An angioplasty device comprising: - a guide wire to be inserted into a blood vessel, - a flexible tubular body extending along a longitudinal axis between a proximal end and a distal end and having a proximal part, which includes the proximal end, and a distal part which includes the distal end, with the tubular body comprising: - an inflatable balloon arranged radially about the tubular body in the distal part and capable of being inflated to increase the internal diameter of the blood vessel; - a first leaktight internal conduit extending parallel to the longitudinal axis at least in the distal part and opening out, on the one hand, at the proximal end or at an intermediate position between the proximal end and the inflatable balloon, and on the other hand at the distal end in such a way as to permit the insertion of the guide wire into the first conduit and the sliding of the tubular body along the guide wire; - at least one second leaktight internal conduit extending parallel to the longitudinal axis and opening out, on the one hand, at the proximal end, and on the other hand into the balloon, in such a way as to connect the proximal end of the tubular body in a leaktight manner with the inflatable balloon and to permit the injection of a fluid into the balloon; - one or more injection orifice (s) situated in the distal part and including at least one downstream injection orifice situated downstream from the balloon and/or at least one upstream injection orifice situated upstream from the balloon; and - a third leaktight internal conduit opening out, on the one hand, at the proximal end and on the other hand into the one or more injection orifice(s) in such a way as to permit the injection of a contrast agent through the one or more injection orifice(s) when the guide wire is in the first conduit and the inflatable balloon is deflated, with the third conduit not opening on the first conduit. - a guide wire to be inserted into a blood vessel, - a flexible tubular body extending along a longitudinal axis between a proximal end and a distal end and having a proximal part, which includes the proximal end, and a distal part which includes the distal end, with the tubular body comprising: - an inflatable balloon arranged radially about the tubular body in the distal part and capable of being inflated to increase the internal diameter of the blood vessel; - a first leaktight internal conduit extending parallel to the longitudinal axis at least in the distal part and opening out, on the one hand, at the proximal end or at an intermediate position between the proximal end and the inflatable balloon, and on the other hand at the distal end in such a way as to permit the insertion of the guide wire into the first conduit and the sliding of the tubular body along the guide wire; - at least one second leaktight internal conduit extending parallel to the longitudinal axis and opening out, on the one hand, at the proximal end, and on the other hand into the balloon, in such a way as to connect the proximal end of the tubular body in a leaktight manner with the inflatable balloon and to permit the injection of a fluid into the balloon; - one or more injection orifice (s) situated in the distal part and including at least one downstream injection orifice situated downstream from the balloon and/or at least one upstream injection orifice situated upstream from the balloon; and - a third leaktight internal conduit opening out, on the one hand, at the proximal end and on the other hand into the one or more injection orifice(s) in such a way as to permit the injection of a contrast agent through the one or more injection orifice(s) when the guide wire is in the first conduit and the inflatable balloon is deflated, with the third conduit not opening on the first conduit. - an inflatable balloon arranged radially about the tubular body in the distal part and capable of being inflated to increase the internal diameter of the blood vessel; - a first leaktight internal conduit extending parallel to the longitudinal axis at least in the distal part and opening out, on the one hand, at the proximal end or at an intermediate position between the proximal end and the inflatable balloon, and on the other hand at the distal end in such a way as to permit the insertion of the guide wire into the first conduit and the sliding of the tubular body along the guide wire; - at least one second leaktight internal conduit extending parallel to the longitudinal axis and opening out, on the one hand, at the proximal end, and on the other hand into the balloon, in such a way as to connect the proximal end of the tubular body in a leaktight manner with the inflatable balloon and to permit the injection of a fluid into the balloon; - one or more injection orifice (s) situated in the distal part and including at least one downstream injection orifice situated downstream from the balloon and/or at least one upstream injection orifice situated upstream from the balloon; and - a third leaktight internal conduit opening out, on the one hand, at the proximal end and on the other hand into the one or more injection orifice(s) in such a way as to permit the injection of a contrast agent through the one or more injection orifice(s) when the guide wire is in the first conduit and the inflatable balloon is deflated, with the third conduit not opening on the first conduit.