How does one know if they have a connection between the right & left sides of the heart (patent foramen oval)?
Answers:
If you're breathing there's a connection.
If not, there isn't (and you're also dead).
EDIT: Ooops! Sorry I read the question as l & r sides of 'the brain'. doh!
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During development of the fetus, the inter-atrial septum develops to eventually separate the left and right atria. The foramen ovale remains open during fetal development to allow blood from the venous system to bypass the lungs and go to the systemic circulation. This is because prior to birth, the oxygenation of the blood is via the placenta and not the lungs. A layer of tissue begins to cover the foramen ovale during fetal development, and will close it completely soon after birth. After birth, the pressure in the pulmonary circulation drops, and the foramen ovale closes. In approximately 25% of adults the foramen ovale does not seal over. In this case, elevation of pressure in the pulmonary circulation (ie: pulmonary hypertension due to various causes, or transiently during a cough) can cause opening of the foramen ovale. This is known as a patent foramen ovale (PFO).
Foramen Ovale, Not Normally There, One Might See the Flow to/From the Lungs as a Indirect Connection. If I Remember Correctly, From Embryolgy, the Foramen Ovale Closes Normally In the Ebryonic Development of the Heart, if it Doesn't, Perhaps Paradoxical Embolism. I don't Think a Patent Foramen Ovale Can Be Heard On Auscutation.
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