Intravascular sensing method and system

Abstract

Methods and systems for calculating a corrected Fractional Flow Reserve. Methods include delivering a pressure sensing device including a pressure sensor to a location in an artery having a stenosis, positioning the pressure sensor distal to the stenosis, measuring the distal pressure, measuring the proximal pressure, and calculating a corrected Fractional Flow Reserve using the measured proximal and distal pressures and applying a correction factor or correction equation. The correction factor or correction equation corrects for changes in the measured distal pressure caused by a presence of the pressure sensing device. A data set of correction factors or correction equations may be stored in a memory component of the system. The corrected Fractional Flow reserve may approximate the Fractional Flow Reserve that would be obtained if a different sized device was used to measure the distal pressure, such as a pressure sensing guidewire having a 0.014 inch outer diameter.

1 . A method of calculating a corrected Fractional Flow Reserve comprising:
 delivering a pressure sensing device to a location in an artery, the pressure sensing device comprising a pressure sensor, and the location having a stenosis;   positioning the pressure sensor distal to the stenosis;   measuring a pressure distal to the stenosis while the pressure sensor is positioned distal to the stenosis;   measuring a pressure proximal to the stenosis; and   calculating a corrected Fractional Flow Reserve using the measured proximal and distal pressures and applying a correction factor or correction equation;   wherein the correction factor or correction equation corrects for changes in the measured distal pressure caused by a presence of the pressure sensing device.   
     
     
         2 . The method of  claim 1  further comprising selecting the correction factor or correction equation from a group of at least two correction factors or correction equations, wherein the selection of the correction factor or correction equation is determined by a maximum cross-sectional area of a portion of the pressure sensing device crossing the stenosis during the step of measuring the distal pressure or by a type of the pressure sensing device. 
     
     
         3 . The method of  claim 2  wherein the selection of the correction factor or correction equation is further determined by one or more of a size of the stenosis, a size of a lumen of the artery, and a rate of blood flow. 
     
     
         4 . The method of  claim 3  wherein the pressure sensing device further comprises one or more sensors configured to measure the size of the stenosis, the size of the lumen, and/or the rate of blood flow. 
     
     
         5 . The method of  claim 1  wherein the corrected Fractional Flow Reserve approximates a Fractional Flow Reserve that would have been obtained if the distal pressure was measured using a different device having a different maximum cross-sectional area in a portion of the different device that would cross the stenosis while the different device measured the distal pressure. 
     
     
         6 . The method of  claim 5  wherein the different device is a pressure sensing guidewire. 
     
     
         7 . The method of  claim 5  wherein the portion of the different device that would cross the stenosis has a maximum diameter of about 0.014 inches. 
     
     
         8 . The method of  claim 1  wherein the corrected Fractional Flow Reserve approximates a Fractional Flow Reserve that would have been obtained if the distal pressure was measured without any device crossing the stenosis. 
     
     
         9 . The method of  claim 1  further comprising providing a visual display of the corrected Fractional Flow Reserve. 
     
     
         10 . The method of  claim 1  wherein calculating a corrected Fractional Flow Reserve comprises multiplying the measured distal pressure by a correction factor to calculate a corrected distal pressure and calculating the corrected Fractional Flow Reserve using the corrected distal pressure. 
     
     
         11 . The method of  claim 1  wherein calculating a corrected Fractional Flow Reserve comprises calculating a calculated Fractional Flow Reserve using the measured proximal and distal pressures and applying a correction equation to the calculated Fractional Flow Reserve to obtain a corrected Fractional Flow Reserve. 
     
     
         12 . A method of calculating a corrected Fractional Flow Reserve comprising:
 delivering a pressure sensing device to a location in an artery, the location having a stenosis;   positioning the pressure sensing device distal to the stenosis;   measuring a pressure distal to the stenosis while the pressure sensing device is positioned distal to the stenosis;   measuring a pressure proximal to the stenosis;   selecting a correction factor or correction equation, wherein the selection of the correction factor or correction equation is determined by the maximum cross-sectional area of a portion of the pressure sensing device crossing the stenosis during the step of measuring the distal pressure; and   calculating a corrected Fractional Flow Reserve using the measured proximal and distal pressures and applying the correction factor or correction equation;   wherein the corrected Fractional Flow Reserve approximates a Fractional Flow Reserve that would have been obtained if the distal pressure was measured using a different device having a different maximum cross-sectional area in a portion of the different device crossing the stenosis while measuring the distal pressure or if no device was present crossing the stenosis while measuring the distal pressure.   
     
     
         13 . The method of  claim 12  wherein the pressure sensing device further comprises one or more sensors configured to measure a size of the stenosis, a size of the lumen, and/or a rate of blood flow. 
     
     
         14 . The method of  claim 13  wherein the selection of the correction factor or correction equation is further determined by one or more of the size of the stenosis, the size of a lumen of the artery, and/or the rate of blood flow. 
     
     
         15 . The method of  claim 12  wherein the different device is a pressure sensing guidewire. 
     
     
         16 . The method of  claim 12  wherein the different device has an outer diameter of about 0.014 inches. 
     
     
         17 . The method of  claim 12  wherein the corrected Fractional Flow Reserve approximates a Fractional Flow Reserve that would have been obtained if the distal pressure was measured with no device present crossing the stenosis. 
     
     
         18 . A system for calculating a corrected Fractional Flow Reserve associated with a stenosis in an artery comprising:
 a pressure sensing device configured for placement within an artery to measure pressure distal to a lesion;   a processing device in communication with the pressure sensing device; and   a data set comprising a group of at least two correction factors or correction equations, each correction factor or correction equation corresponding to a maximum cross-sectional area of a portion of a standard pressure sensing device that crosses a stenosis when measuring a pressure distal to the stenosis or to an identity of a standard pressure sensing device, wherein the data set is stored within a memory component of the processing device or within a memory component accessible by the processing device;   wherein the processing device is configured to select a correction factor or correction equation based upon a maximum cross-sectional area of a portion of the pressure sensing device of the system which crosses a stenosis when measuring a pressure distal to the stenosis or based on an identity of the pressure sensing device of the system;   wherein the processing device is further configured to calculate a corrected Fractional Flow Reserve using the selected correction factor or correction equation and pressure data received from the pressure sensing device.   
     
     
         19 . The system of  claim 18  wherein the corrected Fractional Flow Reserve approximates a Fractional Flow Reserve that would have been obtained if the pressure data was obtained using a different device having a portion with a different maximum cross-sectional area crossing the stenosis or with no device positioned within the stenosis while measuring the distal pressure. 
     
     
         20 . The system of  claim 19  wherein the corrected Fractional Flow Reserve approximates a Fractional Flow Reserve that would have been obtained if the pressure data was obtained using a different device, wherein the different device has a maximum outer diameter of about 0.014 inches in a portion of the different device that would cross the stenosis while the different device measured the distal pressure.