Iatrogenic Pediatric Vascular Lesions Treatment & Management

If a hematoma or bleeding develops, manual pressure should be applied to the site, and any coagulopathy should be corrected. ^[4]  In the event of a suspected iatrogenic injury, early recognition and catheter removal are essential.

Hard signs of arterial injury (hemorrhage or expanding hematoma) are indications for surgical exploration. Any child with a threatened or nonviable limb should be taken to the operating room (OR) for definitive repair. Additionally, patients with limb ischemia who fail to improve on anticoagulation should undergo surgical intervention. ^[4]  On the other hand, late repair may be undertaken before the adolescent growth spurt occurs in some children with limb-length discrepancies.

Three approach strategies have been described on the basis of the type of injury, as follows:

• Type I - Life-threatening or limb-threatening injury (hard signs); patients with these injuries require immediate surgical exploration
• Type II - Injuries that do not immediately jeopardize limb integrity and are not life-threatening, but in which a vascular injury is evident; Doppler ultrasonography (US) or preoperative angiography, if available, is the best first step; otherwise, angiography can be performed during surgery
• Type III - Injuries without hard signs in which, because of their location and mechanism of injury, vascular trauma should be suspected; these are best approached with angiography or computed tomography (CT) angiography (CTA)

Acute aortic thrombosis is another absolute indication for surgery. Nonoperative therapy is associated with a 100% mortality, and several reports describe success with surgery for aortic thrombosis.

Most neonates and children in the intensive care setting are poor surgical candidates because of their medical illnesses. In such cases, the risks of surgery must be weighed against the risk of limb loss and limb-growth discrepancy.

Rapid recognition of the injury and definitive intervention are essential for limb salvage.

The principles of managing peripheral vascular injuries in children are different from those in adults. Severe arterial spasm and the long-term effects of diminished blood flow on limb growth must be considered. When vasospasm is suspected rather than thrombosis, catheter removal is imperative because this alone may reverse the process. Papaverine administration is often used to reverse or minimize vasospasm.

The arterial spasm compromises repair of an arterial injury. In children, minor blood loss worsens the vasospasm, promoting early thrombosis. Adequate preoperative intravascular resuscitation is imperative. At times, this may clarify a doubtful examination finding when the issue is vasoconstriction.

If surgery is not performed, it is important to monitor limb length over time and repair the artery if a significant discrepancy develops. This monitoring and repair should be performed before the adolescent growth spurt occurs.

The first maneuver in treating vascular injury is removing the inciting factor. The catheter should be promptly removed when signs of ischemia develop. ^[4]  A new catheter should not be replaced at the same site, even if the signs revert. If thrombosis is suspected, anticoagulation therapy should be initiated unless contraindicated. ^[4]

Infants who lose their lower-extremity pulses after transfemoral catheterization often regain the pulses after 1-2 days. Close neurovascular monitoring should be performed for the first 48 hours following commencement of therapeutic anticoagulation. ^[4] ​ Collateralization is more rapid in infants than in adults; accordingly, anticoagulation and observation are preferred in this type of injury when the extremity has preserved sensibility and movement and when a Doppler signal is audible.

If the injury is of venous origin, elevating the extremity is appropriate to accelerate the resolution of edema. If the injury in question is arterial, lowering the extremity and keeping it warm produces vasodilation and improves circulation. The risks of surgery must be weighed against the risk of limb loss or limb-growth discrepancy.

In cases of chronic ischemia (>30 d), arteriography is indicated. Patients clinically present with claudication and extremity growth retardation, which is considered clinically significant when the discrepancy between the extremities reaches 2-3 cm. Even if the pulses do not recover, if the ankle-brachial index (ABI) is adequate and if the patient is asymptomatic, no surgical intervention is required.

