Coiled heat exchanger for cryosurgical instrument

A cryosurgical instrument comprising:

• a shaft having a closed distal end defining an expansion chamber and an open proximal end adapted and configured to receive an inflow of cryogen and to exhaust a flow of expanded cryogen;
• and
• a heat exchanger comprising:
• a solid core element extending along a longitudinal axis of the heat exchanger;
• and
• first and second cryogen delivery tubes, the first cryogen delivery tube including an uncoiled portion extending along the longitudinal axis and a coiled portion that spirals around and contacts the solid core element, the second cryogen delivery tube having a coiled portion that spirals around and contacts the uncoiled portion of the first cryogen delivery tube,
• wherein the coiled portions are spaced apart, and
• wherein the spirals of the cryogen delivery tubes are spaced from each other and in fluid tight contact with an inner surface of the shaft so as to form a spiraling cryogen exhaust pathway from the distal end of the shaft to the proximal end of the shaft.