Conventional and Computed Tomographic Arteriography in Penetrating Vascular Injuries



Conventional and Computed Tomographic Arteriography in Penetrating Vascular Injuries



Jonathan L. Eliason


The mid-20th century saw the emergence of contrast angiography to clarify and define the extent of vascular wounds. Percutaneous catheter-based angiography began to replace surgical cutdown and needle injection of contrast in the 1950s and 1960s, and became the gold standard for the diagnostic evaluation of penetrating vascular injury over subsequent decades. However, as the quality of computed tomography (CT) imaging using spiral multidetector techniques has improved, diagnostic imaging for penetrating vascular injury has migrated away from invasive catheter-based angiography. The exception to this trend is the patient in whom a combined diagnostic and therapeutic endovascular intervention is planned. Nevertheless, CT angiography (CTA) is often used as a guide for planning minimally invasive procedures.



Imaging for Penetrating Vascular Injuries of the Neck


CT angiography can be used in place of catheter-based angiography for penetrating vascular injuries in the neck, excluding patients who should typically undergo immediate surgical exploration. In the absence of hard signs of vascular injury, the physical examination alone is unreliable for excluding an arterial injury. Numerous reports have described delayed neurologic deficits from pseudoaneurysms or other arterial wounding patterns that were not initially identified following penetrating injury. Imaging, therefore, is an important component of the thorough evaluation of patients with penetrating trauma to the neck.


Catheter-based angiography has proved sensitive and specific for arterial injury in the neck. Despite this, stab wounds in asymptomatic patients do not seem to warrant routine arteriography owing to a very low rate of detection of significant vascular injury; gunshot wounds are more likely to result in positive findings leading to surgical intervention. Symptoms (e.g., hematoma, swelling, altered mental status) result in higher rates of detection of arterial injury with angiography. The cost-effectiveness of catheter-based angiography was evaluated in 111 patients with penetrating neck trauma. The cost was $3 million per central nervous system (CNS) event prevented, leading some to believe that angiography in the neck should be largely abandoned in favor of less expensive and less invasive imaging such as ultrasound or CT.


CT has emerged as a very important imaging modality for penetrating neck trauma. Its utility lies in part in the evaluation of aerodigestive tract injury, although these injuries have a higher false-positive rate than vascular injuries, in which the sensitivity and specificity for arterial injuries are both greater than 95%. Metal artifacts from ballistic injury limit the utility of CT in some patients. CT has been demonstrated to accompany decreased rates of unnecessary neck exploration and limits the need for oesophagogram or catheter-based arteriogram. If CT demonstrates ballistic trajectories that are remote from important structures then additional invasive imaging can be avoided. CTA is also a useful for preoperative planning when the patient’s stability permits and there is need for clarification of the best surgical approach (Figures 1 and 2).


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FIGURE 1 A, Axial computed tomography (CT) image showing hemodialysis (HD) catheter placement entering the left subclavian artery adjacent to the left vertebral artery origin. B, Axial CT image showing HD catheter traversing the aortic arch. C, Reconstructed CT image revealing the course of the HD catheter from the left subclavian artery extending down into the mid-descending thoracic aorta. D, CT angiogram of the neck revealing codominant vertebral arteries (white arrows) ordered to determine risk of potential endovascular coverage of the left vertebral artery.

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FIGURE 2 A, Arch aortogram with a faint outline of the hemodialysis (HD) catheter seen within the left subclavian artery on the subtracted image. B, Selective left subclavian artery angiogram via sheath injection revealing the outline of the HD catheter entering the left subclavian artery adjacent to the left vertebral artery (black arrow). C, Fluoroscopic image revealing stent graft placement within the left subclavian artery deployed across the site of iatrogenic penetration simultaneous with removal of the HD catheter. D, Completion arch aortogram revealing the widely patent left subclavian artery following stent graft placement, but notably absent visualization of the left vertebral artery, internal mammary artery, and thyrocervical trunk.


Imaging for Penetrating Vascular Injuries of the Thorax


CTA has clearly emerged as the screening modality of choice with blunt injury to the aorta. In contrast, the benefit of CTA is less clear with penetrating vascular injuries to the chest. The majority of penetrating injuries to the chest occur from knife wounds or projectiles from handguns. Injuries from nail guns and other atypical injuries have also been reported. Penetrating wounds that traverse the mediastinum are often lethal as a result of involvement of the heart and great vessels, whereas those that are outside the mediastinum typically do not result in vascular injury, but rather cause pulmonary, chest wall, and diaphragm wounds. Nevertheless, CTA is useful in patients in whom the missile trajectory crosses the midline and can involve the mediastinum. If these patients are hemodynamically stable, CTA can aid with determining patients in whom expeditious operation is warranted, patients who warrant aerodigestive tract evaluation, and those patients in whom diagnostic angiography may be of benefit (Figure 3).


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FIGURE 3 Computed tomography angiography (CTA) of the chest demonstrates a large proximal subclavian artery pseudoaneurysm in a hemodynamically stable patient with a zone 1 penetrating neck injury. CTA facilitated operative planning and guided surgical incision.

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Aug 25, 2016 | Posted by in CARDIOLOGY | Comments Off on Conventional and Computed Tomographic Arteriography in Penetrating Vascular Injuries

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