Methods and devices for delivering refrigerant to cryo catheter
Publication Date: 2007-Aug-31
The IP.com Prior Art Database
Present methods of delivering refrigerant to a cryoablation catheter have two strategies available to them: deliver the liquid refrigerant at high pressure at ambient temperature, or refrigerate it first and deliver it at a lower pressure. The latter is difficult to achieve because of the need for effective counter current heat transfer within the extension hose assembly and catheter. Present methods of pressurizing the refrigerant include heating the tank to elevate its temperature and thus increase its vapor pressure. The method is efficient of energy and of refrigerant, if all the refrigerant is to be used. However, if the tank has enough refrigerant for many uses, this requires extra energy to heat the unused refrigerant as well, and then leaves the tank at an elevated temperature and pressure. The large amount of refrigerant at elevated temperature increases the level of hazard should there be a leak in the system. The present invention aims to remedy these problems. This invention isolates the proper quantity of refrigerant and then pressurizes it to a controlled pressure for delivery into the catheter system. Three methods are described: (1) use of a separate tank of gas such as air or N2, (2) use of a refrigerant gas powered hydraulic pressure amplifier, and (3) use of an electric motor for hydraulic application of pressure. Each has its advantages, but the latter is preferred.