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

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.