A rare subclavian artery aneurysm potentially misidentified as the internal jugular vein in ultrasound-guided central venous catheterization -a case report-

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Korean J Anesthesiol. 2024;77(6):635-639

Publication date (electronic) : 2024 September 13

doi : https://doi.org/10.4097/kja.24468

Dae Yun Choi¹, Daeseok Oh^,2

¹Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea

²Department of Anesthesiology and Pain Medicine, Inje University Haeundae Paik Hospital, Busan, Korea

Corresponding author: Daeseok Oh, M.D. Department of Anesthesiology and Pain Medicine, Inje University Haeundae Paik Hospital, 875 Haeun-daero, Haeundae-gu, Busan 612-896, Korea Tel: +82-51-797-0415 Fax: +82-51-797-2669 Email: h00508@paik.ac.kr

Received 2024 July 8; Revised 2024 September 12; Accepted 2024 September 12.

Abstract

Case Report

An 88-year-old female patient (height: 158 cm, weight: 46 kg) with an American Society of Anesthesiologists physical classification of III was scheduled for lumbar laminectomy and posterior fusion. She had a history of hypertension and complained of lumbago with radicular pain aggravated by spinal stenosis following an L2 compression fracture three years prior. She received medications for hypertension, atrial fibrillation (amlodipine, beta-blockers, and apixaban), and back pain (gabapentin, tramadol, acetaminophen, and celecoxib). A preoperative evaluation based on blood tests, including complete blood count, electrolytes, liver function tests, creatinine, and blood urea nitrogen levels, showed no specific abnormalities. Chest radiography revealed right lower lobe subsegmental atelectasis. The electrocardiogram showed normal sinus rhythm with a heart rate of 86 bpm and left bundle branch block. Transthoracic echocardiography revealed an ejection fraction of 58%, enlarged left atrial dimensions, and aortic sclerosis. No cardiovascular or respiratory symptoms were observed preoperatively, and she tolerated activity levels equivalent to four metabolic equivalent tasks. Anesthesia was induced, and endotracheal intubation was performed using glycopyrrolate (0.2 mg), 2% lidocaine (40 mg), propofol (70 mg), and rocuronium (40 mg). For maintenance, 1.8% sevoflurane and remifentanil were administered at a target plasma concentration of 2 ng/ml. After confirming the results of the modified Allen test, an arterial line was inserted into the left radial artery. The patient was placed in the Trendelenburg position (bed tilted head down approximately 15°) to distend the IJV and prevent air embolism, and the head was turned slightly to the contralateral side to expose the IJV. We used an ultrasound (CX50^TM, Philips) linear transducer (L/12-3 MHz) to confirm the right IJV for central line catheterization. During ultrasonography, we observed two blood vessels with different diameters on the lateral side of the common carotid artery (CCA) (Fig. 1A). When sliding the probe up and down to map out the trajectory of the vessels, the blood vessel with the larger internal diameter disappeared at the upper neck level. When applying Color Doppler and Pulse Wave modes, pulsation was measured in the larger blood vessels (Fig. 1B), indicating it might be an artery. However, ultrasound could not definitively determine its origin. Notably, she had no history of central venous catheterization.

Fig. 1.

Ultrasound transverse view of the right supraclavicular fossa region. (A) The right SAA is seen lateral to the right CCA. (B) Vascular ultrasound with pulsed wave Doppler. An: aneurysm of the subclavian artery, IJV: internal jugular vein, CCA: common carotid artery.

The surgeon was informed of the possibility of an undetected vascular disease, including an aneurysm. The patient’s history revealed no trauma, hereditary disease, and no past histories of cerebral hemorrhage or aneurysm, nor any relevant family history. The surgeon discussed this matter with the patient’s guardian and decided to proceed with the surgery without additional evaluation. An alternative approach was considered, involving performing the procedure on the left side instead of the right. However, ultrasound imaging revealed that the left IJV was collapsed and exhibited calcification. Consequently, the left subclavian vein was assessed and found to be in relatively better condition compared to other veins. Therefore, we performed central venous catheterization on the left subclavian vein after confirming the absence of specific structural abnormalities using ultrasound. Surgery was completed without any specific complications.

Postoperatively, a right SAA was confirmed on the patient’s angio-neck CT (Fig. 2). Additionally, an approximately 5 mm-sized saccular aneurysm in the left intracranial artery was also present. The patient was transferred to the vascular surgery department for vascular evaluation, including assessment of the cerebral blood vessels. No additional vascular abnormalities were identified, and no connective tissue disease was observed during the evaluation. Considering the patient’s age and life expectancy, the potential benefits of the surgery were deemed minimal. Consequently, no surgery was performed on the aneurysm due to refusal by the patient and her guardian.

