▁have ▁had ▁a ▁crypt ogen ic ▁stroke , ▁and ▁more ▁so ▁in ▁those ▁who ▁have ▁a ▁stroke ▁before ▁the ▁age ▁of ▁ 5 5 . ▁Tre at ment ▁with ▁ant ico ag ul ant ▁and ▁anti plate let ▁medic ations ▁in ▁this ▁group ▁appear ▁similar . ▁ ▁Ost ium ▁prim um ▁▁ ▁A ▁defect ▁in ▁the ▁ost ium ▁prim um ▁is ▁occasionally ▁class ified ▁as ▁an ▁at rial ▁sept al ▁defect , ▁but ▁it ▁is ▁more ▁commonly ▁class ified ▁as ▁an ▁at ri ov ent ric ular ▁sept al ▁defect . ▁Ost ium ▁prim um ▁defect s ▁are ▁less ▁common ▁than ▁ost ium ▁sec und um ▁defect s . ▁This ▁type ▁of ▁defect ▁is ▁usually ▁associated ▁with ▁Down ▁synd rome . ▁ ▁Sin us ▁ven os us ▁ ▁A ▁sin us ▁ven os us ▁AS D ▁is ▁a ▁type ▁of ▁at rial ▁sept um ▁defect ▁in ▁which ▁the ▁defect ▁involves ▁the ▁ven ous ▁in flow ▁of ▁either ▁the ▁superior ▁v ena ▁c ava ▁or ▁the ▁inferior ▁v ena ▁c ava . ▁ ▁A ▁sin us ▁ven os us ▁AS D ▁that ▁involves ▁the ▁superior ▁v ena ▁c ava ▁makes ▁up ▁ 2 ▁to ▁ 3 % ▁of ▁all ▁inter at rial ▁communication . ▁ ▁It ▁is ▁located ▁at ▁the ▁j unction ▁of ▁the ▁superior ▁v ena ▁c ava ▁and ▁the ▁right ▁at rium . ▁ ▁It ▁is ▁frequently ▁associated ▁with ▁anom alous ▁d rain age ▁of ▁the ▁right - s ided ▁pul mon ary ▁ve ins ▁into ▁the ▁right ▁at rium ▁( inst