0:00

Okay, next we're gonna, in this video talk about membranous septal length.

0:05

And so what's the rationale behind membranous septal length? Why do we care?

0:10

Um, well,

0:11

heart block turns out is one of the most frequent complications of tavr. Uh,

0:16

and it's really common for patients to get a new left bundle branch block, um,

0:20

approximately 13 to 28% of patients. And then even a new heart block,

0:24

which requires pacemaker, uh, in around four to 20% of patients depending on,

0:29

um, the, the study you look at, uh,

0:32

and it turns out that there are multiple risk factors for heart block, um,

0:36

right bundle branch block, um, before the tavr, low implantation,

0:42

short membrane septal length eccentric, L V O T and annular calcifications.

0:47

So all these factors are important. The annular calcifications,

0:50

we're actually gonna talk about that in a separate video. Um,

0:53

and then these two,

0:54

low implantation and short membrane septal length are kind of related. Um, and,

0:58

and it turns out that, um,

1:00

we can measure membrane septal length and provide that additional information,

1:05

um, to our interventional colleagues, um,

1:07

that may help them determine which patients are at higher risk of need for

1:11

pacemaker. So I just wanna note, um, before moving on,

1:14

that this is not a routine measurement that's done. It's something that's,

1:19

I would say not part of the, the standard of care yet. Um, but I,

1:23

I certainly wanna include it in this series because I think it may be something

1:26

that we need to start doing in the future. Um, you know,

1:29

depending on how the data evolves. So here's a study that came out recently.

1:34

This was actually a trial, um,

1:36

where they were trying to minimize permanent pacemaker implantation after

1:41

tavr, um, by looking at membranous septal length.

1:43

And the concept here is that the membranous septum is this little bit of tissue

1:48

that lives right below the aortic valve and before the muscular part of the

1:51

septum and the short of the membrane septal length,

1:55

the more risk that that device when it's implanted is gonna, uh,

1:59

basically impact the conduction tissue,

2:01

which lives in this basal septal area right here. Um,

2:05

so this is actually a case, um, from our, uh,

2:07

institution of a patient with a short member septal length.

2:11

And then you can see clearly that after the TAVR device was placed, um,

2:15

the device is sitting below the level of the membranous septum. Um,

2:19

and this patient did have a left bundle branch block after tavr. Fortunately,

2:23

they didn't need a pacer. Um, but nonetheless,

2:25

that's an outcome you'd like to avoid. So, uh, in this study,

2:30

they looked at the membranous septal length and they found that the bulk of

2:35

their patients who needed pacers had a really short membranous septum less than

2:39

five millimeters.

2:40

And then what they did is prospectively in a hundred patients,

2:44

they measured the membrane septal length,

2:46

and they tried their best to position the device at a depth less than the

2:50

membrane septal length. So try to avoid those deep implantations,

2:54

and sure enough that they found that if they avoid those deep implantations,

2:57

that the new pacemaker

2:59

Rate reduced from around 10% to 3%, uh,

3:02

if they were paying attention to the membrane septal length.

3:05

So this is some of the, you know, initial data that,

3:07

that helps us think that this, you know, might be an important measure to watch,

3:12

uh, out for. And, and again, it's not completely established yet, um,

3:16

but it's something that, you know, to be aware of and,

3:19

and maybe more important in the future. So just to sum up,

3:22

a membrane septal length less than eight millimeters, um,

3:25

is generally considered higher risk.

3:27

That information actually comes from this reference down here. That's a,

3:31

a summary statement, um, about, um, evaluation of, uh,

3:34

pre TAVR CT scans. Um, so currently, like I mentioned,

3:38

it's not standard component of TAVR reports. However,

3:40

it might be an important variable, uh,

3:42

in the future as further data becomes available.