Transmitting acoustic and electromagnetic signals from a catheter balloon

1 . A system, comprising: a processor; and a catheter, comprising:

at least a first transducer;

at least a first balloon, the first transducer located in an interior of the first balloon, the processor configured to operate the first transducer at an operational frequency, wherein:

the first transducer transmits an acoustic signal that provides a first acoustic field with multiple lobes along a longitudinal axis of the first transducer,

each of the lobes has a spatial intensity maximum in a spatial intensity distribution of the first acoustic field,

the spatial intensity distribution being at a surface of the first balloon and parallel to a surface of the first transducer,

the spatial intensity distribution of the first acoustic field having one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the first transducer is 50% or less of a value of one of the spatial intensity maxima of the first transducer,

each of the reduced spatial acoustic intensity locations being between the spatial intensity maxima for lobes that are adjacent to one another along the longitudinal axis of the first transducer, and

each of the reduced spatial acoustic intensity locations being on the surface of the first balloon between the spatial intensity maxima that are adjacent to one another along the longitudinal axis of the first transducer; and

at least a first electrode configured to transmit an electromagnetic signal, the first electrode being positioned on the first balloon over one of the reduced spatial acoustic intensity locations of the first transducer.

2 . The system of claim 1 , wherein the operational frequency of the first transducer is greater than or equal to 1 MHz and less than or equal to 20 MHz.

3 . The system of claim 1 , wherein the catheter further comprises:

at least a second and third electrode on the first balloon, the second and third electrodes comprising outer electrodes positioned such that the first transducer is between the second and third electrodes along the longitudinal axis of the first transducer.

4 . The system of claim 1 , wherein the catheter further comprises at least a second electrode on the first balloon, the second electrode comprising an outer electrode positioned such that a line that is perpendicular to the longitudinal axis of the first transducer can extend through the second electrode without extending through the first transducer.

5 . The system of claim 1 , wherein the catheter further comprises a flex-circuit on the balloon, wherein the first electrode is positioned on the flex-circuit.

6 . The system of claim 1 , wherein the first electrode is a segregated, ring, or mesh electrode surrounding the circumference of the balloon.

7 . The system of claim 1 , wherein the first electrode is positioned at a location that is over one of a spatial intensity minima of the acoustic field of the first transducer.

8 . The system of claim 1 , wherein the catheter further comprises:

at least a second transducer located in the interior of the first balloon, the second transducer configured to transmit a second acoustic signal that provides a second acoustic field; and

at least a second electrode, the second electrode being positioned on the first balloon between the first and second transducers at a location outside the acoustic fields of the first and second transducers.

9 . The system of claim 8 , wherein the processor is configured to operate each of the first and second transducers at an operational frequency where each of the first and second transducers transmit their respective acoustic signal that provides a single lobe of acoustic energy,

the operational frequency of the first and second transducers being greater than or equal to 1 MHz and less than or equal to 60 MHz.

10 . The system of claim 8 , wherein the processor is configured to operate the first and second transducers configured to operate at different operational frequencies.

11 . The system of claim 8 , wherein the processor is configured to operate the first transducer at an operational frequency of greater than or equal to 6 MHz and less than or equal to 20 MHz, and wherein the processor is configured to operate the second transducer is configured to operate at an operational frequency of greater than or equal to 20 MHz and less than or equal to 60 MHz.

12 . The system of claim 1 , wherein the catheter further comprises:

a backing member; and

at least a second transducer located in the interior of the first balloon, the second transducer configured to transmit a second acoustic signal, wherein the first and second transducers surround the backing member, and wherein the backing member has an enhanced flexibility region located between the first and second transducers.

13 . The system of claim 12 , wherein the enhanced flexibility region spirals around the backing member.

14 . The system of claim 12 , wherein the enhanced flexibility region is an opening that extends through a wall of the backing member.

15 . The system of claim 12 , wherein the first and second transducers are separated by enough distance that transmission of the acoustic signals from the first and second transducers to a treatment site forms lesions in the treatment site that are spaced apart from one another.

16 . The system of claim 12 , wherein the processor is configured to operate each of the first and second transducers at an operational frequency where each of the first and second transducers transmit their respective acoustic signal that provides a single lobe of acoustic energy,

the operational frequency of the first and second transducers being greater than or equal to 1 MHz and less than or equal to 60 MHz.

17 . The system of claim 12 , wherein the processor is configured to operate the first and second transducers at different operational frequencies.

