Interventional Radiology in Trauma

I. Introduction

The role of interventional radiology is rapidly evolving. As a diagnostic and therapeutic modality, interventional radiology (IR) is an important adjunct in every body region and for a wide variety of injuries.

II. General Considerations

A.

The IR suite should be staffed and equipped as an intensive care unit (ICU) setting. Where the trauma team or ICU team continue are aspects of critical management. Full monitoring with easy viewing, audible alarms, and user-friendly phone communication must be ensured at the patient's side and in the viewing room. Other personnel and resources should include critical care nursing, respiratory therapy, fluid warmers, external warming devices, and environmental control.

B.

IR access in the injured patient is typically via femoral approach. Imaging progresses from general to selective. Aortogram should be performed initially to identify the patient's anatomy, preexisting conditions, and unsuspected injuries. This is followed by a more selective “run” demonstrating the organ or region of interest. Finally, selective catheterization is performed for diagnosis and emboliza-tion as needed.

C.

If embolization is indicated, it is done as selectively as possible to minimize the amount of tissue under perfision and infarction. Embolization with absorbable gelatin (Gelfoam) slurry is temporary, allowing recanalization of the vessel after a period of time. Embolization with metal coils results in permanent occlusion. Embolization is highly effective (95% success rate) for hemorrhage control and has a low complication rate (approximately 5%). Postembolization rebleeding occurs rarely, and repeat embolization is usually effective.

D.

Risks of arteriography include groin hematoma/pseudoaneurysm, retroperitoneal hematoma, intravenous contrast allergy, and intravenous contrast nephropathy. The incidence of each complication is less than 5%. Anaphylaxis is rare, but airway and pharmacologic adjuncts should be immediately available in each room of the IR suite. Although studies have suggested that a history of seafood allergy does not accurately predict adverse reaction to intravenous contrast, most radiologists avoid routine use of intravenous contrast with this history. Cerebral arteriography carries a <1% risk of stroke. Regarding contrast nephropathy, oral N-acetylcysteine (NAC) and intravenous isotonic sodium bicarbonate may decrease the incidence of this complication, but in the trauma population, the benefit of either agent is not clear.

E.

Although arteriography is considered the gold standard of vascular imaging, it has limitations (Table 14-1). False negatives studies are due to vasospasm, spontaneous thrombosis, or technical factors that hinder selective catheterization. False positives arteriographic studies are often errors in interpretation due to overlying vessels or venous stasis.

III. Specific Considerations

A.

Aorta and great vessels

• Accurate identification of thoracic aortic and great vessel injury is imperative to plan the potential operative approach and the details of circulatory support. Thoracic aortography and great vessel arteriography are still considered the gold

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  standards for imaging vascular structures in the chest. Aortography generally includes frontal and left anterior oblique projections. The most common site of injury from blunt trauma is the proximal descending aorta at the ductus arteriosus.

  TABLE 14-1 Signs of Vascular or Parenchymal Injury

  Arterial cutoff Mural irregularities or flap Laceration Thrombosis Dissection Free-flow contrast extravasation Stagnant intraparenchymal accumulation of contrast Parenchymal blush Stagnant arterial or venous flow Diffuse vasoconstriction Pseudoaneurysm Arteriovenous fistula Vessel displacement Intraparenchymal avascular zones Disruption of visceral contour Displaced organ (Adapted from Dondelinger RF, Trotteur G, Ghaye B, Szapiro D. Traumatic injuries: Radiological hemostatic intervention at admission. Eur Radiol 2002;12:979–993.)

• In the traditional algorithm, the patient with an abnormal mediastinal silhouette on chest radiograph proceeded directly to thoracic aortography. Rapid, multi-slice chest computed tomography (CT) with properly timed contrast injection has become the screening study of choice for the thorax. Arteriography is reserved for patients whose CT demonstrates mediastinal hematoma, abnormality of the aorta or great vessels such as dissection or pseudoaneurysm, or is indeterminate for injury.
• Patients with instability due to known or suspected thoracic aortic injury require immediate operative intervention. Experience in endovascular treatment of thoracic aorta is accumulating. At centers with experience in endovascular thoracic aortic techniques, stable trauma patients with known or suspected thoracic aortic injury must undergo a chest CT using a dedicated endovascular protocol. The three-dimensional reconstruction of the aorta is used to determine whether stent grafting is technically feasible, and if so, how to construct the stent graft. Although early reports have been promising, other results suggest that the technologic advancements of the stents for placement in the thoracic aortas of the younger trauma patients may be imperfect at this time. Proximal stent collapse has been seen in patients at several centers.
• IR is useful in the diagnosis and treatment of subclavian artery injury, which is challenging to expose surgically. In the stable patient, endovascular stenting of subclavian and axillary artery injury compares favorably in terms of operative times and short-term outcomes. Also, IR intraluminal balloon occlusion has been described to obtain proximal control of subclavian artery injury, followed by operative exposure and injury repair.

