TRANSVENOUS CLOSURE OF SECUNDUM ATRIAL SEPTAL-DEFECTS - PRELIMINARY-RESULTS WITH A NEW SELF-EXPANDING NITINOL PROSTHESIS IN A SWINE MODEL

Background Our purpose was to evaluate a new prosthesis for percutaneo us closure of secundum atrial septal defects (ASDs). Methods and Resul ts Percutaneous closure of surgically created fossa ovalis ASD was att empted in lj minipigs. The mean balloon-stretched ASD diameter was 12. 3+/-2.3 mm (range, 10 to 16 mm). The self-expanding prosthesis was bra ided from 0.005-in Nitinol wires in the shape of two flat buttons with a short connecting waist with a diameter corresponding to that of the defect to be closed. Polyester filling was added to enhance thromboge nicity. Pulmonary arteriography with levo-phase was obtained before pl acement; immediately after placement and at 1-week, 1-month, and 3-mon th follow-ups. Four animals were killed at 1 week, 1 month, and 3 mont hs for histopathological correlation. Three deaths resulted from ventr icular fibrillation (one during anesthesia and two during the placemen t procedure). Successful placement of the prosthesis was achieved in t he remaining 12 animals. Overall immediate ASD closure on angiography Occurred in 7 of 12 animals (all polyester-filled prostheses). Absent or trace shunt by angiography was present in 11 of 12 devices at 1 wee k, with the remaining one demonstrating a small shunt. All septal defe cts were completely closed at 1 month with the exception of one case i n which delayed partial dislodgment of an undersized prosthesis into t he right atrium had developed. Closure rate at 3 months was 100%. Neoe ndothelialization and fibrous incorporation of the prosthesis were com pleted within 1 to 3 months. Conclusions Effective and permanent occlu sion of secundum ASDs is feasible with a device that offers the advant ages of easy placement, self-centering, and repositionability.