The impact of stent design on the structural mechanics of the crossing Y-stent: an in vitro study.

INTRODUCTION: Crossing Y-stent technique is a valid option for coiling wide-necked bifurcation aneurysms. Two main designs of stents, the closed- (CCS) and open-cell (OCS), are used in combination for a crossing Y-construct. This in vitro study was conducted to assess the mechanical characteristics of each stent-combination and to suggest an optimal combination for clinical practice.

METHODS: The Enterprise and the Neuroform3 stents were used as closed-cell and open-cell stents, respectively. Four different Y-stent combinations; double CCSs (CCS-CCS; Enterprise-Enterprise), OCS followed by CCS (OCS-CCS; Neuroform-Enterprise), CCS followed by OCS (CCS-OCS; Enterprise-Neuroform), and double OCSs (OCS-OCS; Neuroform-Neuroform) were tested in a bifurcation aneurysm model. Images of the model were obtained by digital subtraction angiography (DSA), and morphological changes of Y-constructs caused by interaction between stents were compared.

RESULTS: Double OCSs showed the best stent apposition to model branches and no collapse of the second stent at the intersection, whereas Y-stent combinations using a CCS as the second stent showed tubular collapse of the second stent at the crossing point. These combinations revealed unsatisfactory apposition to the model branch in which the second stent was deployed. Most narrowing of the second stent was noted in the double CCSs construct, which resulted in poorest stent apposition.

CONCLUSION: Based on a simple in vitro experiment, we suggest that double OCSs Y-construct is optimal for achieving best stent-wall apposition. Furthermore, our findings suggest that Y-stent combinations utilizing a CCS as the second stent may increase the risk of thromboembolic complications due to poor stent-wall apposition.