Patent ID: 7775988

Claim:
A method for determining a blood flow in an individual coronary artery of a patient, comprising at least the following steps: positioning a temperature sensor mounted at a distal portion of a guide wire at a distal position in the coronary artery; positioning an infusion catheter in the coronary artery such that a distal end of the infusion catheter is proximally of the temperature sensor; measuring blood temperature; infusing cold indicator fluid with a known infusion rate and known or measurable temperature into the coronary artery using the infusion catheter; measuring a temperature of a mixture of blood and indicator fluid using the temperature sensor, wherein measuring the temperature of the mixture of blood and indicator fluid using the temperature sensor comprises retracting the temperature sensor towards the distal end of the infusion catheter while measuring the temperature of the mixture of blood and indicator fluid; and calculating the coronary blood flow by a formula including at least the measured blood temperature, the known infusion rate, the known or measurable cold indicator fluid temperature, and the measured mixture temperature.