Patent ID: 7527622

Claim:
A catheter comprising: a proximal end portion and a distal end portion, the proximal end portion defining at least one fluid inlet port and at least one fluid outlet port; a first expandable membrane and a second expandable membrane, the first expandable membrane defining a cooling chamber, the second expandable membrane disposed around the first expandable membrane to define an interstitial space therebetween; a coolant injection lumen in fluid communication with the at least one fluid inlet port and the cooling chamber; a primary coolant return lumen in fluid communication with the at least one fluid outlet port and the cooling chamber, the coolant injection tube, the cooling chamber, and the primary coolant return lumen defining a first fluid pathway; a secondary coolant return lumen in fluid communication with the at least one fluid outlet port and the interstitial space, the interstitial space and the secondary coolant return lumen defining a second fluid pathway, wherein the secondary coolant return lumen is in fluid communication with the primary coolant return lumen at the proximal end portion; and, at least one sensor disposed in the second fluid pathway.