Balloon Dilation Technique Influences Stent Shortening and Intentional Stent Fracture During Overexpansion of Drug-Eluting Stents: A Bench-Testing Study.

Abstract

Background and aims: Drug-eluting stents (DES) are not designed for overexpansion to supra-nominal diameters or intentional stent fracture (ISF). The optimal dilation technique to minimize stent shortening (SS) and achieve ISF to accommodate pediatric somatic growth has not been described.

Methods: Three sizes of two commonly used DES were implanted within a silicone model to simulate blood vessels. Each stent was serially dilated in 1 mm increments under fluoroscopy using three techniques: 2 cm length, semi-compliant balloons (Technique 1), 2 cm, noncompliant balloons straddling the entire stent (Technique 2), or noncompliant balloons in an "inside-out" manner (balloon shorter than stent or 2 cm balloon aligned with distal end of stent (no straddle); (Technique 3). Technique 1 crossed over to noncompliant balloons once stent "napkin-ringed" (NR). Percent SS = (L_nominal - L_final)/L_nominal* 100.

Results: Technique 1 resulted in the greatest SS (median 85%, IQR 82, 87) and universal napkin ringing. Technique 2 caused less SS (median 14%, IQR 7, 15), and Technique 3 caused the least SS (median 7%, IQR 3, 11). ISF was achieved in all, however, the inside-out technique caused ISF at smaller stent diameters (median 114% recommended postdilation limit vs. 122%-131%) and lower inflation pressures (median 15 vs. 28-29 ATM). ISF was achieved in Technique 1 after napkin ringing but required larger noncompliant balloons than other techniques (median 8.5 vs. 7 mm).

Conclusion: Inside-out dilation resulted in less SS and fracture at smaller diameters with lower inflation pressures. This technique may improve the ISF success rate of DES in pediatric patients.