Cryosurgical System with Low Pressure Cryogenic Fluid Supply

Abstract

A liquid cryogen fluid system for providing cryogenic liquid to a cryoprobe in a cryosurgical system for treating fibroadenomas and other lesions in the body. The system includes a cryoprobe to cryoablate a fibroadenoma with a treatment regimen that takes less time and consumes less cryogen than currently accepted regimens.

1 . A cryosurgical system comprising:
 a cryoprobe;   a cryogen source comprising a reservoir of cryogenic liquid, said reservoir comprising a volume of cryogenic liquid and volume of pressurized gas;   a supply tube connecting the cryoprobe with the reservoir;   a pressure pump for pumping pressurized gas into the reservoir;   a fluid pathway communicating from the volume of pressurized gas to atmosphere, and a valve disposed in said fluid pathway;   a control system operable to control the pressure pump to pump gas into the reservoir, and operate the valve upon a system fault or system shutdown to open the value and vent the pressurized gas in the reservoir to the atmosphere.   
     
     
         2 . A cryosurgical system of  claim 1  further comprising:
 a second fluid pathway communicating from the volume of pressurized gas to atmosphere, and a second valve disposed in said fluid pathway, said second fluid pathway being large enough to vent the pressure in the reservoir within a short time from 1 to 5 seconds. 
 
     
     
         3 . An apparatus for supplying liquid cryogen, wherein the flow rate of the liquid cryogen is controlled by controlling the pressure of propellant gas acting directly or indirectly on the liquid cryogen, said apparatus comprising:
 a liquid cryogen reservoir chamber, and means for controlling said pressure of propellant gas acting on the liquid cryogen in the chamber to drive the liquid from the chamber at a desired flow rate;   wherein the means for controlling the propellant gas pressure comprises a source of pressurized propellant gas, and an electromechanically operated valve coupled between the liquid cryogen reservoir chamber and atmosphere, said electromechanically operated valve being operable to control the pressure remaining in the cryogen reservoir chamber, without controlling the pressure supplied to the cryogen reservoir chamber; and   a control system for controlling the electromechanically operated valve to vary the pressure in the reservoir, the control system programmed to operate the electromechanically operated valve to bleed pressure from the reservoir as necessary to maintain the pressure in the reservoir within the predetermined range or about a predetermined set point.   
     
     
         4 - 6 . (canceled)