Evaluation and Management of Chronic Thoracic Venous Obstructions
Clinical presentation, anatomic patterns of TCVO, and revascularization strategies.
Chronic thoracic central vein obstruction (TCVO), including both stenosis and occlusion, is a potentially morbid condition, especially in patients with end-stage renal disease who rely on a patent central venous system to preserve hemodialysis access. Unfortunately, TCVO is a common complication for patients on hemodialysis. The true incidence of TCVO in patients requiring hemodialysis is unknown and reports vary greatly, affecting anywhere from 4% to 50% of this population.1,2 Aside from the development of venous obstructive symptoms, venous occlusions often lead to placement of dialysis catheters at suboptimal access sites, such as in the femoral veins, which in turn may increase the risk of infection and morbidity. Still, for some patients, even alternative access sites may have been exhausted and the ability to restore access through a TCVO can be lifesaving.
ETIOLOGY AND CLINICAL PRESENTATION
There are several possible etiologies of TCVO. Most commonly, the obstructions relate to catheter use, which can lead to endoluminal obstruction by thrombus or intravascular scarring from catheter-induced trauma to the venous endothelium. This subsequently causes inflammatory changes and turbulence from arterialized flow into the vein.3 Extrinsic compression of the vein can also lead to a chronic occlusion. Compression can be due to overlying musculoskeletal structures (thoracic inlet or brachiocephalic vein [BCV] compression syndromes) or tumor compression.
TCVO usually develops slowly over time, allowing the formation of collateral veins, which may mitigate or prevent symptoms.4 In some instances, a chronic asymptomatic obstruction may become symptomatic through the establishment of an ipsilateral arteriovenous access. When a TCVO becomes symptomatic, the results can be severely debilitating. Facial, breast, or upper extremity edema are common. If the obstruction is severe, it can also lead to dialysis access dysfunction or occlusion, dyspnea, pain, visual or other neurologic changes, headaches, and syncope.3,5 The presence, severity, and progression or regression of these symptoms must be assessed on initial and all subsequent patient encounters. Additionally, the presence and creation of reliable hemodialysis access must be assessed and prioritized.
When evaluating a patient with TCVO, the anatomy and clinical presentation must be carefully delineated. The Society of Interventional Radiology has released guidelines to help ensure TCVO reporting is comprehensive and reproducible.5 In fact, even the terms central and peripheral veins lack standard definitions; therefore, one of the objectives of the guideline was to standardize terminology in order to improve reporting. For the purposes of this article, the thoracic central veins include the intrathoracic portions of the internal jugular (IJ) and subclavian (SC) veins, as well as the BCVs and superior vena cava (SVC). The anatomic boundaries of the thorax are the C7-T1 intervertebral disc space and the lateral margin of the first rib.
A precise definition for the pattern of TCVO is important. There are four predominant anatomic patterns of TCVO.5 Type 1 describes patent bilateral BCVs and a patent SVC with occlusion of only one IJ or SC vein. Type 2 is any TCVO that includes unilateral BCV obstruction or occlusion of both the IJ and ipsilateral SC veins (functionally similar to a single BCV obstruction) (Figure 1). Type 3 requires bilateral BCV occlusion with a patent SVC (Figure 2). Type 4 is any SVC occlusion irrespective of the patency of other thoracic veins (Figure 3).
Open surgical bypass has largely fallen out of favor compared with endovascular recanalization techniques. Once a decision has been made to proceed with thoracic venous recanalization, there are several preprocedural steps the interventionalist can take to maximize the chances for a safe and successful procedure. Imaging with chest CT venography can be invaluable because it provides useful information about the obstruction, including exact location, length of obstruction, and nearby critical structures (ie, arteries, lungs). Additionally, it allows the operator to create a crossing strategy before the procedure, which can save valuable time during the case. Thoracic magnetic resonance venography has also been utilized for these purposes in centers with familiarity and expertise. Doppler ultrasound of the bilateral neck, chest, and upper extremities can be helpful to determine patency of peripheral venous inflow, as well as identify potential venous access points if revascularization is attempted.
Before proceeding with revascularization, the goal of the procedure must be clear: are TCVO symptoms being treated, or is the procedure purely to establish hemodialysis access? The former requires restoration of venous inflow and outflow for symptom resolution and maintenance of patency, whereas the latter requires only safe access into the right atrium, even if an extravascular route is required along the way. The next step is to determine the ideal venous access points. Multiple points of access are often required, and having these access points prepared from the outset saves valuable time during the procedure. Consideration of mechanical advantage can drastically reduce procedure times and increase technical success. For example, when managing an SVC occlusion, a right IJ approach allows direct caudal transmission of forces versus an upper extremity approach, which necessitates navigating angles into the BCV.
After venous access is established, a robust triaxial support system is created with long sheaths, guide catheters, and diagnostic or dedicated crossing catheters. To cross the obstruction, 0.035-inch hydrophilic wires in long lengths (260 cm) are typically used as a first-line tool and are successful in the majority of cases. It may be helpful to use 0.018-inch or arterial chronic total occlusion wires with weighted tips to engage and traverse particularly fibrotic occlusions.
