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23 • Surgical Damage Control and Temporary Vascular Shunts 295
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be needed for adequate placement of clamps and allow for
placement of an interposition graft to noninjured segments
of the vessel. The shunt is then clamped in the center and
removed from the proximal and distal portions of the interrupted vessel allowing for fore- and back-bleeding prior to
application of appropriately positioned clamps. Repeat balloon-catheter thrombectomy and instillation of heparinized
saline solution is recommended in most cases to conrm
and optimize inow and outow following shunt removal.
Systemic heparinization may not be possible depending on
the status of the patient and concomitant injuries. If not,
instillation of a heparinized saline solution into the proximal and distal ends of the injured vessel (i.e., local heparinization) should be performed followed by re-clamping.
Inspection of the proximal and distal end of the artery
where the shunt was secured is important to conrm
healthy, uninjured vessel wall. In most cases, the vessel should be trimmed/débrided to avoid degeneration of
the injured or ischemic segment of the artery or vein that
was used to secure the shunt. Appropriate conduit should
be prepared with great saphenous vein being the optimal
choice in most situations. Adequate length is important,
and one should err on the side of caution in the event that
the bypass segment needs to be longer than the shunted
segment. After the shunt is removed and these preparatory
steps are taken, the vascular reconstruction should be completed with meticulous attention to technical detail (e.g.,
spatulated ends, monolament suture, and fore- and backbleeding and ushing prior to restoring ow).
Dwell Time
There is no exact answer as to how long a temporary vascular shunt can remain in place, and given the wide range of
scenarios in which they may be applied, optimal dwell time
is at the discretion of the damage control team. Because
shunt-related complications, such as thrombus formation,
with or without distal embolization or occlusion, increase
with time, the device should be removed as soon as possible; typically, as soon as circumstances allow for denitive
vascular reconstruction. Although clinical reports document shunts remaining patent for up to 52 hours, these are
extreme cases and more common scenarios have shunts in
place between 2 and 5 hours. Typically, shunts temporize
the vascular injury and maintain distal ow during the
time it takes to stabilize an extremity fracture, perform a
higher-priority operation or optimize a patient’s physiology
before attempting denitive vascular reconstruction. Dwell
times of 2 to 5 hours are also common among recent military reports as the time needed to transport a casualty to a
higher level or echelon of care. Some civilian series report
dwell times that reect a “resuscitation time” or that are
required to normalize patient physiology in the damage
control setting (averages of 24 hours).
16
Special Considerations
ANATOMIC LOCATION (VESSEL SIZE)
An important consideration regarding whether or not to
place a temporary shunt relates to the anatomic location
of the vascular injury. Shunts are more amenable to, and
perform better in larger vessels. Interruption of blood ow
in large, more proximal locations has a greater impact on
the limb or end organ as the vessel is more commonly the
main channel on which inow or outow depends. As such,
continued tourniquet application or ligation of large, proximal vascular injuries has more severe consequences which
can be mitigated by restoring ow with a shunt. Temporary
shunts are also technically easier to place in large vessels
which have high ow rates and better patency.
In contrast, small vessels located in the distal extremity
or the torso vasculature are often part of a redundant circulation and are thus less signicant. It is also more challenging to place a shunt in a small vessel which carries less
ow and is more prone to thrombosis.21 Examples include
the forearm, where both the ulnar and radial arteries supply the hand, and the leg, where a redundant tibial circulation perfuses the foot. Injury to one of these arteries does
not typically threaten limb and ligation may be the favored
maneuver. Although placement of shunts in small vessels
should be the exception, there are patients with multiple
distal artery injuries, or those with incomplete collateral
perfusion which will benet from temporary restoration of
ow using this technique.
As with all forms of vascular trauma, real time assessment of distal perfusion prior to making a reperfusion decision is required. Surgeons Lavenson, Rich, and Strandness
were among the rst to report the usefulness of continuous wave Doppler in determining distal perfusion and limb
viability in the setting of vascular trauma.33 The presence
or absence of an audible Doppler signal distal to the injury
provides important information as one decides whether to
ligate, shunt, or reconstruct any vascular injury. Continuous wave Doppler can also be repeated over the course of
the management scenario and used to conrm the ow
through the shunt or vascular reconstruction.
ANTICOAGULATION
Full-dose anticoagulation is often not needed to maintain
patency of temporary vascular shunts and should be used
with caution in the setting of severe injury. Although systemic anticoagulation is appealing from the standpoint of
maintaining shunt patency, one must consider the risk of
causing bleeding complications from other sites of injury
(e.g., brain, pelvic, or solid organ). Even slow bleeding from
soft tissue wounds, bone fractures, or fasciotomy incisions
can become problematic with the use of full anticoagulation.
