Patent foramen ovale

Alternative names:

PFO

Definition:

A term used to describe the failure to close of a normal opening (in a fetus) between the left and right atria (upper chambers) of the heart.

Causes, incidence, and risk factors:

The foramen ovale is an opening between the left and right atria (upper chambers) of the heart. This allows blood to bypass the lungs (which are not used) in an unborn infant. The foramen ovale normally closes soon after the infant is born.

The foramen ovale may remain open in as many as 1 out of 5 people. In the absence of other cardiac defects, an open foramen ovale is of no consequence. Congenital heart disease, which increases the pressure on the right side of the heart may cause blood to flow through a patent foramen ovale (right-to-left shunt) causing cyanosis, a bluish appearance of the skin.