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Kaplan Qbank USMLE



Author5 Posts
  #1

in patent ductus the following happens?

1.left ventricular stroke volume increases

2.right ventricular stroke volume increases.


  #2

LEFT ventricular stroke vol increases

  #3

yeAH and afterwards raight ventricular afterload (pul. HTN) inc. tht leads to rt. ventricular hypertrophy!

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  #4

hi to all.

I just have a doubt about the answer. PDA comunicates the aorta with the pulmonary artery right???

If that is so, it makes more sense that the one with the overload and the increase in stroke volume like ssrpk said should be the right ventricle and not the left.

If my assumpiton is wrong please someone explain. thank you all


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  #5

Well,

Right, the PDA communicates the aorta and the pulmonary aorta, In a regular left to right shunt, there is greater pressure in the aorta than in the pulmonary aorta, so the blood flows from higher to lower pressure, from aorta to pulmonary artery, So there is an increased pulmonary blood flow, this increased blood volume is going to return back in the heart thru the pulmonary veins to the left side. So there is a left ventricular overload.

Now as time passes, this increased blood flow to the pulmonary arteries will lead to smooth muscle hyperplasia, narrowing the diameter of the vessels , and thus increasing the resistance slowly. When the pulmonary vessel resistance becomes greater than the aortic resistance, then there will be a reversal of shunt. Increase pulmonary vessel resistance leads to right ventricular hypertrophy.








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