Patent foramen ovale or PFO is a congenital heart defect in which a small hole in the upper chambers of the heart between the left and right atria called the foramen ovale fails to close after birth. Twenty five percent of the population has PFO and many live their lives without closing it. However, in some people there can be serious health complications such as blood clots and stroke that warrant closure. People in professions that deal with sudden pressure changes like airline pilots or scuba divers are at a higher risk of stroke and may need their PFO closed. Specialists are also discoveri