B. Carotid and vertebral arteries

Arteriography is the gold standard in diagnosis of cerebrovascular injury. Traditionally, penetrating injury to zone I or zone III of the neck mandated cervical four-vessel arteriography (bilateral carotid and vertebral arteries). For zone I injuries, in the presence of normal physical exam and chest radiograph, routine arteriography has been questioned. Arteriography has utility in zone III by aiding operative planning and identifying injuries amenable to embolization.

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TABLE 14-2 High Risk for Blunt Cerebrovascular Injury

Severe cervical hyperextension/rotation/hyperflexion, especially with displaced or complex midface or mandible fracture Closed head injury with diffuse axonal injury Near-hanging with cerebral anoxia “Seat belt sign” of anterior neck Basilar skull fracture involving the carotid canal Cervical vertebral body fracture or distraction (except isolated spinous process fracture) (Adapted from Biffl WL, Moore EE, Offner PJ, Burch JM. Blunt carotid and vertebral arterial injuries. World J Surg 2001;25:1036–1043.)

In blunt mechanism of injury, several patterns of injury have been suggested as being high risk for blunt cerebrovascular injury (BCVI) and probably warrant aggressive screening (Table 14-2). Arteriography remains a gold standard, but most centers have adopted CT angiography or magnetic resonance angiography (MRA) as the initial screening procedure.

C. Maxillofacial injury

• Profuse hemorrhage from maxillofacial injury usually responds to direct compression, reduction of fractures, suture ligation, and nasal packing. Persistent maxillofacial hemorrhage may necessitate arteriography and embolization. Surgical ligation of the external carotid artery may not control hemorrhage because of extensive contralateral collateral flow. After arteriogram of the common carotid artery, selective arteriogram of the external carotid artery is performed, with selective embolization of bleeding branches of the external carotid artery. Of the branches of the external carotid artery, the most common source of hemorrhage is the maxillary artery.
• Complications include stroke, facial nerve palsy, trismus, and tissue necrosis (including tongue).
• Carotid artery-cavernous sinus fistula should be considered in patients with facial trauma and proptosis, abnormal visual acuity, and pulsating globe. Arteriography has the capability to diagnose and treat this condition by means of detachable balloon occlusion.

D. Peripheral vascular injury

• In blunt or penetrating lower extremity injuries, arteriography is generally indicated when a pulse deficit is present on physical exam or when ankle-brachial index (or ankle-ankle index) is less than 0.9. Arteriography is generally not indicated for penetrating injury with “hard sign” of vascular injury (absent pulse, expanding hematoma, bruit/thrill, obvious distal ischemia). In these situations, immediate operative exploration is indicated.
• Proximity or trajectory per se do not mandate arteriography if the pulse exam is normal and the ankle-brachial or ankle-ankle index are greater than 0.9.
• The extremity with penetrating wounds at multiple levels or multiple projectiles (such as shotgun wounds or multiple bone fragment) and where multilevel injury is possible arteriography is usually indicated and helpful and may be warranted even with hard sign of vascular injury. Arteriography aids operative planning by identifying the level and extent of arterial injury.
• In blunt injuries, arteriography is a useful adjunct in the evaluation of the mangled extremity. Absence of at least one-vessel flow into the foot or hand precludes limb salvage. Traditionally, posterior knee dislocation mandated routine arteriography, but recent literature questions routine arteriography in absence of ischemia, hard signs of vascular injury, or signs of peripheral embolization.
• Each case should be individualized and if consults are used, orthopedic surgeons or vascular surgeons discussed.

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E. Liver

• Hepatic arteriography and embolization is a crucial component of the management of hepatic injuries. Arteriography assesses the anatomy of the individual's hepatic arterial system. The portal venous phase allows diagnosis of portal vein injury. Laparotomy followed by hepatic arteriography/emboliza-tion (or in the reverse sequence, depending on patient hemodynamics) should be considered complementary techniques to identify and control hepatic hemorrhage. Most hepatic vascular injuries can be controlled in the operating room with surgical techniques such as direct ligation and packing. In particular, perihepatic and intrahepatic packing is effective for venous injuries. However, after surgical control, arteriography with embolization is often the only effective method short of anatomic resection to control unrecognized and intraparenchymal hepatic arterial hemorrhage. Immediate postoperative hepatic arteriography/embolization should be considered in all patients who require perihepatic packing and damage control laparotomy for hepatic injuries.
• In select patients, embolization can be primary therapy. Among hemodynamically stable patients with CT evidence of liver injury (and no evidence of hollow viscus injury), pseudoaneurysm, large hemoperitoneum, and extravasation of intravenous contrast are associated with a high failure rate of nonoperative management. These patients should undergo hepatic arteriography and embolization.
• Routine arteriography for patients with grade IV or V hepatic injuries without contrast extravasation, pseudoaneurysm, or significant hemoperitoneum is controversial.
• Patients chosen for initial nonoperative management of high-grade hepatic injury should be monitored in an ICU setting. Those who subsequently develop signs or symptoms of ongoing hemorrhage should undergo immediate hepatic arteriography and embolization, preferably selective.
• Although the liver has a dual blood supply, embolization of the common hepatic artery should be considered a last resort when more selective embolization is not possible. Embolization of the main right hepatic artery should also be avoided if possible, as this necessitates subsequent cholecystectomy.
• Late sequelae of hepatic injury includes hepatic necrosis, abscess, biloma, hematoma, and hemobilia. Postinjury collections can be treated by IR percutaneous drainage.

