Endovascular cryotreatment catheter
View Patent ↗An elongated catheter device with a distal balloon assembly is adapted for endovascular insertion. Coolant injected through the device may, in different embodiments, directly cool tissue contacting the balloon, or may cool a separate internal chamber. In the first case, the coolant also inflates the balloon, and spent coolant is returned to the handle via a return passage extending through the body of the catheter. Plural balloons may be provided, wherein a secondary outer balloon surrounds a primary inner balloon, the primary balloon being filled with coolant and acting as the cooling chamber, the secondary balloon being coupled to a vacuum return lumen to serve as a robust leak containment device and thermal insulator around the cooling chamber. Various configurations, such as surface modification of the balloon interface, or placement of particles, coatings, or expandable meshes or coils in the balloon interface, may be employed to achieve this function.
1. A method of treating tissue through cooling, comprising:
disposing a cooling device proximate the tissue, the device having a distal end portion including a primary expandable member enveloped by a secondary expandable member to define an interstitial space therebetween, the primary expandable member being in fluid communication with first and second lumens, the interstitial space being in fluid communication with a third lumen, wherein the second and third lumens are in fluid communication with one another at a proximal portion of the device;
injecting a cooling fluid into the primary expandable member through the first lumen;
expanding the cooling fluid inside the primary expandable member to cool the tissue;
expelling the cooling fluid from the primary expandable member through the second lumen; and
applying a source of vacuum to the third lumen.
2. The method of claim 1 , further comprising:
setting a back pressure in the second lumen to control the expanding of the cooling fluid in the primary expandable member.
3. The method of claim 2 , further comprising:
restricting the expelling of the cooling fluid from the primary expandable member into the second lumen to generate the back pressure.
4. The method of claim 1 , wherein the cooling device further includes a pressure transducer in the primary expandable member, further comprising:
monitoring a pressure condition in the primary expandable member.
5. The method of claim 4 , further comprising:
setting a back pressure in the second lumen in response to a pressure condition in the primary expandable member.
6. The method of claim 5 , further comprising:
restricting the expelling of the cooling fluid from the primary expandable member into the second lumen to generate the back pressure.
7. The method of claim 1 , further comprising:
upon a breach of the primary expandable member, expelling the cooling fluid from the primary expandable member through the third lumen.
8. The method according to claim 1 , further comprising injecting particles into the interstitial space through the third lumen.
9. The method according to claim 1 , further comprising injecting a fluid into the interstitial space through the third lumen.
10. The method of claim 1 , further comprising:
maintaining the interstitial space between the primary and secondary expandable members.
11. The method according to claim 10 , wherein maintaining the interstitial space includes providing a mesh structure at least partially surrounding a portion of the primary expandable member.
12. The method according to claim 11 , wherein the mesh structure includes a plurality of helically wound flexible elements.
13. The method according to claim 12 , wherein at least one of the plurality of helically wound flexible elements defines a circular cross-section.
14. The method according to claim 10 , wherein maintaining the interstitial space includes providing a surface modification of at least a portion of the primary expandable member.
15. The method according to claim 10 , wherein maintaining the interstitial space includes providing a coil element positioned about at least a portion of the primary expandable member.