Introduction

In the United States, pediatric trauma remains the leading cause of death among children over 1 year of age; and vascular injuries constitute a small but important subset of this. Although injury-prevention measures such as increased use of seat belts and child-safety seats have effectively reduced the death rate from unintentional injury in children, modern series indicate that vascular injuries still occur in 0.6% to 1% of pediatric trauma patients which is comparable to the demographics of this problem decades ago. Iatrogenic injuries represent a significant proportion of the pediatric vascular trauma managed in specialty centers across the United States because of an increase in percutaneous vascular access procedures in children. Furthermore, current warfare has resulted in noncombatant injuries, many of which occur in children. These injuries frequently have a vascular-injury component.

The management of these injuries remains largely nonstandardized in the current literature owing to several factors. First, these patients are cared for by a wide range of subspecialists, including pediatric surgeons, adult vascular surgeons, trauma surgeons, orthopedic surgeons, and plastic surgeons, who each bring a unique perspective and management philosophy to the patient’s care. Furthermore, as children age, their vascular biology evolves significantly, which bears consideration when faced with a pediatric vascular injury ( Table 20-1 ). Neonates and young children have smaller circulating blood volumes and proportionately smaller arteries that are highly prone to vasospasm, while the need for future growth of blood vessels and limbs and the long-term durability of vascular repairs must be considered. Thus, while older children are likely to have the best outcomes when managed similarly to adults with vascular injury, younger patients may require different approaches; however, defining an appropriate age cutoff and the nature of these differences has proven elusive. Finally, definitive arterial reconstruction has not always been viewed as the preferred management approach. Instead, injured vessels were historically ligated, or the child was given systemic heparin without repair. This expectant therapy often resulted in poor limb outcomes with loss of axial growth from thrombosis, limb overgrowth from arteriovenous fistula formation, or even amputation from critical limb ischemia. A more aggressive approach is now advocated by some surgeons as this approach may result in better outcomes in the management of extremity vascular injuries. This lends support to making an early diagnosis and to performing definitive repair as a viable management strategy. This chapter is structured to address the multiple components of pediatric vascular injury from iatrogenic, penetrating, and blunt-traumatic etiologies. Herein, we will examine the scope of the problem, invasive and noninvasive diagnostic modalities, nonoperative management options, and open and endovascular treatments. We will also address limitations in current knowledge about these various options.

Demographics and Etiology

Iatrogenic trauma to both the peripheral and central vessels of children represents a significant proportion of the worldwide experience with pediatric vascular injuries. Diagnostic catheterization, cannulation for extracorporeal life support (ECLS) or cardiopulmonary bypass, placement of arterial lines (ranging from umbilical arterial catheters to radial arterial lines), arterial puncture for blood gas analysis, and venipuncture have all resulted in significant vascular trauma in children. Multiple centers have reported their individual experience in the form of small case series with only one retrospective case-control study on this subject. From these reports, iatrogenic injuries resulting from diagnostic and therapeutic catheterization, placement of vascular access catheters, and indwelling vascular catheters represents from 33% to 100% of an institution’s experience with pediatric vascular trauma; and, due to the nature of these procedures, all resulting vascular injuries are penetrating in nature.

Approximately half of pediatric vascular injuries across all ages are iatrogenic although the proportion of iatrogenic injuries varies inversely with patient age such that neonates have the highest percentage which then declines in the 2- to 6-year age range (50% iatrogenic) followed by those over 6 (33% iatrogenic). Vascular complication rates vary widely from 2% to 45% depending on the type of catheter-based procedures considered. Catheter-based cardiovascular interventions such as balloon angioplasty of aortic stenosis or coarctation have the highest rates of iatrogenic pediatric vascular injury. Even with heparinization and use of appropriately sized catheters, the thrombosis rate ranges from 1% to 25%.

The relative incidence of vascular injury due to trauma increases with the age of the child. Two-thirds of injuries are noniatrogenic in children over 6 years of age. Of these, between half and three-fourths are due to a penetrating mechanism—knives, glass, gunshot wounds and, in wartime settings, improvised explosive devices (IED) and high-energy gunshot wounds. Blunt vascular injuries (BVI) resulting from long bone fractures and knee dislocation, as well as great vessel and aortic injuries from seatbelt and deceleration injuries, are well described in pediatric patients but are far less common than penetrating injuries.

