Methods for measuring cross-sectional areas in luminal organs

1. A method for measuring a cross-sectional area of and a fluid velocity at a targeted treatment site, the method comprising the steps of:

introducing an impedance device into a treatment site, the impedance device comprising an elongated body comprising two detection electrodes positioned in between two excitation electrodes, the impedance device selected from the group consisting of an impedance catheter and an impedance wire;

injecting a first solution of a first compound having a first conductivity into the treatment site;

measuring a first conductance value at the treatment site using the impedance device, the first conductance value indicative of a bolus of the first solution; and, in either order,

a) calculating a cross-sectional area of the treatment site based in part upon the first conductivity of the first solution, the first conductance value, a conductivity of blood, and a known distance between the two detection electrodes of the impedance device; and

b) measuring a velocity of fluid flow through the treatment site using the impedance device;

wherein the treatment site comprises a site selected from the group consisting of a body vessel, a biliary tract, a coronary artery, a carotid artery, a femoral artery, a renal artery, a iliac artery, a cerebral artery, and an aorta.

2. The method of claim 1 , further comprising the steps of:

injecting a second solution of a second compound having a second conductivity into the treatment site; and

measuring a second conductance value at the treatment site using the impedance device, the second conductance value indicative of a bolus of the second solution; and

wherein the calculating step comprises calculating a size parameter of the treatment site based in part upon the first conductance value, the first conductivity of the first solution, the second conductance value, and the second conductivity of the second solution.

3. The method of claim 2 , wherein the first compound and the second compound are the same compound.

4. The method of claim 2 , wherein the first compound and the second compound each comprise saline.

5. The method of claim 2 , wherein the first conductivity does not equal the second conductivity.

6. The method of claim 2 , wherein the size parameter of the treatment site is selected from the group consisting of a cross-sectional area at the treatment site and a diameter at the treatment site.

7. The method of claim 1 , further comprising the step of:

inflating a balloon coupled to the impedance device to breakup materials causing a stenosis at the treatment site.

8. The method of claim 7 , further comprising the step of:

implanting a stent into the treatment site by inflating the balloon.

9. The method of claim 8 , wherein the balloon is inflated using a fluid, and the method further comprising the steps of:

providing electrical current into the fluid filling the balloon at various degrees of balloon distension;

measuring a conductance of the fluid inside the balloon; and

calculating a size parameter of a lumen of the balloon.

10. The method of claim 1 , further comprising the steps of:

measuring a first pressure gradient at the treatment site using a pressure transducer coupled to the impedance device; and

calculating an additional size parameter of the treatment site based in part on the first pressure gradient.

11. The method of claim 1 , wherein the step of injecting the first solution temporarily displaces blood present at the treatment site.

12. The method of claim 1 , further comprising the steps of:

selecting an appropriately-sized stent based on the calculated cross-sectional area; and

implanting the stent into the treatment site.

13. The method of claim 1 , further comprising the step of:

warming the first solution prior to injection.

14. The method of claim 1 , further comprising the step of:

selecting an insertion device to be introduced into the treatment site based upon the calculated cross-sectional area.

15. The method of claim 14 , wherein the insertion device comprises a balloon catheter.