Vascular implant

A medical implant, comprising:

• first and second ring members each having an expanded configuration, a collapsed configuration and a diameter, and each ring member comprising a resilient framework having a generally cylindrical form, wherein the ring members are discrete and separated from one another by a gap, and
• wherein each ring member has a first end and a second end opposite the first end, and wherein the first end is wider than the second end when the first and second ring members are in the expanded configuration;
• a tubular sleeve, disposed in the gap and 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;
• and
• a constricting element, which is fit around an outside surface of the sleeve at a location in the gap so as to reduce a diameter of the lumen at the location, wherein the constricting element has a diameter less than the first and second ring diameters in the expanded configuration.