Translational studies and clinical reports on the topic
show that full-dose anticoagulation is not needed for shunts
to remain patent during the early, damage control phase of
care. Dawson and colleagues demonstrated in a porcine
model that the Argyle shunt stayed patent for 24 hours
without full anticoagulation, a nding that was conrmed
by Gifford et al. who used the Sundt device.
series from military and civilian settings also show that vascular shunts are effective without systemic doses of heparin. These reports acknowledge the selective use of full-dose
heparin in rare cases when the injury is isolated or associated with a complicating factor such as initial shunt thrombosis or a heavy burden of clot in the outow circulation.
34,35
Clinical
296 SECTION 4 • The Management of Vascular Trauma
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It is the authors’ recommendation that systemic anticoagulation not be a routine part of temporary vascular
shunt use. Instead, we recommend use of heparinized saline
infused onto and into the vessels in question (i.e., regional
use of heparin) during shunt placement. Doses of systemic
anticoagulation should be reserved for select cases in which
there are no concomitant injuries and/or cases in which the
shunt remains in place for longer periods of time.
VENOUS SHUNTING
Attendant with the success of arterial shunts is the question of the value of this technique for isolated or concomitant venous injuries. The majority of experience with
shunting of venous injuries is from wartime reports in
which combined artery and vein injuries were more common. Preservation of venous outow has practical benets,
including reduced venous hypertension and blood loss from
distal wounds, including fasciotomy incisions. Preservation
of venous outow may also help maintain arterial patency
and thus improve limb or end-organ perfusion.
Like arterial shunts, placement of these devices in venous
injuries is straightforward. Although ow rates are lower
than those in arterial shunts, the patency of venous shunts,
especially those placed in larger more proximal veins, is
comparable.
ries has been reported by military and civilian authors,
including Parry and colleagues from Atlanta who described
18 cases in which orthopedic xation and/or damage control surgery was facilitated with this approach. All venous
shunts in the series from Atlanta were patent upon reexploration at a mean dwell time of 22 hours.36 Wartime
experience with vascular shunts was predominately in the
management of arterial injuries. However, most of the wartime reports included subsets of patients in whom venous
shunting was useful and effective in the management of
their injuries.
21–23
The use of shunts in extremity vein inju-
In this approach, the early use of vascular shunts to restore
perfusion serves as an initial step in determining whether or
not to press on with attempted limb salvage.
Temporary shunts can reduce the warm ischemic time
that negatively affects peripheral nerves, neuromuscular
junctions, and skeletal muscle. Preserving these functional
units improves quality limb salvage (i.e., an extremity that
is more functional). Studies have conrmed this relationship between ischemic time and nerve and muscle damage
and in recent years, limb salvage research has focused on
the principles of achieving quality, and not just statistical
Severe extremity
injury
Operation
exploration
Vascular injury?
Ye s
Simple Complex
Primary repair
(Consider shunt)
Shunt placement
No
Debridement/
Fixation as indicated
ROLE IN LIMB SALVAGE
The decision to attempt to salvage a severely injured limb
versus perform an amputation is often difcult. Arguably
the most immediate and inuential factor in limb preservation is the perfusion status of the extremity. Timely restoration of blood ow is a critical principle upon which limb
viability and functionality rests. Contemporary analysis of
data from the National Trauma Data Bank by Alarhayem
et al. demonstrated that the previously held 6-hour ischemic threshold may be shorter than previously supposed.
In their analysis of over 4400 patients with lower extremity arterial injury, amputation rates were signicantly lower
when repair occurred within 60 minutes (6%), compared to
repair within 1- to 3-hour (11.7%) or 3- to 6-hour windows
(13.4%).
et al. performed a review of 101 cases of lower extremity
injury and found that limb salvage was greatly inuenced
by ischemic time.38 When ischemic time was longer than 6
hours, limb salvage rates decreased from 87% to 61% and in
this report, the use of vascular shunts was associated with a
lower amputation rate (13% vs. 27%). An adapted treatment algorithm from this report is presented in Fig. 23.8.38
37
To evaluate the effect of shunt use on limb salvage, Glass
Debridement/
Fixation as indicated
Ye s
Debridement/
Fixation
Revascularization
(consider fasciotomy)
Fig. 23.8 Limb salvage algorithm implementing temporary vascular shunts. (Adapted from Glass GE, Pearse MF, Nanchahal J. Improving
lower limb salvage following fractures with vascular injury: a systematic
review and new management algorithm. J Plast Reconstr Aesthet Surg.
2009;62:571–579.)
Delayed
reevaluation - limb
viable?
No
Amputation
23 • Surgical Damage Control and Temporary Vascular Shunts 297
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limb salvage.
39,40
As part of this approach to attain func tional
limb salvage, the authors recommend using vascular shunts as
one way to limit malperfusion during damage control operations and the reconstruction of vascular trauma.
Whereas use of shunts in proximal limb injuries is intuitive and more common, this adjunct can also be useful in
restoring ow through certain distal vascular injuries. Of
particular importance are injuries in which more than one
artery of an otherwise redundant circulation (i.e., collateral vessels) to an extremity or end organ are interrupted.
As stated previously, continuous wave Doppler is useful
in these situations to determine the status of arterial ow
and whether or not a vascular shunt may be benecial.
