II. Pathophysiology
- Superior Vena Cava Obstruction to flow- Internal Vascular Invasion- Vena cava thrombosis (uncommon complication of implantable devices, pacers, AICD, Dialysis Catheter)
- Tumor infiltration
 
- External Compression (e.g. right lung or Mediastinal Mass)- Most common Mediastinal Masses include Lung Cancer and Lymphoma
- Mediastinal Mass gradually compresses superior vena cava, blocking entry into right atrium
- Results in retrograde flow and regional edema
 
 
- Internal Vascular Invasion
- Superior Vena Cava Obstruction Compensation- SVC is a thin walled, low pressure large vein 2 cm in width and 4-6 cm in diameter
- Upper body venous engorgement distributes the fluid
- High venous pressures within SVC may be compensated with collateral circulation over 1-2 weeks- Example: Azygous vein may provide some collateral drainage
 
 
III. Causes
- Malignancy (60% of all cases)- Bronchogenic Carcinoma (80% of malignancy causes)
- Malignant Lymphoma (15% of malignancy causes)
- Metastatic Disease (to lung, mediastinum or Lymph Nodes)- Breast adenocarcinoma
- Testicular seminoma
 
 
- Vena Cava thrombosis (majority of non-malignant cases)- Long-term venous catheters (40% of thrombosis cases)
- Idiopathic
- Behcet's Syndrome
- Polycythemia Vera
- Paroxysmal Nocturnal Hemoglobinuria
- Long-term shunts
- Long-term Pacemakers
 
- Other Benign Disease (Rare)- Mediastinal fibrosis- Post-Radiation Therapy
- Idiopathic
- Histoplasmosis
- Actinomycosis
- Tuberculosis
 
- Benign Mediastinal tumor- Aortic aneurysm
- Dermoid tumor
- Goiter
- Sarcoidosis
 
 
- Mediastinal fibrosis
IV. Symptoms
- Presentations are typically subacute and progressive
- 
                          Dyspnea (50%)- Worse with bending forward
 
- Neck and facial swelling (40-82%)- Head fullness or pressure Sensation
- Provoked by lying supine
 
- Swelling of trunk and upper extremities (40%)
- Local Airway Compression- Cough
- Dysphagia
- Choking Sensation
- Hoarseness
- Lacrimation
- Nasal Congestion
 
- 
                          Headache
                          - Common presenting complaint
- Secondary to Increased Intracranial Pressure
 
- Referred Pain
- Neurologic- Dizziness (provoked by bending forward)
- Visual changes or Blurred Vision
- Headaches
- Syncope
- Altered Mental Status
 
V. Signs: General
- Classic findings- Jugular Venous Distention, Cyanosis and edema, exacerbated by the supine position
 
- Thoracic chest vein distention (65%)
- Neck vein distention (55%)
- Facial Edema (55%)
- Tachypnea (40%)
- Plethora of the face and Cyanosis (15%)
- Edema of upper extremities (10%)
- Paralysis of Vocal Cords (3%)
- Horner's Syndrome (3%)
- Distended antecubital veins
- Tongue Swelling
- Clear lungs despite Dyspnea and Tachypnea
VI. Signs: Provocative
- Pemberton's Sign- Patient elevates both arms overhead and observe face for one minute
- Positive if significant facial swelling (plethora), Cyanosis, increased Dyspnea or Lightheadedness within the first minute
 
- Bendopnea- Patient bends forward at waist and observed for 30 seconds
- Increased Shortness of Breath within 30 seconds is considered positive
- Also seen with CHF, pulmonary fibrosis
 
VII. Associated Conditions
VIII. Differential Diagnosis
IX. Imaging
- 
                          Chest XRay
                          - Mass identified in 90%
- Right superior mediastinum widening (75%)
- Hilar Adenopathy (50%)
- Right Pleural Effusion (25%)
 
- 
                          Chest CT with IV Contrast (preferred)- Identifies mass lesions and sites of SVC obstruction and thrombosis
- Collateral vessel development is a sensitive and specific marker of SVC Syndrome- Test Specificity: 96%
- Test Sensitivity: 92%
 
 
- 
                          Ultrasound
                          - Consider in the evaluation for upper extremity Deep Vein Thrombosis
 
- Other Imaging modalities- MR Venogram
- Cavogram
 
X. Management
- Severity of airway and vascular compromise varies by timing of progression- Rapid progression may not allow for compensation, resulting in acute airway compromise (uncommon)
 
- Supportive care for airway compromise- ABC Management- Endotracheal Intubation may be needed in airway compromise
 
- High-Dose Corticosteroids- Most effective in steroid-responsive malignancy such as Lymphoma or thymoma
 
- Elevate the head of the bed
- Avoid Diuretics
 
- ABC Management
- Identify mass etiology
- Reduction in mass size- Emergent Intervention RadiologyConsultation
- Other modalities- Radiation Therapy (e.g. Non-Small Cell Lung Cancer)
- Chemotherapy
- Surgical decompression
 
 
- Consult Oncology and Cardiothoracic Surgery acutely- Palliative CareConsultation once stabilized
 
- 
                          Anticoagulation with Heparin- Indicated for venous thrombosis
- Consult for catheter directed Thrombolysis or thrombectomy in hemodynamically Unstable Patients
 
- Endovascular stenting- Common acute management with 85 to 100% success rate
- Improvement is seen within days
- Effective even when tumor mass is not reducible
 
XI. Prognosis
- Poor prognostic sign- Predicts 90% mortality in 3 years
- Median survival: 6 months
 
XII. References
- Bierowski and Nyalakonda (2025) Crit Dec Emerg Med 39(6): 4-21
- Long, Long and Koyfman (2020) Crit Dec Emerg Med 34(11): 17-24
- Swaminathan and Hedayati (2022) EM:Rap 22(6): 7-9
- Higdon (2018) Am Fam Physician 97(11):741-8 [PubMed]
