Imaging Teaching Case Complications of Vascular Access: Superior Vena Cava Syndrome Anil K. Agarwal, MD,1 Hooman Khabiri, MD,2 and Nabil J. Haddad, MD 1 Stenosis or occlusion of central veins in hemodialysis patients is common, especially with previous intravascular catheter or device use. Superior vena cava (SVC) obstruction is emerging as a frequent chronic complication of central vein cannulation that not only jeopardizes the availability of vascular access for hemodialysis, but can become a life-threatening emergency. Clinical features of SVC syndrome can be subtle or dramatic, including facial swelling and shortness of breath, which require expeditious attention and intervention. The approach to SVC syndrome involves judicious use of imaging techniques to define the cause and location. Early management with endovascular intervention with angioplasty and stent placement is the usual first choice. The occlusion can often be recanalized using new techniques such as radiofrequency wire and then salvaged with stents, providing prompt resolution of symptoms. Limitations to interventions include requirement of cutting-edge equipment, expertise, expense, and the usually temporary nature of the resolution. Surgery is considered the treatment of last resort for refractory cases. SVC syndrome can be prevented by minimizing catheter and intravascular device use through early recognition of patients with chronic kidney disease, early referral for education about all choices for kidney replacement modalities, and early placement of arteriovenous access prior to the onset of dialysis therapy. Am J Kidney Dis. -(-):---. ª 2016 by the National Kidney Foundation, Inc. INDEX WORDS: Superior vena cava (SVC); SVC syndrome; obstruction; central vein stenosis; occulsion; dialysis catheter complications; tunneled dialysis catheter; vascular access for hemodialysis; radiofrequency wire; angiography.
INTRODUCTION In 2013, a total of 88.2% of all incident patients with end-stage renal disease (ESRD) began renal replacement therapy with hemodialysis (HD) in the United States.1 Despite an increase in arteriovenous (AV) ﬁstula use at HD therapy initiation from 12% to 17.1% between 2005 and 2013, a majority of patients initiating HD therapy in the United States do so with a central venous catheter (CVC). In particular, in 2013, the proportion of patients using a CVC at HD therapy initiation was 80.2%, a value that has changed little since 2005. Furthermore, in data from 2013, at 90 days after dialysis therapy initiation, 68.3% of HD patients were still using a CVC. Catheters are associated with acute complications of placement, as well as chronic complications of venous stenosis or occlusion. A recent systematic review of 62 cohort studies concluded that CVCs were associated with the highest risk for death, infection, and cardiovascular events compared with other vascular access types and that patients with a functional AV ﬁstula had the lowest risk.2 Superior vena cava (SVC) syndrome is the result of stenosis or occlusion of the SVC or bilateral brachiocephalic veins. The clinical diagnosis of SVC syndrome is based largely on history and physical examination. Appropriate imaging techniques are important to conﬁrm the diagnosis and rule out other causes of SVC syndrome. Determining the exact Am J Kidney Dis. 2016;-(-):---
location and physical characteristics of stenosis or occlusion is crucial prior to intervention, and newer technologies for intervention are available that can be used in select cases. We present the case of an HD patient with debilitating symptoms and signs of SVC syndrome. Clinical diagnosis of SVC syndrome was obvious, but treatment required extensive imaging and intervention, which resulted in resolution of distressing symptoms.
CASE REPORT Clinical History and Initial Laboratory Data A 45-year-old man with ESRD secondary to diabetes mellitus and hypertension presented with 2 years of progressive right arm and facial swelling that started shortly after the creation of a right upper-arm AV graft (AVG). He experienced difﬁculty sleeping at
From the 1Division of Nephrology and 2Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, OH. Received May 27, 2016. Accepted in revised form August 21, 2016. Address correspondence to Anil K. Agarwal, MD, Section of Nephrology at University Hospital East, Interventional Nephrology, The Ohio State University Wexner Medical Center, 395 W 12th Ave, Ground Flr, Columbus, OH 43210. E-mail: anil. [email protected]
2016 by the National Kidney Foundation, Inc. 0272-6386 http://dx.doi.org/10.1053/j.ajkd.2016.08.040 1
Agarwal, Khabiri, and Haddad night and inability to dress himself due to the extensive head and arm swelling. The AVG had been working well, with no episodes of thrombosis. There was a history of multiple CVC placements on both sides of the neck. On physical examination, the patient had massive facial swelling and periorbital edema causing his eyes to be almost shut. There was massive right arm swelling, but no swelling of the left arm. The right arm, forearm, and hand were substantially larger than the left. Extensive venous collateralization was noted on the left side of the chest. The right upper-arm AVG had a palpable thrill.
