Method and apparatus for injecting and for controlling the pressure of fluid being injected into a catheter

A pressure sensing device for use with a surgical apparatus for dilating a vessel, the apparatus comprising an inflatable catheter insertable into a vessel to be dilated, a fluid for inflating the catheter, and a syringe connected to the catheter for forcing the fluid into the catheter, the syringe having a barrel containing the fluid and a piston movable in the barrel to force the fluid into the catheter to thereby increase fluid pressure and inflate the catheter, said pressure sensing device comprising:

• a housing having a longitudinally-extending passageway;
• an open ended sliding cylinder mounted in said passageway for reciprocating movement with respect to said housing, said cylinder receiving said syringe barrel therein, said barrel having a delivery end connected to said catheter, and said cylinder or said barrel having means so that said cylinder is movable by said barrel;
• means for sensing and for generating a signal representative of movement of said cylinder;
• and
• gauge means for displaying said signal, the relationship between said syringe barrel and said cylinder being such that movement of said syringe piston towards said delivery end results in proportional movement of said syringe barrel and said cylinder whereby the amount of movement of said cylinder is representative of changes in the fluid pressure in the catheter.

An angioplasty injector for dilating a tubular body member comprising:

• an inflatable catheter insertable into a body member to be dilated;
• a syringe having a barrel containing fluid for inflating the catheter and a syringe piston for controlling the forcing of fluid into the catheter;
• a housing having a first passageway formed therein;
• an annular member at least partially disposed within said first passageway, said annular member being supported for movement with respect to said housing and receiving therein the syringe barrel;
• locking means connected to said housing for releasably holding said syringe barrel in said annular member;
• a reservoir defined within said housing and at least partially encompassing said annular member in such manner that movement of said annular member results in pressure changes within said reservoir;
• gauge means for displaying the pressure within said reservoir, said pressure being representative of the pressure of fluid in the syringe barrel;
• means for defining a second passageway extending parallel to said first passageway;
• a threaded member guided for movement in said second passageway;
• engagement means for engaging said threaded member so that rotation of said threaded member translates said threaded member with respect to said housing;
• and
• means for interconnecting said threaded member and said syringe piston for conjoint movement so that rotation of said threaded member controls translation of said syringe piston.

A pressure sensing device for measuring the pressure in a closed system comprising:

• a first housing having a wall defining a first passageway extending through said first housing;
• a stepped hollow sliding cylinder positioned at least in part in said first passageway;
• said cylinder having an enlarged exterior diameter proximal portion guided for sliding movement by the wall of said first housing defining said first passageway and a reduced exterior diameter distal portion spaced from said first passageway defining wall to define an annular space therebetween, said first passageway defining wall having a portion at the distal end of said first passageway projecting inwardly towards said cylinder;
• means for defining a reservoir within said housing comprising said annular space, a bore extending from said annular space to an exterior surface of said first housing, first seal means positioned adjacent said inwardly projecting portion of said first housing wall for slidably sealingly engaging said distal portion of said cylinder, second seal means positioned adjacent said proximal end of said cylinder and carried by said distal portion of said cylinder for slidably sealingly engaging said first passageway defining wall;
• and
• gauge means connected to said bore for measuring and displaying pressure of a fluid contained within said reservoir, said cylinder being movable with respect to said first housing to thereby vary pressure within said reservoir.

An injector for use in an angioplasty procedure, the injector controlling the rate and pressure of fluid injection in the angioplasty procedure and comprising:

• housing means for defining first and second parallel passageways, the first passageway receiving a barrel of a syringe used in the angioplasty procedure, the syringe having a syringe piston disposed therein for controlling the rate and pressure of injection of fluid contained in the barrel;
• a threaded member guided for movement in said second passageway;
• engagement means carried by said housing means for engaging said threaded member so that rotation of said threaded member translates said threaded member with respect to said second passageway;
• and
• means for interconnecting said threaded member and the piston for conjoint movement in a first direction to increase pressure and in a direction opposite the first direction to decrease pressure in the fluid used in the angioplasty procedure, said means for interconnecting preventing independent movement of one of said piston and said threaded member with respect to the other.