A Simplified Arteriovenous Malformation Model in Sheep: Feasibility Study
Zhong Qian,a,
Salvador Climenta,
Manuel Maynara,
Jesus Usón-Garalloa,
Marco A. Lima-Rodriguesa,
Camen Callesa,
Hugh Robertsona and
Wilfrido R. Castañeda-Zúñigaa
a From the Department of Radiology, LSU Medical Center at New Orleans (Z.Q., H.R., W.R.C-Z.); the Department of Anatomy, University of Zaragoza, Spain (S.C.); Las Palmas de Gran Canaria University, Spain (M.M.); and the Minimally Invasive Surgery Center, Cáceres, Spain (M.M., J.U-G., M.A.L-R., C.C.).
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FIG 1. Schematic representation of an AVM model in sheep. Circulatory flow is diverted from the contralateral side (left) of the carotid artery through both carotid retia (RM) to the right carotid artery and jugular vein with retrograde flow following surgical creation of an anastomosis. Note the blood flow direction (arrows) after creation of a carotid-jugular anastomosis
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FIG 2. Normal cerebrovascular anatomy on left common carotid arteriogram before surgery.
A, Lateral view shows the rete mirabile (arrowheads) supplied by the ramus anastomoticus (short arrow) and the arteria anastomotica (long arrow).
B, Anteroposterior view shows unilateral rete mirabile (arrowheads) along with its feeding vessels, including the ramus anastomoticus (short arrow), the arteria anastomotica (long arrow), and the IMA (open arrows).
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FIG 3. Photograph of the corrosion cast of the cerebrovascular anatomy on ventral view in the sheep shows the rete mirabile and its associated arteries compared with angiograms. Note that the internal carotid artery, a single large arterial trunk, bends sharply to join the circle of Willis
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FIG 4. Left common carotid angiogram immediately after surgical creation of the anastomosis.
A, The carotid artery (arrows) on the anastomotic side is opacified in the early phase, indicating a high-flow diversion from catheterized side.
B, Bilateral retia mirabilia (arrowheads) are clearly identified, simulating an AVM nidus. The ramus anastomoticus (short arrows) and arteria anastomotica (long arrows), supplying the rete structure, represent the feeding vessels, while the same vessels on the anastomotic side act as the draining veins, emptying into the right jugular vein (open arrows) through the anastomosis.
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FIG 5. Schematic drawings show comparison of the rete mirabilia and the supply arteries in the pig and sheep.
A, In the pig, the rete mirabile receives most of its blood supply from the ascending pharyngeal artery, whereas only a small amount of flow is derived from branches of the IMA.
B, In the sheep, the fetal ascending pharyngeal artery undergoes atrophy, becoming a residual thread after birth. Branches of the IMA, the ramus anastomoticus, and the arteria anastomotica form the major arterial contributions to the rete mirabile.
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