Imaging Studies Computed tomography (CT) venography of the chest demonstrated a short-segment occlusion of the SVC between the conﬂuence of the brachiocephalic vein above and the azygous venous inﬂow below (Fig 1). The SVC was of good caliber below the occlusion. The left brachiocephalic vein was absent, consistent with chronic occlusion. The right brachiocephalic vein was patent and moderately enlarged. Massive collaterals throughout the chest, shoulder, and mediastinum were demonstrated.
Diagnosis The patient exhibited almost the entire spectrum of SVC syndrome, with imaging correlate of SVC occlusion involving the segment between the conﬂuence of the brachiocephalic vein and the azygous vein inﬂow. An intervention was planned.
Clinical Follow-up Endovascular recanalization was performed under general anesthesia. The right upper arm and right femoral area were prepared and the venous limb of the AVG was accessed. A 7F by 55-cm sheath was advanced over the wire. Venography through the sheath conﬁrmed the ﬁndings (Fig 2A). A multiloop snare device device was introduced and opened just above the SVC occlusion at the level of the brachiocephalic vein conﬂuence. Then a right common femoral vein was accessed and a 9F by 55-cm sheath was placed. Venography was performed to better evaluate
Figure 1. Computed tomography angiogram shows the occluded segment of the superior vena cava (SVC). Note a large number of collateral veins over the entire upper body and particularly enlarged collaterals on the left in this patient with SVC and left brachiocephalic vein occlusion. 2
the SVC. A directional catheter and conventional hydrophilic wire were unable to cross the SVC occlusion. A radiofrequency Powerwire (Bayliss Medical) was then introduced through the femoral sheath. Careful multiplane oblique ﬂuoroscopy was performed, spanning an arc of at least 90 to ensure proper alignment of the radiofrequency wire located caudal to the occlusion with the snare located cephalad to the occlusion (Fig 2B). Careful pulse activation of the radiofrequency wire was performed 5 times before the occluded segment was successfully crossed. Direct ﬂuoroscopic guidance was used to ensure continued alignment of the wire in the direction of the snare. The wire was snared and externalized via the right upper-extremity sheath. Careful sequential angioplasty was performed up to 8 mm 3 4 cm with postangioplasty venography after each balloon dilatation to ensure the absence of extravasation (Fig 2C). After balloon dilatation to 20 mm, the right femoral sheath was exchanged for a 12F by 45-cm sheath. A 24 3 60-mm Wallstent (Boston Scientiﬁc Corp) was deployed in the newly recanalized SVC and serially dilated to 22 mm. A poststent/angioplasty venogram demonstrated a wide-open SVC (Fig 2D). In the recovery area and during the ensuing few days, the patient had shortness of breath and ﬂuid overload thought to be due to the establishment of high AV ﬂow and mobilization of ﬂuid from his upper torso. He had immediate and continued improvement in his facial and arm swelling beginning a day after the procedure and continuing for several days. After several days of dialysis, he was discharged from the hospital.