18 . The system of claim 12 , wherein the processor is configured to operate the first transducer at an operational frequency of greater than or equal to 6 MHz and less than or equal to 20 MHz, and wherein the processor is configured to operate the second transducer at an operational frequency of greater than or equal to 20 MHz and less than or equal to 60 MHz.

19 . The system of claim 1 , wherein the catheter further comprises:

a backing member;

at least a second transducer; and

at least a second balloon, wherein:

the second transducer is located in the interior of the second balloon,

the first and second transducers surround the backing member, and

the backing member has a first enhanced flexibility region located between the first and second transducers.

20 . The system of claim 19 , wherein:

the processor is configured to operate the second transducer at an operational frequency where the second transducer transmits an acoustic signal that provides a second acoustic field with multiple lobes along a longitudinal axis of the second transducer,

each of these lobes has a spatial intensity maximum in a spatial intensity distribution of the second acoustic field,

this spatial intensity distribution is at a surface of the second balloon and parallel to a surface of the second transducer,

the spatial intensity distribution of the second acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the second transducer is 50% or less of a value of one of the spatial intensity maxima of the second transducer, and

each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for lobes that are adjacent to one another along the longitudinal axis of the second transducer,

the catheter further comprising at least a second electrode configured to transmit an electromagnetic signal, the second electrode being positioned on the second balloon at one of the reduced spatial acoustic intensity locations of the second transducer, wherein over least one of the first or second electrodes comprises a cylindrical expandable mesh of wires configured to provide 360° circumferential electrical contact with a vessel wall.

21 . The system of claim 20 , wherein the catheter further comprises:

at least a third balloon, wherein the backing member has a second enhanced flexibility region located between the second and third balloons.

22 . The system of claim 21 , wherein the catheter further comprises at least a third electrode on the third balloon configured to transmit an electromagnetic signal, wherein:

the first balloon is located on the proximal end of the catheter, the third balloon is located on the distal end of the catheter, and the second balloon is located between the first and third balloons,

the first electrode comprises the cylindrical expandable mesh of wires configured to provide 360° circumferential electrical contact with the vessel wall, and

the third electrode comprises an octagonal star.

23 . The system of claim 22 , wherein the catheter further comprises a third transducer located within the third balloon, wherein:

the third transducer is configured to be operated at an operational frequency where the third transducer transmits an acoustic signal that provides a third acoustic field with multiple lobes along a longitudinal axis of the third transducer,

each of these lobes has a spatial intensity maximum in a spatial intensity distribution of the third acoustic field,

this spatial intensity distribution is at a surface of the third balloon and parallel to a surface of the third transducer,

the spatial intensity distribution of the third acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the third transducer is 50% or less of a value of one of the spatial intensity maxima of the third transducer, and

each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for lobes that are adjacent to one another along the longitudinal axis of the third transducer, and

the third electrode is positioned on the third balloon over a reduced spatial acoustic intensity location of the third transducer.

24 . A method of delivering energy to a treatment site, comprising:

advancing a distal end of a catheter to the treatment site within a patient,

the catheter having at least a first transducer located in an interior of a first balloon,

operating the first transducer at an operational frequency where the first transducer transmits an acoustic signal having an acoustic field with multiple lobes along a longitudinal axis of the first transducer,

each of the lobes having a spatial intensity maximum in a spatial intensity distribution of the acoustic field,

the spatial intensity distribution being at a surface of the balloon and parallel to a surface of the first transducer,

the spatial intensity distribution of the first acoustic field having one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the first transducer is 50% or less of a value of one of the spatial intensity maxima of the first transducer,

each of the reduced spatial acoustic intensity locations being between the spatial intensity maxima for lobes that are adjacent to one another along the longitudinal axis of the first transducer, and

each of the reduced spatial acoustic intensity locations being on the surface of the first balloon between the spatial intensity maxima that are adjacent to one another along the longitudinal axis of the first transducer, the catheter further comprising at least a first electrode configured to transmit an electromagnetic signal, the first electrode being positioned on the first balloon over one of the reduced spatial acoustic intensity locations of the first transducer.

25 . The method of claim 24 , wherein the catheter further comprises at least a second balloon proximal the first balloon and a second electrode on the second balloon configured to sense nerve activity, the method further comprising:

using the first electrode to stimulate nerves of a renal artery by transmitting the electromagnetic signal; and

using the second electrode to sense nerve activity of the renal artery.