21,33
Injuries to small, distal vessels that result in the absence
of any arterial signal should be considered for shunting
regardless of size.41 In our experience, if shunts in small,
distal vessels thrombose it does not preclude performance
of a thrombectomy and continued pursuit of limb salvage.
Often the thrombosed shunt can be removed, a thrombectomy performed, and vascular reconstruction carried out as
needed.
21
FASCIOTOMY (PROPHYLACTIC)
The development of extremity compartment syndrome has
negative implications for limb salvage. When diagnosed,
extremity compartment syndrome requires immediate performance of a fasciotomy to relieve elevated pressures and
restore normal perfusion to affected tissue beds. However,
recognizing the onset of compartment syndrome is challenging, especially in patients who are being transported
through multiple levels of care, often at different medical
facilities. As such, prophylactic fasciotomy is acknowledged
as a common practice when vascular shunts are used.
Although a difcult topic to study with prospective methodology, at least one retrospective report from the US military
has shown a four-fold increase in mortality associated with
delayed or missed diagnosis of compartment syndrome.
Patients requiring temporary shunt placement often
have the greatest number of risk factors for the development of extremity compartment syndrome, including ischemia, underlying muscle, and possibly bone contusion and
they frequently require large volume resuscitation. These
factors explain the high rate of prophylactic fasciotomy
reported in military and civilian series (ranging from 60%
to 100%).
21,25,27
The association between shunt use and
compartment syndrome is so strong that when considering
patients with combined vascular and orthopedic injuries,
the lack of a temporary vascular shunt has been shown to
be associated with an increase in the development of compartment syndrome.
43
For these reasons, the military’s practice recommends
performing prophylactic fasciotomy in cases of extremity vascular injury regardless of shunt use, especially in
patients to be cared for by different providers throughout
different echelons of care.42 For cases in which the need for
prophylactic fasciotomy is in question, one can consider
the following as more objective measures to tip the scale in
favor of performing the procedure: severe extremity injury
(Abbreviated Injury Score 3 or higher, or Mangled Extremity
Severity Score 5 or higher), combined arterial and venous
injury, prolonged ischemia or tourniquet time (more than
42
1–2 hours), penetrating or crush mechanism(s), injury to
multiple below-knee or forearm arteries, open-fractures or
nerve injuries, and large intraoperative blood loss.
VASCULAR BRANCH POINTS
Injuries that are close to, or that involve bifurcation points
such as the distal common femoral or brachial arteries,
deserve special consideration in the context of vascular
shunts. In these cases, the most common approach involves
temporarily occluding the branch vessel to stop retrograde
bleeding and placing the shunt in the main channel. As
a creative means to restore ow in both lumens, Choudry
etal. described using an improvised shunt fashioned from
a dual lumen 14.5-Fr Mahurkar (Covidien, Manseld,
MA) catheter to restore ow in the supercial and deep
femoral arteries in the setting of a common femoral artery
injury.48 These injuries are rare enough that there is little
clinical experience to guide attempts to shunt both branch
point vessels. If a proximal arterial branch point injury is
encountered (e.g., the femoral bifurcation), the authors
recommend vessel loop occlusion of the large side branch
(e.g., the deep femoral artery) to stop retrograde bleeding
and then placement of the shunt into the main axial vessel (e.g., the supercial femoral artery). Other means such
as a large clip, a Rummel tourniquet, or even a ligature
can be used to occlude the branch vessel which can then
be reconstructed at a later time when the wound is explored
and the shunt removed. Although there is room for creativity
in these situations, the surgeon must be mindful of damage control principles and keep whatever option chosen
as quick as possible.
TRUNCAL VASCULAR INJURIES
Temporary vascular shunts also have shown utility as an
alternative to ligation for the management of visceral vascular injuries. Torso vascular injuries may be associated
with genitourinary or gastrointestinal contamination, large
blood loss (with hemodynamic instability and coagulopathy), and challenging operative exposures. Although these
situations tend to force a surgeon to ligate bleeding “out of
desperation,” restoration of ow with a vascular shunt may
be a better option that will mitigate end-organ damage and
adverse physiology.
Mesenteric arterial injuries are rare and associated with
high mortality rates. Like other anatomic locations, the
immediate decision point in managing an arterial injury in
the mesentery is whether to ligate, shunt, or repair. Reports
of intraluminal shunting of the mesenteric vessels (e.g., the
superior mesenteric artery [SMA]) are few, but do include
translational research and clinical experience.50 Subramanian and colleagues describe two patients with shunts that
were placed in the SMA. Although both shunts thrombosed,
only one patient expired (after care was withdrawn).27 Reilly
et al. described the successful use of an SMA shunt during
damage control surgery for penetrating injury to the abdomen. Despite a dwell time of nearly 36 hours, the shunt
remained patent with demonstrable viability of both the
small and large bowel upon re-exploration.51 Shunting of
SMA injuries is recommended in the damage control setting
as an alternative to reconstruction and is particularly
49
44–48
298 SECTION 4 • The Management of Vascular Trauma
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relevant for injuries within Fullen’s anatomic zones I and
II (i.e., origin of the artery at the aorta to the middle colic
branch).
