A real-world take on forming the perfect plug — with timing, layering, and control. If you’re injecting Onyx, this is the rhythm you’ll want to master.

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Script:

Welcome back. In this segment, I want to talk about a technique I personally use a lot — the classic push and plug technique — and exactly how I do it.

Once my microcatheter is in position and I’m happy with the placement, I start the Onyx injection.

At the very beginning, a little bit of Onyx penetrates into the nidus. That small initial penetration increases the resistance to further flow, and that’s when the reflux starts to happen. The Onyx starts pushing back and begins to layer around the catheter tip.

Now, I let that reflux happen just a little bit — a short segment. I don’t wait too long. Just a couple of seconds.

Then I reset my blank roadmap and re-inject.

This time, I usually find that the Onyx starts layering inside that same refluxed segment — building the plug a little deeper.

I stop again, just for a few seconds. Reset the roadmap. Re-inject. And I repeat this cycle.

Again, I don’t wait too long between steps — just a few seconds at a time. And with each cycle, I watch for the Onyx to layer inside the already formed segment.

Eventually, I’ll reach a point where I stop seeing layering. Instead, I see the reflux getting longer. That’s when I stop.

At that point, I set a timer on the angio machine for two minutes.

And in most cases — not all, but most — when I re-inject after the two-minute pause, the Onyx flows forward beautifully into the nidus. The plug has matured, the resistance behind it is stable, and now the embolic moves exactly where I want it.

That’s the rhythm of how I personally do the push and plug technique — short, controlled cycles, with visual feedback every step of the way.

Now let’s talk about microcatheter entrapment.

This is something we really don’t want. Because if you let the reflux go too far and the Onyx hardens around the catheter — you might have to cut it or leave it behind. And that’s never ideal.

So, whenever possible, I use a detachable tip microcatheter.

With a detachable tip, you can control your Onyx reflux precisely. The goal is to keep the reflux between the two markers on the catheter. You don’t have to reach both markers — it just needs to stay somewhere in between.

And as long as the reflux stays within that zone, you can inject as long as you want. There’s nothing trapping me. I know that if I need to, I can simply detach and walk away clean.

That’s why I use detachable tips whenever I can. They give you control, safety, and confidence throughout the injection.

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Contact & Resources:

For questions or collaboration, feel free to reach out:

Email: [email protected]

YouTube channel: youtube.com/drmostafafarid

You don’t eat an apple from the core — and you don’t treat an AVM that way either. A practical look at how to build your treatment plan layer by layer.

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Script:

Welcome back. Now I want to talk about something really important — your mindset when you decide to treat an AVM.

You have to make a real decision to commit to curing this AVM. And I don’t mean that you have to cure it by endovascular treatment alone. No, not at all. What I mean is, you have to be committed to helping the patient through the entire journey. Whether it’s embolization, surgery, radiosurgery — or a mix of all of them — you have to own the case.

Because once you start treating the AVM, you become the one who knows it best. You’ve seen it from the inside. You understand the feeders, the veins, the compartments. You’ve done the angios, the planning, the mapping. You’re the one who’s watched it evolve after each session.

So yes, you really have to stick around. You follow up the patient, you support them psychologically, you guide them. Even if you can’t go further with embolization — maybe the anatomy has changed, maybe you hit a technical wall — then you refer, or consult a senior operator, or consider radiosurgery.

But you don’t disappear.

Now let’s talk about how we actually treat the AVM.

Here’s a rough but surprisingly accurate analogy I always use: treating an AVM is like eating an apple.

You never start at the core. You begin at the outer layer and work your way in. Same thing here.

You start with the indirect feeders — the pial collaterals coming from outside the AVM’s main territory.

When you go to embolize these feeders, make sure your microcatheter is well positioned. You don’t want it to be far from the nidus. It needs to be perinidal — right at the end of the artery, as close as possible to the nidus.

Why? Because if you start embolizing from upstream — where the pial collaterals are — your liquid embolic can go into normal brain and cause ischemia. So positioning here is critical.

Then in the next session, you move on to the direct feeders. And I divide these into two types.

First are the micro shunts — the smaller, lower-flow feeders.

Second are the macro shunts — the big, high-flow ones.

And again — always start with the small ones first.

Because if you go for the macro shunt too early, the high flow will carry your embolic straight into the draining vein. And if you occlude that vein while the AVM is still filling — that’s catastrophic.

The pressure builds inside the nidus, and it can rupture. That’s a disaster.

That’s why we always go from small to large. From periphery to center.

And here’s what’s interesting: by the time you reach the final session, the AVM has shrunk. That macro shunt you saw in session one? It’s smaller now. The draining vein? Also smaller.

That’s how you know you’re almost done.

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Contact & Resources:

For questions or collaboration, feel free to reach out:

Email: [email protected]

YouTube channel: youtube.com/drmostafafarid

Not all arteries are what they seem. In this episode, we explore a tricky group of feeders that quietly complicate your embolization plan — and why knowing their behavior changes everything.

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Script:

Okay, welcome back. Let’s dive right into arterial feeders now.

So, most of the time, arterial feeders end directly into the AVM nidus. Pretty straightforward, right?

