| 摘要 |
The invention relates to a perivascular ring having an inner diameter adjustable by inflation/deflation and adapted to be implanted and closed about a vessel for controlling the inner diameter of said vessel and thus the flow and/or pressure of a fluid flowing in said vessel, e.g. the portal vein. The ring of the invention is capable of regulating blood flow to the liver, in particular after an hepatectomy or hepatic transplant, and to substantially improve the survival chances of the patient. The ring according the invention has an adjustable inner diameter (øi) for implantation and locking about a vessel. The ring comprises: an outer belt (3) having a substantially constant diameter in the closed position; an inner chamber (4) that is inflatable and deflatable in the closed position so as to change the inner diameter (øi) thereof; a flexible inflation/deflation tube (5) one end of which is connected to the inner chamber (4) and the other end of which is connected to inflation means (6); wherein the outer (3) and inner (4) chambers define open collars, one of which at least, preferably that defining the outer belt (3), is provided with means (7) for closing the ring (1) around the duct (2). The inner chamber (4) has, in the rest and closed position, an inner diameter (øir) corresponding to the smallest reduced diameter required for use for controlling the diameter of the duct (2).
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