DISCUSSION William Hunter ﬁrst described SVC syndrome due to a syphilitic aortic aneurysm in 1757.3 Malignancy has been the predominant cause of SVC syndrome, although with the emergence of central venous devices, up to 40% of all causes and 71% of benign causes of SVC syndrome have been attributed to these.4 However, patients with dialysis-related SVC syndrome are not as frequently symptomatic as those with malignancy, and the prevalence of SVC syndrome in HD patients may be underestimated. In a case series, HD patients had a slower onset of symptoms and higher likelihood of complete SVC obstruction (85%) than those with a chest neoplasm, whose obstruction was more likely to be partial (67%).5 Furthermore, the prognosis in HD patients was nearly as bad as in those with malignancy. Within 2 years, 31% of the patients died; 60% of these were symptomatic. The SVC is the ﬁnal common pathway for venous drainage of the upper half of the body. The SVC is formed by the conﬂuence of bilateral brachiocephalic veins and is w7 cm in length. It receives the azygous vein prior to entering the pericardium that covers its lower half. There are multiple mechanisms causing SVC syndrome (Box 1). Malignancies usually cause direct inﬁltration or compression of the SVC. In HD patients, the obstruction occurs due to a combination of stenosis and thrombosis. The pathophysiology can be explained by Virchow’s triad, comprising vessel injury, hypercoagulability, and stasis caused by an intravascular device. Also, the turbulence due to an Am J Kidney Dis. 2016;-(-):---
Central Venous Catheter Induced Superior Vena Cava Syndrome
Figure 2. Endovascular recanalization. (A) Angiography shows occlusion of the superior vena cava (SVC) at the level of the confluence of the innominate veins and the presence of collateral vessels. (B) When crossing the lesion with radiofrequency wire, using a snare to mark the position of the target vessel before crossing the lesion is a must. (C) Careful sequential angioplasty of the lesion beginning with smaller balloons and gradually using larger balloons. Note the focal waist on the balloon marking the “shelf” of fibrosis. (D) Placement of stent to recanalize the SVC. Note the absence of previously visualized collaterals.
intravascular device and increased ﬂow from creation of an AV access may incite inﬂammatory, thrombotic, and ﬁbrotic responses, resulting in neointimal hyperplasia, adhesive bands and stenosis, or occlusion of the lumen.6 As SVC ﬂow is compromised, collateral ﬂow develops via the azygous, intercostal, internal mammary, and long thoracic veins, partially offsetting the initial symptoms. Later, shortness of breath and orthopnea, swelling of the face and arm, feeling of fullness of the head and lightheadedness, visual Am J Kidney Dis. 2016;-(-):---
symptoms, chest pain, dysphagia, glottis edema, hoarseness, cough, and pleural effusions occur. As in our case, physical examination can show swelling of the face and arms, periorbital edema, collateral vein engorgement, cyanosis, papilledema, and altered consciousness. Symptoms often worsen on lying down or bending forward. Airway compromise can be life-threatening. Diagnosis of SVC syndrome is usually easy, but should be differentiated from pulmonary disease, 3
Agarwal, Khabiri, and Haddad Box 1. Causes of Superior Vena Cava Syndrome
Extraluminal (compression) Tumors with or without invasion and thrombosis of superior vena cava syndrome: bronchogenic carcinoma, lymphoma, metastatic cancers Mediastinal processes: fibrosis, nonmalignant tumors (eg, thymoma, cystic hygroma, teratoma) Vascular causes: aneurysms, arteriovenous fistulas, pericardial disease Infections Intraluminal: Usually a result of intravascular devices Thrombosis Stenosis/occlusion Idiopathic
heart failure, pericardial tamponade, and cellulitis. Imaging studies are crucial to determine the cause, management, and prognosis. Duplex ultrasonography is suboptimal in the evaluation of the SVC or central veins due to interference by the bony thorax. Plain radiographs and CT of the chest can reveal the presence of a malignancy or cardiopulmonary process. Magnetic resonance imaging is superior in deﬁning soft-tissue processes, but gadolinium should be avoided in patients with ESRD due to the risk for nephrogenic systemic ﬁbrosis. CT angiography is very useful in localizing stenosis or occlusion of the central veins and SVC. Finally, digital subtraction angiography is required as the intervention is planned. Management of SVC syndrome depends on the cause and severity, with an approach similar to that for management of central vein stenosis, but with more urgency.7 In general, the head is to be elevated. Dyspnea can be treated with oxygen. A thrombotic occlusion can often be treated with catheter-directed thrombolysis using alteplase or other thrombolytic agents. An indwelling device usually needs removal, though