Flexible microwave catheters for natural or artificial lumens

1. A method for forming a resonating structure within a body lumen, the method comprising:

advancing a flexible microwave catheter into a body lumen of a patient, the flexible microwave catheter including:

an outer sheath;

a radiating portion disposed within the outer sheath at a distal end of the flexible microwave catheter; and

a centering device proximate the radiating portion in a confined condition within the outer sheath;

positioning the radiating portion near targeted tissue;

distally advancing the centering device relative to the outer sheath while the outer sheath is in a fixed position along a longitudinal axis of the flexible microwave catheter, wherein distally advancing the centering device causes deployment of the centering device radially outward from the confined condition within the outer sheath to an unconfined condition distal the outer sheath within the body lumen, such that the radiating portion is at a radial center of the body lumen and a longitudinal axis of the radiating portion is substantially parallel with and at a fixed distance from a longitudinal axis of the body lumen near the targeted tissue; and

delivering microwave energy to the radiating portion such that a circumferentially balanced resonating structure is formed with the body lumen.

2. The method of claim 1 , wherein the circumferentially balanced resonating structure radiates energy 360 degrees around the longitudinal axis of the radiating portion and along a longitudinal span of about 2 cm to about 3 cm.

3. The method of claim 1 , wherein the body lumen is a renal artery.

4. The method of claim 3 , wherein the targeted tissue is one or more renal nerves and the circumferentially balanced resonating structure generates an electromagnetic field that denervates the targeted tissue.

5. The method of claim 1 , further comprising:

providing a continuous fluid flow within the body lumen; and

cooling at least a portion of the body lumen.

6. The method of claim 5 , further comprising:

monitoring a temperature of the continuous fluid flow; and

terminating delivery of microwave energy if the monitored temperature exceeds a threshold temperature.

7. The method of claim 1 , further comprising:

continuing delivery of microwave energy until a sufficient amount of energy is delivered to effectively damage the targeted tissue while preserving a critical structure of the body lumen.

8. The method of claim 1 , wherein the body lumen is at least one of a gastrointestinal lumen, an auditory lumen, a respiratory system lumen, a urinary system lumen, a female reproductive system lumen, a male reproductive system lumen, a vascular system lumen, or an internal organ.

9. The method of claim 1 , further comprising expanding the body lumen to form a structure related to the microwave frequency.

10. The method of claim 1 , further comprising delivering microwave energy at a frequency that is selected to be resonate with the body lumen.

11. The method of claim 1 , further comprising:

monitoring a temperature within the body lumen; and

terminating delivery of the microwave energy when the monitored temperature exceeds a threshold temperature.

12. The method of claim 1 , wherein the radiating portion includes a feed gap forming an open circuit in the flexible microwave catheter.

13. The method of claim 1 , wherein the radiating portion includes a first feed gap and a second feed gap, and wherein the first and second feed gaps each form open circuits in the flexible microwave catheter.