Methods for measuring cross-sectional areas and pressure gradients in luminal organs

1. A method for measuring the cross-sectional area of a targeted treatment site, comprising:

introducing an impedance device into a treatment site, the impedance device selected from the group consisting of an impedance catheter and an impedance wire;

providing electrical current flow to the treatment site through the device;

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 device, the first conductance value indicative of a bolus of the first solution;

injecting a second solution of a second compound having a second conductivity into the treatment site, wherein the second conductivity does not equal the first conductivity;

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

calculating the cross-sectional area of the treatment site based on the first and second conductance values, the conductivities of the first and second solutions, and a known distance between two detection electrodes of the impedance device.

2. The method of claim 1 , wherein the treatment site comprises a body lumen.

3. The method of claim 2 , wherein the body lumen comprises a blood vessel.

4. The method of claim 2 , wherein the body lumen comprises a biliary tract.

5. The method of claim 2 , wherein the body lumen comprises an esophagus.

6. The method of claim 5 , wherein the step of injecting a first solution of a first compound comprises the step of administering said first solution to a patient orally.

7. The method of claim 5 , wherein the step of injecting a second solution of a second compound comprises the step of administering said second solution to a patient orally.

8. The method of claim 1 , wherein the first compound is NaCl.

9. The method of claim 1 , wherein the second compound is NaCl.

10. The method of claim 1 , wherein the impedance device comprises the impedance catheter comprising an inflatable balloon along the longitudinal axis of the catheter.

11. The method of claim 10 , further comprising the step of inflating the balloon to breakup materials causing stenosis at the treatment site.

12. The method of claim 10 , wherein the impedance catheter further comprises a stent located over the balloon, said stent capable of being distended to the desired lumen size and implanted into the treatment site.

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

distending the stent by inflating the underlying balloon; and

releasing and implanting the stent into the treatment site.

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

selecting an appropriately-sized stent based on the cross-sectional area value of the treatment site; and

implanting the stent into the treatment site.

15. The method of claim 1 , wherein the device further comprises a pressure transducer.

16. The method of claim 15 , further comprising the steps of:

measuring a first pressure gradient value from the pressure transducer near the treatment site; and

calculating the cross-sectional area of the treatment site based in part on the first pressure gradient value.

17. The method of claim 1 , wherein the step of injecting the first solution further includes injecting the first solution local to the treatment site.

18. The method of claim 1 , wherein the step of injecting the second solution further includes injecting the second solution local to the treatment site.

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

20. The method of claim 1 , wherein the step of injecting the second solution temporarily substantially displaces the blood at the treatment site.

21. The method of claim 1 , further comprising the step of heating the first solution to body temperature prior to injection.

22. The method of claim 1 , further comprising the step of heating the first solution and the second solution to a common temperature prior to injection.

23. The method of claim 1 , further comprising the step of calculating a first nodal voltage and a first electrical field based on the first conductance and the first current density.

24. The method of claim 23 , further comprising the steps of:

applying finite element analysis to the first nodal voltage and first electrical field values;

determining appropriate device dimensions for minimizing nonparallel electrical field lines at the treatment site; and

selecting an appropriately-sized second device for introduction into the treatment site.

25. The method of claim 24 , wherein the step of finite element analysis is performed using a finite element software package.

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

selecting a second device to be introduced into the treatment site based on the first conductance value and a first current density at the treatment site.

27. The method of claim 26 , wherein the second device is a balloon catheter.

28. A method for measuring the cross-sectional area of a targeted treatment site, comprising:

introducing an impedance catheter into a treatment site;

providing electrical current flow to the treatment site through the catheter;

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

measuring a first conductance value at the treatment site using the catheter;

injecting a second solution having a second conductivity into the treatment site, wherein the second conductivity does not equal the first conductivity;

measuring a second conductance value at the treatment site using the catheter;

calculating the cross-sectional area of the treatment site based on the first and second conductance values, the conductivities of the first and second solutions, and a known distance between two detection electrodes of the impedance catheter;

selecting an appropriately-sized stent based on the cross-sectional area value of the treatment site;

positioning the stent around a balloon attached to the catheter;

introducing the catheter with the stent positioned thereon into the treatment site;

inflating the balloon with a fluid to implant the stent into the treatment site;

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

measuring the conductance of the fluid inside the balloon; and

calculating the cross-sectional area of the balloon lumen.

29. A method for measuring the cross-sectional area of a blood vessel and implanting a stent therein, comprising:

introducing an impedance device into a blood vessel, the impedance device selected from the group consisting of an impedance catheter and an impedance wire;

providing electrical current flow through the device within the blood vessel;

injecting a first solution of a first compound having a first conductivity into the blood vessel;

measuring a first conductance value within the blood vessel at or near the site of injection of the first solution using the device, the first conductance value indicative of a bolus of the first solution;

injecting a second solution of a second compound having a second conductivity into the blood vessel, wherein the second conductivity does not equal the first conductivity;

measuring a second conductance value within the blood vessel at or near the site of the injection of the second solution using the device, the second conductance value indicative of a bolus of the second solution;

calculating the cross-sectional area of the blood vessel based on the first and second conductance values, the conductivities of the first and second solutions, and a known distance between two detection electrodes of the impedance device;

selecting an selecting an appropriately-sized stent based on the cross-sectional area of the blood vessel; and

implanting the stent into the blood vessel.