Dear Sir Thanks for your query. A patent foramen ovale is a congenital condition where a door between the left and right atrium (posterior chambers of heart which receive blood) can open , only from right to left direction if pressure on right side is high. It can not send blood form left to right by definition except for one rare situation. The hazards which has been associated with PFO are passage of paradoxical clots from right heart to left heart. Beside cryptogenic stroke and headaches has been proposed to be associated with this condition but not conclusively proven. Closure of PFO is being done in some centers but it is for certain situations only and not a standard procedure as yet. sincerely Sukhvinder