| Identifier |
arteriovenous_fistula_lee_novel |
| Title |
Arteriovenous Fistula |
| Creator |
Andrew G. Lee, MD; Kristen Brown |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (KB) Class of 2023, Baylor College of Medicine, Houston, Texas |
| Subject |
Arteriovenous Fistula; Arteriovenous Malformations |
| Description |
Summary: • Arteriovenous fistulas (AVFs) and arteriovenous malformations (AVMs) have similar pathophysiology and similar appearance radiographically but are slightly different o AVM: congenital problem involving a direct artery to vein connection with a nidus malformation; big tangle of blood vessels with an arterial feeder and venous drainage > Usually presents as mass effect/hemorrhage but sometimes a steal or seizure o AVF is also an artery-to-vein connection but lacks the nidus; it's just an abnormal connection (the fistula) > Blood can travel anterograde, i.e., the correct direction, such as through the dural venous sinus through the jugular back to the heart > Blood can travel retrograde, i.e., the wrong direction • When classifying AVFs, we are interested in the venous drainage, whether or not there is an associated thrombus, and direction of flow; Conyard classification: o Conyard I: artery to vein, blood traveling anterograde. Typically an incidental finding on an angiogram. Wait and see approach rather than treatment. > Retrograde Ia: might not be treated, but treatment may be necessary if it starts going retrograde into the cortical vein, or if patient has venous sinus thrombosis or venous hypertension (embolization therapy) o Conyard II-III are more dangerous and should be looked at for embolization, surgery, or both • Most common AVF is fistula between carotid artery and cavernous sinus; traumatic, direct tear in carotid would cause a high flow fistula, but low flow fistula is possible depending on carotid branches involved. o "Red eye" shunt: flow goes retrograde into superior ophthalmic vein (SOV) and produces classic findings of proptosis, ophthalmoplegia, loss of vision, central retinal vein occlusion, or steal phenomenon > ischemic optic neuropathy o "White eye" shunt: flow goes posteriorly into petrosal sinus • Dural AVFs: look for venous hypertension causing increased intracranial pressure, which can produce papilledema and appear like pseudotumor cerebri. |
| Transcript |
So today we're going to be talking about the neuro-ophthalmology of arteriovenous fistula. It's similar to but not the same as an arteriovenous malformation. So, for me a malformation is a congenital problem, it was malformed. They have similar pathophysiology and similar appearance radiographically but they're slightly different, and arteriovenous malformations are often the parenchymal version, which is a big tangle of blood vessels with an arterial feeder and a venous drainage, and that usually presents to us as a mass effect, hemorrhage but sometimes steal or seizure. We're not going to be talking about the AVM which is the direct artery to vein with a nidus malformation; we're going to talk about fistulas. So fistula is artery to vein as well, but it really doesn't have this nidus thing; it's just an abnormal connection, and that abnormal connection is the fistula, the F mark. So if the artery is talking to the vein but we're going in the correct direction back to the heart, for example in the venous sinus system artery to dural venous sinus back down the jugular back to the heart, this type of fistula is an anterograde fistula. However if the blood flow is going the wrong direction in the vein, we call that retrograde. So we can have anterograde, which is the correct direction, and retrograde, which is the wrong direction. And so normally if we're classifying AV fistulas, we're going to be interested in both the venous drainage, whether there's an associated thrombus or not, and the direction of flow. Is it anterograde, retrograde? And so, many different classifications, we kind of use the Conyard classification in neurophth at this hospital. And so a Conyard one would be artery to vein anterograde. That kind of fistula is not really going to be a problem; that would never come to me. You might see it on an angiogram because you're angiogramming the person for some other reason and normally then we just wait and see what's going to happen to that, we don't we don't do any treatment for that. All the other classifications in Conyard probably deserve to have a look for embolization or surgery or both and so those are more dangerous Conyard classifications 2, 3, 4. So the line is kind of like at one anterograde. Now there's there's retrograde 1a - we also might not treat that - but once you start getting retrograde, and once it starts going retrograde into the cortical vein, or if you have venous sinus thrombosis or if you have venous hypertension (venous hypertension), these are the ones that we're going to be thinking about treating. And you're gonna need help from your endovascular colleagues about embolization therapy for these types of fistulas. So the way these come to me and the most common one that you're probably familiar with is when it's the carotid artery talking to the cavernous sinus and it's a fistula, so a carotid cavernous fistula is the most common way that an arteriovenous fistula comes to me. In this case it's the carotid artery talking to the cavernous sinus and the flow can go retrograde into the superior ophthalmic vein, and that produces the classic findings of carotid cavernous fistula. Proptosis, a red-eye ophthalmoplegia, they can have loss of vision, central retinal vein occlusion, or steal phenomenon leading to ischemic optic neuropathy. And so the red-eye shunt, the high flow retrograde in the SOV (the superior ophthalmic vein), is the classic carotid cavernous fistula. And that could be traumatic and direct tear in the carotid - that's gonna be a big high flow fistula - or it might be a low flow fistula, those are branches of the internal or external carotid, and those have their own classification system. In the dural arteriovenous fistulas, what we're looking for is venous hypertension, and that's going to cause increased intracranial pressure, and that could come to me as papilledema. So the arteriovenous fistulas can come to me just like AVMs, just like CC fistulas with flow-related problems - that's thrombosis, retrograde flow, venous hypertension, hemorrhages, the usual ways that vascular lesions present - or it could present to me in a more insidious manner where there's no mass, it's just increased intracranial pressure. And the increased intracranial pressure that we're worried about is venous hypertension. So you need to know a little bit about venous hypertension, its relation to our arteriovenous fistula where we have direct connections between artery and vein different than arteriovenous malformation. The classic type, a carotid cavernous fistula, can be the red-eye version or a white-eye version where the flow is going posteriorly into the petrosal sinus that might present to you with a white eye but they still have a venous flow abnormality, and that's a white eyed shunt, a white-eyed posterior draining carotid cavernous fistula. And venous hypertension in the dural sinuses could produce papilledema and come to you as what looks like pseudotumor cerebri. |
| Date |
2021-04 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s69p8z6h |
| Setname |
ehsl_novel_lee |
| ID |
1680586 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s69p8z6h |