Injuries to the major visceral venous structures, including the superior mesenteric and portal vein, are also highly
lethal. In a retrospective study of 51 patients with superior mesenteric venous injuries, Asensio et al. reported a
survival rate of 55% and noted that mortality worsened
with each additional vascular injury. The authors found a
survival benet in primary repair of superior mesenteric
venous injuries although they advocated rapid ligation in
the unstable patient with multiple other life-threatening
injuries. Expectedly, ligation resulted in bowel edema and
venous engorgement with splanchnic hypertension syndrome and bowel necrosis.52 Additional reports of portal vein injuries also recommend repair when possible,
although ligation is described and noted to be combatable
with survival, likely resulting from collateralization.
53–55
Conclusion
Clinical and applied research reports stemming from the
wars in Iraq and Afghanistan propelled several previous
decades of experience showing the utility of temporary
vascular shunts as a tool for some scenarios of vascular
trauma. The reappraisal of vascular shunts has caused a
more critical examination of the ischemic threshold of the
extremity and other end organs and how shunts may positively affect survival and functional recovery. The resurgent
use of vascular shunts has also forced a reappraisal of intraoperative, “sequence of repair” decision-making in the multiply injured patient. In this context, shunts have changed
the age-old debate of “life over limb” to one that accommodates saving “life and limb.” In the damage control setting,
vascular shunts serve as a middle ground between the competing tactics of a quick vessel ligation versus a prolonged
and technically involved repair. As experience and technologies in the area of temporary vascular shunts increase, so
too will their ability to allow surgeons to improve outcomes
when managing complex and lethal injury patterns.
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48. Choudry R, Schmieder F, Blebea J, Goldberg A. Temporary femoral
artery bifurcation shunting following penetrating trauma. J Vasc Surg.
2009;49(3):779–781. https://doi.org/10.1016/j.jvs.2008.11.041.
49. Ball CG, Feliciano DV. Damage control techniques for common
and external iliac artery injuries: have temporary intravascular shunts replaced the need for ligation? J Trauma. 2010;68(5):
1117–1120. https://doi.org/10.1097/TA.0b013e3181d865c0.
50. Ding W, Ji W, Wu X, Li N, Li J. Prolonged indwelling time of temporary vascular shunts is associated with increased endothelial injury
in the porcine mesenteric artery. J Trauma. 2011;70(6):1464–1470.
https://doi.org/10.1097/TA.0b013e31820c9b4e.
51. Reilly PM, Rotondo MF, Carpenter JP, Sherr SA, Schwab CW. Tem-
porary vascular continuity during damage control: intraluminal
shunting for proximal superior mesenteric artery injury. J Trauma.
1995;39(4):757–760.
52. Asensio JA, Petrone P, Garcia-Nuñez L, Healy M, Martin M, Kuncir E.
Superior mesenteric venous injuries: to ligate or to repair remains the
question. J Trauma. 2007;62(3):668–675, discussion 675. https://
doi.org/10.1097/01.ta.0000210434.56274.7f.
53. Mattox KL, Espada R, Beall AR. Traumatic injury to the portal vein.
Ann Surg. 1975;181(5):519–522.
54. Graham JM, Mattox KL, Beall AC. Portal venous system injuries. J
Trauma. 1978;18(6):419–422.
55. Fraga GP, Bansal V, Fortlage D, Coimbra R. A 20-year experience
with portal and superior mesenteric venous injuries: has anything
changed? Eur J Vasc Endovasc Surg. 2009;37(1):87–91. https://doi.
org/10.1016/j.ejvs.2008.09.018.
24
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Considerations for Conduit
Repair of Vascular Injury
NITEN SINGH and REBECCA JOY UR
Introduction
In 1949, Jean Kunlin performed the rst saphenous vein
bypass in the lower extremity of a patient suffering from
ischemia.1 The work was not the result of chance alone as his
predecessors in vascular surgery had been working on perfecting the technique of arterial surgery. Individuals such
as Alexis Carrel developed the technique of a meticulous
anastomosis, as well as experimenting with venous interposition grafts and the use of allografts, and Jay McClean
discovered heparin, which was utilized in Kunlin's successful procedure.2 In the same manner, our current treatment
of vascular trauma is based on lessons learned in the civilian sector as well as from military experiences. For example,
in World War II (WW II), the majority of vascular injuries
were treated with ligation, leading to an amputation rate
of 49%. During WW II, vein grafts were employed in a very
small number of patients (40), resulting in an amputation
rate of 58%.
felt to be necessary due to the long transport time required
for wounded service personnel. With decreased transport
times and knowledge of these past experiences, Rich and
colleagues successfully implemented arterial repair in the
majority of patients in the Vietnam War and subsequently
reported an amputation rate of 13%. In that experience,
nearly all interposition grafts were reversed great saphenous vein, and that form of reconstruction was used in
46% of the cases.5 In the civilian setting in the 1960s and
1970s, the abandonment of ligation as treatment for vascular trauma led to amputation rates that ranged from
2% to 10%.6 It is these advances, both in the civilian and
the military settings, that have led to the current standard
of repairing vascular injury—in those that will tolerate
repair—with interposition or bypass grafting as needed.
