# US 10,499,817 B2 · Pressure sensing guidewire and methods for calculating fractional flow reserve > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,499,817 B2 - Document ID: US10499817B2 - Status: Granted - Kind: B2 - Application number: 15/720,886 - Filed: 2017-09-29 - Published: 2018-01-25 - Granted: 2019-12-10 - Earliest claimed: 2013-10-14 - Assignees: Boston Scientific Scimed, Inc. - Applicants: Boston Scientific Scimed, Inc. - Inventors: Daniel J. Gregorich - Web page: https://patentgrep.com/patent/US10499817B2 ## CPC - A61B 5/02007: {Evaluating blood vessel condition, e.g. elasticity, compliance} - A61B 5/02154: {by optical transmission} - A61B 5/6851: {Guide wires} - A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)} - A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract Medical devices and methods for making and using medical devices are disclosed. An example method may include a method for calculating fractional flow reserve including providing a pressure sensing guidewire, advancing the pressure sensing guidewire through a blood vessel to a first position distal of an intravascular occlusion, determining a distal pressure within the body lumen with the pressure sensing guidewire, proximally shifting the pressure sensing guidewire to a second position proximal of the occlusion, determining a proximal pressure within the body lumen with the pressure sensing guidewire, measuring an aortic pressure, and calculating a pressure drift. The pressure drift may be the difference between the aortic pressure and the proximal pressure. The method may also include calculating a drift-compensated fractional flow reserve. The drift-compensated fraction flow reserve may correspond to (the distal pressure+the pressure drift) divided by the aortic pressure. ## Claims ### Claim 1 A method for calculating fractional flow reserve, the method comprising: determining a first pressure within a body lumen with a pressure sensing guidewire; measuring a second pressure; normalizing the first pressure with the second pressure; determining a third pressure within the body lumen with the pressure sensing guidewire; determining a fourth pressure within the body lumen with the pressure sensing guidewire; calculating a pressure drift, wherein the pressure drift is the difference between the second pressure and the third pressure; and calculating a drift-compensated fractional flow reserve, wherein the drift-compensated fraction flow reserve corresponds to (the second pressure+the pressure drift) divided by the second pressure. ### Claim 2 (depends on 1) The method of claim 1, wherein determining a first pressure within a body lumen with a pressure sensing guidewire includes determining the first pressure at a location proximal of an intravascular lesion. ### Claim 3 (depends on 1) The method of claim 1, wherein measuring a second pressure includes measuring an aortic pressure. ### Claim 4 (depends on 3) The method of claim 3, wherein measuring an aortic pressure includes measuring the aortic pressure with a pressure sensing catheter. ### Claim 5 (depends on 1) The method of claim 1, wherein determining a third pressure within the body lumen with the pressure sensing guidewire includes determining the third pressure at a location distal of an intravascular lesion. ### Claim 6 (depends on 1) The method of claim 1, wherein determining a fourth pressure within the body lumen with the pressure sensing guidewire includes determining the fourth pressure at a location proximal of an intravascular lesion. ### Claim 7 (depends on 1) The method of claim 1, further comprising displaying the drift-compensated fraction flow reserve on a display unit. ### Claim 8 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes an optical pressure sensor. ### Claim 9 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes a piezoelectric pressure sensor. ### Claim 10 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes a proximal shaft portion and a distal shaft portion, the distal shaft portion having a plurality of slots formed therein. ### Claim 11 (depends on 10) The method of claim 10, wherein the distal shaft portion has a variable inner diameter. ### Claim 12 A method for calculating fractional flow reserve, the method comprising: advancing a pressure sensing guidewire to a first position proximal of an intravascular lesion; determining a first proximal pressure with the pressure sensing guidewire; measuring an aortic pressure; normalizing the first proximal pressure with the aortic pressure; advancing the pressure sensing guidewire to a second position that is distal of the intravascular lesion; determining a distal pressure with the pressure sensing guidewire; shifting the pressure sensing guidewire to the first position; determining a second proximal pressure with the pressure sensing guidewire; calculating a pressure drift, wherein the pressure drift is the difference between the second proximal pressure and the aortic pressure; and calculating drift-compensated fractional flow reserve, wherein the drift-compensated fraction flow reserve corresponds to (the distal pressure+the pressure drift) divided by the aortic pressure. ### Claim 13 (depends on 12) The method of claim 12, wherein measuring an aortic pressure includes measuring the aortic pressure with a pressure sensing medical device inserted within the patient. ### Claim 14 (depends on 13) The method of claim 13, wherein the pressure sensing medical device includes a catheter. ### Claim 15 (depends on 12) The method of claim 12, further comprising displaying the drift-compensated fraction flow reserve on a display unit. ### Claim 16 (depends on 12) The method of claim 12, wherein the pressure sensing guidewire includes an optical pressure sensor. ### Claim 17 (depends on 16) The method of claim 16, wherein the distal shaft portion has a variable inner diameter. ### Claim 18 A method for calculating fractional flow reserve, the method comprising: advancing a pressure sensing guidewire to a first position proximal of an intravascular lesion; determining a proximal pressure at the first position with the pressure sensing guidewire; determining an aortic pressure with a pressure sensing catheter; normalizing the proximal pressure with the aortic pressure; shifting the pressure sensing guidewire to a second position distal of the intravascular lesion; determining a distal pressure within the body lumen at the second position; shifting the pressure sensing guidewire to the first position; determining a second proximal pressure within the body lumen at the first position; calculating a pressure drift, wherein the pressure drift is the difference between the distal pressure and the second proximal pressure; and calculating a drift-compensated fractional flow reserve, wherein the drift-compensated fraction flow reserve corresponds to (the distal pressure+the pressure drift) divided by the aortic pressure.