| 摘要 |
A medical implant includes first and second ring members, each including a resilient framework having a generally cylindrical form. A tubular sleeve is fixed to the first and second ring members so as to hold the ring members in mutual longitudinal alignment, thereby defining a lumen passing through the ring members. A constricting element is fit around the sleeve at a location intermediate the first and second ring members so as to reduce a diameter of the lumen at the location. |