3,4
At that time, ligation of vascular injuries was
Identification of the Optimal
Vascular Conduit
The search for the optimal vascular conduit, in both elective and emergency situations, has been a source of debate
and the source of many research projects. The ideal vascular conduit should be durable, able to be incorporated by the
host or recipient, resistant to infection, and readily available.
In numerous studies of elective peripheral vascular bypass,
autologous vein has proven superior to prosthetic modalities in the lower extremities, whereas prosthetic grafts are
generally better suited for the larger caliber central arteries. Unlike elective situations, trauma cases differ in the
sense that patients are generally younger and have healthy
vessels free of atherosclerotic occlusive disease that can
300
complicate repair. The limiting factor in trauma is the fact
that many individuals have concomitant orthopedic, softtissue, or abdominal injuries that need to be addressed in
addition to the vascular injury. Furthermore, although
vascular repair is usually feasible, it is the ability to place
the repair conduit through a contaminated wound or softtissue decit that often limits success. Specically, the need
to assure adequate soft-tissue coverage to protect the conduit from contamination and disruption often determines
ultimate success or failure.
As documented throughout this text, the approach to
vascular trauma is generally straightforward. Approaches
to the injured vessel include primary repair or restoration
of perfusion using an interposition or bypass graft. The
technique of patch angioplasty is also a useful approach in
select injuries that are less severe. Finally, ligation may be
used as a damage control approach in some cases. When
considering whether to reconstruct or ligate an arterial
injury, one should consider the patient's physiologic condition and other coexisting injuries. Also, one must consider
the degree of ischemia likely to result from vessel ligation.
If the artery is minimally disrupted, it may be able to be
débrided, mobilized, and repaired primarily.
In the situation where the artery cannot be repaired primarily, or cannot be safely ligated there is the need for an
interposition or longer bypass graft. As detailed in Chap-
ter 23, temporary vascular shunts are useful as a bridge
to interposition or bypass grafting when ligation is not an
option. When considering interposition or bypass grafting, one must address the same technical factors that are
important in elective vascular reconstruction as follows: (1)
inow vessel, (2) outow vessel, and (3) conduit. Although
the vascular injury itself may be straightforward, the
patient is often not straightforward and may have suffered
multiple injuries. The overall injury severity and any hemodynamic instability will impact the choice of conduit and
the outcome of the procedure (Fig. 24.1). The ease of availability and necessary length of conduit are also factors to
be considered when pursuing this form of reconstruction.
It would be nice to imagine that one solution applies to both
military and civilian scenarios, but the settings (and the
nature of the wounds) are most often different. This chapter
will describe the options for selection of the vascular conduit to be used for repair of vascular injury.
Types of Conduit
The use of a conduit in vascular trauma is, in principle, the
same as its use for atherosclerotic occlusive or aneurysmal
disease. Vascular conduits can be considered in the following
24 • Considerations for Conduit Repair of Vascular Injury 301
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incision, skip incisions, or a newer minimally invasive technique. The single incision is the most expedient and most
commonly described technique for greater saphenous vein
harvest. However, this is associated with wound infection
and dehiscence in 17% to 44% of patients.
9,10
In an effort
to decrease wound complications, attempts have been made
to harvest this vein with multiple, shorter incisions and
intervening “skin bridges.” Although this technique may
take additional time and familiarity with the approach, it
has been shown to decrease wound complications (9.6%)
in at least one large series.11 The least invasive technique
for saphenous vein harvesting is the newer endoscopic
approach. With this technique, the vein is harvested with
electrocautery through several percutaneous incisions.
Although risk of wound infection is decreased with the
endoscopic technique, this does carry the added risk of
thermal injury to the vein. Although it is desirable to reduce
wound morbidity associated with saphenous vein harvest,
Fig. 24.1 Massive soft-tissue destruction from an improvised explosive
device blast.
it seems that as the method becomes less invasive, the time
needed for the procedure increases, as does the need for
expertise with the endoscopic procedure. Because of this,
the less-invasive approaches to saphenous vein harvest are
not practical in most centers for cases of vascular trauma.
categories: (1) autologous vein and artery (i.e., autografts),
(2) prosthetics, and (3) biologics. Vascular trauma has a
rate of wound contamination that is proportional to the
mechanism of injury and degree of soft-tissue injury. The
degree of contamination can be minor such as with a single
stab wound or a laceration with a piece of glass, or it can
be major such as with an open femur fracture with soft-tis-
sue wound. More than a decade of war in Afghanistan and
Iraq has laid bare the complexities associated with vascular trauma in highly contaminated wounds resulting from
improvised explosive devices (IEDs).7 Traditional teaching has emphasized the use of autologous vein grafts for
vascular repair in the setting of contamination. However,
due to the complexities of different trauma scenarios such
as bilateral lower extremity injury, this conduit (e.g., the
great saphenous vein) may not be feasible or appropriate.