When traditional endovascular methods fail, experienced interventionalists may utilize sharp or radiofrequency (RF)-assisted recanalization techniques. Sharp recanalization techniques require the use of the back end of a wire, 20- to 22-gauge (15–20 cm) percutaneous or transseptal needles, or transjugular intrahepatic portosystemic shunt needles.6 A target—such as a catheter, snare (Figure 1), balloon, or partially deployed vascular plug or stent—is typically placed from the opposite approach to allow precise targeting under fluoroscopy using meticulous triangulation techniques. The RF-energized guidewire is a very useful tool in the interventionalist’s armamentarium for occlusions that are completely recalcitrant to other endovascular techniques.7 The RF wire is advanced and activated in stepwise 1- to 2-second bursts to cross the occluded vessel; however, much like a needle, the RF wire has the ability to penetrate both intended and unintended structures and requires a high level of expertise to avoid catastrophic complications.
Once the occlusion has been crossed and a safe crossing route has been confirmed, which can be done with over-the-wire tractography or cone-beam CT if needed, angioplasty balloons are used to dilate the track. It is the authors’ strategy to attempt angioplasty alone for lesions that are fairly easily crossed using traditional techniques and show a good angiographic result after dilation. For lesions that demonstrate immediate postangioplasty recoil or short-term recurrence or require advanced recanalization techniques, stent support is generally provided. Both balloon-expandable and self-expanding stents can be used centrally, but balloon-mounted stents should be avoided at points of potential external compression. Similarly, both bare-metal stents (BMSs) and covered stents are utilized for TCVOs, each with advantages and disadvantages. Covered stents can be lifesaving in areas where vessel injury may lead to significant hemorrhage, such as below the pericardial reflection. However, covered stents may unintentionally and unnecessarily occlude draining veins such as the azygos or contralateral BCV. An alternative approach when only catheter placement is necessary is to pass a needle from the level of the occlusion toward the skin surface. This allows passing of a wire to establish stable access, which can then be used to place a catheter. Newer commercially available devices have been designed to aid in this approach. As with all sharp recanalization techniques, care must be taken to avoid nearby critical structures.
After the procedure, patients may require anticoagulation (eg, warfarin, enoxaparin, apixaban) or antiplatelet therapy (eg, clopidogrel, acetylsalicylic acid), but data are lacking to provide high-level guidance. Patients are generally followed in clinic at 1, 3, and 6 months and then annually to assess for symptom resolution, dialysis access function, and recurrence of symptoms.
Even seemingly straightforward treatment of TCVOs can result in devastating consequences, considering the anatomic location of the central thoracic chest veins in relation to the pericardial reflection and adjacent cardiac and arterial structures. Interventionalists must always bear in mind that the exact location of the pericardial reflection in relation to the SVC is somewhat variable and cannot be visualized. Small wire venous perforations into the mediastinum are largely inconsequential, but large vein rupture or ongoing hemorrhage in the pericardial sac can lead to clinically significant symptoms, pericardial tamponade, or even death.
Injury to adjacent structures such as the lung, trachea, aorta, and pulmonary arteries can be avoided by meticulous targeting techniques. Cone-beam CT can be useful, although it may be limited by a patient’s body habitus or respiratory or cardiac motion.
For any procedure requiring treatment of SVC occlusion, an ultrasound-guided window to the pericardium should be marked and prepped prior to the start of revascularization. Should pericardial tamponade occur, emergent pericardial aspiration or drain placement can then proceed quickly at the previously marked site. Additionally, appropriately sized occlusion balloons and covered stents should be readily available in the procedure room to control hemorrhage (Figure 4).
TCVO can cause profound symptoms and impair effective renal replacement therapies. Clinical evaluation and delineation of obstructive etiologies and anatomy allow for targeted revascularization strategies. Thoracic venous recanalization can be performed effectively and safely by experienced and cautious interventionalists to allow amelioration of patients’ symptoms and facilitate long-term hemodialysis access.
1. Adwaney A, Lim C, Blakey S, et al. Central venous stenosis, access outcome and survival in patients undergoing maintenance hemodialysis. Clin J Am Soc Nephrol. 2019;14:378-384.
2. Krishna VN, Eason JB, Allon M. Central venous occlusion in the hemodialysis patient. Am J Kidney Dis. 2016;68:803-807.
3. Kundu S. Review of central venous disease in hemodialysis patients. J Vasc Interv Radiol. 2010;21:963-968.
4. Trerotola SO, Kothari S, Sammarco TE, Chittams JL. Central venous stenosis is more often symptomatic in hemodialysis patients with grafts compared with fistulas. J Vasc Interv Radiol. 2015;26:240-246.
5. Dolmatch BL, Gurley JC, Baskin KM, et al. Society of Interventional Radiology reporting standards for thoracic central vein obstruction: endorsed by the American Society of Diagnostic and Interventional Nephrology (ASDIN), British Society of Interventional Radiology (BSIR), Canadian Interventional Radiology Association (CIRA), Heart Rhythm Society (HRS), Indian Society of Vascular and Interventional Radiology (ISVIR), Vascular Access Society of the Americas (VASA), and Vascular Access Society of Britain and Ireland (VASBI). J Vasc Interv Radiol. 2018;29:454-460.e3.
6. Cohen EI, Beck C, Garcia J, et al. Success rate and complications of sharp recanalization for treatment of central venous occlusions. Cardiovasc Intervent Radiol. 2018;41:73-79.
7. Guimaraes M, Schonholz C, Hannegan C, et al. Radiofrequency wire for the recanalization of central vein occlusions that have failed conventional endovascular techniques. J Vasc Interv Radiol. 2012;23:1016-1021.