Failure to post-dilate BeSmooth peripheral stents to adult vessel size diameters during benchside tests.

Background: Low-profile stent implantation remains a rescue treatment for aortic coarctation and branch pulmonary arteries stenosis in small children. Stent re-expansion to cope with vascular growth remains problematic.

Objectives: To evaluate ex vivo feasibility and mechanical behaviour of over-dilating BeSmooth peripheral stents (Bentley InnoMed, Germany).

Methods: Three BeSmooth peripheral stents in diameters of 7, 8, and 10 mm were dilated to nominal pressure and then 13 atm. BeSmooth Ø7 × 23 mm was sequentially post-dilated using 12, 14, and 16 mm high-pressure balloons. BeSmooth Ø10 × 57 mm was post-dilated with a 14 mm balloon and then with a 48 mm bare-metal Optimus XXL stent hand-mounted on a 14 mm balloon (stent-in-stent). BeSmooth Ø8 × 57 mm was directly post-dilated with a 48 mm bare-metal Optimus XXL stent hand-mounted on a 16 mm balloon (stent-in-stent). The stents' diameter and length were measured. Digital inflation pressure was noted. Balloon rupture and stent fracture patterns were closely evaluated.

Results: At 20atm pressure, BeSmooth Ø7 × 23 mm shortened to 2 mm forming a 12 mm diameter solid ring circle and the woven balloon ruptured radially. At 10 atm pressure, BeSmooth Ø10 × 57 mm fractured longitudinally in various dispatched breaking points at a diameter of 13 mm without shortening and ruptured the balloon with multiple pinholes. At 10 atm pressure, BeSmooth Ø8 × 57 mm fractured centrally at three different points at a diameter of 11.5 mm without shortening and the balloon broke radially in half.

Conclusions: In our benchmark tests, extreme shortening, severe balloon rupture, or unpredictable stent fracture patterns at small balloon diameters limits safe post-dilation of BeSmooth stents beyond 13 mm. BeSmooth stents are not ideal candidates for off-label stent interventions in smaller patients.