| 摘要 |
A method and apparatus for using a secondary refrigerant (14) to precool and liquefy a primary refrigerant (12), then vaporizing and expanding the primar y refrigerant to cool a cold tip (20) of a cryosurgical instrument for ablatio n of biological tissue, such as cardiovascular tissue, in particular endocardi ac tissue and tissue inside a cardiac blood vessel. The secondary refrigerant (14) has a critical temperature above the critical temperature of the primar y refrigerant (12), and a cooling temperature below the critical temperature o f the primary refrigerant, thereby facilitating the use of of the precooling step to provide liquid primary refrigerant in an operating room environment in which the primary refrigerant could not otherwise be provided in the liquid phase.
|