If autologous vein is not available, vascular hemorrhage
can be controlled by ligation, the use of temporary vascular
shunts, or reconstruction using a commercially available
prosthetic or biologic conduit.
8
Although rarely used, arterial conduits may provide a better size match for the injured vessel and they do not require
lysis of valves. Arterial conduits may also have improved
handling characteristics, better compliance match, and even
superior patency. The use of autologous arterial conduit is
feasible and efcacious, but remains limited in the setting of
trauma due to the paucity of harvest sites, their challenging
anatomic locations, and the lack of redundancy or length.
The internal mammary (internal thoracic) artery is the most
commonly used arterial conduit. However, due to its conned location, access is only feasible through a median sternotomy. The gastroepiploic artery has also been used with
favorable patency in coronary artery bypass surgery when
the internal mammary artery and the saphenous vein are
not available.12 The most commonly explanted autologous
artery is the radial artery, which ranges from 2 to 4 mm. The
internal iliac artery can be used, but this is infrequent except
in select cases of pediatric injury. Klonaris et al. described the
benets of using the internal iliac artery for repair of infected
femoral artery pseudoaneurysm resulting from trauma from
repeated access during illicit drug use. This report describes
AUTOLOGOUS CONDUIT
The gold-standard conduit is autologous tissue and most
commonly a vein. In rare cases, one may choose to use an
arterial conduit for vascular reconstruction. Because the
venous system has multiple, redundant outow tracts there
are several choices for vein harvest. The lower extremity has
the longest and most commonly used options, including the
greater and lesser saphenous veins, the femoral vein, and
dorsal foot vein. The cephalic and basilic veins of the upper
extremity can be used independently or as a longer singlesegment graft. In the neck, the anterior, exterior, and inter-
the use of internal iliac artery for reconstruction in 9 (5
patch, 4 interposition graft) of 12 patients. At a mean of 19
months after repair, Klonaris et al. reported no complications or instances of limb loss.13 Finally, the external carotid
artery can serve as an autologous conduit in repair of proximal internal carotid artery injuries. In these cases, the external carotid can be transposed onto the mid or distal internal
carotid in situations where the proximal portion is injured.
Other arteries such as the deep inferior epigastric may be
used as a microvascular graft to replace a damaged arterial
segment, but these smaller arteries are not typically a consideration in trauma.
14
nal jugular veins are options for vascular conduit. The veins
of the neck are most commonly used as adjuncts for carotid
artery repair because of their proximity.
Use of autologous vein requires adhering to the tenants
of safe and effective dissection and procurement. In general,
supercial veins may be harvested using a single continuous
PROSTHETIC CONDUITS
Since the rst prosthetic graft made of woven nylon, a
variety of grafts have been developed, including collagenimpregnated, woven nylon (Hemashield Dacron, Maquet
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Germany), heparin-bonded Dacron, expanded polytetrauoroethylene (ePTFE), heparin-bonded ePTFE (PROPATEN,
Gore Medical, Flagstaff, AZ), hooded PTFE (Distao, Bard
PV, Tempe, AZ), ring reinforced ePTFE, and even multilayer–
hybrid grafts consisting of both woven nylon and ePTFE
(Triplex, Vascutek Terumo, Scotland, UK and FUSION
Maquet Cardiovascular, Wayne, NJ). Biosynthetic vessels
(Omniow II, LaMaitre Vascular, Burlington, MA) consisting of a woven ovine collagen overlying polyester have been
used with some success in infected elds but is unavailable
for sale in the United States.
15
For large vessels such as the aorta and iliac arteries, prosthetic grafts have been used with great success. However,
higher rates of thrombosis remain a disadvantage of prosthetic grafts in smaller vessels regardless of conduit composition. In the classic studies of Bergen and Veith, comparing
vein to ePTFE for reconstruction of age-related disease,
short-term (2-year) patency was comparable between the
conduits. When longer-term patency rates of these studies
were reported, saphenous vein was found to be superior.
16,17
Prosthetic grafts are used today for elective bypass procedures, but mainly in the femoral and above-knee location.
Adjuncts such as heparin bonding of the luminal surface
of the ePTFE have been used with modest or mixed results
in attempts to improve patency. The use of prosthetic grafts
Fig. 24.2 PTFE interposition graft repair of right common carotid artery.
(Image courtesy of Todd Rasmussen, Mayo Clinic.)
in trauma has been espoused by some who purport that
short segments or lengths of prosthetics are durable and
react more favorably than vein in contaminated elds.
Figure 24.2 shows a through and through carotid artery
injury repaired with a short segment PTFE interposition
graft. Some of these studies also point to preservation of the
autologous vein for future revascularization as an advantage of using prosthetic conduits as the initial option.
