Superior Vena Cava Obstruction Belinda A. Campbell, John M. Troupis, and Jonathan Langton Contents 1 Introduction ....................................................................... 2 2 Pathophysiology and Etiology .................................................... 2 3 Symptoms and Clinical Features ................................................. 2 4 Radiological Features ............................................................. 3 4.1 Anatomy ............................................................................ 3 4.2 Imaging Modalities and Features of SVCO ........................................ 3 5 Management Options ............................................................. 6 5.1 Choice of Treatment Modality ..................................................... 7 5.2 Role of Endovascular Stenting ..................................................... 7 5.3 Role of Palliative Radiotherapy .................................................... 9 5.4 Role of Chemotherapy ............................................................. 11 6 Conclusion ......................................................................... 11 References ................................................................................ 12 Abstract In the current era of increased availability and frequency of surveillance imaging for oncology patients, superior vena caval obstruc- tion (SVCO) is often an incidental finding in asymptomatic patients. Less commonly, SVCO may present with advanced symptom- atology, and in these cases the SVCO may represent rapid disease progression and/or the first presentation of malignancy. Contrast enhanced computed tomography (CT) is exceptionally useful for the diagnosis of SVCO, and often reveals extrinsic compres- sion by mediastinal lymphadenopathy as the more common mechanism for malignant SVCO. Non-small cell and small cell lung cancers constitute the more common histolo- gies, with metastatic mediastinal lymphade- nopathy or direct mediastinal invasion B. A. Campbell (*) Department of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia e-mail: [email protected]J. M. Troupis Department of Diagnostic Imaging, Monash Health, Clayton, Australia e-mail: [email protected]J. Langton Department of Interventional and Diagnostic Imaging, Monash Health, Clayton, Australia e-mail: [email protected]# Springer International Publishing AG 2018 R. D. MacLeod, L. Block (eds.), Textbook of Palliative Care, https://doi.org/10.1007/978-3-319-31738-0_73-1 1
Transcript
Superior Vena Cava Obstruction
Belinda A. Campbell, John M. Troupis, and Jonathan Langton
AbstractIn the current era of increased availability andfrequency of surveillance imaging for
oncology patients, superior vena caval obstruc-tion (SVCO) is often an incidental finding inasymptomatic patients. Less commonly,SVCO may present with advanced symptom-atology, and in these cases the SVCO mayrepresent rapid disease progression and/or thefirst presentation of malignancy. Contrastenhanced computed tomography (CT) isexceptionally useful for the diagnosis ofSVCO, and often reveals extrinsic compres-sion by mediastinal lymphadenopathy as themore common mechanism for malignantSVCO. Non-small cell and small cell lungcancers constitute the more common histolo-gies, with metastatic mediastinal lymphade-nopathy or direct mediastinal invasion
B. A. Campbell (*)Department of Radiation Oncology and Cancer Imaging,Peter MacCallum Cancer Centre, Melbourne, Australiae-mail: [email protected]
J. M. TroupisDepartment of Diagnostic Imaging, Monash Health,Clayton, Australiae-mail: [email protected]
J. LangtonDepartment of Interventional and Diagnostic Imaging,Monash Health, Clayton, Australiae-mail: [email protected]
# Springer International Publishing AG 2018R. D. MacLeod, L. Block (eds.), Textbook of Palliative Care,https://doi.org/10.1007/978-3-319-31738-0_73-1
causing the SVCO. Radiotherapy is the tradi-tional treatment of choice for patients withSVCO. For patients with severe symptoms,treatment of SVCO constitutes a medical emer-gency and requires urgent treatment with endo-vascular stenting to restore patency andproduce rapid relief of potentially life-threatening symptoms.
1 Introduction
Superior vena caval obstruction (SVCO) is achanging entity in palliative care and oncologypractice. The advent of improved radiologicalimaging, and its more widespread availability forthe follow-up of cancer patients, has meant thatSVCO is more frequently detected early while it isstill asymptomatic. As such, the severe symptom-atology that was not infrequently seen in the pastis now a less common phenomenon in modernclinical practice. Nonetheless, left untreated,SVCO has the potential to cause significant symp-tomatology, undermining quality of life andpotentially impacting on patient survival. In thischapter, the etiology, clinical features, radiologi-cal features, and management options of SVCOare discussed. For the purposes of this book, thischapter will focus on malignant etiologies ofSVCO in the setting of palliative care.
