Ultrasound-based neuromodulation system

An intravascular, ultrasound-based ablation system comprising:

• a catheter comprising a guidewire lumen, at least one cable lumen and at least one fluid lumen;
• a balloon positioned at a distal end of the catheter, an interior of the balloon being in fluid communication with the at least one fluid lumen of the catheter, wherein the balloon is configured to inflate when fluid is delivered into the interior through the at least one fluid lumen of the catheter;
• a tip extending distally from a distal end of the balloon, the tip comprising an internal guidewire passage;
• an ultrasound transducer positioned within the balloon, the ultrasound transducer comprising a cylindrical tube with inner and outer surfaces, each of the inner and outer surfaces comprising an electrode, wherein the ultrasound transducer defines an internal space adjacent the inner electrode surface, the internal space being in fluid communication with the interior cavity of the balloon so that, when in use, fluid entering the balloon passes along both the inner and outer surfaces to transfer heat away from the ultrasound transducer;
• at least one electrical cable positioned within the at least one cable lumen of the catheter, the at least one electrical cable being electrically coupled to the electrodes along the inner and outer surfaces of the ultrasound transducer;
• and
• a backing member extending from the catheter to the tip and connecting the catheter with the tip, the backing member positioned within the internal space of the ultrasound transducer, wherein the backing member comprises a central opening that is generally aligned with the guidewire lumen of the catheter and the internal guidewire passage of the tip to permit the system to be delivered to a desired vascular position over a guidewire, wherein the backing member serves as a fluid barrier between fluid circulated within the balloon interior and the central opening.

An intravascular, ultrasound-based ablation system comprising:

• a catheter comprising at least one cable lumen and at least one fluid lumen;
• a balloon positioned at a distal end of the catheter, an interior of the balloon being in fluid communication with the at least one fluid lumen of the catheter;
• an ultrasound transducer positioned within the balloon, the ultrasound transducer comprising a cylindrical tube having a proximal end and a distal end and inner and outer surfaces, wherein each of the inner and outer surfaces comprises an electrode;
• the proximal end of the cylindrical tube comprising a stepped portion, wherein a portion of the outer diameter formed by the outer surface of the cylindrical tube is smaller than a portion of the outer diameter of the cylindrical tube located distal to the stepped portion;
• at least one electrical cable positioned within the at least one cable lumen of the catheter, the at least one electrical cable being configured to supply electrical power to the ultrasound transducer, wherein the at least one electrical cable comprises a first conductor and a second conductor;
• a stand-off assembly located within an interior and along or near the proximal end of the cylindrical tube of the ultrasound transducer, the stand-off assembly being electrically conductive and in contact with, at least intermittently, the electrode along the inner surface of the cylindrical tube of the ultrasound transducer;
• wherein the first conductor is connected to an exterior of the cylindrical tube along the stepped portion, and wherein the second conductor is connected to the stand-off assembly so that the second conductor is electrically coupled to the electrode along the inner surface of the cylindrical tube;
• and
• a ring surrounding the stepped portion of the cylindrical tube, the ring being sized and shaped to surround the portion of the outer diameter of the cylindrical tube located distal to the stepped portion, wherein the ring is electrically conductive so that the first connector is electrically coupled to the electrode along the outer surface of the cylindrical tube, and wherein the ring allows for more uniform electrical loading of the ultrasound transducer when the electrical transducer is energized.

An intravascular, ultrasound-based ablation system comprising:

• a catheter comprising a cable lumen extending from a proximal end to a distal end of the catheter;
• an ultrasound transducer positioned at or near a distal end of the catheter, the ultrasound transducer comprising a cylindrical tube with inner and outer surfaces, each of the inner and outer surface comprising an electrode;
• a backing member extending from the distal end of the catheter and positioned within an interior of the ultrasound transducer, the backing member configured to support the ultrasound transducer, wherein the backing member is electrically coupled to the electrode along the inner surface of the cylindrical tube of the ultrasound transducer;
• an electrical cable positioned within the cable lumen of the catheter and extending from the proximal end to the distal end of the catheter, wherein a proximal end of the electrical cable is coupled to a generator configured to selectively provide electrical power to the ultrasound transducer through the electrical cable, the electrical cable comprising a first electrical connector and a second electrical connector, wherein the first connector is electrically coupled to the electrode along the outer surface of the ultrasound transducer, and wherein the second connector is electrically coupled to the backing member and the electrode along the inner surface of the ultrasound transducer;
• wherein an impedance of the electrical cable is substantially equal to an impedance of the ultrasound transducer, thereby providing a more efficient power transfer from the generator to the ultrasound transducer when the ablation system is in use.