Breakable stent for interventions in infants and neonates: an animal study and histopathological findings

Matthias Sigler ^1*, Katja Schneider ², Michael Meissler ³, Kay König ⁴ and Martin B. E. Schneider ²

¹ Georg-August-University Goettingen, Germany
² German Paediatric Heart Centre, St. Augustin, Germany
³ Tierexperimentelle Einrichtung, Campus Virchow-Klinikum, Charité Berlin, Germany
⁴ Department of Paediatric Cardiology, Charité Berlin, Germany

^* To whom correspondence should be addressed. E-mail: msigler{at}gwdg.de.

Accepted 21 April 2005

Abstract

Objective: Use of stents in infants and neonates is limited due to growth of the stented vessel, especially when coronary stents are employed. Enlargement of the diameter of the stented segment by redilatation is restricted by design and size of the stent. We therefore developed a breakable stent for the use in neonates and infants that can be broken open by balloon dilatation during reintervention.

Materials and methods: Medical grade stainless steel breakable stents (n=16) were interventionally implanted in systemic arteries in neonatal piglets (n=7). Patency of the stented segments was demonstrated by repeated angiography. Redilatation was performed up to 3 times. After a follow up of 18 to 165 days the animals were sacrificed and the tissue block containing the stent excised. Besides standard histology we employed scanning electron microscopy for biocompatibility screening.

Results: "Breaking" of the stents was achieved by redilatation using a conventional angioplasty balloon catheter. During follow-up, patency of all stented segments was demonstrated angiographically. One stent dislocated during implantation. One rupture of the vessel occurred during redilatation when an inadequately large balloon catheter was used for dilation. No other complications were observed. Scanning electron microscopy demonstrated complete cellular coverage of the stent struts. Histological examination revealed thinning of the vessel wall and partial rupture of the media at the site of breaking of the stent. An only mild inflammatory reaction was detected.

Conclusion: The new breakable stent can be broken open by simple angioplasty. Feasibility, effectiveness, and biocompatibility was demonstrated in an animal model. Surgery for removal of stents in paediatric patients due to disproportion of a formerly implanted stent and the vessel during growth may be avoided by the use of a breakable stent.

Keywords: congenital heart disease, infant, interventional therapy, neonate, stent

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