2 Pathophysiology and Etiology
The superior vena cava is the major route forvenous return to the heart from the head, arms,and upper torso. Despite the high flow volume, thesuperior vena cava is a relatively low pressure andthin walled structure that is readily compressibleby adjacent masses arising in the superior or mid-dle mediastinum. Slowly progressive SVCOallows for the development of a collateral blood-flow network, with enlargement of alternativedraining pathways via the azygous, hemiazygous,intercostal, mediastinal, paravertebral, thoracoe-pigastric, internal mammary, thoracoacromio-clavicular, and anterior chest wall veins.Therefore, in slowly progressive SVCO, this
collateral venous network can alleviate the symp-tom development related to the venous congestionthat is seen in more rapid onset SVCO.
SVCO may result from extrinsic or intrinsicluminal narrowing of the superior vena cava. Inthe current medical era, the most common causeof SVCO is due to luminal occlusion from malig-nant mediastinal masses (60–85% of cases ofSVCO) (Lepper et al. 2011; Straka et al. 2016).However, as the utility of intravascular devices(e.g., catheters, pacemakers) increases, thrombusis an increasingly common, nonmalignant causeof SVCO. Infectious causes (e.g., tertiary syphilis)of SVCO are now rarely seen since the advent ofantibiotic therapy.
The more common malignant causes forSVCO include non-small cell lung cancer(22–57%), small cell lung cancer (10–39%), andlymphoma (1–27%) (Straka et al. 2016). In thesecases, obstruction may arise from extrinsic com-pression of the SVC by enlarged mediastinallymph nodes or by direct invasion into the SVC.Of note, SVCO is the first presentation of malig-nancy in up to 60% of patients with a malignantSVCO (Lepper et al. 2011).
3 Symptoms and ClinicalFeatures
The clinical features of SVCO are determined bythe degree of increased venous pressure in theupper body. Typically, patients present with dys-pnea and swelling of the upper body. Elevatedvenous pressure results in interstitial edema ofthe head, neck, arms, and upper thorax, andedema of the larynx or pharynx can cause hoarse-ness, cough, dyspnea, dysphagia, and stridor. Onfurther examination, the jugular veins appeardistended. Characteristically, visibly dilatedveins are seen on the anterior chest wall, and arenoncollapsing above the level of the heart, con-sistent with the venous distension of collateralvessels (Fig. 1). Facial plethora and cyanosis areless commonly presenting signs. Rarely, thepatient may present with symptoms of cerebraledema, a serious and life-threatening consequence
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of SVCO, with headache, confusion, dizziness,and altered conscious state.
As previously mentioned, the severity ofsymptomatology depends not only on the degreeof SVC compression, but also the rate of onset.Slowly progressive SVCO allows for the devel-opment of collateral venous channels, and thus theclassically recognized symptomatology of SVCOmay not be seen. A classification scheme for thegrading of SVCO symptomatology was proposedby Yu et al. in 2008 (Table 1), patterned after theCommon Terminology Criteria for AdverseEvents (CTCAE) v3.0 of the National Institutesof Health (Yu et al. 2008). In this proposed grad-ing system for SVCO, a grade of 0 to 5 is definedbased on the severity of signs and symptomsattributable directly or indirectly to the underlyingSVCO. An important distinction is the acknowl-edgment and differentiation of nonsevere, severe,and life-threatening situations. The majority ofpatients with SVCO are likely to present withmild or moderate symptomatology (75%); theremaining patients are likely to be asymptomatic(10%) or experience severe (10%) life-threatening(5%) or fatal (<1%) symptoms (Yu et al. 2008).