Pediatric truncal vascular trauma is encountered less often than extremity trauma; however, these injuries are highly lethal with mortality rates in excess of 50%. This injury grouping includes thoracic, abdominal and cervical vascular wounds due to either a penetrating or blunt mechanism. Concomitant major injuries are common, particularly with abdominal vascular injuries, as the wounding mechanism is frequently of a high-energy nature. The distribution of vascular injuries in the abdomen is divided among renal, mesenteric, iliac, and aortic injuries, which are commonly associated with other organ injuries. Blunt and penetrating cerebrovascular injuries are also well described in the pediatric population. Immediate exploration is indicated for hemodynamically unstable patients with penetrating cervical trauma, whereas a noninvasive workup should be performed in all others. CT angiography (CTA) is usually adequate for initial evaluation of the cervical vessels, while catheter angiography is rarely indicated. Outcome, as well as the need for surgical intervention, is largely dependent on the hemodynamic and physiologic condition of the patient. The presence of a major venous injury in the torso (e.g., vena cava, large visceral vein, high-grade solid organ injury with venous disruption) is associated with the poorest outcome. This association holds true whether the torso venous injury is isolated or is part of a constellation of injuries.

Modern warfare commonly occurs in proximity to civilian populations, resulting in injuries of the local population including children. Contemporary war studies focus on adults, and there is a paucity of data reporting on vascular injuries of pediatric populations. The few series that do exist on wartime injury of the local pediatric population suggest that vascular injury in children is a subset encountered, although more detailed information on the distribution of these injuries is emerging ( Fig. 20-1 ). When compared to civilian vascular injuries, wartime pediatric vascular injuries are much more often from a penetrating mechanism. In addition, wartime vascular injuries have a blast component from improvised explosive devices and high-velocity gunshot wounds. The blast component further injures blood vessels and surrounding tissue and makes repair complex. Simple suture repairs and patch angioplasty are replaced by interposition bypass and complex tissue coverage procedures. Despite the challenges noted here, in our wartime experience in Iraq and Afghanistan, the limb-salvage rate in these children is 90% (Todd E. Rasmussen, San Antonio, TX, personal communication, Oct. 1, 2011), which is comparable to the limb-salvage rate reported by U.S. trauma centers in modern series.

Distribution of 161 pediatric vascular injuries managed during Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF). Numbers are n (%).

(Data courtesy Todd E. Rasmussen, San Antonio, TX.)

Anatomic and Physiologic Considerations

Numerous anatomic factors contribute to the high rates of iatrogenic vascular injury seen in children. Pediatric vascular access involves cannulation of small vessels in a very compact anatomic space with relatively large catheters. Ultrasound studies have shown that as many as 12% of femoral vessels in children ages 0 to 9 are either partially or completely overlapping. Thus, attempts at venous access can easily result in inadvertent arterial punctures, especially if done without ultrasound guidance. The use of larger-sized arterial catheters also predisposes the child to vasospasm, resulting in potential limb ischemia. Historic studies have suggested that catheters with a diameter of >50% of the arterial diameter or with a clearance of less than 1.9 mm around the catheter more often resulted in femoral arterial spasm.

Physiologic factors in children who sustain vascular injury from a traumatic or iatrogenic mechanism predispose injured vessels to occlusion. Pediatric vessels are smaller in caliber and are observed to be more reactive than adult vessels although the exact etiology of vasospasm of the developing peripheral vasculature remains poorly understood. However, seemingly spontaneous neonatal thrombosis and severe persistent vasospasm (lasting hours) does occur. In addition, polycythemia and relatively low–intravascular-volume states exist and can contribute to thrombosis. Lastly, children undergoing invasive vascular procedures often have poor cardiac function at baseline with relatively low flow to distal tissue beds, which further predisposes them to thrombosis from an iatrogenic vascular injury.

Iatrogenic and traumatic vascular injuries may result in obstruction of the lumen and subsequent thrombosis or may cause local vasospasm that may result in thrombosis. When an injury results in arterial occlusion, the classic physical findings of limb ischemia develop early and progress. Rapid recognition of the injury and definitive intervention are essential for limb salvage. When vasospasm is suspected (rather than thrombosis), removal of any indwelling vascular catheters is essential as this alone may reverse the process and may allow improvement in the pulse exam. Adjuncts like administration of papaverine into the artery to reverse or minimize vasospasm are often utilized.

Limb hypoperfusion can also occur as a result of a traumatic arteriovenous (AV) fistula, pseudoaneurysm, or complete vascular transection following an access procedure or a penetrating vascular injury. AV fistulae may subsequently result in high output cardiac failure in children especially when initial cardiac reserve is limited. This is the result of gradual enlargement of the fistula communication and subsequent increase in demand for cardiac output. Such clinical scenarios can result in limb overgrowth and high-output congestive heart failure necessitating intervention.

