Hypoplastic left heart syndrome and norwood glenn fontan | NCLEX-RN | Khan Academy


– For Hypoplastic Left
Heart Syndrome, the defect is straight forward enough,
or what we call HLHS. Like I said, the defect is
straight forward enough, I wanna spend most of this video focusing on how we fix it. The stage of three surgeries
is really interesting. Basically, the like the name suggests, we don’t have a left
ventricle functionally. It didn’t develop so we don’t
have a big pumping chamber sending blood through
the aorta to the body. Now, the baby cannot survive like this so usually, for the first
few days to few weeks, we have the ductus arteriosus still open, and also an ASD to sustain life. But we basically need surgery right away. So, diving right into the
three stages of surgeries, the first one is called Norwood-Sano. These are all gonna be
named after the surgeons who came up with them. Norwood-Sano; Sano is the guy who came up with the shunt. If I could list our problem right here, we have no systemic flow. Nothing’s going through the aorta because the left ventricle is so small it doesn’t exist and doesn’t work. No systemic flow. By the way, without a left
ventricle sending blood to the aorta, the aorta
itself is not this nice, thick, robust structure that
we have in normal heart. It’s this tiny, little thing. But, that doesn’t even
matter because our first goal is to provide some blood to the body. Remember, right now we’re drying the body. What the surgeons do is they basically sew this pulmonary artery coming out of the right ventricle to the aorta. Now, everything I will draw here will be kind of conceptual. I can’t really draw it
anatomically correct. I’m just trying to modify
what we already have. So, basically the idea
is what’s coming out of the right ventricle
is supposed to usually all go to the lungs. Now it’s going to our new
aorta that we’ve constructed. Our first order of business is to provide some blood to the body. Okay, kind of like this. Now we have this new aorta. Let me clean this up a little bit for you. Also, for completeness, I’m gonna mention that between the right and left atrium there’s usually an ASD,
or a big septum defect, so we just leave that open for now. We don’t really touch that
during the first procedure. For Norwood-Sano, number one, we wanna make this huge vessel coming
out of the right ventricle now go to the body. At this stage in our Norwood procedure we have blood flow to
the systemic arteries to our body, but now we
have no pulmonary flow, because the pulmonary
artery has been borrowed, basically, to provide systemic flow, because our only functional,
pumping ventricle right now is the right ventricle. Our priority is getting it
to pump blood to the body. Now we have no pulmonary flow. What we do is now is the Sano
shunt part of the procedure. We basically put a huge shunt
from the right ventricle to what’s the pulmonary artery tree. Now it’s still connected
to the right ventricle, like it’s supposed to be, but
not through the outflow here. This portion has been
sewn over to the aorta. But, we still have a
shunt here to get blood from the right ventricle to the lungs to receive oxygen. If we think about what color of blood is flowing through our new
constructed aorta right now we have blue blood coming
from the right atrium and since we have a septal defect here, we have red blood coming
from the lungs here. So, the mixing here results
in the right ventricle having purple blood. Now, this purple blood is both going into our big, new artery and going to the lungs through our shunt. This procedure is basically
done as soon as possible after the baby’s born,
and this is how they stay for a couple months,
as a Norwood-Sano baby. Sometimes in the hospital
you hear them referred to as, “Oh, this baby is a Norwood-Sano,” which means this is their
heart, their circulation at this stage. So, right now we’ve solved the problem of having no systemic flow and we’ve used the Sano shunt to solve the problem of no pulmonary flow. All right, so the baby
grows up, couple months. I would say four months, basically, until we wanna do the next step. By now we’ve also
allowed this PDA to close so I just take it out of there. All right. Moving on to our next procedure. It’s called the Glenn, two “n’s.” If you notice, I’ve taken
down our orange shunt going from the right ventricle
to the pulmonary artery here. Again, our problem is back
to the no pulmonary flow. By this time the right
ventricle should be used to pumping blood to the body, but by taking down the shunt
we have to solve the problem of a more permanent way
of providing blood flow to the pulmonary artery
and therefore to the lungs. In the second and third procedures that’s exactly what we do, which is to plug the
