Patent ID: 6551250
Filing Date: 2003-04-22
Classification: A61B

Abstract:
A system for measuring the velocity of blood flowing in a coronary blood vessel, said system comprising:a guidewire adapted for coupling to a conventional device that is used during coronary intervention procedures, said guidewire comprising an elongated guidewire shaft having flexibility, pushability and steerability for use in coronary intervention procedures; at least two temperature sensitive elements each comprising a temperature sensor mounted along a distal segment of said elongated guidewire shaft: said temperature sensors being disposed at equally spaced intervals over said distal segment of said guidewire shaft; means for measuring the velocity of coronary blood flow with said temperature sensors, when said distal segment is positioned within a coronary blood vessel, by detecting in sequence the fluctuating thermal signal produced by changing the thermal energy level of the coronary blood stream as it flows in the vessel; said measuring means comprising: means for changing the thermal energy level of the coronary blood stream by introducing a slow infusion of solution, having a temperature different than the temperature of the blood and being miscible with blood, into the coronary blood vessel, said infusion being introduced upstream at the coronary ostium and being carried downstream to induce a transient temperature difference in the coronary blood stream of a fraction of a degree centigrade, and whereby said temperature difference is interrupted by the phasic oscillations generated by pulsatile blood flow entering from the aorta; and, means for measuring the time interval between said phasic oscillations by detecting in sequence with each one of said thermal sensors the pattern of temperature fluctuation of the blood at different locations in the blood vessel, as it flows in the coronary blood vessel, and for producing a value for said time interval which is indicative of the velocity of the blood flow in the coronary blood vessel.