Diagnostic Evaluation

Diagnosis of pediatric vascular injuries requires a high index of clinical suspicion and a careful physical examination. Before the performance of invasive vascular procedures in children, establishing a preprocedure baseline pulse examination is essential for detection of subtle postprocedure blood-flow deficits after the procedure. As in adults, examination of the affected and contralateral extremity includes skin color, capillary refill, and pulse examination. In the setting of hemorrhagic shock, extremity vasoconstriction can lead to an abnormal pulse examination even in the absence of a vascular injury. One series specifically noted a 26% incidence of peripheral arterial vasospasm at surgical exploration but found that, in every case, the process ultimately resolved without a vascular reconstruction. Thus, in the multiply-injured child, life-threatening injuries must be identified, resuscitation and rewarming must be instituted, and then peripheral pulses must be reassessed.

In the setting of penetrating trauma, hard signs of vascular injury such as external bleeding or an expanding hematoma are reliable indicators of a significant arterial injury that warrants surgical intervention. In the absence of such indicators, the pulse examination and noninvasive testing guide further management. In such cases, measurement of the injured extremity index (IEI) using continuous-wave Doppler is a reliable, noninvasive means of initially assessing for arterial injuries in children. The IEI is comparable to the ankle-brachial index (ABI) but is a more general term not confined to the assessment of lower extremity vascular occlusive disease; it refers to the Doppler occlusion pressure measured in an injured extremity relative to that measured in an uninjured extremity.

The injured extremity index must be performed with appropriately sized manual blood pressure cuffs. The cuff should easily encircle the arm and should cover 75% of the length of the upper arm. A continuous-wave Doppler probe is used to determine the pressure at which the arterial signal occludes with cuff inflation. The calculation is taken from the brachial artery in an uninjured extremity. If both arms are available, the higher of the two occlusion pressures is used as the denominator of the ratio equation. For a lower extremity injury, an appropriately sized cuff is positioned similarly just proximal to the ankle, and Doppler occlusion pressures are measured at both the dorsalis pedis and posterior tibial arteries. The highest ankle pressure is used as the numerator to calculate the IEI ratio. If an injured upper extremity is being assessed, the cuff is placed distal to the injury and the occlusion pressure measured at the wrist, taking the higher value of the radial or ulnar artery occlusion pressure. Extrapolating from expected ABI values in children over 2 years of age, the IEI should be 1.0 or slightly greater in the absence of a vascular injury; whereas, in children 2 and under, the normal range is somewhat lower with a mean of 0.88. When a vascular deficit is suspected by an abnormal pulse or a low IEI (<0.9 in children over 2; <0.88 in children 2 and under), it is important to consider whether poor perfusion is the result of arterial injury, vasospasm, or limb hypoperfusion from shock as described above.

If there is concern for a vascular injury with a diminished pulse and IEI that does not correct with resuscitation and rewarming, a confirmatory and localizing study can be helpful if the zone of injury is not clearly delineated. In children, duplex ultrasound can confirm occlusion and can localize the site of injury as well as diagnose an AV fistula or pseudoaneurysm. This modality can also help differentiate between vasospasm and arterial thrombosis. CTA is now being used more often for diagnosis of vascular injuries in children and has been shown to be more reliable for truncal and great vessel injuries than distal ones ( Fig. 20-2 ). If the diagnosis remains unclear despite noninvasive testing, conventional angiography may be considered bearing in mind that the risk of angiography increases in younger patients and that it may exacerbate the problem. In some cases, angiography can be useful in localizing the site of the injury and in distinguishing an arterial injury from vasospasm ( Fig. 20-3 ). If diagnostic tests are inconclusive in the presence of an abnormal examination, surgical exploration is indicated regardless of the age or the size of the patient. In extreme circumstances, a patient may be so critically ill that surgical exploration itself would be life-threatening; and a limb that is hemostatic may not be explored immediately.

CTA can be used to evaluate for vascular injuries in large vessels including the carotid artery ( A, black arrow ) and the subclavian artery ( B, white arrow ). Contrast should be injected contralateral to the suspected injury. In very small children, a hand injection may be necessary. In both instances, the injuries resulted from a tiny metal fragment ( B, black arrowhead ). The carotid pseudoaneurysm (A) was managed with open exploration and repair with an interposition graft, while the subclavian artery injury was repaired with a vein patch angioplasty.

( A, From Cannon JW, Peck MA: Vascular injuries in the young. Perspect Vasc Surg Endovasc Ther 23:100–110, 2011; B, courtesy Jerry Pratt.)

Focal areas of narrowing on arteriography are more likely to be injuries as opposed to vasospasms, which tend to be more gradual in contour and longer. A, The arrow indicates a focal filling defect in the superficial femoral artery. B, The asterisk (*) indicates an area of vasospasm in the tibioperoneal trunk.