4 Radiological Features
4.1 Anatomy
The superior vena cava (SVC) is responsible forreturning blood to the right heart from the upperlimbs, neck, and head. It is formed from the con-fluence of the right and left brachiocephalic veinsand drains into the right atrium and courses alongthe right side of the middle mediastinum, adjacentto the trachea and ascending aorta, which are bothto the left. In healthy adults, free of cardiopulmo-nary disease, it has been assessed with high-resolution electrocardiography (ECG) – gatedcomputed tomography (CT) angiography as mea-suring between 1.08 and 4.42 cm in cross-sectional area (Lin et al. 2009).
Inferiorly, the azygos vein, which extends fromthe abdomen, right and anterior to the thoracicvertebrae, inserts into the SVC after passing overthe right tracheobronchial angle at the level of thecarina. The azygous vein connects with the distalSVC from the posterior aspect.
Further smaller tributaries include esophageal,pericardial, and mediastinal veins (Gray 1918).Most draining veins are connected by smallerplexuses that are normally not well appreciatedon routine cross-sectional imaging.
When the SVC is obstructed, thebrachiocephalic veins, mediastinal venous plexus,and the tributaries dilate as a means of creatingcollateral venous circulation.
4.2 Imaging Modalities andFeatures of SVCO
Imaging modalities vary considerably in theirclinical utility for sensitivity and specificity inthe diagnosis of SVCO.
4.2.1 Chest X-rayChest radiography may demonstrate widening ofthe upper right mediastinal border suggestingSVC dilatation or a mediastinal mass. In the set-ting of a peripherally inserted central catheter(PICC), frontal and lateral radiographs are theprimary imaging tools for assessment of the
Fig. 1 Clinical photograph of a patient presenting withsuperior vena cava syndrome secondary to lung cancerwith mediastinal lymph node metastases. Note the pres-ence of visibly dilated veins on the anterior chest wall andupper arms, edema of the upper body, facial plethora, andcyanosis (Photograph kindly provided with permission toprint by Professor David L. Ball, Peter MacCallum CancerCentre, Australia)
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position of the catheter, with the tip expected to beeither 85% of the distance from thesternoclavicular junction to the carina or 9 mmabove the carina (Dulce et al. 2014).
4.2.2 UltrasoundUltrasound (US) may offer indirect evidence ofcentral venous obstruction as direct visualizationof the SVC is challenging due to both adjacentlung and bone overlay. Monophasic waveforms orlack of normal respiratory phasicity in thebrachiocephalic, internal jugular, or subclavianveins at Doppler US and echocardiography areconsidered useful indicators for SVCO. Althoughdirect visualization of the SVC is limited, therehas been a recognized limited role in the assess-ment of the proximal SVC by utilizing the supra-sternal and right supraclavicular windows(Khouzam et al. 2005).
4.2.3 Computed Tomography (CT)Computed tomography (CT) imaging withoutcontrast enhancement may demonstrate indirectfindings of SVCO such as abnormal PICC orcentral venous catheter (CVC) position, or calci-fications along the SVC that could be caused bycalcified thrombi, fibrin sheaths, or retained leadfragments.
Contrast enhanced CT is considered exception-ally useful for the diagnosis of SVCO (Fig. 2).Although dedicated protocols have been devel-oped (Lin et al. 2009; Bae et al. 2008; Kim et al.2003), the SVC can be assessed both with andwithout dedicated protocols. Using diluted con-trast material combined with optimal vascularwindow settings may minimize streak artifact.Additional delayed imaging beyond 50 s may beuseful when thrombus is a possibility.
There is a high correlation between the CTimaging appearances of SVCO and the presentingclinical symptoms and signs (Plekker et al. 2008).The most commonly visible collateral venous cir-culation includes the azygous-hemiazygous-accessory hemiazygous system, the vertebral andsubscapular plexuses, the mediastinal venousplexus, esophageal venous plexus, diaphragmaticvenous plexus, lateral thoracic plexus, and super-ficial thoracoabdominal venous plexus (Gosselinand Rubin 1997). The appearance on contrastenhanced CT can vary depending on the exactlocation of the SVCO. If the obstruction is abovethe azygous arch, antegrade flow from the azy-gous to the right atrium will be demonstrated.However, if the obstruction is below the arch,the entire azygous and hemiazygous veins willbe heavily opacified due to the blood re-routingvia this pathway to the inferior vena cava (IVC).