But — and this is a big but — there’s a special group called en passage feeders.

Now… what are en passage feeders?

Basically, they’re little branches that come off a main artery that’s just traveling past the AVM. The main artery is actually heading to normal brain — not the AVM itself. But while it’s passing by, tiny side branches sneak off and start feeding the nidus.

And these feeders — they can be a real headache.

Why?

Because:

• ​ They’re hard to access with your microcatheter.
• ​ And even if you get there, embolizing them is risky.
• ​ You could end up refluxing embolic agent back into the main artery and cause brain ischemia.

And here’s the kicker — you usually don’t see these on a regular brain angiogram. Nope. You need selective angiography.

So what do we do?

We take the microcatheter we’re planning to use for embolization anyway, and we perform super selective angiograms.

But be ready: these angiograms are usually pretty diluted.

Why? Because the catheter’s tiny, and the artery’s big — so the contrast gets washed out fast by the blood flow.

Still, even if the images aren’t perfect, they give you clues.

If you want better selective images though, you can use a balloon catheter.

Here’s how it works:

You inflate the balloon to block the blood flow. Then you inject contrast through the balloon’s lumen. Now — with the blood flow arrested — your contrast stays longer, and you get a much clearer look. It’s like slowing down a rushing river just enough to see what’s inside.

Alright, moving back to the AVM nidus.

When it comes to MRI, personally I’m a big fan of T2-weighted images.

Because on T2, flowing blood shows up as jet black signal voids, while CSF is bright white. It gives you this really nice contrast. The black tangled vessels against the bright background — it just pops out at you.

And when you find the nidus, the next question is — where exactly is it?

Is it MCA territory? ACA? PCA?

Because depending on that, you can start classifying your feeders.

If the feeder comes from the territory where the nidus sits — it’s a direct feeder. If it comes from another territory — usually through collaterals — it’s an indirect feeder.

Let’s say you have an AVM in the parietal lobe — supplied mainly by the MCA, but also getting a bit from the ACA.

In this case:

• ​ MCA = direct feeders.
• ​ ACA = indirect feeders.

And the ACA feeders usually reach the nidus through pial collaterals.

And understanding this is super important when planning your treatment.

Alright, that’s the anatomy part pretty much wrapped up. Next — we’ll jump into treatment strategy — why treating an AVM is kinda like eating an apple.

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Contact & Resources:

For questions or collaboration, feel free to reach out:

Email: [email protected]

YouTube channel: youtube.com/drmostafafarid

Start here if you’re new to brain AVMs. We break down the first steps in understanding what you’re really looking at — and how to begin seeing things others might miss.

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Script:

Hey everyone, welcome. So today’s talk is for you if you’re just starting out with brain AVMs. If you’re a complete beginner, this is where you need to be.

First of all, AVMs — they’re complicated. It honestly takes a lot of time and patience to really understand their angioarchitecture and how to treat them safely.

And in the beginning, I really urge you to sit down and study all the imaging. Take a good hard look at the MRI. Look at any previous angiograms, CT angios, MR angios — anything you can find. Everything helps. The more you see, the more you understand.

The key to treating AVMs — the real key — is understanding.

If you understand the anatomy, if you know exactly which arteries are feeding the AVM, how many veins are draining it, where it sits in the brain — then you’re already halfway there.

And the location matters so much. Is it near the speech center? Next to the brainstem? Hugging the thalamus? Each of these comes with its own challenges. Because traditional endovascular treatment through the arteries can sometimes hurt the surrounding brain if you’re not careful.

So if you’re treating an AVM near the speech area, you have to talk to the patient and family beforehand. Let them know — after the procedure, there could be some speech problems, at least for a while.

Now, when you’re trying to understand an AVM — really get it — you can’t just look at one image alone. You have to correlate everything.

Here’s how you do it. Open the coronal MRI next to the AP angiogram. Put them side by side. They’re basically the same plane — both showing you a front-to-back view.

Then do the same with the sagittal MRI and the lateral angiogram. Again, side by side — both working in the same right-to-left plane.

And here’s the trick: scroll through the slides together. Slide by slide. Scroll through the MRI and at the same time, scroll through the angiogram.

You’ll start noticing — this vessel I’m seeing on MRI matches that shadow on the angio. That draining vein in the MRI? It’s the same one I’m seeing emptying on the angio.

At first, it’s confusing. But if you stick with it, it clicks. You start to see the AVM in 3D inside your head.

Now, about the draining veins. They’re tricky. You don’t always spot them right away.

Usually, each lobule of the AVM nidus drains into small primary veins. And these then join up to form the bigger draining vein or veins.

Sometimes the main draining vein splits into branches. Sometimes it stays as one straight vein, draining either to the superficial or deep venous system.

Here’s a mental image that helps: think of the AVM as a tree.

The nidus is the leaves. The veins are the branches and the trunk. If you’re lost, think: where’s the center of the tree? That’s usually where the veins start to exit.

It’s a simple analogy, but it helps more than you think.

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Contact & Resources:

For questions or collaboration, feel free to reach out:

Email: [email protected]

YouTube channel: youtube.com/drmostafafarid