Angioplasty device comprising: - a guide wire intended 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 including the proximal end and a distal part including the distal end, the tubular body comprising: - an inflatable balloon which is capable of being inflated to increase the internal diameter of the blood vessel and which is disposed radially around the tubular body in the distal part; - a first 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 at the distal end, so as to allow the insertion of the guide wire into the first conduit and the sliding of the tubular body along the guide wire; - a second internal conduit extending parallel to the longitudinal axis opening out on the one hand at the proximal end and on the other hand in the balloon so as to allow the injection of a fluid into the balloon; characterized in that the first internal conduit has a diameter greater than the external diameter of the guide wire in the proximal portion of the tubular body, and a diameter substantially equal to the external diameter of the guide wire in the distal end of the tubular body, the tubular body further comprising one or more injection orifices located in the distal part and opening into the first internal conduit upstream of the first internal conduit portion, the diameter of which is substantially equal to that of the guide wire, so as to allow the injection of a contrast product through the injection orifice(s) when the guide wire is in the first internal conduit. - a guide wire intended 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 including the proximal end and a distal part including the distal end, the tubular body comprising: - an inflatable balloon which is capable of being inflated to increase the internal diameter of the blood vessel and which is disposed radially around the tubular body in the distal part; - a first 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 at the distal end, so as to allow the insertion of the guide wire into the first conduit and the sliding of the tubular body along the guide wire; - a second internal conduit extending parallel to the longitudinal axis opening out on the one hand at the proximal end and on the other hand in the balloon so as to allow the injection of a fluid into the balloon; - an inflatable balloon which is capable of being inflated to increase the internal diameter of the blood vessel and which is disposed radially around the tubular body in the distal part; - a first 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 at the distal end, so as to allow the insertion of the guide wire into the first conduit and the sliding of the tubular body along the guide wire; - a second internal conduit extending parallel to the longitudinal axis opening out on the one hand at the proximal end and on the other hand in the balloon so as to allow the injection of a fluid into the balloon;