# 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  
In Table 2, the stents adopted over the years for the treatment of both CoA and pulmonary artery stenosis are collected. Even in this case, it is clearly possible to notice how the majority of devices are used off-label, due to the limited investment from industry. The proper device is generally selected among coronary, peripheral, carotid, biliary, and renal stents according to the vessel caliber, which may be extremely different case by case, requiring stents in a variable range of size from a few millimeters up to a few centimeters [105]. The goal of the stenting procedure in this case is more traditional, aiming to restore blood flow in a stenotic site in place of balloon angioplasty, given improved acute and long-term outcomes [55; 105]. However, somatic growth accommodation represents the most critical aspect regarding the stenting procedure in great vessels, requiring subsequent rediation and eventually reinterventions according to the age at presentation. Specifically, according to the American Heart Association, stent placement for CoA is indicated in patients in whom stent expansion to adult size is possible, with a coarctation gradient above 20 mmHg or significant hypertension [62]. Similarly, stenting is indicated for proximal or distal pulmonary artery stenosis when accommodation of further stent dilation to adult size is possible [62]. However, in specific cases, it might be also reasonable to implant small stents that cannot achieve adult size in small children as part of a palliative approach [105]. Baloon-expandable stents represent nowadays the gold standard in the treatment of great vessel stenosis given their superior radial strength, well-predictable placement, and the possibility of growth accommodation through further balloon expansion [105]. However, inherent complications are not absent, including vessel rupture, stent migration, re-stenosis, and aneurysm formation, which generally occur in long-term follow-up [67; 105; 107]. Conversely, self-expandable stent application in this context is still at its outset, with very scarce studies investigating their performance. While some authors hypothesize that removing the need for ballooning might reduce the risk of stent fracture, vessel dissection, and aneurysm formation [103], some others sustain that the unequal rate of expansion in different por \begin{table}
\begin{tabular}{c c c} \hline \multicolumn{2}{c}{**Off-Label Use**} & \multicolumn{1}{c}{**Ad Hoc for CHD**} \\ \hline \multicolumn{2}{c}{**Balloon-Expandable**} & \multicolumn{1}{c}{**Self-Expandable**} \\ \hline \multicolumn{2}{c}{} & Growth Stent (O) [104] \\ \multicolumn{2}{c}{} & Cook Formula 418 and 535 (O) [99] & \\ \multicolumn{2}{c}{} & Palmaz Genesis (C) [100; 101; 102] & \\ \multicolumn{2}{c}{} & Ev3 Maxi (O) [102] & \\ \multicolumn{2}{c}{} & Palmaz Genesis XD (C) [55; 65] & \\ \multicolumn{2}{c}{} & IntraStent Mega LD (O) [55] & \\ \multicolumn{2}{c}{} & IntraStent Max LD (O) [55] & \\ \multicolumn{2}{c}{} & Palmaz XL (C) [55] & \\ \multicolumn{2}{c}{} & Valeo (O) [55] & \\ \hline \multicolumn{2}{c}{} & iCAST Atrium * (C) [105] & \\ \multicolumn{2}{c}{} & Palmaz Blue (C) [105] & \\ \multicolumn{2}{c}{} & Palmaz Genesis (C) [105] & \\ \multicolumn{2}{c}{} & Cook Formula 418 (O) [105] & \\ \multicolumn{2}{c}{} & Zilver Cook (O) [105] & \\ \multicolumn{2}{c}{} & \multicolumn{2}{c}{} & IntraStent Max (O) [105] & \\ \multicolumn{2}{c}{} & IntraStent Mega (O) [105] & \\ \multicolumn{2}{c}{} & Edwards Valeo Lifestent (O) [106] & \\ \hline \end{tabular}  
* Drug-eluting stent (DES); others, where no specification is provided, are bare metal stents (BMS).  
\end{table} 
Table 2: Stents adopted in the treatment of CoA and pulmonary artery stenosis. A distinction is made between off-label and specifically developed designs. Devices are classified among balloon-expandable and self-expandable stents, with closed-cell (C) or open-cell (O) geometry.