Efficacy of the Yakes Arteriovenous Malformation Classification System that Directs Curative Endovascular Therapies Routinely

Purpose: To determine if arteriovenous malformation (AVM)’s angioarchitecture characteristics can be predictive and direct specific curative endovascular procedures accurately and consistently to cure high-flow malformations in all anatomic locations.

Materials and Methods: Angiographic analysis of high-flow AVMs determined four major angioarchitectures. Type I has a direct arterial–arteriolar to vein–venule connection (e.g., as commonly seen in pulmonary arteriovenous fistula [AVF], congenital renal AVF, and so on). Type II has arterial–arteriolar connections to a “nidus” that then have several outflow veins with no intervening capillary beds in any of the vascular interconnections. Type IIIa has arterial–arteriolar connections to an aneurysmal vein (“nidus” is the vein wall) that drains into a dominant outflow vein with no intervening capillary bed in these connections. Type IIIb has the same angioarchitecture as type IIIa except that there are more than one (several) outflow veins. Type IV is an “infiltrative” form of AVM whereby innumerable microarteriolar branches fistulize through a tissue (e.g., ear AVMs), totally infiltrating it and shunting into multiple outflow veins. Capillary beds also exist in the tissue and are admixed with the innumerable AVFs. Without the capillaries, the tissue could not be viable and therefore must be present.

Results: Type I can be effectively treated with mechanical devices (e.g., coils, Amplatzer plugs). Type II can be effectively treated with ethanol embolization, transcatheter, and direct puncture. Type IIIa can be effectively treated by transcatheter ethanol, retrograde vein catheter access, or direct puncture access of the aneurysmal vein and treatment with ethanol and coils or even by coils alone. Type IIIb can be effectively treated as above but can be more challenging by the vein route because more veins (not a single outflow vein) require closure. Type IV can be effectively treated by transcatheter or direct puncture of the innumerable microfistulous AVFs by embolization with a 50%–50% ethanol nonionic contrast mixture.

Conclusions: This newly reported AVM classification system has a direct impact on determining the curative endovascular and direct puncture embolization procedures and determines the embolic agents that will successfully treat and cure complex AVMS in all anatomies.