A catheter (10) comprises an expandable portion (12) for the treatment of stenotic sites (S) of vessels (JV1, JV2) in the body of a patient. The aforesaid expandable portion (12) includes:—an expandable formation (122), which, when expanded, is able to undergo a localized depression in an area corresponding to an annulus or stenosing ring (S) in the vessel treated (JV1, JV2), detecting the presence of said stenosing ring and—a cutting formation (124, 126), which can be positioned at the stenosing ring for cutting the stenosing ring so as to bring about yielding of the stenosis produced by said ring. Preferential application is in the treatment of internal jugular veins.