Similarly, thrombosis associated with umbilical artery catheters should be managed with anticoagulation and catheter removal. ^[13]

Immediate heparinization with 15-25 U/kg/hr intravenously (IV) after an IV bolus of 50 U/kg reduces the propagation of thrombus. Heparin should be continued following repair of small arteries or when vasospasm is still present. Long-term antiplatelet therapy is warranted after arterial reconstructions to decrease thrombosis at repair sites. ^[2]

In a study in which 76 children were monitored for 32 months, a set of guidelines was established for initial medical management of vascular injuries. ^[7]  Any patient who did not regain femoral pulses when the catheter was removed immediately received heparin and was observed for 6 hours. If femoral pulses were still absent after 6 hours, surgery was performed. If femoral pulses returned but distal pulses were absent, heparin therapy was continued. The literature suggests that the duration of observation prior to surgical revascularization varies greatly between health services, ranging from 3 to 48 hours. ^[4]

Thrombolytic agents have been used with success in neonates. In the previously mentioned study, two neonates who were not candidates for surgery received heparin and thrombolytic therapy for iliac artery thromboses secondary to umbilical artery catheters. In both cases, normal circulation was present at age 13 months and 18 months without a limb-length discrepancy.

Currently, a recombinant tissue plasminogen activator (rtPA; eg, alteplase) is the agent of choice (0.25-1.5 mg/hr). Fibrinogen levels are measured to ensure lysis of the thrombus, with discontinuance of infusion once systemic fibrinogen levels fall, indicating complete clot dissolution. Heparin is used simultaneously and continued after thrombolysis in order to avoid clot extension. Through the same catheter, angiography is performed to identify the need for further treatment, angioplasty, thrombectomy, or reconstruction. ^[2]

In children undergoing cardiac catheterization, prophylactic anticoagulation with heparin at 100-150 U/kg reduced the incidence of thromboembolism from 40% to 8%. A small randomized trial demonstrated that heparin 50 U/kg tended to be as effective as 100 U/kg when administered immediately after arterial puncture. ^[14]

For arterial endovascular procedures, prophylactic anticoagulation with aspirin does not significantly reduce the incidence of arterial thromboembolism. However, for the ambulatory setting, children can be given low-dose aspirin (4-5 mg/kg/day) as an antiplatelet aggregator.

Drugs that have been proposed for use in pediatric vascular injury include unfractionated heparin (UFH) sodium, pentoxifylline, heparin calcium, and alteplase.

Dosing for UFH sodium is as follows:

• Infants younger than 1 year - Initial bolus of 50-75 U/kg IV infused over 10 minutes; maintenance dosage of 28 U/kg/hr (range, 15-35 U/kg/hr) adjusted as needed by 2-4 U/kg/hr every 4-8 hours
• Infants aged 1 year or older - Initial bolus of 75 U/kg IV infused over 10 minutes; maintenance dose of 20 U/kg/hr (range, 15-25 U/kg/hr) adjusted by 2-5 U/kg/hr as needed every 4-8 hours

Dosing for pentoxifylline (the IV form is investigational in the United States) is as follows:

• 20 mg/kg/day IV divided every 8 hours, at a rate not to exceed 1200 μg/kg/hr

Dosing for heparin calcium (no longer marketed in the United States) is as follows:

• 1-1.5 mg/kg/day

Dosing for alteplase (rtPA) is as follows:

• Infants younger than 3 months - 0.03-0.06 mg/kg/hr IV
• Infants aged 3 months or older - 0.06-2 mg/kg/hr IV

Although thrombolytic therapy has been successfully used in pediatric injuries, there remains a lack of evidence on the safety profile of such therapy in children. ^[4]  Descriptive studies have helped explain clinical thrombotic disease in this group of patients; however, supporting data from controlled randomized trials are lacking, and thus, treatment must be individualized in each case.

Approximately 8-39% of pediatric patients who weigh less than 14 kg have absent distal pulses after catheterization; medical treatment is the first treatment approach.

Current treatment strategies for pediatric vascular injuries resemble the strategies for treating vascular trauma in adults, as follows:

• Early definitive arterial reconstruction
• Repair of venous injuries
• Use of temporal vascular shunts
• Systemic and regional heparin administration
• Balloon thrombectomy
• Liberal use of fasciotomies

Pediatric-specific issues include the following:

• Treatment and surveillance of associated vasospasm
• Allowance for subsequent vascular growth
• Long-term follow-up for patency, aneurysmal degeneration, and limb-length discrepancy

Historically, early exploration for vascular injuries in children was not strongly advocated, except in cases of exsanguinating hemorrhage. It is now recognized, however, that this expectant approach has yielded poor results, including tissue loss, loss of function and limb-length discrepancy. ^[4]  Unnecessary interventions were a concern in the setting of vasospasm, as were poor postoperative results in children younger than 2 years. Nevertheless, the lifelong consequences of a deferred operation outweigh the risk of a negative exploration. Children have a short ischemic threshold.