Table 1 Proposed grading system for superior vena cava syndrome (Yu et al. 2008) (Permission to reprint kindlyprovided by Elsevier and Dr. Frank Detterbeck, Yale Cancer Center, USA)
Grade CategoryEstimatedincidence (%) Definitiona
0 Asymptomatic 10 Radiographic superior vena cava obstruction in the absence of symptoms
1 Mild 25 Edema in head or neck (vascular distention), cyanosis, plethora
2 Moderate 50 Edema in head or neck with functional impairment (mild dysphagia,cough, mild or moderate impairment of head, jaw or eyelid movements,visual disturbances caused by ocular edema)
3 Severe 10 Mild or moderate cerebral edema (headache, dizziness) or mild/moderatelaryngeal edema or diminished cardiac reserve (syncope after bending)
4 Life-threatening
5 Significant cerebral edema (confusion, obtundation) or significantlaryngeal edema (stridor) or significant hemodynamic compromise(syncope without precipitating factors, hypotension, renal insufficiency)
5 Fatal <1 DeathaEach sign or symptom must be thought due to superior vena cava obstruction and the effects of cerebral or laryngealedema or effects on cardiac function. Symptoms caused by other factors (e.g., vocal cord paralysis, compromise of thetracheobronchial tree, or heart as a result of mass effect) should not be considered as they are due to mass effect on otherorgans and not superior vena cava obstruction
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Further variations may include demonstration ofthe paravertebral, intervertebral, and epiduralveins where blood extends via the ascending lum-bar veins to the azygous system. Chest wall andbreast collateral veins may also dilate andintensely enhance (Lawler and Fishman 2001),as might abdominal venous collaterals in theabdominal wall or in the liver manifesting asperfusion anomalies.
4.2.4 Magnetic Resonance VenographyMR venography, utilizing Gadolinium-enhancedMR venography (gadobenate deglumine [Multi-Hance; Bracco Diagnostics, Milan, Italy],0.1–0.2mmol/kg), can include static high-resolutionfirst-pass, time-resolved, or steady-state acquisitions(Kim andMerkle 2008). Furthermore, nonenhanced
MR venography with three-dimensional (3D)steady-state free precession (SSFP) has beenshown to be a useful tool for evaluation of theSVC (Tomasian et al. 2008) .
4.2.5 Radiographic VenographyVenography with the assistance of dynamic radio-graphic imaging (conventional venography) hasnumerous advantages for demonstrating stricturesincluding extent and location, with further assess-ment of collateral pathways, thrombus, and rela-tive functional (partial or complete) obstruction.Conventional venography has the advantage ofallowing the procedure to extend into interventionto assist with either alleviation or resolution of theobstruction.
Fig. 2 A 63-year-old male with colorectal carcinomametastases and SVCO secondary to malignant mediastinalnodal mass. (a) Axial image with purple arrow demonstrat-ing an intrinsic filling defect within the central and poste-rior superior vena cava. (b) Axial image slightly more
inferiorly than (a) with purple arrow demonstrating/highlighting the contrast outlining the tumor. (c) Coronalimage with purple arrow highlighting the well-demonstrated tumor mass occupying the lumen of thesuperior vena cava
Superior Vena Cava Obstruction 5
5 Management Options
Management is aimed at alleviating symptomscaused by the SVCO, and also at treating themalignant tumor that is causing the obstruction.Therefore, deciding on the optimal managementpathway for SVCO will depend on the severity ofthe symptoms, the diagnosis of the underlyingobstructing tumor, the stage of the malignancy,and the likely responsiveness of the tumor totreatment. Yu et al. published a proposed manage-ment algorithm based on these factors (Fig. 3)(Yu et al. 2008). Also to be considered are theprevious treatments, comorbidities, and overallprognosis of the patient. Early involvement ofthe multidisciplinary team is strongly advisablefor optimal patient care.
