If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:10:36

Hypoplastic left heart syndrome and norwood glenn fontan

Video transcript

for hypoplastic left heart syndrome the defect is straightforward enough or we call h l HS like I said the defect is straightforward enough I want to spend most of this video focusing on how we fix it because the stage of three surgeries here is really interesting basically like the name suggests we don't have a left ventricle functionally it didn't developed 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 so these are all going to 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 so nothing's going through the aorta because the left ventricle is so small doesn't exist and doesn't work no system dynamic 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 matter because our first goal is to provide some blood to the body remember right now we're dry in the body so the surgeons do is they basically so this pulmonary artery coming out of the right ventricle to the aorta now this is going to be everything I've drawn I will draw here will be kind of conceptual I can't really draw an anatomically correct I'm just trying to modify what we already have 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 the 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 so now we have this new a order you 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 a ASD or a big septum defect so we'll just leave that open for now we don't really touch that during the first procedure for nor would say no number one we want to make this huge vessel coming out of the right ventricle now go to the body so 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 so our priority is getting it to pump blood to the body so now we have no pulmonary flow what do we do is now cesano shunt part of the procedure we basically put a huge shunt from the right ventricle to what's the pulmonary artery tree so now it's still connected to the right ventricle like it's supposed to be but now 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 so if we think about what color of blood is flowing through our new constructed a order 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 is born and this is how they stay for a couple months as an or with Santo baby sometimes in the hospital you hear them referred to as oh this baby is in Norwood santé 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 shunt the sanno shunt to solve the problem of no pulmonary flow all right so the baby grows up couple months I would say four months based into life we want to 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 Glen to ends if you notice I've taken down our orange shunt going from the right ventricle to the pulmonary artery here so again our problem is back to no pulmonary flow but this time the right ventricle should be used to pumping blood to the body but by taking down a shunt we have we have to solve the problem of a more permanent way of providing blood flow to the pulmonary artery and therefore to the lungs and 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 so if we look here into the right atrium other two sources of venous blood returning to the right side giving the right atrium blue deoxygenated blood this one on top is called the SVC standing for superior vena cava so superior vena Kaiba of course this one underneath is the inferior I see before Glen we just care about the SVC right now so do you see how it's plugged into the right atrium right here so in the Glen what we do is we take the SVC and we plug it directly into the pulmonary artery as the see my drawing is very anatomically not correct so 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 pony artery not to our shunt not through the right atrium so instead this right atrium is kind of closed off on top the SBC receives venous the astra native blood from the head and from the top of the body so we have blue blood coming in here so as a Glen 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 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 mixed with the red blood in the left atrium go into the ventricle and gets pumped to the body so with the mixing of the blue blood and the red blood across the ASD and pumped out by the right ventricle and the Glenn baby they still have purple blood saturations usually in the 80s we wanted to be in the 80s but what we've done is taken down that shunt which was obviously not permanent we're looking for a permanent way of getting blood to the lungs freeing up the right ventricle to be our systemic pumping chamber so that's our Glenn and 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 so now the IVC instead of being plugged into the right atrium it's going to be closed off and instead being plugged right into the pulmonary artery the eye be see when you erase this right here it's a little confusing because the superior vena cavas over here I just wrote that out to show you the spelling now the SVC and the IVC are both going into directly into the pulmonary artery basically all of the venous drain of the blood is that 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 to chamber heart but what I mean by that is we have really one functional atrium because there's a hole here connecting the two they trim still holds the blood coming back from the lungs that left atrium and we have one functional ventricle the hero and 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 we follow the path of blood flow and in the Fontan baby we have blue blood coming back from the vena cavas directly to the we have red blood returning from the lungs entering to the left atrium flowing over to the right atrium which is why I said functionally the left and right atrium atria are like one so it flows over here into the right atrium coming down here to the right ventricle and finally into our big adapted big vessel out of the heart the aorta and from there our body is oxygenated and provided with blood flow now I think it's a pretty genius way I mean this takes years the Fontan is usually done when the baby is two to four years old it's a pretty genius way of since we only have one ventricle let's make it do the most important job but ventricle does which is pumping to the body and think of a different way to direct blood to the lungs now one important question you might ask is why go through this whole norwood Sano business with the shunt and everything and not 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 so passive flow is not going to happen if the resistance is really high so remember as a baby since the 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 one way for the poner resistance to drop until passive flow is enough to get our blood to the lungs so 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