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Free Floating Thrombus

Summary

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  • Free floating thrombus (FFT) is a rare but potentially life-threatening condition characterised by a mobile thrombus in the cardiovascular system, typically attached to a vessel wall by a thin stalk
  • FFTs are associated with high risk of embolization and subsequent ischaemic events
  • Prompt diagnosis and treatment are crucial to prevent serious complications

Pathophysiology

  • FFTs form when a thrombus develops and remains partially attached to the vessel wall
  • Common locations include:
    • Left atrium (most frequent)
    • Aorta
    • Carotid arteries
    • Deep veins of the lower extremities
  • Risk factors:
    • Hypercoagulable states
    • Atrial fibrillation
    • Atherosclerosis
    • Trauma
    • Malignancy

Demographics

  • Incidence is not well-established due to rarity of the condition
  • More common in elderly patients
  • Higher prevalence in patients with:
    • Cardiovascular disease
    • History of thromboembolism
    • Atrial fibrillation

Diagnosis

  • Often an incidental finding on imaging studies
  • Clinical presentation may include:
    • Symptoms of embolization (e.g., stroke, limb ischaemia)
    • Asymptomatic in some cases
  • Diagnostic criteria:
    • Mobile thrombus
    • Thin stalk attachment to vessel wall
    • Independent motion from surrounding structures

Imaging

  • Echocardiography:
    • Transthoracic echocardiography (TTE): initial screening tool
    • Transesophageal echocardiography (TEE): gold standard for cardiac FFTs
  • CT angiography:
    • High sensitivity for detecting FFTs in large vessels
    • Allows for evaluation of surrounding anatomy
  • MRI:
    • Useful for characterising thrombus composition
    • Can differentiate between thrombus and tumour
  • Doppler ultrasound:
    • Valuable for detecting FFTs in peripheral vessels

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  • 60-year-old patient with left sided weakness and inattention.
  • CTA showed acute thrombus arising from plaque in the right ICA.
  • The filling defect extending distally within the lumen of the vessel was consistent with free floating thrombus.

Treatment

  • Anticoagulation:
    • First-line treatment for most FFTs
    • Heparin followed by oral anticoagulants (e.g., warfarin, direct oral anticoagulants)
  • Thrombolysis:
    • Consider in selected cases
    • Risk of thrombus fragmentation and embolization
  • Surgical intervention:
    • Indicated for large FFTs or those refractory to medical management
    • Thrombectomy or embolectomy
  • Endovascular approaches:
    • Catheter-directed thrombolysis
    • Mechanical thrombectomy devices
  • Follow-up imaging:
    • Regular monitoring to assess thrombus resolution and detect recurrence

Differential diagnosis

Differential Diagnosis Differentiating Feature
Aortic dissection Linear intimal flap on imaging
Aortic atheroma Calcification and plaque on vessel wall
Cardiac myxoma Attachment to interatrial septum
Vegetation Associated with valvular lesions
Tumour embolus History of malignancy
Arteritis Vessel wall thickening and inflammation
Intramural haematoma Crescentic thickening of vessel wall
Artefact on imaging Disappears with different imaging views
Papillary fibroelastoma Typically attached to cardiac valves
Aortic aneurysm with thrombus Dilated aortic segment