Arterial complications following cardiac catheterization in infants and children (12) constitute the major cause of iatrogenic pediatric vascular injuries (13,14,15,16). Approximately 75% of iatrogenic vascular injuries follow femoral arterial puncture for angiography, and approximately 25% upon umbilical artery or other peripheral artery catheterization attempts. Formerly, as many as 25% of patients undergoing transfemoral cardiac catheterization sustained temporary or permanent injury, particularly if balloon angioplasty catheters were used (17). Currently, the risk of significant vascular complications requiring operative intervention has been reduced to less than 1%, through use of atraumatic technique, the smallest catheter possible, and periprocedure heparin and platelet inhibitors (18,19,20). Mechanical obstruction due to thrombosis, vessel dissection, or intimal flap accounts for approximately 65% of the complications, with groin or retroperitoneal bleeding, pseudoaneurysm, arteriovenous fistula formation, and distal arterial embolization accounting for the remaining 35%. Tissue loss, neuropraxia, and distal limb growth deficiencies may occur as a result of such injuries. Prompt recognition and treatment of these injuries is essential. Systemic heparinization yields good to excellent results in some 75% to 90% of patients with isolated angiographic injuries. Thrombectomy may be required if there is extensive arterial thrombosis with insufficient collateral flow. Unfortunately, simple thrombectomy alone is successful in only 50% of cases, and more complicated repair may be required for a successful outcome. Immediate vascular intervention or reconstruction is more likely to be necessary for obstructions involving long arterial segments or important collateral vessels.

Leg length inequality following pediatric cardiac catheterization and vessel injury is another complication. Normal limb growth may be anticipated if revascularization is prompt and successful. Late reconstruction frequently results in near-normal catch-up growth in the affected extremity among the few children in whom collateral circulation is insufficient to sustain normal growth (21,22,23).

Thromboembolic complications from indwelling umbilical artery catheters present special challenges, although limb blood flow appears to normalize once they are removed (24,25,26,27,28). These events can usually be avoided by positioning the catheter tip in the distal thoracic aorta, ideally at the T8 level, rather than the distal abdominal aorta, maintaining a continuous infusion of heparinized saline solution and limiting the duration of catheter use.
Operative intervention is required for cases of catheter tip embolization, as well as umbilical or hypogastric artery perforation upon insertion or vascular avulsion upon removal, both of which can lead to exsanguination (29). Catheter-associated aortic thrombosis typically presents with decreased lower-extremity pulses and distal cyanosis, but may also be accompanied by severe hypertension, congestive heart failure, and acute oliguria from reduced renal perfusion when thrombosis involves the suprarenal aorta (30). The diagnosis is made by color duplex ultrasonography (CDU) of the aorta, femoral, and iliac arteries, or by magnetic resonance angiography or spiral computed tomography (CT) of the abdomen and pelvis. Diagnostic angiography is rarely necessary, but may be used if the catheter is still present. Acute neonatal aortic thrombosis in neonates nearly always mandates prompt thrombectomy if life and limbs are to be saved.

Gangrene of the extremities can occur in infants subsequent to femoral venipuncture, intravenous therapy, and intramuscular injections, emphasizing the need to perform such procedures only as indicated (31,32,33). Arterial and venous punctures, intentional or unintentional, can result in arteriovenous fistulas, pseudoaneurysm, limb ischemia, and venous insufficiency, problems that may become irreversible over time (34). Carotid injury can result during insertion of internal jugular venous catheters. Pseudoaneurysms of the radial artery can be controlled with surgical ligation or direct pressure. Microsurgical techniques are typically required for repair of central vessels, whereas systemic heparinization may suffice for injury to peripheral vessels (35). Fasciotomy must be performed if compartment syndrome or compressive neuropraxia from neurovascular hematoma develops. Amputation may become necessary if therapy fails, but should be delayed to allow additional collateral flow to develop in adjacent marginal tissues (36). Spontaneous nontraumatic thrombotic vascular conditions of infancy, when complicated by ischemia, are managed similarly to iatrogenic vascular injuries, via arteriotomy and balloon catheter thrombectomy (37,38,39).