Life-threatening SVCO is uncommon, butnotably requires emergency medical manage-ment. Positioning the patient in a seated positionmay help to reduce some of the pressure in theupper half of the body and may provide some
degree of symptom relief. Oxygen, diuretics, andcorticosteroids are traditional medical treatmentsthat may also be helpful in providing some symp-tomatic relief in this situation, although there is apaucity of published evidence to support or quan-tify the benefit of these interventions. In theuncommon situation of stridor and airway com-promise, intubation and airway management isrequired. Radiological imaging, includingvenogram, is performed to confirm the SVCO,and followed by urgent intravascular stentingthat is aimed to achieve rapid relief of the obstruc-tion. If there is associated thrombosis, then anti-coagulation and/or direct thrombolysis shouldalso be considered. Of note, SVCO slows venousreturn from the upper body, and therefore intrave-nous and intramuscular administration of drugsinto the upper limbs should be avoided.
In patients with undiagnosed malignancy andnonemergency SVCO, it is advisable to first orga-nize for prompt tissue biopsy and staging evalua-tion, as this will allow for optimal management of
Fig. 3 Proposed management algorithm (Yu et al. 2008) (Permission to reprint kindly provided by Elsevier and Dr. FrankDetterbeck, Yale Cancer Center, USA)
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the underlying tumor. These investigations will beimportant to determine if the patient is to betreated with curative- or palliative-intent, andwill influence the choice of treatment modalitiesbased on the expected responsiveness of the tumor(Fig. 3). Tissue biopsy may be obtained by endo-scopic bronchial ultrasound of the mediastinalmass and offers a less invasive alternative tomediastinoscopy. Alternatively, in patients withmore disseminated disease, a disease site that ismore readily accessible to biopsy may be identi-fied on the staging investigations.
5.1 Choice of Treatment Modality
For malignant causes of SVCO, the two mostcommonly practiced treatments are endovascularstenting and external beam radiotherapy. Lesscommonly, chemotherapy may be considered forchemo-sensitive tumors, or surgery may be con-sidered for resectable tumors.
There are several factors to be considered in thechoice of treatment modalities for SVCO. Forpatients with SVCO caused by malignancy, it isgenerally accepted that radiotherapy achieves aslower onset of response than stenting. Thus,stenting is often considered the treatment ofchoice for symptomatic patients requiring urgentintervention. For patients with severe SVCO,stenting offers an effective and rapid treatmentfor the relief of symptoms, with relief of headacheoccurring virtually immediately, resolution offacial edema within 24 h, and edema of arms andtrunk within 72 h (Rowell and Gleeson 2002).Whereas in patients receiving radiotherapy forSVCO, the rapidity of response can generally beexpected to take up to 1–2 weeks following treat-ment. On the other hand, the main advantage ofexternal beam radiotherapy over stenting is thatradiotherapy is a noninvasive technique. Unfortu-nately, there are no published randomized data toreliably compare quality of life outcomes or dura-bility of response, and nonrandomized reports aresubject to potential selection bias between thecohorts.
5.2 Role of Endovascular Stenting
5.2.1 Endovascular Stenting:Indications
Acute SVCO secondary to malignancy oftenresponds to external radiation and steroids. How-ever, if the SVCO is complicated by life-threatening symptoms, extensive thrombus, or isrefractory to radiotherapy, then catheter-basedtreatments or surgery should be considered asthe treatment of choice. Furthermore, the rapidrelief of symptoms achieved by endovasculartechniques makes SVCO extremely rewarding totreat. Whenever possible, stent placement shouldbe considered at the onset of clinical symptoms,before the development of a tight stenosis, occlu-sion, or extensive chronic thrombus (Mauro et al.2014).
5.2.2 Endovascular Stenting:Technique and TechnicalConsiderations
The primary aim of treatment is to ensure relief ofsymptoms, which can usually be achieved byrestoring inline drainage from one jugular veinto the right atrium (Vascular 2004) (Fig. 4). Asecondary consideration is the preservation ofvenous access sites, by minimizing the numberof large caval tributaries occluded by stents, pre-venting future catheterization.
First, thrombus has to be cleared prior tostenting. Techniques to achieve this include theuse of local thrombolysis or pharmachome-chanical thrombectomy. A plasminogen activator(for example, tPA, rtPA, urokinase) is infuseddirectly into the thrombus (Tzifa et al. 2007).Aspiration techniques and mechanical adjunctsaccelerate the process. Low dose anticoagulationtherapy is always given simultaneously, usuallythrough a peripheral line.
