Arteriovenous malformation (AVM)

These types of malformation are congenital but not hereditary abnormalities

Clinical features:

Symptoms:

• Patients present at almost any age; onset of symptoms may be related to the appearance of the menarche, to pregnancy or to an episode of minor trauma
• Swelling
• Discolouration
• Bleeding
• Pain
• High-output cardiac failure
• Limb hypertrophy

Signs:

• Lesions with an arterial component are usually pulsatile
• A machinery-type murmur is heard on auscultation
• Venous lesions engorge and empty with dependency and elevation, respectively

Diagnosis;

• Appearance in later life requires distinction from malignant lesions such as sarcoma and metastatic deposits
• Apart form biopsy to exclude malignancy in cases of doubt, the diagnosis is usually clinical

Investigation:

• A CXR allows assessment of cardiac size
• US can be used to assess venous lesions
• CT and particularly MRI give valuable information about deep extent when excision is contemplated

Management:

• AVMs may not require treatment except for counselling and the reassurance for both the patient and, in children, the parents
• Occasionally operation may be required to exclude malignancy
• Complete excision provides good long-term control but is rarely feasible
• Amputation is sometimes required as a last resort
• Therapeutic embolisation, in which the lesion is filled from within with thrombogenic coils or gel, is the mainstay of treatment:
• Carries a risk of ischaemia in surrounding or distal vital tissues
• Venous lesions can be treated by direct injection of sclerosant and/or partial excision of prominent veins once the normality of the deep venous system (sometimes absent or hypoplastic) has been assured