(From Cannon JW, Peck MA: Vascular injuries in the young. Perspect Vasc Surg Endovasc Ther 23:100–110, 2011, Fig 1.)

Management of Pediatric Vascular Injuries

Historically, early exploration for suspected vascular injuries in children has not been strongly advocated except for exsanguinating hemorrhage following vessel avulsion or transection. However, poor long-term results from this management approach are now more widely recognized, including early tissue loss and long-term limb-length discrepancy. Operative intervention was avoided in the setting of vasospasm due to the seemingly poor postoperative results in children under 2 years of age. Much of this debate stems from a lack of data on this subject; however, it seems that the devastating life-long consequences of a deferred operation far outweighs the risk of a negative exploration in almost every instance. Furthermore, the idea that there is a relatively short ischemic-threshold time beyond which limb quality deteriorates rapidly and the idea that “time is tissue” compel surgeons to intervene early in order to obtain the best possible results. In most instances of vascular occlusion, thrombectomy of the affected vessel with patch angioplasty repair of the arteriotomy site can be achieved, even in children under 2, using either a small Fogarty embolectomy catheter (Edwards Lifesciences, Irvine, CA) or an aspiration thrombectomy with an angiocatheter. In some cases of iatrogenic iliac arterial injuries, if the injury is identified during the index procedure, a covered endovascular stent can be deployed to repair the injured vessel (Pedro J. del Nido, Boston, MA, personal communication, Oct. 31, 2010), although the long-term implications of this management approach are unknown. Open repair of injured iliac arteries remains the preferred gold-standard method.

Extremity Injuries

Early repair of vascular injuries in children has been advocated by some surgeons for decades. However, management did not always include prompt recognition and repair of injuries; and unacceptable outcomes in the form of high rates of amputation and limb-length discrepancy were the result. While children have greater abilities to develop collaterals than adults, they suffer as high as 50% amputation rates after major vascular disruption with delayed or nonoperative management. With femoral artery disruption, long-term outcomes indicate extremely high rates of limb-length discrepancy which can take several years to become evident yet may respond to delayed vascular reconstruction with catchup growth.

Based on these observations, as indicated above, the management strategy for most pediatric vascular injuries should parallel the tenants of vascular-trauma care in adults ( Fig. 20-4 ). These include early definitive arterial reconstruction, repair of venous injuries, use of temporary vascular shunts, systemic and regional heparin administration, balloon catheter thrombectomy, and the liberal use of fasciotomies. The pediatric-specific technical considerations include the management challenges associated with vasospasm, as well as the need to allow for subsequent vascular growth by creating a spatulated anastomosis and by using interrupted sutures. Following surgical reconstruction, extremely long-term follow-up should be performed to track patency and to detect any aneurysmal degeneration of the repair or any limb-length discrepancy.

A, Isolated penetrating injury to the right leg of an 8-year-old boy, resulting in a pulseless leg with absent Doppler signals. B, The wound was hemostatic; so heparin (75 units/kg) was bolused in the emergency department (ED); and the patient was taken for operative exploration. Through a medial approach, the below-knee popliteal artery was found to be injured. C, Greater saphenous vein that was harvested from the contralateral leg was used for the reconstruction. A below-knee popliteal–to-posterior tibial bypass graft was performed with interrupted sutures. Note the spatulated saphenous vein, which had been prepared for the distal anastomosis.

When an iatrogenic vascular injury results in an incomplete vessel occlusion such as a small intimal flap or partial dissection, it may be possible to delay or avoid definitive surgical intervention if the limb remains viable. Systemic heparinization should be employed if not contraindicated to prevent propagation of any thrombosis stemming from the site of injury. Small flaps and dissections often respond favorably to catheter-directed balloon angioplasty, particularly if they are in the direction of antegrade arterial flow. Serial monitoring of the circulatory status should continue thereafter, and open operative intervention should follow if the examination deteriorates.

One of the largest recent experiences in pediatric vascular trauma comes from the vascular registry of combat injuries managed in Iraq and Afghanistan ( Fig. 20-5 ). High-energy penetrating blast wounds from improvised explosive devices and gunshot wounds result in extensive tissue damage often with an associated vascular injury component. All such adult and pediatric extremity trauma cases were managed similarly with the use of heparin, with thrombectomy, with extensive soft-tissue débridement, with fasciotomy, with repair of venous injuries, and with interposition reversed saphenous vein reconstruction of arteries. Pediatric arterial anastomoses were performed using an interrupted suture technique with nonabsorbable polypropylene suture. The care of these patients from initial reconstruction to final wound closure or skin grafting was conducted by a multidisciplinary team of medical and surgical specialists led by the operative vascular surgeon. These favorable results lend significant support to the philosophy of early diagnosis and operative management of vascular injuries in children.

