# Stents in Congenital Heart Disease: State of the Art and Future Scenarios
## 4 Stents in the Treatment of Congenital Heart Disease
### Great Vessel Stenting: CoA and Pulmonary Artery Stenosis
tions of the vessel during growth might lead to an eccentric radial force, causing late stent migration [108]. Moreover, these devices cannot be dilated beyond their nominal diameter, and implantation of an oversized self-expandable stent is not advised as it might stimulate neointimal growth and vessel erosion [108]. For what concerns device geometry, open-cell design is generally preferred as it is associated with a larger final size and allows for the reopening of side branches [54; 105]. The limited number of reports about DES implantation for aortic and pulmonary artery stenosis is explained also in this case by the lack of experience in their use in infants. Indeed, longer follow-up is needed to assess their performance and utility in congenital anatomical stenosis. There are recent studies [109; 110] investigating the use of covered stents to limit wall injuries; however, they are not able to always quantify the usefulness in preventing reinterventions compared to non-covered ones. Trying to overcome the issue related to somatic growth accommodation, self-disrupting stents were investigated at the beginning of the century. A well-known example is the Growth stent (QualMed, Winsen, Germany), initially developed for aortic coarctation [104]. It is composed of two separate halves of laser-cut and electropolished stainless steel, which are connected with bioabsorbable sutures to create a circular structure. Complete absorption of the sutures occurs after 6 months; then, the two separate halves would remain in place without limiting somatic growth and allowing for easier implantation of a larger conventional stent with potential expansion to adult size. However, the high reintervention rate and early redilation need reported in the first trials, without fulfilling the adaptive growth requirement [104], led to the failure of this design. To address growth issue, the most common strategy nowadays is the use of newer stent designs combining a low delivery profile with high redilation potentials, such as the Palmaz Genesis XD, Palmaz XL, Intristent Mega, and Intristent Max LD, which can be easily dilated up to adult vessel diameters (20-25 mm). Within this category, it is relevant to mention the so-called Cheatham Platinum (CP) stent (NuMED, Hopkinton, New York, USA), which is the first device to be approved for CoA [111]. It is constituted of platinum and iridium wires arranged in a zig pattern, with an expansion range of up to 30 mm, existing also in a covered version (DES). Its high dilation potential highly reduces the need for additional stent implantation, reducing the rate of restenosis with respect to other devices [100]. It is interesting to cite also the Minima stent (Renata Medical, Newport Beach, CA, USA) [112], a cobalt-chromium balloon-expandable device that is currently under clinical trials for application in congenital vascular stenosis. Its unique design allows for an initial size of less than 4 mm for implantation at birth, with the possibility to expand to over 22 mm, maintaining structural integrity and radial strength. Another recent advancement is given by the BeGrow stent (Bentley InnoMed, Hechingen, Germany), developed for pulmonary artery stenosis, which is currently completing a clinical trial [113]. It consists of a cobalt-chromium balloon-expandable stent with a unique design to allow for dilation up to 11.5 mm; the presence of predetermined breaking points allows for a controlled and reliable rupture when this size is exceeded for growth accommodation and/or subsequent implantation of larger stents.