Infectious complications from invasive monitoring procedures can be a consequence of critical care, monitoring especially in neonates. Abscesses can develop at the site of arterial, venous, or capillary puncture, and are treated by incision and drainage. Septic tenosynovitis can result from radial arterial catheterization, and also requires incision, counterincision, and drainage, and late reconstruction if tendon damage is permanent. Septic thrombophlebitis from peripheral intravenous catheterization requires excision of the involved peripheral vein.

The advent of extracorporeal membrane oxygenation, predictably, has given rise to novel problems related to cannulation of the carotid artery, when venoarterial bypass is used (40,41). Although carotid ligation upon decannulation remains the standard practice in most centers, carotid reconstruction is increasingly being performed, with good results. Aortic dissection upon cannulation can occur. It is recognized based on diminished pulses in the lower extremities and dampening of the umbilical arterial catheter pulse pressure wave following decannulation. The diagnosis is confirmed using a phased array echocardiographic Doppler system. Repair requires cardiopulmonary bypass and use of an aortic homograft.

Iatrogenic injuries include aortoesophageal fistula due to retained cricopharyngeal foreign bodies, such as coins, and undrained periesophageal abscesses, common iliac artery injury due to rectal suction biopsy, aortic injury due to improper trochar placement during laparoscopy, and therapeutic radiation for solid abdominal tumors (42,43,44,45). Aortoesophageal fistula can be avoided by prompt treatment of inciting conditions, but if undetected, is heralded by sudden massive hematemesis of bright red blood, and can be successfully treated only by immediate recognition of this pattern, vigorous resuscitation, and aggressive operative repair. The same is true for tracheoinnominate artery fistula, which typically follows upon long-term placement of an excessively lengthy, metal tracheostomy tube, and is heralded by sudden massive hemoptysis, often with a preceding minor episode, followed by rapid exsanguination. Common iliac artery injury can be avoided during rectal suction biopsy by using a posterior approach and by limiting biopsies to the distal rectum, no more than 4 cm above the dentate line. Avoidance of radiation arteritis, typically involving the aorta and renal arteries, thus causing renovascular hypertension, requires both proper dosimetry and shielding, and necessitates close collaboration with the radiation oncologist.

Vascular injuries have a 2:1 male prevalence, and 80% are caused by a penetrating mechanism (2,3,4,5,6,7,8,46,47,48,49,50,51,52,53). Extremity vascular injuries vastly outnumber truncal vascular injuries. Extremity arterial injuries are slightly more common than extremity venous injuries, whereas truncal venous injuries slightly outnumber truncal arterial injuries. Upper- and lower-extremity injuries occur in approximately equal proportions. Most patients with major vascular injuries also have significant associated injuries of major nerves, bones, and adjacent soft tissues and organs.

The fatality and amputation rates for pediatric patients undergoing emergent repair of injured peripheral vessels are low, approaching zero for the former and 5% for the latter. However, although salvage of life and limb is excellent in peripheral vascular trauma, the associated nerve and tendon damage present in upward of 30% to 50% and 20% to 25% of such patients, respectively, may limit functional recovery in as many as 25% to 35% of its victims. By contrast, the fatality rates for patients undergoing emergent repair of injured truncal vessels is high, approaching
10% for abdominal injuries, 20% for cervical injuries, and 35% for thoracic injuries in experienced centers. The most frequent cause of death, predictably, is exsanguinating hemorrhage.

Injuries to the popliteal artery warrant special comment. Prompt, aggressive treatment is essential for successful outcome (54). However, the excellent collateral circulation present in children may sometimes result in palpable distal pulses, despite complete discontinuity of the popliteal artery (55). Therefore, it is essential that all children with suspected popliteal injuries, penetrating or blunt, undergo urgent duplex ultrasonography or angiography, to obviate the possibility of missed injury and the development of late complications, such as pseudoaneurysm and arteriovenous fistulae. As in adults, injuries to the popliteal veins in children also require prompt recognition and repair.

Thoracic vascular injuries are associated with high fatality rates (1). Most patients with thoracic aortic injuries die at the scene, during ambulance transport, or within 6 hours of hospital admission (56). The majority of these injuries are due to severe deceleration causing aortic disruption (57,58). Aortic injuries require immediate control of blood pressure, and repair the injury, which usually requires the use of cardiopulmonary bypass. As in adults, first rib fractures in children are associated with major vascular injuries, and mandate urgent arteriography for diagnosis and immediate operative repair if there is a major vascular injury (59).