Cryotherapeutic devices for renal neuromodulation and associated systems and methods
Cryotherapeutic devices for renal neuromodulation and associated systems and methods are disclosed herein. A cryotherapeutic device configured in accordance with a particular embodiment of the present technology can include an elongated shaft having a distal portion and a supply lumen along at least a portion of the shaft. The shaft can be configured to locate the distal portion intravascularly at a treatment site proximate a renal artery or renal ostium. The supply lumen can be configured to receive a liquid refrigerant. The cryotherapeutic device can further include a cooling assembly at the distal portion of the shaft. The cooling assembly can include an applicator having a distributor in fluid communication with the supply lumen and a balloon configured to deliver cryotherapeutic cooling to nerves proximate the treatment site when the cooling assembly is in a deployed state.
1. A cryotherapeutic device, comprising:
a shaft having a distal end portion configured to be advanced intravascularly toward a treatment site within a renal artery of a human patient, wherein the distal end portion of the shaft has a wall defining a lumen;
a balloon extending circumferentially around the distal end portion of the shaft, wherein the balloon is transformable between a low-profile delivery state and an expanded deployed state;
a supply tube carried by the shaft, wherein the supply tube is configured to carry refrigerant flowing distally toward the balloon, and wherein the supply tube includes a lateral opening within the lumen;
a supply opening extending laterally through the wall of the shaft within the balloon;
an exhaust opening extending laterally through the wall of the shaft within the balloon, wherein the exhaust opening is proximal to the supply opening;
a capillary tube including a first portion within the supply tube and a second portion extending from an interior of the supply tube toward the supply opening via the lateral opening of the supply tube; and
a plug within the lumen, wherein the plug extends around the second portion of the capillary tube within the lumen.
2. The cryotherapeutic device of claim 1 wherein the capillary tube is entirely within a combination of the supply tube and the plug.
3. The cryotherapeutic device of claim 1 wherein the plug extends into the supply opening around the second portion of the capillary tube.
4. The cryotherapeutic device of claim 1 wherein the second portion of the capillary tube extends from the interior of the supply tube toward the supply opening at an angle relative to the supply tube from 25° to 75°.
5. The cryotherapeutic device of claim 1 wherein:
the wall of the distal end portion of the shaft has an outer surface spaced apart from the lumen and an inner surface opposite the outer surface; and
the capillary tube has a distal end defining an orifice flush with the outer surface of the wall of the distal end portion of the shaft.
6. The cryotherapeutic device of claim 5 wherein the distal end of the capillary tube is not perpendicular to a length of the second portion of the capillary tube.
7. The cryotherapeutic device of claim 1 wherein the capillary tube includes a rounded elbow between the first and second portions of the capillary tube.
8. The cryotherapeutic device of claim 7 wherein the rounded elbow defines an angle from 25° to 75°.
9. The cryotherapeutic device of claim 1 wherein the plug includes an adhesive material.
10. The cryotherapeutic device of claim 9 , further comprising an injection opening extending laterally through the wall of the shaft, wherein the plug extends into the injection opening.
11. The cryotherapeutic device of claim 10 wherein the supply opening and the injection opening are circumferentially spaced apart from one another in a plane perpendicular to a length of the distal end portion of the shaft.
12. The cryotherapeutic device of claim 11 wherein:
the plane is a first plane;
the exhaust opening is a first exhaust opening;
the cryotherapeutic device further comprises a second exhaust opening extending laterally through the wall of the shaft within the balloon;
the first and second exhaust openings are circumferentially spaced apart from one another in a second plane perpendicular to the length of the distal end portion of the shaft; and
respective circumferential positions of the supply opening and the injection opening in the first plane are circumferentially offset relative to respective circumferential positions of the first and second exhaust openings in the second plane.
13. The cryotherapeutic device of claim 1 wherein:
the distal end portion of the shaft includes a reinforcing member; and
the exhaust opening extends through the reinforcing member.
14. The cryotherapeutic device of claim 13 wherein the reinforcing member is embedded in the wall of the distal end portion of the shaft.
15. The cryotherapeutic device of claim 14 wherein the reinforcing member is radiopaque.
16. The cryotherapeutic device of claim 1 wherein the supply opening is centered along a length the distal end portion of the shaft within the balloon.