Stenoses can usually be crossed with relativeease by an interventional radiologist, but moreadvanced techniques may have to be applied inthe setting of occlusion and transmural invasion ofthe SVC. Combined femoral axillary or bilateralaxillary approaches may be required to cross anocclusion (Massmann et al. 2016). The use of stiffcatheters, and even transjugular intrahepatic
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portosystemic shunt (TIPS) needles to crosstumor and regain access to the caval system,increases the likelihood of complications andrequires careful intraoperative monitoring for car-diac tamponade.
Stent selection is an important aspect of theprocedure. Large diameter (10–14 mm) baremetal stents are typically used, except in venousperforation or transmural tumor invasion, wherecovered stents would be deemed more appropriate(Fig. 5). If stent thrombosis occurs rapidly afterplacement, then the cause must be determined andtreated appropriately with balloon plasty or addi-tional stent placement (Fig. 4), after local throm-bolytic therapy.
In cases where immediate and full restorationof flow is achieved across an SVC stenosis, in theabsence of thrombus, then heparinization may not
be required. Local thrombolysis should be consid-ered in patients with residual thrombi adherent tothe stent or vessel wall. It is usual practice tofollow heparin therapy with oral anticoagulantsfor several months, to allow neo-endothelium tocover the stent (Mauro et al. 2014).
5.2.3 Endovascular Stenting: PatientSelection
Patient cooperation during any interventional proce-dure is imperative. Some patients with severe SVCOsyndrome may have difficulty lying flat. If this is thecase, then the procedure should be performed under ageneral anesthetic (Vascular 2004).
Stenting of the airway should always precedemanagement of caval obstruction in patients whopresent with synchronous tracheobronchialnarrowing secondary to mediastinal disease burden.
Fig. 4 Sequential stenting of the SVC. (a) SVC stenosiswith alternate drainage of contrast via the azygos system.(b) Initial stent deployed in the distal portion of the SVC,
residual filling defects requiring further stenting. (c) Inlinestenting of the right innominate vein, restoring return ofblood from the ipsilateral jugular vein to the right atrium
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Contraindications to the use of thrombolyticagents include: active bleeding, brain metastases,and intracranial or intraspinal trauma within2 months. These factors would preclude venousstenting in the setting of extensive venous throm-bosis. Other relative contraindications, such asanatomy predisposing to severe technical difficul-ties, transmural tumor invasion, and advanceddisease in preterminal patients, are important toconsider. It is also important to note that trans-mural invasion is not an absolute contraindication,but would require the use of a covered stent.
5.2.4 Endovascular Stenting:Complication Risk
Complications related to venous stenting are rela-tively few and only seen in 5–7% of procedures(Ganeshan et al. 2009). Usual puncture site com-plications apply and include: venous thrombosis,arteriovenous fistula, venous pseudoaneurysm,and pneumothorax (jugular punctures). Stentrelated complications include misplacement or
migration, fracture or fragmentation, especiallyif the stent inadvertently crosses the thoracic out-let. Misplaced stents crossing the thoracic outletfracture from repeated compression between theclavicle and first rib. Rates of stent infection,bacteremia, and septicemia are minimized withstrict aseptic technique. Extremely rare complica-tions include caval perforation and pericardialtamponade.
5.2.5 Endovascular Stenting:Outcomes
In malignant SVC obstruction, the main aim ofendovascular stenting is to achieve immediaterelief of symptoms. About 68–100% of successfulSVC stent deployments result in almost instantcomplete or significant improvement of symp-toms, sustained to a follow-up of 16 months(Mauro et al. 2014). Patients report relief of ten-sion in the face and neck within minutes of stentexpansion and restoration of flow in the SVC.Edema in the face and neck resolves after1–2 days and by day three in the scapula regionand upper limbs. There is limited data on long-term patency, but in survivors re-occlusion of theSVC occurs in up to 40% (Mauro et al. 2014;Ganeshan et al. 2009). Previous thrombosis andsmaller final stent diameters are associated withthe highest rates of re-occlusion (Fagedet et al.2013).
