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Superior vena cava syndrome

This is obstruction to the superior vena cava ( SVC ) blood flow by external compression , 
thrombosis or direct invasion of SVC ( Scottish Palliative Care Guidelines )

SVC syndrome ( SVCS ) is the term used to describe the collection of clinical signs and symptoms that result due to a partial or complete obstruction of blood flow through the SVC

 

SVC is a thin walled compliant vessel formed by the junction of the left and right innominate 
( brachiocephalic veins ) SVC transports blood from the head and neck , upper extremities and parts of chest wall towards the heart SVC accounts for about 1/3rd of the total venous return to the heart When SVC is obstructed – blood starts to flow via multiple small collaterals to the azygous vein or the inferior vena cava ( the largest one is via the azygous -hemizygous vein which consists of azygous vein , hemizygous , intercostal , lumbar veins ) As SVC has thin wall and low venous pressure – it is amongst the first of the mediastinal structures to be obstructed Intracranial venous pressure which is normally maintained between 2 to 8 mm Hg may rise up to 40 mm Hg with acute SVC obstruction

 

Historically ( pre-antibiotic era ) syphilitic thoracic aortic aneurysm causing SVC compression bulky mediastinal adenopathy caused by tuberculosis

 

Malignancy- mediastinal malignancies account for bulk of cases now ( > 90 % )
 most ( 75 % to 85 % ) of cases are due to lung cancer
○ non- small cell lung cancer ( NSCLC ) is the most common cause
○ small lung cancer ( about 15 % of all lung cancers ) can also cause SVC obstruction
 Lymphoma – particularly non-Hodgkin’s lymphoma accounts for 10 % to 15 % of all cases
 other mediastinal malignancies as germ cell neoplasms or thymic tumours , metastatic tumours

SVC obstruction can be the presenting symptom of a previously undiagnosed tumour in about 60 % of cases ( for e.g lymphoma in younger patients )

Upto 4 % of all patient with lung cancer develop SVCSUp to 4 % of patients with NHL develop SVCS

 

Other benign – iatrogenic thrombus formation that compromise venous flow back to heart seen due to increasing use of indwelling catheters , pacemakers and implantable cardioverter- defibrillators fibrosing mediastinitis

 

Presentation may vary – main determinant is the increase in venous pressure in the upper body from SVC obstruction- based on rapidity of SVC occlusion ( may develop over a few weeks or even days ) if collateral develop ( it may take few weeks for the collaterals to develop ) – for e.g if azygous vein is patent and the speed of SVC occlusion is slow the patient may be asymptomatic Presentation can also be with life threatening features if the occlusion happens rapidly with complications as 
○ cerebral oedema ( headache , dizziness , confusion → coma )
○ respiratory compromise due to edema of larynx and pharynx

 

Tamir Friedman et al in their brilliant article ” Malignant Venous Obstruction : Superior Vena Cava Syndrome ” have divided clinical findings under 4 headings as

 

headaches blurred vision papilloedema ↓↓ level of consciousness

 tongue swelling dyspnoea stridor / laryngeal oedema Nasal stuffiness conjunctival oedema periorbital oedema facial oedema / plethora proptosis neck & chest wall venous distension upper extremity swelling and plethora

 

differentials include 
○ congestive heart failure 
○ Cushing syndrome
○ cardiac tamponade
○ thoracic aortic aneurysm
○ tuberculosis
 during assessment – consider
○ CNS status
○ respiratory system evaluation
○ haemodynamic status
○ full medical history and timeline of symptoms
○ known cancer ?
○ any recent intravascular procedures ? central lines.

 

death from SVC compression is uncommon 
( only if complications as severe cerebral oedema or haemodynamic alterations develop ) prognosis / management will depend upon the aggressiveness of the underlying malignancy / cause

 

Management will be guided by cause and under the guidance of hospital specialist teams CXR may show mediastinal widening Contrast enhanced CT is the imaging of choice MRI , PET like modalities help provide further information on node status and mediastinal involvement

 

Steroids – widely advocated and possibly used evidence of use is poor
 Phillipp M Lepper et al state that steroids are recommended only on patients with steroid sensitive tumours and in patients undergoing external beam radiation therapy
 Scottish Palliative Care Guidelines recommend 
○ dexamethasone 16 mg orally or parenterally administered immediately and subsequent day
○ dexamethasone 8mg bd ( 2nd dose before 2 PM if possible )
 
They observe that steroids may be helpful despite the the absence of evidence to support their use and that it should be discontinued promptly if no benefit and reduce gradually in responders.

 

Management – loose clothing and upper arms supported on pillows head raising to decrease hydrostatic pressure and head and neck oedema role of diuretics is not clear ( some guidelines advocate furosemide IV / oral ) avoid IM/ IV injection in arms multiple specialist teams comprising of medical oncology , radiation oncology , surgical oncology , haematology and interventional radiology may be involved in management treatment options have increased lately and may include radiotherapy , chemotherapy , thrombotic treatment , SVC stenting , endovascular therapy.

 

If the cause is benign life expectancy is not changed but in cases of underlying malignancy there is a significant drop in survival ( some papers quote < 6 months )

REFERENCES

  1. Superior Vena Cava Obstruction Scottish Palliative Care Guidelines Scottish Palliative Care Guidelines – Superior Vena Cava Obstruction
  2. Seligson MT, Surowiec SM. Superior Vena Cava Syndrome. [Updated 2021 Jul 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441981/
  3. Philipp M LepperSebastian R OttHanno HoppeChristian SchumannUz StammbergerAntonio BugalhoSteffen FreseMichael SchmückingNorbert M BlumsteinNicolas DiehmRobert BalsJürg Hamacher
  4. Friedman, Tamir et al. “Malignant Venous Obstruction: Superior Vena Cava Syndrome and Beyond.” Seminars in interventional radiology vol. 34,4 (2017): 398-408. doi:10.1055/s-0037-1608863

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