▁include ▁pul mon ary ▁hy pert ension , ▁right - s ided ▁heart ▁failure , ▁at rial ▁f ibr ill ation ▁or ▁flutter , ▁stroke , ▁and ▁Eisen men ger ' s ▁synd rome . ▁ ▁While ▁pul mon ary ▁hy pert ension ▁is ▁unusual ▁before ▁ 2 0 ▁years ▁of ▁age , ▁it ▁is ▁seen ▁in ▁ 5 0 % ▁of ▁individuals ▁above ▁the ▁age ▁of ▁ 4 0 . ▁ ▁Pro gression ▁to ▁Eisen men ger ' s ▁synd rome ▁occurs ▁in ▁ 5 ▁to ▁ 1 0 % ▁of ▁individuals ▁late ▁in ▁the ▁disease ▁process . ▁ ▁Pat ent ▁for amen ▁ov ale ▁A ▁pat ent ▁for amen ▁ov ale ▁( P FO ) ▁is ▁a ▁rem nant ▁opening ▁of ▁the ▁f etal ▁for amen ▁ov ale , ▁which ▁normally ▁clos es ▁after ▁a ▁person ' s ▁birth . ▁In ▁medical ▁use , ▁the ▁term ▁" pat ent " ▁means ▁open ▁or ▁un ob struct ed . ▁In ▁about ▁ 2 5 % ▁of ▁people , ▁the ▁for amen ▁ov ale ▁fails ▁to ▁close ▁properly , ▁leaving ▁them ▁with ▁a ▁P FO ▁or ▁at ▁least ▁with ▁what ▁some ▁phys icians ▁class ify ▁as ▁a ▁" pro - P FO ", ▁which ▁is ▁a ▁P FO ▁that ▁is ▁normally ▁closed , ▁but ▁can ▁open ▁under ▁increased ▁blood ▁pressure . ▁On ▁e ch oc ardi ography , ▁sh un ting ▁of ▁blood ▁ ▁may ▁not ▁be ▁noted ▁except ▁when ▁the ▁patient ▁c ough s . ▁ ▁P FO ▁is ▁linked ▁to ▁stroke