Makindo Medical Notes.com

Related Subjects: |Pulmonary Embolism |Deep Vein Thrombosis |DVT/PE in pregnancy |CTPA

The subclavian vein is located beneath the clavicle and is a continuation of the axillary vein, eventually merging with the internal jugular vein to form the brachiocephalic vein.

About

• There are many causes of Subclavian vein thrombosis
• This is an upper-extremity deep-vein thrombosis

Aetiology is Virchow's triad

• Changes in blood
• Changes in flow
• Changes in the vessel

Causes

• Causes of Primary SCVT
  • Effort induced thrombosis (Paget von Schroetter syndrome): Often associated with effort-induced thrombosis, also known as Paget-Schroetter syndrome, which typically affects young, healthy individuals after vigorous physical activity.
  • Idiopathic (frequently associated with undiagnosed malignancy)
• Causes of Secondary SCVT
  • Mechanical trauma: Compression of the subclavian vein
  • Chronic CVC placement or Pacemaker leads: intravascular devices can cause trauma and lead to thrombosis.
  • Clavicle fracture: Compression of the subclavian vein
  • Haemodialysis catheters: intravascular devices can cause trauma to the vein wall and lead to thrombosis.
  • Long term TPN feeds: intravascular devices can cause trauma to the vein wall and lead to thrombosis.
  • Prone position in surgery
  • Antithrombin III deficiency, Factor V Leiden mutation, Protein C/S deficiency
  • Lung cancer malignancy (rare) - more common with Pancoast tumour. Some cancers can predispose patients to venous thrombosis.

Clinical

• Swelling, oedema and dilated upper limb veins
• Limb may feel heavy, look for lymphadenopathy - cervical and axillary
• Dilated Veins: Visible distension of superficial veins in the neck, shoulder, or arm.
• Cyanosis: Bluish discoloration of the skin, particularly in the hand or fingers.
• Breast examination

Investigations

• FBC, U&E, ESR/CRP, Elevated D Dimer, Thrombophilia screen for some
• CXR and CT or MRI Venography
• Mammography may be considered
• Ultrasound of upper limb veins can visualize the clot and assess blood flow in the vein.
• Venography: Contrast venography is the gold standard but is more invasive.
• Younger patients: Thrombophilia screen

Complications

• Pulmonary embolism
• post-thrombotic syndrome secondary to venous outflow obstruction and valvar insufficiency
• Range from mild oedema to incapacitating venous stasis leading to ulcer or gangrene
• Septic thrombophlebitis
• Embolism
• Superior vena cava
• Loss of access due to occlusion

Differential diagnoses of subclavian vein thrombosis include

• Superior vena cava syndrome
• Lymphatic obstruction
• Cellulitis
• Thoracic outlet obstruction
• Pancoast tumour
• Necrotizing fasciitis
• Superficial thrombophlebitis

Management

• Depends on the cause. Catheter-based thrombolysis in some. Stenting may be considered if narrowing.
• Anticoagulation with LMWH and then Warfarin
• Consider looking for underlying causes e.g. malignancy or thrombophilia in those under 45 or with a h/o familial VTE
• Removal of Central Venous Catheters: If a catheter is the cause, removing it may be necessary once the acute phase is managed.

References

• Subclavian Vein Thrombosis