A, Penetrating wound to the right thigh of a 5-year-old girl. B and C, The right foot had a weakly palpable pulse. There was a Doppler signal, but the IEI was diminished at 0.35. The right foot and great toe manifested a noticeable pallor when compared to the uninjured left extremity. D, (Arrow) The wound was hemostatic; so heparin (75 units/kg) was bolused in the emergency department. The right leg was explored, and the injured superficial femoral artery (SFA) was exposed. The injured segment was 4 cm distal to the takeoff of the deep femoral artery. E, (Arrows) A reversed greater saphenous vein interposition graft was used to replace the injured segment of the SFA. Interrupted 6.0 monofilament expanded polytetrafluoroethylene (ePTFE) sutures were used for both the proximal and distal anastomosis.

Several commonly accepted methods of artery reconstruction exist, including primary repair, vein patch angioplasty, and interposition repair using reversed greater saphenous vein (GSV), other autologous vein, or synthetic grafts (expanded polytetrafluoroethylene [ePTFE] or Dacron). Minimal injuries can be reconstructed, primarily when there has been a clean transection of the vessel, or repaired with a patch angioplasty where there is moderate loss of wall circumference but vessel continuity is preserved. However, primary repair is not possible when the injury is more extensive, when injury involves loss of surrounding tissue, or when there has been direct destruction of the vessel. For these more complex reconstructions, GSV is preferred because it is the most size-appropriate and most-available arterial replacement conduit. The ipsilateral GSV should be avoided to avoid compromising venous outflow of an injured extremity. Lesser saphenous and upper extremity veins may be used for reconstruction provided they are size appropriate. Synthetic conduit is generally avoided due to infection and patency concerns. Furthermore, injured arteries are frequently too small for commonly available synthetic grafts (6-mm diameter and larger), and patency using smaller synthetic grafts (3-mm to 5-mm diameter) is unknown. In addition, these grafts also do not enlarge over time as the child’s artery grows.

The technique for constructing a vascular anastomosis in children with small, growing vessels warrants further discussion. Numerous classic studies have supported the recommendation of performing an interrupted suture technique for arterial anastomoses in growing vessels. There are now more-recent animal research models that have compared various repair methods and materials. Titanium clip, running dissolvable suture, and interrupted permanent suture anastomoses have been evaluated in an effort to determine the best method to connect growing vessels. In these studies, no one method has proven to be superior. However, a running-type anastomosis using permanent suture tended to inhibit vessel growth. Anastomosis methods have not been directly compared in pediatric patients, and long-term follow-up is poor. It is therefore not possible to know with certainty the advantages and limitations of the various methods. While a running-type anastomosis with dissolvable suture may be considered, this material has been shown experimentally to be more thrombogenic than permanent monofilament suture. Thus, an interrupted suture technique using nondissolvable polypropylene suture should protect against narrowing and will be less thrombogenic. When performing arterial anastomoses in growing vessels, one additional technique to protect against narrowing is to create a spatulation. This bevel-shaped connection between the vein graft and the native artery creates a functionally enlarged communication that allows for some vessel growth without stricturing.

Patch angioplasty and primary repair were used exclusively in one pediatric series, avoiding interposition bypass entirely. This is a perfectly acceptable strategy in low-velocity penetrating injuries and in some blunt injuries because it avoids luminal growth issues at anastomosis sites. However, this approach is not likely to succeed in the setting of high-energy trauma, such as fragmentary wounds seen in wartime and complex civilian trauma. Reconstruction in these situations requires vessel débridement, and interposition repair is much more likely to be necessary to allow a tension-free repair. In these cases, there are often concomitant fractures, soft-tissue defects, nerve injuries, and vein injuries to contend with as well. These complex injury patterns are best managed with a team approach, often with a vascular shunt being placed to temporize while other injuries are managed first.

Injured deep veins of the proximal extremities, namely the femoral, popliteal, and axillary veins, should undergo repair whenever possible. Larger more proximal veins and central veins transport large amounts of blood and have few collateral options when acutely injured. Injury without repair of these vessels leads to significant edema and possibly phlegmasia. Primary repair, lateral venorrhaphy, nonreversed vein interposition, and synthetic interposition bypasses have all been described. Early patency of all types of vein reconstruction is excellent. Vein repair is important for alleviation of limb edema, for improvement of patency of arterial repairs, and for overall improved limb function.