Micro-Injection Pump

Abstract

A micro-injection pump for angiography and micro-intervention procedures comprises first and second linear traverses each have a pusher element movable by stepper motor drive for controlling discharge from a respective micro-syringe engaged by the pusher element. The first micro-syringe preferably contains a volume of a soluble contrast medium, and the second micro-syringe preferably contains a volume of an insoluble contrast medium. Fluid discharged by the micro-syringes is directed to a bifurcated micro-droplet generator having a straight primary passage and an obliquely merging tributary passage. Insoluble contrast medium from the second micro-syringe flows through a micro-sized injection needle extending partially and coaxially within the primary passage to a termination point just downstream from where the tributary passage joins the primary passage. Soluble contrast medium from the first micro-syringe passes through the tributary passage to provide a flow field surrounding the injection needle for shearing off discrete same-sized boluses from the terminal tip of the injection needle at regular frequency in coordination with a predetermined motion profile of the first and second linear traverses. Motion control of the linear traverses is possible using LABVIEW® virtual instrumentation software arranged to communicate with a 2-axis indexer control connected to first and second motor indexers for driving the stepper motors of the linear traverses. Linear potentiometers on the linear traverses, rotary encoders connected to the motors, a flowmeter, and pressure transducers indicate motion and flow parameters of the system in real-time to provide a feedback loop in the system so that a desired media delivery waveform is realized.

What is claimed is:  
     
         1 . A micro-injection pump comprising: 
 a bifurcated micro-droplet generator including a tributary passage merging with a primary passage, and an injection needle extending within said primary passage to a termination point downstream of a location where said tributary passage merges with said primary passage;    a first syringe in fluid communication with said tributary passage for supplying a first fluid, said first syringe having a plunger;    a second syringe in fluid communication with said injection needle for supplying a second fluid, said second syringe having a plunger;    a first linear traverse operatively connected to said plunger of said first syringe for controllably discharging said first fluid from said first syringe;    a second linear traverse operatively connected to said plunger of said second syringe for controllably discharging said second fluid from said second syringe; and    a catheter arranged downstream of said micro-droplet generator;    whereby said first fluid is used to separate droplets of said second fluid from said injection needle at said termination point and carry said droplets through said catheter.    
     
     
         2 . The micro-injection pump according to  claim 1 , further comprising computer control means connected to said first and second linear traverses for controlling the respective motions of said first and second linear traverses.  
     
     
         3 . The micro-injection pump according to  claim 2 , further comprising at least one sensor associated with said first linear traverse and connected to said computer control means for measuring position, velocity, and acceleration of said first linear traverse, and at least one sensor associated with said second linear traverse and connected to said computer control means for measuring position, velocity, and acceleration of said second linear traverse.  
     
     
         4 . The micro-injection pump according to  claim 3 , wherein said at least one sensor associated with said first linear traverse and said at least one sensor associated with said second linear traverse include a linear potentiometer.  
     
     
         5 . The micro-injection pump according to  claim 3 , wherein said at least one sensor associated with said first linear traverse and said at least one sensor associated with said second linear traverse include a rotary encoder.  
     
     
         6 . The micro-injection pump according to  claim 2 , further comprising a pair of pressure sensors associated one with each of said first and second syringes and connected to said computer control means for measuring fluid pressure in said first and second syringes, respectively.  
     
     
         7 . The micro-injection pump according to  claim 2 , further comprising a pair of flowmeters associated one with each of said first and second syringes and connected to said computer control means for measuring flow rate of said first and second fluids, respectively.  
     
     
         8 . The micro-injection pump according to  claim 2 , wherein said computer control means includes a user interface having a delay control portion for assigning a user-selectable time delay for delaying the start of the motion of said second linear traverse.  
     
     
         9 . A micro-injection pump comprising: 
 a syringe for supplying a fluid, said syringe having a plunger;    a catheter arranged downstream of said syringe and in fluid communication therewith;    a linear traverse operatively connected to said plunger for controllably discharging said fluid from said syringe; and    computer control means connected to said linear traverse for controlling the motion of said linear traverse in accordance with a predetermined flow profile to discharge said fluid from said syringe at varying flow rates during a stroke of said plunger.    
     
     
         10 . The micro-injection pump according to  claim 8 , wherein said predetermined motion profile is selected by a user interfacing with said computer control means.  
     
     
         11 . The micro-injection pump according to  claim 8 , further comprising a flowmeter connected to said computer control means and arranged to measure flow from said syringe, wherein said computer control means includes a proportional plus integral plus derivative (P.I.D.) feedback control loop to ensure said predetermined flow profile is actually followed.  
     
     
         12 . A method of injecting a chosen fluid into the vasculature of a patient comprising the steps of: 
 providing a first syringe and charging said first syringe with a conveying fluid;    providing a second syringe and charging said second syringe with said chosen fluid, said second syringe communicating with an injection needle;    enclosing a discharge tip of said injection needle within a fluid conduit in communication with said first syringe to establish a flow field of said conveying fluid surrounding said discharge tip;    actuating said first and second syringes in a controlled manner to cause discrete boluses of said chosen fluid to be separated from said discharge tip of said injection needle with the aid of said flow field;    providing a catheter in communication with said fluid conduit for carrying said boluses and said conveying fluid into said vasculature.    
     
     
         13 . The method according to  claim 12 , wherein said first and second syringes are actuated such that said boluses are separated from said discharge tip at a regular frequency.  
     
     
         14 . The method according to  claim 12 , wherein said chosen fluid is an insoluble contrast medium.  
     
     
         15 . The method according to  claim 12 , wherein said chosen fluid is a therapeutic fluid.