F. Spleen

• Splenectomy remains the safest therapy for hemodynamically unstable patients with splenic injury. Among hemodynamically stable patients with splenic injury, the current indications for splenic arteriography and embolization vary widely by institution. Suggested criteria for performing arteriography are one or more of the following CT findings: splenic injury with hemoperitoneum, high-grade injury, intravenous contrast extravasation, or pseudoaneurysm. In most centers, splenic arteriography and embolization for splenic salvage is highly selective and reserved for young patients; in other centers, it is used more liberally. The optimal role of arteriography/embolization for splenic injury is still evolving. The two major types of splenic embolization are main artery embolization and selective embolization.
• The overall failure rate (rebleeding) after embolization is 14%. Failure of splenic embolization warrants splenectomy, although repeat embolization has been described. Complications of splenic embolization also include abscess (4%) and infarction (21%).
• Vaccinations for encapsulated organisms are routinely administered after main artery embolization. The role of vaccination after selective embolization is unclear.

G. Pelvis

• Arteriography plays a critical role in identification and control of pelvic arterial hemorrhage and is a crucial component of the management of pelvic injuries. Depending on the injury pattern, embolization is effective as either primary therapeutic intervention or as an adjunct to external pelvic fixation or

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  laparotomy. The internal iliac (hypogastric) arteries and its branches are amenable to embolization.
• The initial management of pelvic fracture with diastasis should be an attempt to “close” the pelvic ring, which can be achieved by placing a pelvic binder (using a bedsheet or Trauma Pelvic Orthotic Device [T-POD]) or by external fixation. These measures theoretically reduce hemorrhage by promoting tamponade of venous hemorrhage. Mechanism of injury, hemodynamic stability, physical exam findings, focused abdominal sonography for trauma (FAST), and radiography of chest and pelvis determine the subsequent evaluation and treatment. Pelvic arteriography and embolization should be considered in the following patients:
  • Hemodynamically unstable blunt injury with pelvic fracture on x-ray and negative FAST or diagnostic peritoneal lavage (DPL).
  • Hemodynamically stable blunt injury with CT demonstrating a large pelvic hematoma or pelvic contrast extravasation, pseudoaneurysm, or arteriovenous fistula.
  • Immediately following trauma laparotomy for intra-abdominal hemorrhage and ongoing pelvic hemorrhage.
• Pelvic embolization is largely safe and effective. Risks of pelvic embolization include rectal ischemia and gluteal necrosis. Sexual dysfunction occurs rarely in males and may be related to the pelvic fracture.
• Repeat pelvic arteriography should be considered if hypotension or acidosis persist after initial arteriogram is negative and other sources of hemorrhage have been excluded.
• Although selective embolization is preferable to proximal internal iliac artery embolization, selective embolization may be quite time-consuming. Unstable patients with multiple sites of pelvic arterial hemorrhage may best be served by unilateral (or bilateral) internal iliac artery embolization, which can be performed rapidly. However, bilateral internal iliac artery embolization increases the risk of rectal and gluteal ischemia and necrosis.

H. Kidney

Stable patients with evidence of renal injury on intravenous contrast CT may benefit from selective embolization. Infarction of large areas of the kidney is well-tolerated, presuming a functional contralateral kidney. Urinoma is a known complication of renal embolization and is treated by IR percutaneous drainage.

I. Inferior vena cava filter

Injured patients who are at extremely high risk for deep venous thrombosis and pulmonary embolism can be predicted (Table 14-3) (Chapter 50). In this group, inferior vena cava (IVC) filters reduce the risk of pulmonary embolism; placement of prophylactic IVC filter should be considered.

TABLE 14-3 Indications for Prophylactic IVC Filter

Patient who cannot receive anticoagulation because of increased bleeding riskb and has injuries resulting in immobility, such as: Severe closed head injury (Glasgow Coma Scale score <8) Paraplegia or quadriplegia Complex pelvic fractures with long bone fractures Multiple long bone fractures * Intracranial hemorrhage, ocular injury with hemorrhage, solid organ injury, pelvic or retroperitoneal hematoma, cirrhosis, active ulcer disease, end-stage renal disease, preexisting or postinjury coagu-lopathy. (Adapted from Rogers FB, Cipolle MD, Velmahos G, et al. Practice management guidelines for the prevention of venous thromboembolism in trauma patients: The EAST Practice Management Guidelines Work Group. J Trauma 2002;53:142–164.)

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However, it is unclear how long caval interruption is beneficial. Both permanent and retrievable IVC filters are available. Retrievable filters require manipulation at varying intervals to remain retrievable.

J. Other procedures

Other interventional procedures include percutaneous drainage of postoperative or postinjury collections (intra-abdominal/pelvic abscesses, hematomas, bilomas, urinomas, and thoracic empyemas), exchange of surgical drains and catheters, and insertion of peripherally-inserted central catheters (PICCs). These procedures are usually performed under guidance of flu-oroscopy, CT, or ultrasound.