Depending on the location and type of injury, surgical intervention for iatrogenic vascular trauma may include primary repair, patch angioplasty, thrombectomy, or lower-limb bypass surgery. ^[4]  Although there has been a significant shift towards endovascular treatment of adult vascular injuries, the role of endovascular revascularization in the pediatric population remains to be defined. ^[4]  Other emerging minimally invasive options include percutaneous or catheter-directed thrombectomy, which has shown some potential utility in the treatment of arterial thromboses. ^[4]

The goal of surgery is to restore vascular supply to ischemic territories. Surgical repair can be accomplished by means of thromboembolectomy, patch angioplasty, primary anastomosis, or bypass grafting. When the injury exceeds 30% of the circumference of the vessel, surgical repair should be performed with means other than simple closure, such as vein patching or grafting. Minimal injury or clean transection can be primarily reconstructed.

The best grafting material in children is autologous vein. The great saphenous vein (GSV) is commonly used. The ipsilateral GSV is to be avoided, so as not to compromise the venous outflow of an injured extremity.

Synthetic conduits have a higher incidence of infection and lower patency rates, and in small children, they do not account for the required growth.

Vein repair is important to alleviate limb edema, improving the patency of arterial repairs and enhancing overall limb function. ^[2]

In the rare circumstance of acute aortic thrombosis, aortic thrombectomy is the procedure of choice when conditions are deteriorating (eg, worsening congestive heart failure and hypertension, intestinal ischemia, renal failure, lower-extremity ischemia, or multiorgan failure). A transabdominal approach allows for a bowel resection, if needed.

Surgical management of iatrogenic vascular trauma in this population represents a technical challenge; the small vessel size and arterial spasms can cause difficulties. In experienced hands, this can be a limb-salvage strategy with good long-term outcomes. Vein patch angioplasty is a safe option, especially in femoral artery injuries, with excellent patency rates. ^[14]

Vasospasm significantly complicates treatment. As much as 26% of the incidence of peripheral arterial vasospasm is found at surgical exploration, but ultimately, resolution without vascular reconstruction is possible.

One report described a transverse incision at the aorta above the iliac bifurcation. A 3-French balloon catheter may then be used to extract the clot from the iliac arteries. A 2-French balloon catheter may be used for the femoral arteries. To gain control of the renal orifices, longitudinal aortomy may be necessary. Interrupted sutures are used to close the incision; they allow for subsequent arterial growth. In particular, 7-0 polypropylene sutures have been used to close the aorta.

Thromboembolectomy alone suffices in 43% of patients, and 14% of patients require surgical repair with arteriography with or without resection of an arterial segment. About 71% of patients recover their pulses, whereas 57% have audible Doppler signals and never regain their pulses. Therefore, clinical follow-up involves periodic measurement of the ABI.

The most common adverse events after surgical repair are surgical wound infection and arterial rethrombosis. Surgical wound infection is reported to occur in 3-22% of cases and depends on several factors, including age, associated soft-tissue trauma, albumin level, and time elapsed before repair. Arterial rethrombosis is reported to occur in 14% of patients.

Surgical principles to bear in mind in repairing a vascular injury include the following:

• Widely prepare the surgical field, including both legs, in anticipation of the need to use venous grafts
• Obtain good exposure and vascular dissection to achieve proximal and distal control of the injured vessel
• After extracting the clots, use heparin in the segments to be anastomosed
• Identify and isolate the collateral vessels, maintaining their integrity
• Resect nonviable tissue; do not perform anastomoses when the intimal layer is detached; separate nonabsorbable sutures are appropriate in allowing for the child’s growth
• The triangulation technique, as described by Carrel, facilitates the anastomosis in small vessels; interrupted nonabsorbable sutures seem optimal, in that they accommodate vascular growth, whereas continuous absorbable sutures, though sometimes used, appear to be more thrombogenic; spatulation of the vascular ends to anastomose may protect against narrowing
• Cover the anastomosis with healthy soft tissue
• Liberally use fasciotomy when indicated; for repairs performed longer than 6 hours after the injury, consider associated venous injury and the possibility of massive edema with compartment syndrome; doing so improves the quality of limb salvage
• Always try to repair the vein, if it is injured
• Perform surgical arteriography at the end of the procedure

Use of temporary vascular shunts is quite useful for proximal-extremity arterial trauma, remaining patent in 85-95% of cases, and may be useful in limb salvage for brachial or femoral injuries. The shunts reduce overall ischemia time and serve as a bridge to definitive repair. Reduction in ischemia time may reduce the rates of compartment syndrome and nerve injury and improve the quality of limb salvage, preventing late amputation due to poor limb function.

