Podcast Transcript: Radial vs. Femoral Access in IO Procedures

So once we have the patient prepped, ready to go, we will put the local anesthetic on the skin. You're assessing with a ... It's more or less a 20 gauge needle 018 system. I use ultrasound for the access, I like the direct visualization. I'm not doing a through and through wall puncture. It's a single wall puncture directly visualizing the tip of the needle the entire time. Once you're in you get good return, you're threading your 018 wire, and the sheaths that we use are the Terumo glide sheaths.

The Slender sheaths in particular are designed such that the wall of the sheath is thinner than a standard access sheath that you would use, say, from a femoral approach. By doing that, by thinning out that wall what they've done is they have decreased the outer sheath size by about one French while maintaining the inner lumen diameter. So we're essentially using a five French sheath with a smaller outer diameter than what we would be seeing with a five French sheath in the groin. So with a two millimeter radial artery, that still allows for some blood flow around the sheath. The sheath's design, it's an 018 so it slips with a nice taper over that 018 wire. And I think that's key because what you don't want to do, in fact the thing you want to avoid at all costs with radial artery access is swapping out catheter sheaths. That's certainly going to send your artery into spasm. So it's nice that they have designed a sheath that inserts over an 018 system so it's a single, smooth insertion. It's also hydrophilic on the outside so that facilitates the access as well.

Once we get into the system and we've got good blood return through the sheath, we'll then put in a medicinal cocktail that is designed to reduce the risk of perisheath thrombosis and also stimulate some vasodilation. We use 2.5 milligrams of verapamil, 200 mics of nitro, and 5,000 units of heparin. We use a full dose heparin instead of the low-dose 3,000 units. There is some data to show that radial artery occlusion rates are a lot lower if you're using the full-dose heparin. So 5,000 units of heparin, 200 mics of nitro, 2.5 of verapamil, and then we hemodilute that. We will draw up in a 20 to 30 cc syringe, from the sheath, the patient's own blood to dilute the medication and then slowly administer that back through the sheath over the course of about two minutes. That's mainly to prevent that burning sensation that the verapamil can cause, that can incite some spasm, it can cause some anxiety in the patient who at this point is probably just crossing over that threshold into conscious sedation.

Once you've got the cocktail in you're kind of good to go at that point. I will mention that there is some data out there that instead of giving the nitroglycerin through the sheath some practices are using sublingual nitro. And they've shown that they can increase the radial diameter size by about five millimeters without a deleterious effect on blood pressure by giving it sublingual. It's an interesting point, we don't do that, but it's something that others have adopted in practice.

So again, your cocktail is in, you're ready to go, sheath is in. Now it's a matter of just picking your guide catheter. And as I mentioned before, this is actually a pretty critical decision. You want to know ahead of time the shape that you want to use. You want to make sure your inner luminal diameter is appropriate. Because once you have a guide catheter in and you're down in the aorta there's no way you're going to be able to swap this thing out for a different one without causing spasm in that artery. I've tried it, it's never worked out for me. So I would just say that as a point of fair warning that you want to give it some thought as far as the guide catheter is concerned.

I think guide catheters for us have been a little bit of a process of trial and error. We first started out when we were doing this using the Terumo catheters because we had the support of the rep there and we sort of just purchased all the stuff as a packaged deal. The Sarah, the Jacky catheters, they've got a great shape, they definitely move well, they respond well to torque. What we found was the problem with those catheters the inner lumen was not hydrophilic and it was actually just about at the threshold of what you would expect the inner lumen of a five French catheter to be. So if we were doing treatments where we wanted to use an antireflux catheter like the Surefire device we found that in passing that device through the catheter it would move well until it got to the tip and then it would sort of get bound up. And maybe one out of three times it would pass through and you were able to do the treatment and the other two times it would bind up on the fabric of the antireflux umbrella and just sort of destroy the Surefire catheter. So that was no good and that's also when we learned that you can't swap out catheters without causing a lot of spasm in the radial artery.

So just to reemphasize this process of introducing radial artery access in our practice was not exactly smooth-sailing the whole way but the idea is that you learn from the mistakes of others, and when you're implementing in your own practice, we've got some knowledge that we can add to the database to help you do it well.

The Launcher catheter is one that we kind of found with the help of Surefire because we were looking for a catheter that had slightly larger inner lumen diameter with a roughly equivalent outer diameter. So these Launcher catheters are known for their larger inner lumen. We talked before about getting good injection rates for diagnostic mappings and stuff, these catheters are actually fantastic for that. I mean you can get seven cc per second injections through them without any problem whatsoever. So you're certainly going to be able to do whatever you need to do from a flow rate standpoint and from a pressure standpoint with that catheter.

So long-winded answer, I apologize, but that was sort of like soup to nuts how we go through the initial approach.