While folks are coming to the microphone, perhaps if I could ask, Ram, what do we know
about the status of the myocardium in those borderline under the EFE?
Is the myocardium of-- the left ventricular myocardium, is it healthy?
That's a great question.
We suspect that the myocardium is not normal.
Our colleagues-- Andy can probably comment on this, as well-- but we're trying to learn
more through imaging to try to understand that.
We have taken biopsies, at times, from papillary muscles and other areas as we're resecting
EFE.
And it's clear that they have a potential to lay down more scar tissue, more EFE.
So I think that fibrosis is a part of this.
I just don't know to what extent we have that and how to distinguish the patients who don't
have that from those that do.
And thank you for the nice presentations.
I would like to ask to Dr. Powell, I was thinking that both entities that were presented were
pretty different, one from the other.
And I think some things might be taken into consideration when talking about univentricular
borderline left ventricle, comparing with when you talked with unbalanced atrioventricular
septal defect.
So I was wondering if you used some echocardiographic variables that had been really consistent
over time, which are, for example, to modify antrioventricular valve index or the right
ventricular, left ventricular inflow index in surgical decision-making?
Well, first, I agree that those are two different situations, and they should be considered
differently.
For the unbalanced canal defect, we haven't relied heavily on the AV valve index, to the
best of my knowledge, in our surgical decision-making.
A lot of it has to do with the morphology of that common AV valve and how it's attached,
particularly on the left side.
And the surgeons can speak more specifically to this.
But they're able to divide the ventricle and divide that common AV valve in such a way
that it can, essentially, move some of that AV valve tissue over off to the left side.
That's exactly right.
I think that what you want is an adequate-sized left-sided orifice.
And when you're looking at, on an echocardiogram, the distribution of the leaflets over the
ventricles is not necessarily what has to be the case when you're operating surgically.
So what we'll do is change our septation location on the AV valve such that we're not limited
anymore by where it naturally needs to fall.
We use a two-patch technique.
And in my mind, that allows us to really redistribute the valve in a way that I find is not as possible
when we're using a modified single-patch technique or the Australian technique, in which the
leaflets are placed down onto the crest of the VSD.
That's great.
But how do you deal with the left ventricle inflow?
Because that way, you can divide the valve in the appropriate, in the exact, location,
but you cannot work on the left ventricle inflow.
And do you take that into consideration, the left ventricle?
So what I find to be a better marker of problems with separating valve is really how the papillary
muscle architecture is.
So we focus more on what does the subvalvular apparatus look like, rather than the AVI index.
If we have a single left ventricle papillary muscle closing the cleft, it will result in
a terribly stenotic valve.
And so in that situation, we will have to use other techniques to either create two
papillary muscles, if that is possible, or to only partially close the cleft or patch
the cleft so as to not compromise the inflow to that valve.
And I'll be, I think, at one of the sessions on Wednesday, I'll be describing some of these
techniques that we're using.
But again, on echo, I'm looking more at the subvalvular apparatus than I am the distribution
at the level of the annulus.
And what about the VSD size?
Have you taken a look inside that?
Because the VSD size has demonstrated to be a marker of higher mortality.
If you have a larger VSD, you have more mortality.
Do you look into that before taking a decision?
You know, I would say that, probably, the patients that we see the most trouble with
are transitional AV canals.
The large VSD patients, it's much easier to distribute the valve over the ventricles.
It's when you don't have a VSD or when the tethering attachments of the superior and
inferior bridging leaflet limit the ability to maneuver that leaflet and redistribute
it.
What we find we have to do is, actually, cut many of those attachments to then create a
VSD, a large VSD, and then close it, separately.
And I find that to be very helpful.
Thank you very much.
Andy, this is a question for you.
So when you're looking at these ventricles, one of the things that you actually see is
that they are much globular than the typical spherical-looking ventricle.
And we know that globular ventricles do not tolerate pressure that well, and, actually,
long-term wise, they have a higher chance of failing than a spherical ventricle does.
So have you looked into it?
Because one of your MRIs, if you look at the septum, the movement of the septum is, actually,
very abnormal.
So have you looked into doing some regional wall motion studies or using feature tracking
or strain analysis or whatever to see whether there's any regional wall motion abnormality
in these ventricles where we're getting a biventricle kind of repair on borderline ventricles?
We didn't specifically look in that.
So we didn't look at feature tracking or any regional measures in that study, nor did we
look at any measures of sphericity, which we could, of course, go back and do.
Right now, those three parameters are ones that we primarily focused on.
But thank you for the suggestion.
I'm going to say it's truly remarkable what you're doing.
I think we're really all learning from you and the program that you're running.
I guess my question, nevertheless, is that, clearly, a lot of your patients are not, sadly,
going to make it through a biventricular pathway.
And when we look after our single ventricle patients, the things we want to do is we do
not want to volume-load the circulation.
We do not want to give them a restrictive atrial septum.
So are you worried that the patients who don't make it are going to end up turning a good
Fontan into a bad Fontan?
And are there lessons you're learning as to the patients that you should have bailed out
on earlier or you shouldn't even have embarked on the progress?
Well, we're certainly learning.
That part, I can answer very easily.
The patients who have undergone single ventricle palliation after recruitment, for the most
part, have not suffered as a result of it.
So we've continued to the Fontan.
And the key there is to make sure that they don't reach a certain threshold where their
pulmonary vasculature starts to see reversible changes.
And this is where the monitoring period becomes important.
It's important to make sure that you follow the gradient and bring them back for catheterization
if there's any concern for restriction of the atrial septum that's leading to elevated
pressures.
I will say that a lot of the patients that were in this series were also not necessarily
candidates for Fontan, either, because of right ventricular dysfunction, significant
tricuspid regurgitations.
So we're pushing a lot of patients down the biventricular repair because they have risk
factors for a single ventricle, as well.
And many of them kind of stay in a glenn plus a shunt territory for a period of time, until
we can determine what the next best approach is.
But I think it's very important to monitor them very carefully and intervene early.
But if you do that, you don't burn the bridges for a Fontan, ultimately.
How do go around the way you counsel these patients in a period of intense public scrutiny,
where one patient that you lose could have been a Fontan, a good Fontan?
Well, I think it's very important early on to engage-- one of the nice things about the
staged approach is, because it's over a period of years, you have an opportunity to really
discuss with the families the options.
So you're not committing to one approach versus the other.
And we have many opportunities to discuss.
So I find that many of the families, when they come to a biventricular conversion, are
much more prepared in terms of the expectations, what to expect afterwards.
And I often show them the same slides I show at a medical conference and make sure that
they understand the risks and benefits.
There's no question these are hard conversations.
They're long conversations, and often, it's multiple conversations, where you kind of
reinforce what you said before, answer a new round of questions, and go over things in,
maybe, a different way of presenting it, just to make sure.
I need to be confident that they understand the benefits and risks of trying to do something
like this.
So it really is an example of shared decision-making between the providers and the patients and
their families.
Excellent
Thank you very much.
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