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Current time:0:00Total duration:5:18

Video transcript

transposition is finally a defect where the name actually describes what it is transposition is a switching one for one switch a for b and b going where a is supposed to go transposition of the great arteries so the two great arteries that come out of the heart are the pulmonary artery which leads to the lungs in the aorta oops it's not our rates arteries the other one is the aorta that leads to all the arteries in the body transposition of the great arteries so literally it means the aorta being where the pulmonary artery is supposed to be and the pulmonary artery being where the arrow dose is but really quick you're a drop of blood you come into the heart into the right atrium going to the right ventricle supposed to get pumped out through this blue vessel the pulmonary artery into the lungs then you come back as oxygenated blood into the left atrium going to the left ventricle gets pumped out through this red a order to the body so in transposition I'm going to erase this whole part this is all messed up remember these two are plugged into the opposite place where they're supposed to be whoo okay let's you erase that as I'm erasing take a minute and think about how our loop changes so now a drop of blood or is it going so staying with the blue the pulmonary artery the bleeding to the lungs now plugs over here into the left ventricle we raise a little bit more there so we can get our aorta is now plugged into the right side as receiving deoxygenated blood from the body okay or that doesn't look very pretty but I just want you to get the idea of this switch so now your blue blood coming in here you go to the right ventricle and it's going out this red bud vessel this is going to be filled with blue blood and then if your red blood coming back into the heart this way through the pulmonary veins remember the vessels that return blood to the heart have now switched so red blood still comes back into the left atrium goes to the left ventricle and then is going out back to the lungs again through the pulmonary artery as you see that the color inside the vessel does not match the color of the vessel that I've drawn so if you just follow this path that I described right here you should realize that we actually don't have a circuit like we usually do we actually have two completely closed off circuits so we have the body going to the right side and going right back to the body's we have a blue cycle the body going to the heart right atrium right ventricle and here back into the aorta right into the body we don't go through the lungs in this cycle so the blood never gets oxygenated it just stays blue and on the right side we have blood coming from the lungs red blood right left atrium left ventricle back out through the pulmonary arteries back to the lungs or picks up more oxygen so we have a red cycle and a blue cycle and there's no mixture I'm going to say wait a minute you can't live like that right you will die very quickly because you never pick up any oxygen you just got two cycles running parallel to each other never mixing which is why for this patient of this trial to survive there has to be a communication between the two systems and that's why usually transposition comes with a VSD I would almost say always ventricular septal defect so ventricular septal defect which is a part of a lot of different cardiac defects and sometimes you can just be on its own and close up as the baby grows older in this case the VSD is life-sustaining it gives these two cycles a place to mix so at least we get some oxygen into the body also don't forget that newborns have a ductus arteriosus here between the aorta and the pulmonary artery so ductus arteriosus in this case also providing a way for the two loops to have some communication this way of course we're still cyanotic because even at its best when we have a mixture of the two kinds of blood going out into the aorta so our goal here is that there's enough mixing that at least a blood we're sending out to the body is purple with some oxygen in it and this child is going to be blue and in fact they probably can't survive on the first six months without some type of surgery but thankfully now we have standard surgical procedures to plug everything back and connect the two loops to make one big circuit so when you see transposition of the great arteries think of the fact that the two great arteries leading out of the heart are switched we've got two independent cycles that are parallel in that for this child to be alive we need some kind of communication between them