Microcatheter system

A microcatheter system comprising:

• a microcatheter having a distal end and a proximal end, a passage, a plurality of zones and a first probe, wherein an internal diameter of the passage is constant throughout, and wherein each zone having an outside diameter constant across the respective zone that is progressively greater than an immediately adjacent and more distal zone;
• wherein the proximal end of said microcatheter is configured as the first probe connecting to a first receptacle a first microcatheter extension or a microcatheter hub to said microcatheter, and wherein an outside diameter of the first probe is constant and less than an internal diameter of the first receptacle;
• and
• said first microcatheter extension having a distal end and a proximal end, a second passage, a first portion and the first receptacle, wherein an internal diameter of the second passage is constant throughout, and wherein an outside diameter of the first portion is constant throughout, and wherein the distal end of said first microcatheter extension is configured as the first receptacle to receive the first probe of the proximal end of said microcatheter, and wherein an outside diameter of the first receptacle is no greater than a largest diameter of the zones in the plurality of zones,
• wherein the internal diameter of the passage of said microcatheter is the same as the internal diameter of the second passage of said first microcatheter extension, and
• wherein an outside diameter of the first portion of said first microcatheter extension is the same as the outside diameter of the largest diameter of the zones in the plurality of zones.

A microcatheter assembly comprising:

• a microcatheter body having an external surface, an internal passage, a distal end, and a proximal end;
• the microcatheter body divided into a plurality of zones, wherein the external surface of each of the zones has an outer diameter that is progressively greater than an immediately adjacent and distal zone and the respective outer diameter is substantially constant across each zone;
• an extension body having a second external surface, a second internal passage, a distal end, and a proximal end, the second external surface at the distal end having an outer diameter equal to the largest outer diameter of the microcatheter body;
• a connection assembly comprising a probe received within a receptacle, the probe having an external surface with an outer diameter in contact with an internal surface of the receptacle, the connection assembly having an outer diameter equal to the largest outer diameter of the microcatheter body;
• wherein the probe includes a third internal passage and wherein the probe is integral with one of the microcatheter body and the extension body and the receptacle is integral with the other of the microcatheter body and the extension body;
• the connection assembly positioned at the proximal end of the microcatheter body and the distal end of the extension body and the internal passage, second internal passage and third internal passage define a continuous constant diameter passage between the distal end of the microcatheter body and the proximal end of the extension body.