatively young population suffering
from aortic trauma: stent-grafts are actually produced mainly for treatment
of chronic aortic pathologies, especially aneurysms, and do not come
in adequate diameters for the small vessels of young people. Moreover,
the mean age (38.7 years)45 of this population
raises many questions about the long-term follow-up after endoluminal
treatment.
Additional studies on the role of endovascular interventions in aortic
injury are required to acchieve a stronger support for its use in this
scenario.
OUR
EXPERIENCE
Between January 1993 and April 2003, 20 patients with acute injury or
rupture of thoracic aorta were admitted to the Emergency Department
of our Institution. There were 16 (80%) males and four (20%) females
whose ages ranged from 19 to 77 years (mean age of 43 years). Fifteen
patients had history of motor vehicle crash, two suffered from a motorcycle
crash and three had lesions secondary to penetrating traumas.
Seven patients died in the emergency department, five of them arrived
in extremely critical conditions. The other two died during urgent thoracotomy
dictated by hemodynamic deterioration, before bleeding could be controlled.
An early chest radiograph was obtained in fourteen patients. SCT and/or
aortography studies were performed in 12 patients with stable hemodynamic
conditions. Three cases also underwent TEE.
Associated lesions were found in every patient of our series (Table
4), and were present mainly in those cases that died in the emergency
department. The most common lesions were other thoracic injuries in
16 patients.
Table
4 - Localization of concomitant injuries
|
|
Injury |
n |
|
|
Other thoracic traumas (including fractures and great vessels) |
16 |
|
Abdominal visceral |
8 |
|
Closed-head injury |
7 |
|
Peripheral fractures |
6 |
|
Head fractures |
4 |
|
Abdominal vascular |
2 |
|
Neck fracture |
1 |
|
Table
5 summarizes the clinical and surgical features of patients.
Table
5 - Patients admitted to our service with thoracic aortic trauma
|
|
Case |
Sex |
Age |
Lesion Characteristics |
Procedure |
In-hospital Outcome |
Follow-up |
|
|
1 |
M |
31 |
Isthmic rupture (MVC) |
Autopsy findings |
|
|
|
2 |
M |
31 |
Descending thoracic aortic dissection and rupture (MVC) |
Graft interposition (Clamp and sew) |
Discharged |
Alive after 96 months |
|
3 |
M |
28 |
Isthmic rupture (MVC) |
Urgent thoracotomy |
Death in emergency-room (hemorrhagic shock) |
|
|
4 |
M |
38 |
Ascending aorta perforation (STAB WOUND-large fork for cooking)
|
Sternotomy (Simple suture) |
Discharged |
Alive after 60 months |
|
5 |
M |
68 |
Isthmic rupture (MVC) |
Autopsy findings |
|
|
|
6 |
M |
19 |
Descending-thoracic aorta perforation(GUNSHOT) |
Urgent thoracotomy |
Death in emergency room (hemorrhagic shock) |
|
|
7 |
M |
17 |
Isthmic rupture – (MVC) |
Graft interposition (LHBP) |
Discharged |
Alive after 36 months |
|
8 |
M |
43 |
Descending thoracic aortic perforation (METALLIC BAR for building
construction) |
Urgent thoraco-phrenolaparotomy |
Death in surgery room (uncontrolled bleeding) |
|
|
9 |
F |
35 |
Isthmic rupture (MVC) |
Autopsy findings |
|
|
|
10 |
M |
26 |
Descending thoracic aortic injury-pseudoaneurysm (MC) |
Graft interposition (LHBP) |
Discharged |
Alive after 30 months |
|
11 |
M |
63 |
Isthmic injury – pseudoaneurysm (MVC) |
Endovascular exclusion |
Discharged |
Alive after 18 months |
|
12 |
F |
56 |
Isthmic rupture (MVC) |
Graft interposition (Clamp and sew) |
Death in immediate post-operative period (cardiac arrest) |
|
|
13 |
F |
63 |
Ascending aorta rupture (MVC) |
Graft interposition (CPB) |
Discharged |
Alive and paraplegic after 10 months |
|
14 |
M |
52 |
Isthmic injury – pseudoaneurysm (MVC) |
Endovascular exclusion |
Discharged |
Alive after eight months |
|
15 |
M |
34 |
Isthmic injury pseudoaneurysm (MVC) |
Graft interposition (LHBP) |
Discharged |
Alive after six months |
|
16 |
M |
56 |
Ascending rupture (MVC) |
Autopsy findings |
|
|
|
17 |
M |
48 |
Isthmic injury – pseudoaneurysm (MVC) |
Graft interposition (LHBP) |
Death in post-operative period (MOF) |
|
|
18 |
F |
42 |
Isthmic injury – pseudoaneurysm (MVC) |
Graft interposition (LHBP) |
Discharged |
Alive after two months |
|
19 |
F |
22 |
Isthmic and diaphragmatic aortic rupture (MC) |
Autopsy findings |
|
|
|
20 |
M |
77 |
Isthmic localized dissection (MVC) |
Endovascular exclusion |
Discharged |
Alive after one month |
|
MVC:
motor vehicle crash; MC: motorcycle crash.
Hospital
mortality for patients undergoing surgical and endovascular repair was
3/13 (23%). The first case was of a 56-year-old woman involved in a
motor vehicle accident. Thoracic aortic rupture repair was performed
using clamp and sew technique, and during wound closure, she suffered
from an irreversible cardiac arrest. The second was of a 43-year-old
man who died of uncontrolled bleeding during repair of a penetrating
lesion of the median thoracic aorta. The third death was in of a 48-year-old
man who underwent repair of an isthmic pseudoaneurysm using LHBP, and
died on the 12th postoperative day of multiple organ failure.
One patient developed paraplegia following a graft interposition with
CPB. The other nine suffered no major complications, and were discharged
in good condition.
CONCLUSION
The major
difficulty in the evaluation data on blunt aortic injury is that retrospective
reviews often group patients with all aortic lesions together, comparing
outcomes for injuries in a variety of aortic locations, with diverse
methods of timing and vessel repair. At the same time, the treatment
depends on the surgeon's experience at different institutions.
Concomitant severe lesions are usually present in patients suffering
from aortic trauma, thus diagnostic and therapeutic timing must be properly
and rapidly established. Polytrauma patient should be managed under
a multidisciplinary approach, and treated in specialized centers.
Other studies on the role of endovascular interventions in aortic trauma
should be carried out to achieve a stronger support for its use in this
scenario. Preliminary results permit the vascular surgeon to consider
endoluminal treatment as a valuable alternative in selected cases.
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