32 Choi, Claudia Yeong-Un Grabitz, R.G. 510000-1 Publikationsserver der RWTH Aachen University Aachen German II, 86 Bl. : Ill. Objective: To evaluate practicability, efficacy and tissue reaction of a new miniature interventional device for occlusion of large patent ductus arteriosus (PDA) in a neonatal lamb model. Background: A variety of devices are used to close PDAs by interventional measures. Spring coils that are comparatively cheap and safe and were found to have a high cumulative occlusion rate have so far been limited to smaller PDAs due to physical limitation of grip forces, and were not compatible with nuclear magnetic resonance imaging (NMRI) due to the material in use. Methods: Memory shaped double cone Nitinol coils with selectively enhanced stiffness through additionally incorporated strats were mounted on a titanium/nickel core wire. A hook mechanism attaches the coil to the delivery wire allowing intravascular coil retrieval and repositioning. The system was placed through 5 F Teflon catheter. A chronic lamb model (n=9) of large PDAs (>6 mm) was used in which ductus patency was secured by a protocol of repetitive angioplasties. The animals were sacrificed after 10 to 180 days and the ductual region was examined by inspection as well as light- and electron microscopy. Results: In all animals placement of the coils within the PDA was possible. Before final detachment the coils were retrieved and/or repositioned up to 5 times. In 6/8 animals PDA closure was achieved within 1 hour, in one animal a later closure and in two insignificant residual shunts was elicited. Histology and electron microscopy revealed neointimal coverage of the implants but no local or systemic inflammation or erosion of the implant. Conclusion: The device closed effectively large PDAs in our model and may overcome the previous limitations of coils. Clinical trials are indicated. Aachen, Techn. Hochsch., Diss., 2002 ; PUB:(DE-HGF)11, ; 2, ; Dissertation / PhD Thesis 2002 RWTH-CONV-123141 2002 https://publications.rwth-aachen.de/record/61480