In conclusion, percutaneous, endovascularstenting of malignant SVCO syndrome offers ahigh initial success rate and rapid relief of symp-toms, avoiding the morbidity associated withinvasive surgery. Early detection and endoluminaltreatment, before the full symptoms of SVCocclusion develop, are key in facilitating the bestpatient outcome.
5.3 Role of Palliative Radiotherapy
5.3.1 Radiotherapy: Principlesof Treatment
Historically, radiotherapy was the mainstay ofmanagement of SVCO due to malignancy, andtoday remains an important component in themanagement of nonsevere or asymptomatic
Fig. 5 Covered and uncovered stents. Covered stents arecomprised of a fabric, such as polytetrafluoroethylene(PTFE), covering a metal stent (left). Applications forcovered stents included sealing iatrogenic perforations orruptures and exclusion of aneurysms
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SVCO (Yu et al. 2008). Depending on the under-lying tumor type and stage, radiotherapy may bedelivered with either palliative or curative intent.The primary principles of palliative radiotherapyare to (i) deliver a dose of radiotherapy that issufficient to adequately de-bulk the tumor toallow for un-occlusion of the SVC and thereforealleviate the symptoms of the SVCO, while(ii) minimizing the potential morbidity fromradiotherapy-induced side effects that are morecommonly associated with higher doses of radio-therapy. On the other hand, curative-intent radio-therapy involves delivering a higher dose ofradiotherapy with the aim of achieving long-termsterilization of the tumor cells, and in this sce-nario, it is often reasonable to accept a higherrisk of acute side-effects as a trade-off for moredurable tumor control. In making this decision, itis vital for the clinician to pay careful attention tothe relevant patient factors (i.e., comorbidities,performance state, patient wishes) and tumor fac-tors (i.e., histological diagnosis, stage, alternativetreatment options). Discussion in a multi-disciplinary tumor board meeting is stronglyrecommended.
5.3.2 Radiotherapy: Efficacyof Treatment
The use of palliative radiotherapy to relieve SVCOhas evolved over the preceding decades and is nowan established treatment in clinical practice; how-ever, the true efficacy of radiotherapy is not wellreported in the literature. Rowell and Gleesonconducted a Cochrane systematic review of theeffectiveness of SVCO treatments in patients withlung cancer (Rowell andGleeson 2002). The inves-tigators discovered that, in general, the includedstudies failed to define objective criteria for reliefof SVCO, had variable definitions of treatmentresponse, and lacked measurements of symptomsor quality of life (Rowell and Gleeson 2002). Con-sidering these limitations, the authors of the sys-tematic review reported that the response rate toradiotherapy was 94% in patients with no priortreatment for lung cancer, versus 74% in patientswho had previously received treatment for lungcancer (Rowell and Gleeson 2002). The effective-ness of radiotherapy for SVCO did not appear to be
related to any particular radiotherapy fractionationregimen (Rowell and Gleeson 2002).
5.3.3 Radiotherapy: Treatment Doseand Delivery
For palliative patients, external beam radiotherapyoffers a noninvasive treatment option for the man-agement of SVCO caused by malignancy (Fig. 6aand b). Depending on the patient’s symptoms andperformance state, radiotherapy may be deliveredas an outpatient or an inpatient. In general, palli-ative courses of hypofractionated radiotherapy aredelivered in daily fractions, 5 days per week, over1–3 weeks. Standard fractionation schedules forthe palliative treatment of SVCO include 20 Gy infive fractions (20Gy/5F) delivered over 1 week,30 Gy in 10 fractions (30Gy/10F) delivered over2 weeks, or 36 Gy in 12 fractions (36Gy/12F)delivered over 2 ½ weeks. Higher dose radiother-apy fractionation schedules may be considered forpatients who are expected to have longer lifeexpectancies, as it is thought that higher dose ofradiotherapy may achieve more durable local dis-ease control and reduce the risk of SVCO recur-rence. This includes patients with goodperformance state, limited burden of disease, andwith tumor histologies that are known to have amore indolent pattern of behavior. For patientswho are suitable for curative-intent treatment,high doses of radiotherapy are often required fordisease eradication; for example, for patients withnon-small lung cancer who are suitable forcurative-intent radiotherapy are usually treated to60Gy in 30 fractions over 6 weeks, with concur-rent radiosensitizing chemotherapy to furtherimprove tumor control.