presence of a thrombus may require anticoagulation ﬁrst. For SVC stenosis or occlusion, endovascular intervention is the primary choice because it is minimally invasive. Angioplasty alone, though technically highly successful, has poor long-term patency.8,9 This is attributed to the higher recoil of central veins than peripheral veins, as shown by intravascular ultrasonography.10 Results of bare-metal stent placement have been variable, with limited short- and longterm patency requiring frequent intervention.11,12 Recently, covered stents have shown better results in the treatment of central vein stenosis.13,14 A relatively new approach involves placement of a hybrid graft-catheter device.15 The catheter portion of the device bypasses the SVC stenosis. It is limited by often tedious placement and the occurrence of thrombosis or infection with similar frequency as in AVGs. 4
Recanalization of an occluded SVC, as in our patient, requires more extensive endovascular intervention. Sharp recanalization with a classic hydrophilic wire followed by angioplasty and stent placement involves using the back end of a wire or other sharp object to cross an occluded segment. The disadvantage is the relative lack of control of the operator over the exact trajectory of the wire, which is dictated by the angle of approach and amount of resistance offered by the occluding lesion. This may force the wire into a course that is not optimal for subsequent balloon dilatation because it is too peripheral within the occluded vessel or even extravascular. Additionally, it is difﬁcult to change the course after a false passage has been made. However, it is inexpensive, is readily available, and could be useful for short-segment occlusions in which the wire is already in a central path and is meeting more resistant occlusion. A new technology for recanalization uses radiofrequency wire, which is a 0.035-inch exchange length wire with an active end. When energized with a radiofrequency pulse, it creates a small zone of burn within the tissue and can facilitate crossing lesions that would otherwise be impossible to cross. This allows careful and controlled advancement of the wire in short increments without the need for excessive force. Operator control over the course of the wire is signiﬁcantly better than with sharp recanalization. The tendency to follow a false passage is less problematic and the wire can still be guided in various directions. Avoiding vessel perforation requires careful ﬂuoroscopic evaluation and interpretation of the images to stay intravascular and recognize an extravascular course if it happens. Extravascular passage of the wire is unlikely to cause a major complication, particularly because the recanalized vein is not likely to bleed. If the wire enters and crosses adjacent structures such as arteries, subsequent balloon dilatation can cause potentially significant complications. The radiofrequency wire is best used to cross shortsegment occlusions when there are normal vessel segments above and below the occlusion. A vascular snare device on the other side of the occlusion acts as a target to guide advancement of the radiofrequency wire. The wire should be activated and advanced only a few millimeters at a time to avoid adjacent structures. There is a signiﬁcant learning curve with potential for complications unless strict recommendations are followed. With the advent of computerized guiding software, the technique might ﬁnd broader application. As in our case, it is also important to observe the patient for symptoms of volume overload after successful recanalization of the SVC. Unless thoracotomy is considered necessary, surgery is reserved for refractory cases only because of Am J Kidney Dis. 2016;-(-):---
Central Venous Catheter Induced Superior Vena Cava Syndrome
the frequent comorbid conditions in patients with ESRD. The options include vein patch or graft repair of the SVC or surgical bypass of the occlusion with direct anastomosis to the proximal SVC or right atrium. In conclusion, we describe a patient on HD therapy with an AVG, history of multiple CVCs, and gradual onset of severe SVC syndrome. SVC syndrome was diagnosed on presentation and studied with extensive imaging techniques. With careful use of an endovascular recanalization technique, there was resolution of SVC occlusion and symptoms. Prevention of venous stenosis by using the “catheter last” approach through early education and planning for placement of an AV access and use of other modalities of dialysis remains the preferred approach in kidney patients.
ACKNOWLEDGEMENTS Support: None. Financial Disclosure: The authors declare that they have no relevant ﬁnancial interests. Peer Review: Evaluated by 2 external peer reviewers, Feature Editor Kalantor-Zaheh, Education Editor Gilbert, and Editor-inChief Levey.
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