BIOLOGIC CONDUITS
The most modern construct of the vascular conduit is the
biologic graft. These may be allografts, xenografts, or those
created (i.e., grown) using modern regenerative medicine
technologies. Allografts include cryopreserved vein, cryopreserved artery, and preserved treated human umbilical
vein (HUV). Dardik began work on HUV as a conduit starting
in the 1970s.18 At 37 to 40 weeks of gestation, the HUV
(2- to 3-mm diameter) is of similar caliber to that of small
arteries and contains moderate amounts of collagen and
elastin to provide elasticity. In a qualitative analysis of the
microstructure of HUVs, Li et al. showed that the collagen
to elastin ratio in these vessels is similar to an artery of the
same caliber. Studies by Li and colleagues also demonstrated
that HUV had comparable morphologic and microstructural
indices as similar-size arteries. These authors concluded
that because of the similarities, HUV may be a substitute
for small-caliber arteries such as coronary, brachial, radial,
and tibial.19 In a review of 211 femoral-to-popliteal bypass
operations (using the second-generation glutaraldehydestabilized HUV grafts), Neufang et al. reported the primary,
primary-assisted, secondary patency, and limb salvage after
5 years as 54%, 63%, 76%, and 92%, respectively (with no
difference between above-knee and below-knee grafts).
Cryopreserved saphenous vein allografts, also referred
to as cadaveric saphenous vein, have been utilized as an
alternative conduit. Early results with this conduit demonstrated poor patency. Walker et al. studied 35 patients who
underwent lower extremity bypass grafts for symptomatic
ischemia. The primary patency was 67% at 1 month,
28% at 12 months, and 14% at 18 months.21 In an effort
to improve patency, Buckley et al. prospectively enrolled
patients for femoral-to-below-knee popliteal artery bypass
using an anticoagulation protocol. Twenty-four patients
with ischemic lower limbs underwent bypass with cryopreserved vein and were treated with aspirin, low-dose heparin, low-molecular-weight dextran 40, dipyridamole, and
warfarin. The limb salvage rate in this study was 88% at
6 months and 80% at 24 months.22 Although this report
demonstrated improved patency, it enrolled a small number, and patients required high levels of anticoagulation to
obtain the results, an option oftentimes not available to a
multiply injured trauma patient.
Cryopreserved, cadaveric arterial allografts have been
developed as an alternative to cryopreserved vein. Cryopreserved artery is derived from the descending thoracic and
intrarenal aorta, as well as the iliac and femoral arteries of
human cadavers. Due to the variety of diameters, one can
nd an appropriately sized cryopreserved allograft for any
vessel in the body. Cryopreserved allografts are commonly
used for in-line arterial reconstruction in the treatment of
prosthetic graft infections or contaminated wounds such
20
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as a mycotic aneurysm or aortoenteric stula. Although
cryopreserved arterial allografts have been anecdotally
reported in the repair of vascular trauma with contaminated wounds, there are no large series. Reports on the use
of this conduit in infected abdominal and extremity vascular beds suggest that it would be a safe consideration in the
Fig. 24.3 Human acellular vessel (HAV) being sewn to left common
femoral artery. (Image courtesy of Todd Rasmussen, Mayo Clinic.)
setting of resistant or recurrent infection and that it may
have applicability in trauma.
23
Animal-derived conduits (xenografts) include bovine
carotid artery (Artegraft, North Brunswick, NJ), bovine
pericardium, bovine jugular vein (Contegra, Contegra,
Medtronic, Santa Rosa, CA) as well as a porcine pulmonic
xenograft. The use of bovine carotid as a hemodialysis graft
was initially reported by Chinitz.24 The patency of bovine
carotid has been compared to ePTFE in hemodialysis grafts
by Kennealey. Although there was no difference in secondary patency, primary and assisted-primary patency were
higher with bovine carotid than with ePTFE (60% versus 10% and 60% versus 21% at 1 year, respectively).25
Although bovine carotid has not been studied in vascular
trauma, experience in lower extremity bypass demonstrates
good results for patency in bypasses to the above- and belowknee position as well as in tibial vessels with patency of 87%
at one year.26 Similarly, bovine jugular vein plays a role in
reconstruction of the right ventricular outow tract in congenital heart surgery.27 Although its use in trauma remains
to be dened, this conduit is available in diameters from 12
to 22 mm and would appear to be an appropriate size match
for torso vascular structures.
28
The human acellular vessel (HAV) (Humacyte, Inc.,
Durham, North Carolina) is a new bioengineered blood vessel or conduit consisting of decellularized (non-antigenic)
extracellular matrix originating from arterial smooth muscle cells (Figs 24.3 and 24.4).29 This product is manufactured using regenerative medicine techniques and results
Fig. 24.4 Human acellular vessel as a new bioengineered autogenous conduit. (Image courtesy of Todd E. Rasmussen, Mayo Clinic, and created by Sofia
Echelmeyer, Uniformed Services University, Bethesda, Maryland.)
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in an “off-the-shelf ” conduit of uniform caliber that can be
implanted as a patch or as an interposition or bypass graft.
