# US 9,775,523 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 9,775,523 B2 - Document ID: US9775523B2 - Status: Granted - Kind: B2 - Application number: 14/511,931 - Filed: 2014-10-10 - Published: 2015-04-16 - Granted: 2017-10-03 - 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/US9775523B2 ## 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: advancing a pressure sensing guidewire through a body lumen 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 intravascular occlusion; determining a proximal pressure within the body lumen with the pressure sensing guidewire; measuring an aortic pressure; calculating a pressure drift, wherein the pressure drift is the difference between the aortic pressure and the 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. ### Claim 2 (depends on 1) The method of claim 1, further comprising displaying the drift-compensated fraction flow reserve on a display unit. ### Claim 3 (depends on 1) The method of claim 1, further comprising shifting the pressure sensing guidewire back to the first position and determining a second distal pressure within the body lumen with the pressure sensing guidewire. ### Claim 4 (depends on 3) The method of claim 3, further comprising shifting the pressure sensing guidewire back to the second position and determining a second proximal pressure within the body lumen with the pressure sensing guidewire. ### Claim 5 (depends on 4) The method of claim 4, further comprising calculating a second pressure drift, wherein the second pressure drift is the difference between the aortic pressure and the second proximal pressure. ### Claim 6 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes an optical pressure sensor. ### Claim 7 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes a Fabry-Perot pressure sensor. ### Claim 8 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes a piezoelectric pressure sensor. ### Claim 9 (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 10 (depends on 9) The method of claim 9, wherein the distal shaft portion has a variable inner diameter. ### Claim 11 (depends on 1) The method of claim 1, wherein the pressure sensing guidewire includes a pressure sensor and wherein advancing the pressure sensing guidewire through a blood vessel to a first position distal of an intravascular occlusion includes advancing the pressure sensing guidewire through a guide catheter to a location where the pressure sensor is disposed distal of a distal end of the guide catheter. ### Claim 12 (depends on 1) The method of claim 1, wherein measuring an aortic pressure includes measuring the aortic pressure with a second pressure sensing medical device. ### Claim 13 A method for calculating fractional flow reserve, the method comprising: advancing a pressure sensing guidewire through a body lumen of a patient to a first position proximal of an intravascular occlusion; determining a first proximal pressure within the body lumen with the pressure sensing guidewire; measuring an aortic pressure within the patient; equalizing the first proximal pressure with the aortic pressure; advancing the pressure sensing guidewire to a distal position that is distal of the intravascular occlusion; determining a distal pressure within the body lumen with the pressure sensing guidewire; proximally shifting the pressure sensing guidewire to the first position; determining a second proximal pressure within the body lumen 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 14 (depends on 13) The method of claim 13, wherein measuring an aortic pressure within the patient includes measuring the aortic pressure with a pressure sensing medical device inserted within the patient. ### Claim 15 (depends on 13) The method of claim 13, further comprising displaying the drift-compensated fraction flow reserve on a display unit. ### Claim 16 (depends on 13) The method of claim 13, wherein the pressure sensing guidewire includes an optical pressure sensor. ### Claim 17 (depends on 13) The method of claim 13, wherein the pressure sensing guidewire includes a Fabry-Perot pressure sensor. ### Claim 18 (depends on 13) The method of claim 13, 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.