| 摘要 |
<p>An endoprosthesis has a graft sleeve of a first diameter (d1, figure 3), and at least one undersized ring stent 1g-1l attached thereto having a second, smaller diameter: preferably, its internal diameter is smaller by at least 1%. Oversized sinusoidal or saddle-shaped ring stents 1b-1e (and figure 2) may also be included to increase axial and torsional stiffness and to provide a controlled collapse at strategic points of the prosthesis. The undersized ring stents ensure that the fabric of the graft sleeve is held at a smaller diameter. Where the stent-graft is to be deployed in a tortuous location (such as a bend within a blood vessel like the aorta), the undersized ring stents cause any bunched up fabric (crimps) of the graft sleeve to be creased outwardly, away from the lumen of the graft sleeve thus avoiding partial occluding of the lumen. The undersized stent rings may be formed from nitinol wire and may be placed either side of a fenestration in the graft sleeve.</p> |
