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* dear all(tricuspid atresia)explain please
  chocolat - 12/03/10 23:54
im getting confused with this condition ,i read a question in uw
would someone please explains what happens and why is there is a single s2?
thank you.
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* Re:dear all(tricuspid atresia)explain please
  ckindec - 12/04/10 06:24
  tricuspid atresia means no tricuspid valve...thus no connection between the right atria and the right ventricle....

this condition during fetal life is alright as all the blood coming from the placenta into the right atrium gets directed towards the left atria through the patent atrial septal defect...going on to the left ventricle and then rest of the body.....

once the child is born the placental circulation stops and the deoxygenated blood from the body goes to the right atrium....since no tricuspid valve the blood has only one direction to go to ...that is the left atrium through the atrial defect..from here to the left ventricle and then rest of body through aorta..but since this is all deoxygenated blood the baby presents with cyanosis....

if the ductus arteriousus is patent in these cases some blood can go to the lungs and get oxygenated and return via the pulmonary veins into the left atrium...thus one of the conditions where we need to keep the duct patent....

since no blood entering the right ventricle at any time through the whole circulation, no blood flowing acrosss the pulmonary valves and thus only single s2 of the aortic valve present......

in some conditions a Ventricular septal defect will also be present to allow blood into right ventricle, these will have a two component S2..althoug a weak pulmonary component due to a hypoplastic right ventricle...(it never developed properly due to tricuspid atresia)

hope it helps
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* Re:dear all(tricuspid atresia)explain please
  chocolat - 12/04/10 06:48
  that was a very nice explanation and i have really understood the concept....thanks a million for helping me out...really appreciate it....  
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* Re:dear all(tricuspid atresia)explain please
  chocolat - 12/04/10 06:53
  another point is there will be left ventricular hypertrophy as oppsoed to right ventricular seen in most other cyanotic lesions....  
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