NEUROMODULATION CRYOTHERAPEUTIC DEVICES AND ASSOCIATED SYSTEMS AND METHODS

1 . A cryotherapeutic device, comprising:

an elongated shaft having a distal portion, wherein the shaft is configured to locate the distal portion intravascularly at a treatment site;

a supply lumen along at least a portion of the shaft, the supply lumen being configured to receive at least a substantially liquid refrigerant;

an exhaust lumen along at least a portion of the shaft, the exhaust lumen having a first diameter open to transport the refrigerant proximally after expansion; and

a cooling assembly at the distal portion of the shaft, the cooling assembly having an orifice with a second diameter in fluid communication with the supply lumen and an expansion chamber in fluid communication with the orifice, the first and second diameters having a ratio between 4:1 and 10:1, wherein the orifice is configured to deliver the refrigerant in a substantially gas state to the expansion chamber.

2 . The cryotherapeutic device of claim 1 wherein:

the exhaust lumen has an inner diameter between approximately 0.030 inch (0.762 mm) and approximately 0.05 inch (1.27 mm); and

the cooling assembly further comprises a flow restricting lumen in the supply lumen, the flow restricting lumen having a distal end portion in the expansion chamber, wherein the orifice is proximate the distal end portion of the flow restricting lumen, the orifice and the flow restricting lumen having an inner diameter between approximately 0.0030 inch (0.076 mm) and approximately 0.0080 inch (0.203 mm).

3 . The cryotherapeutic device of claim 1 , further comprising a flow restricting lumen in the supply lumen and open to the expansion chamber, wherein the flow restricting lumen has a length between approximately 2 inches (5.1 cm) and approximately 30 inches (76.2 cm).

4 . The cryotherapeutic device of claim 1 wherein:

the treatment site is at least one of a renal artery and a renal ostium;

the supply lumen has a first inner diameter and a first length; and

the cooling assembly further comprises a capillary tube in the supply lumen and open to the expansion chamber, the capillary tube having a second outer diameter less than the first inner diameter and a second length less than the first length, wherein the capillary tube includes a distal portion that defines the orifice, and wherein the refrigerant flows from the supply lumen to the capillary tube in at least a substantially liquid state and exits the orifice in at least a substantially gaseous state; and

the expansion chamber comprises an applicator configured to cause therapeutically-effective, cryogenic renal-nerve modulation.

5 . The cryotherapeutic device of claim 1 wherein a distal end portion of the supply lumen defines the orifice, and wherein the supply lumen has an inner diameter between approximately 0.0040 inch (0.102 mm) and approximately 0.010 inch (0.254 mm).

6 . The cryotherapeutic device of claim 1 , further comprising a flow restricting lumen at least partially in the expansion chamber, wherein the flow restricting lumen includes a distal end portion that defines the orifice, and wherein the supply lumen has a first length and the flow restricting lumen has a second length that is at most ⅓ of the first length.

7 . The cryotherapeutic device of claim 1 wherein the shaft is configured to locate the distal portion intravascularly in a renal artery or ostium of the renal artery.

8 . The cryotherapeutic device of claim 1 wherein the shaft has a first area and the supply lumen occupies a second area in the shaft, and wherein a ratio of the first area to the second area is 4:1 to less than 10:1.

9 . The cryotherapeutic device of claim 1 , further comprising a guide wire lumen extending through at least a portion of the shaft.

10 . The cryotherapeutic device of claim 9 wherein:

the shaft has a proximal end having a proximal opening and a distal end having a distal opening; and

the guide wire lumen extends between at least the proximal and distal openings.

11 . The cryotherapeutic device of claim 9 wherein:

the shaft has a length between a proximal end and a distal end; and

the guide wire lumen has a proximal opening between the proximal and distal ends of the shaft.

12 . A cryotherapeutic device, comprising:

an elongated shaft having a distal portion, wherein the shaft is configured to locate the distal portion intravascularly at a treatment site at least proximate at least one of a renal artery and a renal ostium;

a supply lumen along at least a portion of the shaft, the supply lumen being configured to receive a liquid refrigerant;

an exhaust passage along at least a portion of the shaft, the exhaust passage having a cross-sectional opening configured to transport an expanded refrigerant; and

a cooling assembly at the distal portion of the shaft, the cooling assembly having an expansion chamber configured to receive the refrigerant in a substantially gaseous state from the supply lumen, wherein the cross-sectional opening of the exhaust passage at the cooling assembly and a cross-sectional dimension of the supply lumen at the cooling assembly have a ratio between 4:1 and 10:1.

13 . The cryotherapeutic device of claim 12 , further comprising a capillary tube in the supply lumen and open to the expansion chamber, wherein the capillary tube has an opening with a diameter of at least 0.004 inch (0.102 mm).

14 . The cryotherapeutic device of claim 13 wherein the supply lumen has a first length and the capillary tube has a second length that is at most ⅓ of the first length.

15 . The cryotherapeutic device of claim 12 , further comprising a guide wire lumen configured for an over-the-wire delivery of the cooling assembly.

16 . The cryotherapeutic device of claim 12 , further comprising a rapid exchange guide wire lumen.

17 . The cryotherapeutic device of claim 12 wherein the exhaust passage has a first area and the supply lumen occupies a second area in the exhaust passage, and wherein a ratio of the first area to the second area is 4:1 to less than 10:1.

18 . A method for treating a patient, comprising:

locating an applicator of an elongated shaft intravascularly at a treatment site at least proximate a renal artery or a renal ostium, wherein the applicator is at a distal portion of the shaft;

expanding a refrigerant from an orifice in fluid communication with a supply lumen at the distal portion of the shaft, wherein the supply lumen extends along at least a portion of the shaft;

passing the refrigerant from the applicator via an exhaust lumen, the exhaust lumen extending along at least a portion of the shaft, wherein the exhaust lumen has a first inner cross-sectional area, the orifice has a second inner cross-sectional area, and the first and second inner cross-sectional areas have a ratio between 4:1 and 10:1; and

cooling a portion of the treatment site via a heat-transfer portion of the applicator and causing therapeutically-effective, cryogenic renal-nerve modulation.

19 . The method of claim 18 wherein expanding a refrigerant from an orifice in fluid communication with a supply lumen at the distal portion of the shaft comprises expanding the refrigerant from an orifice having a diameter between approximately 0.003 inch (0.076 mm) and approximately 0.008 inch (0.203 mm).

20 . The method of claim 19 wherein expanding a refrigerant from an orifice in fluid communication with a supply lumen at the distal portion of the shaft comprises expanding the refrigerant from an orifice at a distal end portion of a flow restricting lumen, the supply lumen having a first length, the flow restricting lumen having a second length at most ⅓ of the first length.

21 . The method of claim 18 wherein locating the applicator of the elongated shaft intravascularly at the treatment site comprises extending at least a portion of the shaft over a guide wire, wherein the guide wire extends through a guide wire lumen in the shaft.

22 . The method of claim 21 wherein extending at least a portion of the shaft over the guide wire comprises extending a guide wire completely through a length of the shaft, wherein the length of the shaft is from a distal end to a proximal end.

23 . The method of claim 21 wherein extending at least a portion of the shaft over the guide wire comprises delivering the applicator at the treatment site using a rapid exchange guide wire configuration.