Mandy, a 3-month-old girl, was having difficulty feeding and was not growing at a normal rate. Tests revealed that she had a defect in her fossa ovalis, which meant that a hole remained between her right and left atria. This condition is known as a patent foramen ovale.
What is the purpose of the foramen ovale in the fetus? What should happen to the foramen ovale at birth?
What causes this to happen?
After birth, is pressure higher in the left atrium or right atrium?
Based on your answer to the one above, if the foramen ovale is not fully closed after birth (as in Mandy's heart), which way would the blood be shunting?