Abstract 18075: Mechanical Properties of Stents and Blood Vessels to Determine a Safe Strategy to Unzip Stents Within Growing Blood Vessels
Introduction: Unzipping of a stent is the technique by which a stent is fractured longitudinally using angioplasty balloons. This can allow for the stent to be further redilated and for implantation of a larger diameter stent within it. The technique may be useful in treating stenosis of infant blood vessels. The effectiveness and safety of unzipping stents depends in part on the mechanical properties of the stent and the blood vessel as well as the surrounding structures, the understanding of which is limited.
Hypothesis: Unzipping of stents can be effective and safe if the appropriate stent is implanted in the appropriate blood vessel.
Methods: 60 stents (7 stent types) were implanted in 12 neonatal piglets into different blood vessels. 3 months later, unzipping was attempted by dilating the stents till either the stent fractured or the vessel was injured. The ultimate tensile strength (UTS) of the different stent and vessel types was calculated. 6 piglets were sacrificed to determine histologic grade of vessel injury. The other 6 were survived to determine long term effects of unzipping.
Results: The mean UTS of various stent and vessel types tested is represented in Figure 1. The Genesis and Blue stents had the highest UTS, greater than any blood vessel and therefore, not suitable for unzipping. The Protégé stent had the least UTS but fractured in a disorganized fashion and did not unzip. The VeriFlex, Valeo, Express and Formula stents are perhaps best suited for unzipping as they did not result in significant vessel injury. One piglet developed a pseudoaneurysm on long term follow up. 2 distinct types of vessel injuries and 4 histologic grades of these injuries was developed from this study.
Conclusions: This study may help chose the appropriate stent to implant in an infant with a stenotic blood vessel if the intent is to unzip the stent in the future. The unzipped segment may require reinforcement with another stent implanted within it in order to prevent formation of a pseudoaneurysm.
Author Disclosures: S.K. Sathanandam: None. T. Kumar: None. D. Hoskoppal: None. S. Subramanian: None. C. Knott-Craig: None. R. Waller: None.
- © 2016 by American Heart Association, Inc.