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Current time:0:00Total duration:6:07

Video transcript

the other day one of the pediatric cardiology doctors was joking around with me we're talking about Epstein's anomaly he said I say Epstein's and you say and answer is the lithium so in the minds of a lot of students when you're taking tests Epstein's and lithium always go together so the theory is that mothers who take lithium which is a drug to treat bipolar disorder that's what leads to their children having Epstein's the effect when their they develop that in the uterus according to this doctor I was talking to this is just something we've taken for granted for a long time and it's not really backed up with a lot of evidence it's just one of those heart defects we think of as caused by drugs the mother can take but in reality it can also happen in babies whose mothers are not taking lithium so Epstein's is a defect that involves the right side of the heart we have our right atrium right ventricle down here left atrium left ventricle blue pulmonary artery red a aorta so in Epstein's we have something happening in the tricuspid valve which is usually here between the right atrium and right ventricle and it basically drops downward we call it displaced it's almost like has fallen off towards the ventricle so the way I'm drawing this it's going to look really awkward because I'm trying to modify instead of redrawing this thing just to show you the right atrium extends down here now so the right ventricle is still connected to the pulmonary artery but now the right ventricle is tiny it's this area down here and the tricuspid valve again is between these two chambers but it's usually underdeveloped or floppy or something's wrong with it there's a word associated with Epstein's we call it the atrial ization of the right ventricle let me see if I can spell that a triol ization it basically just means because the right because the tricuspid valve that separates the two drops down then this whole area above that used to be the right ventricle are supposed to be now is but now is the atrium so atrium is bigger ventricle is smaller this makes the right ventricle pretty wimpy it's small and weak now let me come in and draw the septum between the right and left atrium separates the two top chambers in as many as half of the people with Epstein's there's a hole between the right and left atrium so we have our atrial septal defect or ASD defect okay so this is how Apps teams is set up the rest the left side works the same so red blood comes back into the left atrium from the lungs and the left ventricle pumps it to the aorta so why do we have cyanosis let's start from the beginning when this baby is first born keep in mind that when the baby's first born the lungs have very very high resistance this much is four times the amount of resistance that adults have so in our pulmonary artery here we've got a huge force going this way so if you're a drop of blood deoxygenated blood from the body going into the right atrium which is now huge go to the right ventricle if a choice between going into the pulmonary artery here or going back through the tricuspid valve let me just label that really quickly tricuspid remember that it's dropped down and it's not working perfectly so the blood can actually get back behind the tricuspid valve back into the atrium and go across shunt across to the left side here so especially in the beginning of life with this high pulmonary resistance the blood favours this route going to the left side so we have a big strong shunt this way this results in the left atrium having again mixed blood so we have blue from the right side and red coming from the lungs we got purple blood going into the left ventricle in purple blood going out to the aorta sort of cyanosis from this mixing also from the fact that we're not getting too much blood to the lungs so remember for this particular way of shunting we can kind of think of the right atrium right ventricle is just one blog of things the valve here is now working too well to keep it too separate places so as the wimpy right ventricle tries to squeeze whatever power it can generate usually pushes the blood over to the left side instead of through this high resistance pulmonary artery now as soon as the baby's born the resistance the lungs begin to drop so this might be the one disease that actually gets a little better as his child gets into the first few weeks of life so I just rearranged the arrows talking about our resistance and with that the the size of this shunt it's a little smaller so there's still some shunting if we draw the arrow like that there's still some shunting but now we got more blood going into the pulmonary valve there's a resistance in the lungs keep dropping until it's at a normal adult level then more and more blood will go into the lungs so this disease actually gets better as the kid gets older because all we care about is the resistance in here dropping enough so that most of the deoxygenated blood goes to the lungs instead of to the left side then we have less mixing and that will give the left side more red blood instead of purple and that's basically all we care about is functionally how strong the shunt is so as long as most of the blood is go to the lungs then we're okay not to say that people with Epstein's don't need surgery or treatment because most of the time they don't just have Epstein's they have something else that might need to be repaired but as far as this particular thing we've talked about remember that it gets better as the pulmonary resistance drops and there's a chance that this child might get away without surgery