Because the conduit is a non-antigenic biologic, evidence
suggests that overtime it becomes populated by endothelial
cells from the recipient patient.30 The HAV is not yet cleared
by the US Food and Drug Administration (FDA), but pivotal clinical trials designed to assess the safety, efcacy, and
durability of the conduit for dialysis access, peripheral arterial disease, and vascular trauma are underway in the US
and Europe.31 The US Military Health System research program has supported the development and clinical study of
the HAV in the hopes that this conduit may provide an offthe-shelf option that is well incorporated and resistant to
infection for use in the setting of wartime vascular injury.
32
Decision Making in the Choice of
Conduit
LOCATION AND NATURE OF THE INJURY
The anatomic location of the vascular injury plays an
important role in consideration of conduit. If the environment in which conduit will be used is relatively innocuous, such as a low-velocity penetrating wound, the injury
may be amenable to anatomic or in situ interposition graft
reconstruction. In contrast, if the injury is more extensive,
is heavily contaminated, or is associated with soft-tissue
injury, there may not be viable soft tissue to cover an in situ
graft. These more severe cases may preclude anatomic or in
situ reconstruction and instead require positioning or routing of a bypass conduit in an alternative or extra-anatomic
location. Understanding the size of the injured vessel and
the extent of contamination and soft-tissue injury allow
one to make a judgment about the best type of conduit.
Table 24.1 provides a summary of approximate sizes of ves-
sels that may be affected in the setting of severe injury.
Thoracic and Abdominal Injuries
The thoracic aorta and its branches are protected by the
bone and muscular structures of the thorax. Blunt injuries
that carry enough force to disrupt these vessels often result
in death. In the civilian setting, blunt aortic injury (BAI) is
often manifested as a transection of the proximal descending aorta at or immediately distal to the ligamentum arteriosum. In this scenario a patient will survive based on the
integrity of the periadventitial tissue in the mediastinum.
Although this situation is not stable in the long term, a
contained BAI may allow the patient to be transported to
a trauma center and treated with an open interposition
graft or an endovascular stent graft. Penetrating injury to
the thoracic aorta is often lethal due to the numerous vital
structures in the anatomic vicinity. Even low velocity penetrating injuries (i.e., stab wounds) may be lethal in this
location.
quent and accounts for 5% of aortic injuries.35 The majority
of abdominal aortic trauma involves the infrarenal segment
but its branches may also be injured. Penetrating injuries to
the abdominal aorta and its branches are often complicated
by injuries to solid or hollow viscus organs leading to bleeding and or enteric contamination.
33,34
Blunt injury to the abdominal aorta is infre-
36
Table 24.1 Various Sizes of Arteries Affected by Trauma.
Artery Normal Diameter (mm)
Common carotid 10
Innominate 12–14
Subclavian 10
Axillary 8–10
Radial 4–6
Thoracic aorta 20–25
Abdominal aorta 15–20
Common iliac 10–14
External iliac 8–10
Internal iliac 8–10
Common femoral 8–10
Superficial femoral 6–8
Profunda femoral 6–8
Popliteal 6–8
Extremity Vessels
Blunt arterial extremity injury classically leads to disruption of the intima and ow-limiting defects. The difculty
with blunt trauma is conrming the diagnosis and specic
location of vascular injury. As discussed in other chapters
of this textbook, this scenario is often delineated with imaging such as duplex, contrast computed tomography (CT), or
conventional arteriography. Penetrating injuries may lead
to vessel transection or intimal injury due to direct or indirect contusion (i.e., concussive effect). Partial transection of
the vessel may prevent retraction and vasoconstriction and
may lead to more bleeding from the injury. In contrast, complete transection of the elastic arteries in the upper extremities often results in vessel retraction, vasoconstriction, and
a relative degree of hemostasis. In the upper extremity, the
axillary and brachial arteries are frequently injured by penetrating mechanisms, and in the lower extremity, the supercial femoral and popliteal arteries are most affected (see
Fig. 24.5).
37,38
The smaller infrageniculate vessels can also
be injured. However, if in isolation, these injuries are associated with lower rates of mortality and morbidity than the
larger, more-proximal vessels. If multiple tibial vessels are
injured in the same extremity, the degree of ischemia and
even the propensity for limb loss are likely to be worse.
39
IDEAL CONDUIT FOR VASCULAR TRAUMA
The ideal characteristics of conduit include ease of procurement, durability, resistance to infection, ability to incorporate with surrounding tissues, and appropriate diameter for
the vessel being reconstructed. There is a general consensus that until biologic conduits, such as the HAV, become
more commonplace, autologous vein is the favored conduit
option. However, given the varied mechanisms of trauma
and the different sizes of injured vessels, one will need to be
familiar with more than just saphenous vein for vascular
conduit. Table 24.2 lists several commonly used conduits,
each with real or perceived advantages and disadvantages.
As noted, the choice of conduit depends on the anatomic
region of injury. Since the Vietnam War—and especially
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