Methods for estimating post-PCI fractional flow reserve

1. A method for diagnosing and/or treating an intravascular region, the method comprising the steps of:

advancing a pressure sensing device through an ostium of a vessel to a first position beyond a first lesion;

retracting the pressure sensing device to a second position just before the pressure sensing device reaches the first lesion;

retracting the pressure sensing device further to a third position just after the pressure sensing device passes the first lesion;

retracting the pressure sensing device further to a fourth position near the ostium of the vessel;

calculating a first estimated post-treatment fractional flow reserve based on treatment of the first lesion;

treating the first lesion based on the first estimated post-treatment fractional flow reserve,

wherein said step of calculating the first estimated post-treatment fractional flow reserve includes:

measuring a distal pressure (P d ) at the first position,

measuring a distal pressure of the first lesion (P md ) at the second position,

measuring a proximal pressure of the first lesion (P mp ) at the third position, and

measuring an aortic pressure (P a ) at the fourth position so that the first post-treatment estimated fractional flow reserve is calculated to be equal to:

P d /( P a −( P mp −P md )).

2. The method of claim 1 , wherein said step of calculating the first estimated post-treatment fractional flow reserve includes:

determining a first fractional flow reserve (FFR 1 ) at the first position, and

determining a second fractional flow reserve (FFR 2 ) at the second position; and

determining a third fractional flow reserve (FFR 3 ) at the third position; and

so that a third estimated fractional flow reserve is equal to:

FFR 1 /(1−(FFR 3 −FFR 2 )).

3. The method of claim 2 , further comprising the step of calculating a third estimated post-treatment fractional flow reserve based on the first estimated post-treatment fractional flow reserve.

4. The method of claim 1 , further comprising the step of co-registering a location of the pressure sensing device relative to the first lesion with an imaging device.

5. The method of claim 1 , wherein said step of calculating the first estimated post-treatment fractional flow reserve is based on images from an imaging device including an ultrasound imaging device, an X-ray imaging device, an angiographic imaging device, an optical coherence tomography imaging device, or a computerized tomography imaging device.

6. The method of claim 1 , wherein said step of treating the first lesion based on the first estimated post-treatment fractional flow reserve includes grade of collateral flow adjacent to the first lesion.

7. A method for diagnosing and/or treating a medical condition, the method comprising the steps of:

advancing a pressure sensing guidewire through an ostium of a vessel to a first position beyond a plurality of lesions, the pressure sensing guidewire comprising:

an elongate shaft having a distal housing region,

an optical pressure sensor disposed within the distal housing region, and

an optical fiber coupled to the optical pressure sensor and extending proximally therefrom;

retracting the pressure sensing guidewire over the lesions;

retracting the pressure sensing guidewire to a second position near the ostium of the vessel;

calculating an estimated fractional flow reserve value; and

treating at least one of the lesions based on the estimated fractional flow reserve value,

wherein said step of calculating the estimated fractional flow reserve value includes:

measuring a distal pressure distal (P d ) at the first position,

measuring an aortic pressure (P a ) at the second position,

measuring a pressure gradient (P g ) across at least two of the lesions so that the estimated fractional flow reserve is calculated to be equal to:

P d /( P a −(∫ Pg )).

8. The method of claim 7 , further comprising the step of co-registering a location of the pressure sensing guidewire with an imaging device.

9. The method of claim 7 , wherein said lesions includes a first lesion, a second lesion disposed proximal of the first lesion, and a third lesion disposed proximal of the second lesion.