5.3.4 Radiotherapy: Side Effectsof Treatment
As a noninvasive and localized treatment modal-ity, external beam radiotherapy offers a generallywell-tolerated treatment for palliative patientswith SVCO. Common, acute side effects includelocalized esophagitis, localized skin erythema,and fatigue. In patients receiving higher dose frac-tionation schedules, the severity of these symp-toms increases and patients may require analgesiaand a soft food diet to manage the esophagitis.
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These acute side effects frequently peak in inten-sity approximately 10 days after completion oftreatment.
For patients being treated with curative-intentradiotherapy, the longer-term toxicity profile mustalso be considered. Subacute side effects includerisk of radiation pneumonitis, which characteris-tically presents approximately 3–6 months afterradiotherapy, with symptoms of cough, fever, andbreathlessness, and is best managed via earlyintervention with a short course of oral steroidtherapy. Radiation pericarditis is a less commonlyseen subacute side effect following radiotherapyfor upper mediastinal tumors, but is also besttreated early with oral steroid therapy. In cancerpatients treated with curative-intent radiotherapy,long-term toxicity risks from thoracic radiother-apy may also include pulmonary fibrosis, esoph-ageal stricture, spinal cord myelopathy (rare), andradiation-induced second malignancy (rare).
5.4 Role of Chemotherapy
Less commonly, SVCO may be caused bychemosensitive malignancies. These includesmall-cell lung cancer, mediastinal lymphomas,and mediastinal germ-cell tumors. These tumorsusually respond well to appropriate chemotherapyregimens and symptoms of SVCO are quicklyrelieved. Depending on both patient and tumorfactors, chemotherapymay be delivered with eithercurative or palliative intent; therefore, carefultumor staging and discussion in a multidisciplinarymeeting is recommended prior to embarking ontreatment.
6 Conclusion
SVCO is a changing entity in modern medicalpractice. In the current era, malignancy is themost common cause of SVCO; however, it is
Fig. 6 Palliative radiotherapy to treat an asymptomaticSVCO caused by a mediastinal, extraosseousplasmacytoma in a patient with known chemo-refractorymultiple myeloma (a rare cause of SVCO). Durable symp-tom control was obtained in these sites following radio-therapy; the patient succumbed to multiple myeloma5 months later. (a) CT with contrast demonstrated theincidental finding of the asymptomatic SVCO, secondaryto an extraosseous plasmacytoma in the mediastinum. ThisCT scan was originally performed to investigate the
patient’s anterior chest wall pain and deformity, causedby a large osseous plasmacytoma of the rib. (b) Dosimetryfor the palliative radiotherapy plan to treat the symptomaticrib plasmacytoma and the asymptomatic mediastinalplasmacytoma causing the SVCO. The gross tumor vol-ume is marked in red, and the planning target volume ismarked in pale blue. The patient was treated with parallel-opposed 6MV photon beams, to a total dose of 20 Gy in5 fractions, delivered over 5 consecutive days
Superior Vena Cava Obstruction 11
often detected while the patient is still asymptom-atic. This is due to the increasing availability andsensitivity of medical imaging modalities and theincreasing frequency of imaging in the follow-upof oncology patients; as such, patients rarely pre-sent with life-threatening symptoms of SVCO. Itis recommended that all oncology patients withSVCO are discussed in a multidisciplinary meet-ing with review of the available imaging andpathology, prior to treatment. The optimal selec-tion of medical treatment will depend on theseverity of symptoms caused by the SVCO, theetiology of the obstructing lesion, the histology ofthe underlying malignant process, the stage of thedisease, response to previous treatments, andpatient comorbidities and performance state. Themore frequently used treatment modalities includeendovascular stenting and external beam radio-therapy, with chemotherapy and surgery havingless common roles. In the uncommon scenario ofsevere or life-threatening SVCO, urgent endo-vascular stenting is the treatment of choice forrapid relief of symptoms from obstructing lesions.
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