On the other hand, distal shunts have poor patency and do not improve limb salvage. ^[2]  (See the image below.)

For carotid artery trauma, ligation of the distal internal carotid artery may be required when the injury is too distal for repair. Pseudoaneurysms can be treated with percutaneous embolization if they have a small neck. Zone III pseudoaneurysms can be treated with percutaneous graft placement if the lesion extends to the skull base.

Thoracic outlet vascular injury (eg, of the proximal subclavian arteries or innominate artery) may require a median sternotomy. Distal subclavian arterial injuries may require supraclavicular incisions. Trap-door or other combined incisions may be needed for more extensive injuries.

In children, as many as 89% of pseudoaneurysms have been shown to resolve following minimally invasive treatment (eg, ultrasound-guided compression or thrombin injection). ^[4]  Open repair or arterial resection of the pseudoaneurysm may be indicated in large pseudoaneurysms with a wide neck or pseudoaneurysms that fail to thrombose following compression or thrombin injection. ^[4]

Similarly, as many as one third of arteriovenous fistulas (AVFs) spontaneously resolve within 12 months. ^[4]  However, in patients who are symptomatic, surgical options including ligation, resection or oversewing of the fistula should be considered to repair the pathologic communication between vessels. At present, there remains a lack of data on the use of endovascular stents or embolization in pediatric AVF repair.

With the advent of improved suture and graft material and the development of microsurgical techniques, more arterial injuries are addressed in the OR now than before. With atraumatic vascular clamps and needles, 9-0 to 11-0 nylon sutures are used for vascular anastomoses. Topical application of 2% lidocaine or papaverine is used to control vasospasm. Prophylactic antibiotics are used preoperatively.

Reversed saphenous vein grafts are preferentially used for reconstructions of femoral arteries. The dorsal veins of the foot, which have a thick muscularis, can also be used as grafts. Debriding the injured arterial segment completely is crucial in preventing subsequent thrombosis.

In the postoperative period, closely monitor distal neurovascular compromise of the extremity, checking the patient's pulse, color, temperature, and capillary refill. Do not use compressive bandages, and look for edema. Keep the extremity mildly flexed, warm, and initiate movement or ambulation as soon as possible.

Gangrene and loss of a limb secondary to arterial insufficiency in young children are rare. However, limb shortening and claudication are frequent complications of femoral artery thromboembolisms in children. ^[15]  Approximately 10% of children have symptoms or limb-length discrepancy when monitored over the long term.

Many iatrogenic vascular injuries are due to lack of knowledge of the anatomy, physiology, surgical technique, and management strategies relevant to the use of the various vascular devices. Possible complications range from a simple hematoma to limb-threatening ischemia to patient death secondary to hemorrhage. To prevent and minimize such complications, therefore, clinicians must always stay well informed, continue to review these topics, and maintain contact with medical personnel with good training and experience in managing these cases.

A multidisciplinary team approach is fundamental for obtaining good results. This team should ideally include a pediatric surgeon with experience in vascular procedures, a pediatric anesthetist well versed in the management of critically ill children, a pediatric interventional radiologist, and a well-trained support team.

Early postoperative surveillance detects technical problems leading to graft failure. Long-term follow-up identifies aneurysmal dilatation, anastomotic stenosis, late bypass failure, or limb-growth discrepancy.

Invasive procedures are rarely needed. The use of clinical assessment, ABI, and duplex ultrasonography (US) at regular intervals is usually sufficient and reliable.

Short-term and long-term outcomes of neonatal vascular injuries should be further evaluated; these injuries have a high associated cost for disability and quality of life.

A few investigators have used objective methods to document long-term graft patency . In one report, a child was monitored by using pulse-volume recordings for graft patency and low-dose digital radiography for limb growth. The child had a 1-cm limb discrepancy in the revascularized leg after 6 years. Both Doppler studies and pulse-volume recordings demonstrated severe stenosis of the graft despite initial successful revascularization.