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Arteriovenous malformation (AVM) is one of the family of congenital vascular malformations (CVMs) which has an anatomic defect allowing for the inappropriate direct shunting of arterial blood to the venous system to varying degrees.1–4 AVMs are relatively rare in comparison to other malformation lesions (e.g., venous malformation; lymphatic malformation), but most AVMs are clinically much more serious than other malformation with potentially limb or life-threatening condition.5–8
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Because of their associated AV shunting of high velocity, low resistance blood flow from the arterial vasculature directly into the venous system,4–6 AVMs cause profound alterations in cardiovascular hemodynamics. These alterations occur centrally, peripherally, and locally, thus making the AVM the most hemodynamically complex type of CVM.7–9 In addition, the hemodynamic alterations affect the entire cardiovascular system, including the arterial, venous, and the lymphatic systems. These can produce cardiac failure, peripheral arterial insufficiency (e.g., gangrene), chronic venous insufficiency, and lymphatic overload through venous hypertension. They can also have local effects with direct compression to the surrounding tissues and organs causing significant morbidity and high recurrence rates following treatment1,4,5 so that the AVM retains its notorious reputation as the most dangerous of all CVMs.2,10,11
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The incidence and prevalence of the CVMs as well as AVM, reported before the ISSVA and Hamburg CVM Classification systems were established, are not accurate with limited reliability of data because they were often misrepresented based on confusing terminology of the prior traditional name-based classification.3,5,12,13 Nevertheless, among the group of various birth defects involving the vascular system, an overall incidence of CVMs is known to be 1.2% as reported by Tasnadi G et al.,14 with a male–female ratio of 1:1 and with more than 90% evident at the time of birth.1,4,13 Peripheral AVMs were reported to be the least common CVM accounting for approximately 10% to 15% among all clinically significant CVM lesions.4,15 Indeed, the AVM is a much more rare condition among all CVMs as classified by the Hamburg Classification5,12 (Table 21-1). A majority of CVMs are either the venous malformation (VM)16,17 or the lymphatic malformation (LM)18,19 with VMs comprising more than two-thirds of all CVMs.16,17,20
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