Pressure sensing guidewire and methods for calculating fractional flow reserve
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.
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.
2. 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.
3. The method of claim 1 , wherein measuring a second pressure includes measuring an aortic pressure.
4. The method of claim 3 , wherein measuring an aortic pressure includes measuring the aortic pressure with a pressure sensing catheter.
5. 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.
6. 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.
7. The method of claim 1 , further comprising displaying the drift-compensated fraction flow reserve on a display unit.
8. The method of claim 1 , wherein the pressure sensing guidewire includes an optical pressure sensor.
9. The method of claim 1 , wherein the pressure sensing guidewire includes a piezoelectric pressure sensor.
10. 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.
11. The method of claim 10 , wherein the distal shaft portion has a variable inner diameter.
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.
13. 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.
14. The method of claim 13 , wherein the pressure sensing medical device includes a catheter.
15. The method of claim 12 , further comprising displaying the drift-compensated fraction flow reserve on a display unit.
16. The method of claim 12 , wherein the pressure sensing guidewire includes an optical pressure sensor.
17. The method of claim 16 , wherein the distal shaft portion has a variable inner diameter.
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.