We learn that the stroke volume is the same for the right and left side of the heart. So the amount of blood in either circulations should also be the same. (is it? I myself doubt this statement. As in, does it need to?)There's also a list of adaptations in the pulmonary vasculature that accommodates the huge volume of blood. But that's the adult. What about the foetus?
My doubt is that, in the presence of a patent ductus arteriosus in the foetal circulation, doesn't this distribution change? This shunting of blood into the systemic circulation would result in a low pulmonary venous return and hence, a low left ventricular stroke volume. So in the foetus, both blood distribution (in the two circulations) and also the stroke volumes (of either side of the foetal heart) should be differrent. Is this so?
This actually concerns me because the DA joins after the initial three branches (left brachiocephalic and the carotids). So, wouldn't such a shunting drastically reduce blood flow/perfusion to the brain? As in there would be decreased flow to the carotids when compared to the adults.
Finally, what are the consequences of the differential blood volumes in the two circulations and differential stroke volumes of the two ventricles due to a patent ductus arteriosus in a foetus? (If happens)