venous return of the body straight into the pulmonary artery. If we look here into the right atrium, there are two sources of venous blood returning to the right side, giving the right atrium
blue deoxygenated blood. The one on top is called the S-V-C, standing for Superior Vena Cava. So, Superior Vena Cava. Of course this one underneath
is the Inferior, I-V-C. For Glenn we just care
about the SVC right now. Do you see how it’s plugged into the right atrium right here? In the Glenn what we do is we take the SVC and we plug it directly
into the pulmonary artery. S-V-C. My drawing is very
anatomically not correct. It’s conceptual. Don’t worry about exactly
where it plugs in, but functionally, now the
blood coming from the SVC go directly into the pulmonary artery; not through a shunt. Not through the right atrium. Instead, this right atrium,
is kind of closed off on top. The SVC receives venous deoxygenated blood from the head and from
the top of the body. We have blue blood coming in here. As a Glenn, let’s follow
the path of blood. So, if you’re coming
from the top of the body you enter the SVC, you go
into the lungs directly and you come back as red
blood into the left atrium. But, if you’re coming
from the IVC right now, you still go to the right
atrium, mix with the red blood in the left atrium, go into the ventricle and it gets pumped to the body. With the mixing of the blue blood and the red blood across the ASD and pumped out by the right ventricle, as a Glenn baby they
sill have purple blood. Saturation’s usually in the 80’s. We want it to be in the 80’s. What we’ve done is taken down that shunt, which was obviously not permanent and we’re looking for a permanent way of getting blood to the lungs, freeing up the right ventricle to be our systemic pumping chamber. That’s our Glenn. In the third one, the
Fontan, as you’ve guessed it, now we take care of the IVC. The Fontan. Let me just erase some of this. Now the IVC, instead of being
plugged into the right atrium, it’s gonna be closed off, instead being plugged right
into the pulmonary artery. The I-V-C. I’m gonna erase this right here. It’s a little confusing because the Superior
Vena Cava’s over here. I just wrote that out to
show you the spelling. Now the SVC and the IVC are both going directly into the pulmonary artery. Basically all of the
venous drain of the blood is now going directly to the lungs, bypassing the whole
right side of the heart. Remember, the entire job of
the right side of the heart is to get this blood to the lungs. Now we’ve bypassed it so now this whole heart functions as a two-chamber heart. What I mean by that
is, we have really one, functional atrium, because
there’s a hole here connecting the two. The atrium still holds
the blood coming back from the lungs, the left atrium. We have one functional ventricle. The hero in all of this is
that the right ventricle has now been trained to take on the job of the left ventricle
that never developed, providing blood to the whole body. If we follow the path of the
blood flow in the Fontan baby, we have blue blood coming
back from the vena cavas, directly to the lungs. We have red blood
returning from the lungs, entering into the left atrium, flowing over to the right atrium, which is why I said,
functionally, the left or right atria are like one. It flows over here into the right atrium, coming down here to the right ventricle and finally into our adapted, big vessel out of the heart; the aorta. From there our body’s oxygenate and provided with blood flow. I think it’s a pretty genius way. I mean, this takes years. The Fontan is usually done when the baby’s two to four years old. It’s a pretty genius way. Since we only have one ventricle, let’s make it do the most important job a ventricle does, which
is pumping to the body. We can think of a different way to direct blood to the lungs. One important question you might ask is, “Why go through this
whole Norwood-Sano business, “with the shunt and everything, “and now just do the Glenn and Fontan “right off the bat?” It’s important to keep in mind, if we look at this right now, usually we have the right ventricle, a muscle, pumping blood to the lungs. Now this is all passive flow, from the SVC and the IVC. Passive flow is not gonna happen if the resistance is really high. Remember, as a baby, since
their resistance is so high, if we did this right off the bat we wouldn’t get any blood into the lungs. That’s why we wait and we use the shunt. We wait for the pulmonary
resistance to drop until a passive flow is enough to get our blood to the lungs. These three procedures, in a nutshell, is our current standard way of repairing Hypoplastic
Left Heart Syndrome. Patients have a good chance
of surviving into adulthood.

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