Sheath for enabling needle exchange and needle-sharp safety

A needle assembly, comprising:

• a sheath comprising a proximal end, a distal end and a lumen extending therebetween;
• a needle disposed within the lumen of the sheath, the needle comprising a proximal end and a sharpened distal end;
• and
• an actuation mechanism disposed along a proximal portion of the needle assembly, the actuation mechanism comprising a housing, a channel formed within a distal portion of the housing, a spring disposed within a chamber of the housing and a push button engaged with a proximal portion of the housing, the push button configured to move from a first position to a second position within the housing,
• wherein a proximal portion of the sheath is immovably disposed within the channel of the housing,
• wherein a proximal portion of the needle extends through the spring,
• wherein the needle moves in a distal direction relative to the sheath when the push button moves distally within the chamber and the needle moves in a proximal direction relative to the sheath when the push button moves proximally within the chamber.

A system, comprising:

• a catheter, comprising:
• a proximal end,
• a distal end,
• a first lumen extending therebetween, and
• a second lumen extending therebetween;
• a needle assembly disposed within the first lumen;
• and
• a radial ultrasound probe disposable within the second lumen;
• wherein the needle assembly includes a needle disposed within a sheath,
• wherein the needle assembly is movable from a first position in which a sharpened distal end of the needle is positioned proximal to a distal end of the sheath and a second position in which the sharpened distal end of the needle is positioned distal to the distal end of the sheath, and
• wherein the needle assembly includes an actuation mechanism disposed along a proximal portion of the needle assembly, the actuation mechanism comprising:
• a housing,
• a channel formed within a distal portion of the housing,
• a spring disposed within a chamber of the housing, and
• a push button disposed at least partially within the chamber of the housing proximal to the spring, the push button configured to repeatedly move along a longitudinal axis of the housing;
• wherein a proximal portion of the sheath is immovably disposed within the channel of the housing;
• wherein a proximal portion of the needle extends through the spring and is configured to contact an inner surface of the push button such that when the push button moves between the first position to the second position the needle moves in a distal direction relative to the sheath and when the push button moves from the second position to the first position the needle moves in a proximal direction relative to the sheath;
• wherein when in the first position the sharpened distal end of the needle is disposed within the sheath.