Closure of patent foramen ovale with the Amplatzer PFO device
A patent foramen ovale (PFO) is an evolutionary mechanism designed to allow blood oxygenated by the placenta to pass through the fetal right atrium and directly enter the left atrium. This blood bypasses the non-functional pulmonary circulation and delivers oxygenated blood directly to the systemic circulation. The opening is a dynamic passageway between the atria formed by the septum secundum superiorly and the septum primum inferiorly. With an infant’s first breath, the left atrial pressure quickly rises over that of the right atrium and the flap of the septum primum is pressed against the septum secundum, sealing the foramen ovale. In most individuals the septa fuse during the first year of life, permanently closing the foramen and creating the fossa ovale.