Penetrating trauma-related vascular injuries are challenging. When patients present with hard signs of vascular injury such as hemorrhage or expanding hematomas, surgical exploration is mandatory [9]. When soft signs or no clear signs of vascular injury are present and the patient is hemodynamically stable, imaging methods could be useful tools in the diagnosis and management of these patients. CTA continues to be the gold standard for the diagnosis of these injuries. However, POCUS and POCDUS are a cheaper, noninvasive and faster alternative to diagnose these injuries. As described in this manuscript, these tools can provide valuable information at the bedside and guide the decision-making process and follow-up of these patients.
High-frequency linear probes are the probes of choice because higher resolution and lower penetration are needed to assess this kind of injuries. When evaluating a penetrating vascular injury, it is important to scan the region of the trauma in a transverse and longitudinal fashion with B-mode. Flows should be investigated with Color and Duplex Doppler ultrasound. For comparative purposes, it is advised to evaluate both sides of the neck—affected and unaffected sides. Veins in the neck are oval in shape and are compressible. The Duplex Doppler evaluation shows a continuous flow pattern with respiratory variations. Arteries are round in shape and non-compressible. Doppler ultrasound is a useful tool for the assessment of anatomy and flow dynamics of the carotid arteries. The Duplex Doppler evaluation shows a pulsatile flow pattern with low resistance in the common and internal carotid artery and high resistance in external carotid artery.
Large hematomas, subcutaneous air, morbid obesity or large open wounds can represent a challenge, yet several studies have shown that POCUS and Doppler ultrasound remain useful tools to rule in or rule out trauma-related vascular injuries [11, 12, 14, 15]. As described in a previous paper, in patients with clinical suspicion of a vascular injury, POCUS and POCDUS are used to answer 2 basic questions [15]:
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Does the patient have a vascular lesion? Yes or no?
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If the answer is yes: What kind of lesion?
Two pseudoaneurysms of the left common carotid artery were found in this patient. A pseudoaneurysm is the result of a partial rupture of an artery wall, which causes accumulation of periarterial blood. The accumulated blood is surrounded and contained by the adventitia or adjacent hematomas or soft tissues. Traumatic carotid injuries are divided into grades, which can assist in guiding management [18]. Grade I injuries are mild intimal injuries which do no cause significant hemodynamic injury, grade II involve dissections and hematomas which do impact vascular hemodynamics, grade III are pseudoaneurysms (such as in this case), and grade IV and V are occlusions and transection with extravasation, respectively [18]. In this case report, the small pseudoaneurysms could have been caused by direct hit or by the heat the bullet generated next to the artery. Pseudoaneurysms always communicate with the arterial lumen by the pseudoaneurysm neck. While penetrating trauma is a common cause [19, 20], the most common cause is iatrogenic pseudoaneurysm [11, 21].
Evaluation of pseudoaneurysms with Doppler ultrasound on B-mode will demonstrate an anechoic or hypoechoic image containing moving echoes. It may increase in size during systole. The presence of a partially filled lumen by echogenic structures may represent a thrombus. The color flow evaluation will demonstrate the typical swirling motion known as the Yin–Yang sign, which is caused by the circular motion of the blood inside the pseudoaneurysm. During systole, the flow goes toward the pseudoaneurysm and during diastole the blood moves back to the arterial lumen [20, 21]. Spectral analysis will demonstrate turbulent flow. The pulse Doppler with the sample volume placed at the level of the neck of the pseudoaneurysm will show a flow pattern known as “to-and-fro”, a bidirectional flow caused by the continuous entry and exit of blood from the artery to the pseudoaneurysm and vice versa.
The management of traumatic carotid injuries are guided by grade and appropriate and timely interventions are warranted to prevent sequelae, such as stroke and occlusions, causing permanent central nervous system-related morbidity and mortality [18, 22,23,24]. Traditionally, grade I and II have been successfully managed with anticoagulants or anti-platelet equivalents (if there are no contraindications precluding its use). Among patients being managed with anti-coagulant therapy, PT/INR ratio should be maintained between 2 and 3, for 3–6 months [18, 22,23,24]. Unlike grade I–II injuries, however, grade III–V injuries require invasive therapies, either endovascular or surgical.
Grade III blunt carotid injuries have a stroke rate as high as 33% and mortality up to 11% [18, 24] with grade IV and V having even higher risks. Hence, timely and effective treatment often combining anticoagulation with procedural intervention is advisable. Endovascular interventions such as stenting present reasonable alternatives to open surgical techniques. A review by Morr et al. evaluated various stenting interventions to traditional open surgery methods such as endarterectomy [25]. Many factors of the stent characteristics themselves, including bare-metal vs. covered, tapered vs. untampered, and drug eluting vs. cutting/balloon based are pertinent to the discussion. Overall, stenting is a safe alternative to traditional surgical techniques such as carotid endarterectomies in some situations. Complications from endovascular procedures around stenting have been limited to few cases of carotid artery spasm, which can be medically managed with nitrates or calcium channel blockers.
A meta-analysis by Pham et al. evaluated the utility of endovascular stenting in carotid pathologies and included 31 studies with over 140 patients. The review showed that 98.4% of pseudoaneurysm cases were either successfully stented or occluded when appropriate [26]. Endovascular stenting is a safe and appropriate alternative to surgical intervention but randomized clinical trials are still needed. Maras et al. also reviewed the safety and short-term efficacy of covered stents for traumatic extracranial carotid artery pseudoaneurysms [27]. The review included 20 patients with carotid pseudoaneurysms secondary to traumatic injury and demonstrates that endovascular approaches can spare the morbidity and risk of surgical repair while providing similar efficacy in maintaining patency. Notably, endovascular approaches are less likely to result in cranial nerve injuries which are associated with open surgical approaches. While together these reviews and studies suggest a strong role for stenting in grade III blunt carotid injuries, longer follow-up on more patients is needed to further examine this promising treatment in addition to randomized clinical trials.
