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In this next case, we're gonna review how to measure membranous septal length.

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And we're starting with an axial image. And this is just my standard pacs.

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I'm gonna use the, uh, m p R features to do some double obliques,

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but I just wanna point out the membranous septum here on axial images.

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It's right here that lives underneath the aortic valve.

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So you can see the aortic valve leaflets here,

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and then you can see the membranous septum and it's just above the level of the,

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um, muscular part of the septum.

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Now you notice that this is a little bit motion of the acquisition

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and a little bit noisy.

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The motion is related to the fact that this is the 20% phase, like I mentioned,

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which is the,

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usually the optimal phase for measuring the aortic gainless in TAVR patients.

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So that's what we required for this particular patient.

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So what you wanna do to get the member septal length here is you wanna

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first make sure that you have a good look at the member septum. And honestly,

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usually the coronal view gives you a, a great look,

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but you just want to put your cross hairs on the, on the septum,

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make sure you have it in profile.

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And then what you wanna do is you want to basically put your cross hairs in the

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middle of the aortic valve. And again, like we've done with previous cases,

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you wanna make yourself perpendicular theoric valve with the axial view

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and then confirm that on your short axis view.

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And then from here you can actually scroll down from your short axis view

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and identify the meran septum, which you see right here. That's this thin piece,

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right? You see all the muscle, muscle, muscle, muscle. This is left atrium,

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this is interatrial septum. And then this little bit here is the ous septum.

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So you identify that thin little piece and then you can rotate your plane to

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make sure that you're bisecting that thin piece of membranous septum and just

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ignore the red plane here. It's not really, um, relevant to what we're doing.

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And then you take a look at your long access planes and find the one that's

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bisecting. The ous septum should be on the right hand side of the image.

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And sure enough, this one, we don't see the ous septum,

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but we do see it over here. So I'm gonna use that for my measurement.

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There's a ous septum right there. And what I'm gonna do,

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I'm gonna move that cross hairs outta the way,

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and I'm just gonna find the bottom of the aortic valve

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here where it inserts relative to the membrane septum.

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And then I'm gonna make my measurement from the bottom of the aortic valve to

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the membrane septum. And I get roughly 10 millimeters here.

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So that's actually a pretty long emran septum. In theory,

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this patient should have a relatively high margin of error for, uh,

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placement of the TAVR device.

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In terms of risk of subsequent need for a pacemaker,

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generally member,

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their ideal is to have the device sitting above the level of the muscular part

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of the septum, so no

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Deeper than the membranous septum.

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And so a nine millimeters is a pretty long membranous septum and a,

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a decent safety margin for this patient.

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The key number that we usually think of,

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and it's out there in the literature and the guidelines,

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is around eight millimeters, membranous septum, less than eight millimeters,

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and you start worrying about increased risk for conduction abnormalities after

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the TAVR procedure.