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Stretched to the Limit: Comparing Polytetrafluoroethylene-Covered Endovascular Stents Through Serial Dilations
Ernesto Mejia1, Emily C Kish1, Martin L Bocks1
1Division of Pediatric Cardiology, University Hospitals, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, Ohio.
Insights
VBX stents demonstrated more predictable fracture patterns and less recoil than iCast stents during in vitro dilation. However, VBX stents showed increased foreshortening with postdilation, impacting pediatric congenital cardiac interventions.
Area of Science:
- Biomedical Engineering
- Materials Science
- Pediatric Cardiology
Background:
- Covered stents are crucial for congenital cardiac interventions in children.
- Postdilation capability is essential for accommodating somatic growth.
- Understanding stent performance under dilation is vital for pediatric interventions.
Purpose of the Study:
- Compare in vitro performance of iCast and VBX covered stents.
- Determine fracture and polytetrafluoroethylene tear thresholds.
- Define recoil and foreshortening characteristics during serial dilations.
Main Methods:
- iCast and VBX stents of various sizes were subjected to serial dilations.
- Dilation increments were 2 mm until stent fracture or polytetrafluoroethylene tear.
- Maximum tested diameter was 22 mm.
Main Results:
- VBX stents fractured at specific balloon sizes, showing predictable patterns.
- iCast stents exhibited partial to complete fractures between 14- and 16-mm dilations.
- VBX stents had less recoil but more foreshortening during postdilation compared to iCast.
Conclusions:
- VBX stents offer more predictable fracture behavior than iCast stents.
- iCast stents showed unpredictable fracturing patterns.
- Findings inform clinical decisions for pediatric congenital heart interventions.
Background:
Covered stents are used during congenital cardiac interventions to treat stenotic or injured vessels or to exclude unwanted vascular connections. The ability to postdilate a stented vessel to keep pace with somatic growth is critical in children. In this study, we aimed to compare in vitro performance of 2 brands of covered stents during serial dilations to demonstrate the threshold for stent fracture and polytetrafluoroethylene tear and define recoil and foreshortening characteristics.
Methods:
iCast and VBX stents of various sizes were measured before and after expansion and through serial dilations. Dilations were performed at 2-mm increments until stent fracture, polytetrafluoroethylene tear, and "napkin-ring" formation, to a maximum of 22-mm diameter.
Results:
The 5- and 6-mm VBX stents fractured during dilation with 10-mm balloon; the 7-mm VBX stents fractured on the 14-mm balloon; and the largest VBX stents fractured on the 20- or 22-mm balloons. iCast stents experienced partial fracture during dilation with the 14- or 16-mm balloons and complete fracture past dilation with 16-mm balloons. VBX stents recoiled less at nominal diameters. Both stents had similar foreshortening at nominal diameters, although VBX stents had more significant foreshortening with postdilation.
Conclusions:
All iCast stents experienced partial fracture with dilation between 14- and 16-mm diameter and had unpredictable fracturing patterns. VBX stents showed a more predictable fracture pattern and had less recoil with nominal inflation but more foreshortening with postdilation. These findings may add clinical benefit and empower physicians to make optimal decisions regarding future planning of interventions in children with congenital heart disease.
