ABSTRACT
Patent foramen ovale (PFO) is a relatively frequent variant of physiological state and a common finding in the general population; it is not classified as an atrial septal defect or heart disease. PFO plays an important role in fetal circulation, whereby oxygenated blood from umbilical veins and the vena cava inferior is preferentially directed through the Eustachian valve and PFO to the left atrium and into systemic circulation. PFO is judged to be present with the visualization of microbubbles in the left atrium within three cardiac cycles from the right atrial opacification. The potential for paradoxical microembolism into the cerebral arteries can also be assessed using transcranial Doppler with concomitant venous administration of an echo-contrast medium not passing through the pulmonary capillary bed. Depending on the type of occluder to be used, the length of the PFO tunnel, septum secundum width, and PFO size on an inflated balloon are determined prior to the transcatheter closure.