Fig. 2.

Computed tomography angiography images of the neck. (A) Axial view of the serial enhanced neck at the first thoracic spine level. (B) Three-dimensional reconstruction. Computed tomographic findings demonstrate an aneurysm of the subclavian artery. CCA: common carotid artery, An: aneurysm of the subclavian artery, VA: vertebral artery.

Discussion

The right IJV is considered the best route for vascular access due to its low complication rates and satisfactory flow, as well as its straight path to the right atrium [5]. Before puncturing the IJV, it is crucial to identify the anatomical structures of the specific patient to avert complications [4]. In most patients, the IJV route runs laterally to the internal carotid branch and the CCA [6]. However, individual anatomical variations can complicate vascular access using a ‘blind’ landmark method [7]. Therefore, physicians must understand the anatomical relationship between the IJV and CCA to avoid inadvertent arterial puncture [8]. Ultrasound imaging of the entire neck vasculature is recommended to determine the ideal puncture site [4,5]. The physicians must discontinue the procedure upon encountering vascular anomalies such as stenosis, thrombosis, fibrosis, or anatomical variations, and use ultrasound for further evaluation of the abnormality. Then they must then assess the corresponding vessel on the opposite side or consider other central veins, such as the subclavian or femoral veins, for safe catheter insertion.

Various anatomical variations exist in IJV access sites. Ultrasound studies have reported differences in the anatomical relationship between the CCA and IJV, particularly the relative position and overlap of both vessels [4,5,8]. When the head was rotated, the IJV was located anterior or anterolateral to the CCA in two-thirds of the patients studied [6].

In some cases, vascular abnormalities may present as incidental hypoechoic masses on ultrasound. Variations in IJV anatomy are possible, such as bifurcation, duplication, trifurcation, and posterior tributaries of the IJV [9]. Furthermore, variations in the extrathoracic proximal subclavian arteries are possible. Two cases of SAA were discovered incidentally during thyroid gland examinations via ultrasound, similar to our case [6,10]. These SAAs appeared posterior or lateral to the CCA, highlighting the potential for misidentification with the IJV due to their anatomical proximity to the CCA during catheterization. Additionally, infundibular dilatation, though rare in the subclavian artery, is smaller and more symmetrical compared to aneurysms. It typically lacks thrombosis or calcification and commonly occurs at vessel branching points, especially the thyrocervical trunk [11].

True arterial aneurysms present as focal dilatations greater than 1.5 times the normal vessel diameter due to the degeneration of elastin and collagen in the arterial wall’s media [12]. The typical sonographic features of SAA are a dilated, pulsatile, and hypoechoic mass in the neck, with a thrombus potentially observed along the periphery [6,10]. Color Doppler imaging can reveal turbulent flows and eddy currents [10]. In our case, no significant plaque surrounded the subclavian artery wall, although mild atherosclerotic luminal narrowing was noted in the bilateral intracranial arteries on angio-neck CT. Ultrasound is also useful in differentiating hypoechoic masses, including cervical cysts, pharyngoesophageal diverticula, struma, enlarged lymph nodes, benign or malignant neoplasms, and vascular anomalies [6].

Aneurysms of the subclavian artery, though rare, constitute less than 1% of all aneurysm and can lead to serious complications, such as rupture, thrombosis, and embolization [13]. The underlying causes of SAAs are similar to those of the great vessels, such as the aorta [10]. True aneurysms of the subclavian artery are mostly secondary to atherosclerosis and thoracic outlet syndrome, but can also arise from rarer causes, such as fibromuscular dysplasia, cystic medial necrosis, infection, and congenital anomalies, whereas false aneurysms typically result from penetrating trauma, such as catheterization, and consist of a pseudocapsule of the surrounding tissue [13,14]. In older adults, multiple aneurysms are usually attributed to generalized atherosclerosis [15]. Differential diagnoses for multiple systemic aneurysms include heritable disorders, non-infectious autoimmune vasculitides, mechanical injuries, and infectious diseases [12,16]. Our case identified multiple incidental aneurysms, with only hypertension and vascular atherosclerotic changes as identified risk factors.

In conclusion, while SAAs are uncommon, anesthesiologists should consider their potential presence. Considering anatomical variations during IJV catheterization is crucial, and vigilance for incidental SAAs is essential. Using ultrasound guidance for central venous catheterization significantly reduces the likelihood of vascular identification errors. Doppler ultrasound plays a key role in accurately identifying arteries.

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