Method of denervating pulmonary artery

2:

• The method of claim 1, further comprising;
• deploying an expandable member against the vessel wall at the treatment zone.

3:

• The method of claim 1, wherein the treatment zone is located distal to a main pulmonary artery of the pulmonary artery tree and proximal to a third branch point of the main pulmonary artery.

4:

• The method of claim 2, wherein the expandable member includes a balloon, and wherein deploying the expandable member includes inflating the balloon.

5:

• The method of claim 4, wherein the balloon is compliant and wherein inflating the compliant balloon includes circulating fluid within the compliant balloon.

6:

• The method of claim 5, wherein the catheter includes a catheter shaft having a fluid channel, wherein the compliant balloon is mounted on the catheter shaft and has an interior in fluid communication with the fluid channel and containing the ultrasound transducer, wherein the compliant balloon includes a balloon wall having a working section radially surrounding the ultrasound transducer, and wherein the working section has a predetermined straightness when the working section has a first diameter and when the working section has a second diameter that is at least 2 mm greater than the first diameter.

8:

• The method of claim 7, wherein identifying the treatment zone is based on a vessel diameter.

9:

• The method of claim 8, wherein the treatment zone is selected such that it is located where a vessel diameter is less than a deployment diameter of the expandable member.

10:

• The method of claim 9, wherein the deployment diameter is 13 mm or less.

11:

• The method of claim 9, wherein the deployment diameter is 11 mm or less.

12:

• The method of claim 1, wherein advancing the catheter includes floating an expandable member downstream in the pulmonary artery tree to the treatment zone.

13:

• The method of claim 1, wherein the treatment zone is located distal to a main pulmonary artery of the pulmonary artery tree and proximal to a second branch point of the main pulmonary artery.

14:

• The method of claim 1, wherein the treatment zone is located distal to a second branch point of the main pulmonary artery and proximal to a third branch point of the main pulmonary artery.

15:

• The method of claim 13, wherein the catheter does not comprise a balloon.