am mat ory ▁mass ▁with ▁risk ▁for ▁rec urrent ▁is chem ic ▁stroke . ▁▁ ▁Per cut aneous ▁closure ▁of ▁an ▁AS D ▁is ▁currently ▁only ▁indicated ▁for ▁the ▁closure ▁of ▁sec und um ▁AS D s ▁with ▁a ▁sufficient ▁rim ▁of ▁t issue ▁around ▁the ▁sept al ▁defect ▁so ▁that ▁the ▁closure ▁device ▁does ▁not ▁imp inge ▁upon ▁the ▁superior ▁v ena ▁c ava , ▁inferior ▁v ena ▁c ava , ▁or ▁the ▁tr icus pid ▁or ▁mit ral ▁val ves . ▁ ▁The ▁Am pl at zer ▁Sept al ▁Occ l uder ▁( AS O ) ▁is ▁commonly ▁used ▁to ▁close ▁AS D s . ▁ ▁The ▁AS O ▁consists ▁of ▁two ▁self - expand able ▁round ▁disc s ▁connected ▁to ▁each ▁other ▁with ▁a ▁ 4 - mm ▁wa ist , ▁made ▁up ▁of ▁ 0 . 0 0 4 – ▁to ▁ 0 . 0 0 5 - inch ▁N it in ol ▁wire ▁mesh ▁filled ▁with ▁D ac ron ▁fabric . ▁Im plant ation ▁of ▁the ▁device ▁is ▁relatively ▁easy . ▁The ▁pre val ence ▁of ▁resid ual ▁defect ▁is ▁low . ▁The ▁dis adv antages ▁are ▁a ▁thick ▁profile ▁of ▁the ▁device ▁and ▁concern ▁related ▁to ▁a ▁large ▁amount ▁of ▁nit in ol ▁( a ▁nick el - t itan ium ▁comp ound ) ▁in ▁the ▁device ▁and ▁consequ ent ▁potential ▁for ▁nick el ▁to x icity . ▁ ▁Per cut aneous ▁closure ▁is ▁the ▁method ▁of ▁choice ▁in ▁most ▁cent res . ▁Studies ▁evalu ating ▁per