COLD SLURRY CONTAINMENT

Abstract

The present invention provides methods and devices for controlling a cold slurry that is delivered to a target tissue and for limiting heat transferring from surrounding tissue to the target tissue. In particular, a balloon structure is deployed at or near a point of delivery to act as a physical and/or thermal barrier. In some instances, the balloon structure can act as a pressure device obstructing the flow of warm blood into a treatment area, which can melt the cold slurry.

Claims

1. A device for controlling tissue temperature, the device comprising: a first cannula for delivering a cold slurry to a target tissue underneath a patient's skin, thereby cooling the target tissue, the first cannula comprising a first open distal end and a first proximal end in fluid communication with a source of cold slurry; a second cannula comprising a second open distal end and a second proximal end in fluid communication with a source of a thermal insulator; and a balloon disposed around the second open distal end of the second cannula and positioned at or near tissue surrounding the target tissue, the balloon comprising a volume filled with the thermal insulator delivered through the second cannula, wherein the filled balloon limits heat from transferring from the surrounding tissue to the target tissue.

2. The device of claim 1, wherein the balloon includes a first chamber facing the target tissue and a second chamber facing the surrounding tissue; wherein the first chamber is in fluid communication with the first open distal end and is filled with cold slurry delivered through the first cannula; and wherein the second chamber is in fluid communication with the second open distal end and is filled with the thermal insulator delivered through the second cannula.

3. The device of claim 1, wherein the balloon is a second balloon and the claim further comprising: a first balloon disposed around the first open distal end of the first cannula, the first balloon comprising a volume for receiving the cold slurry delivered through the first cannula.

4. The device of claim 3, wherein the first balloon includes multiple segments that are independently filled with the cold slurry.

5. The device of claim 3, wherein the first balloon includes multiple projecting arms.

6. The device of claim 3, wherein the first balloon has a length that is greater than its width.

7. The device of claim 1 further comprising an inner balloon disposed around the first open distal end of the first cannula, the inner balloon comprising an outer surface and a volume for receiving the cold slurry delivered through the first cannula; wherein the balloon is an outer balloon comprising an inner surface; and wherein the outer surface of the inner balloon and the inner surface of the outer balloon form a space for the thermal insulator to fill and limit heat transfer from the surrounding tissue to the target tissue.

8. The device of claim 7, wherein the first cannula includes a first longitudinal axis extending between the first open distal end and the first proximal end; and wherein the second cannula includes a second longitudinal axis extending between the second open distal end and the second proximal end, and the second longitudinal axis is aligned with the first longitudinal axis.

9. The device of claim 8, wherein the first longitudinal axis and second longitudinal axis are the same.

10. The device of claim 1, wherein the first and second cannulas each have a size and shape suitable for inserting through the subject's skin.

11. The device of claim 1 further comprising a cold slurry temperature monitor extending beyond the first open distal end to measure the temperature of the delivered cold slurry.

12. The device of claim 11, wherein the cold slurry temperature monitor includes a temperature sensor at a distal end of the cold slurry temperature monitor.

13. The device of claim 12, wherein the temperature sensor is a forward infrared (FIR) sensor.

14. The device of claim 11, wherein the cold slurry temperature monitor includes a plurality of temperature sensors spaced along a length of the cold slurry temperature monitor.

15. The device of claim 1, wherein the thermal insulator is any one of fluid, gas, air, gel, and aerogel.

16. The device of claim 1, wherein the cold slurry is a mixture of water and glycerol.

17. The device of claim 1, wherein the balloon has a length that is greater than its width.

18. The device of claim 1, wherein the balloon is generally spherical.

19. The device of claim 1, wherein the balloon has a longitudinal axis and is concaved as defined by a point along a line parallel to and offset from the longitudinal axis.

20. The device of claim 1 further comprising a guide, the guide comprising a working channel sized to house the second cannula and the balloon disposed around the second cannula; and wherein the balloon is deployed from the working channel when in use.

21. A device for controlling tissue temperature, the device comprising: a fenestrated cannula for delivering a cold slurry to a target tissue underneath a patient's skin, thereby cooling the target tissue, the cannula comprising a plurality of openings at a distal end and a proximal end in fluid communication with a source of cold slurry; and a plurality of balloons, each disposed in one of the plurality of openings and configured to expand when exposed to cold slurry from the source of cold slurry and thereby provide an increase in surface area for thermal transfer from the target tissue to the cold slurry at the distal end of the cannula.

22. The device of claim 21, wherein one or more of the plurality of openings is configured to impart a shape the plurality of balloons disposed therein when expanded.

23. The device of claim 22, wherein the shape comprises a plurality of expanded members.

24. The device of claim 22, wherein the shape comprises an ovoid.

25. The device of claim 22, wherein the shape comprises a sphere.

26. The device of claim 22, wherein one or more of the plurality of balloons comprise two or more areas of differing elasticity.

27. The device of claim 21, comprising an array of fenestrated cannulas.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a diagram of an approach to delivering a cold slurry and controlling its migration and/or cooling effect.

[0017] FIG. 2 is a side view of a balloon acting as a thermal barrier protecting a nerve from the cooling effect of the cold slurry.

[0018] FIG. 3 is a side view of a balloon acting as a pressure device limiting blood flow into a treatment area.

[0019] FIG. 4 is a sectional view of a cold slurry delivery device.

[0020] FIG. 5 is a view of a cold slurry delivery device for delivering and replenishing cold slurry.

[0021] FIG. 6 is a sectional view of a two-chamber balloon for delivering cold slurry to a target tissue and protecting an adjacent tissue from the cooling effect of the cold slurry.

[0022] FIG. 7 is a view of an example balloon having projecting arms.

[0023] FIG. 8 is a view of an example balloon having multiple compartments.

[0024] FIG. 9 is a view of an example cold slurry temperature monitor.

[0025] FIG. 10 is a view of an example cold slurry temperature monitor with multiple temperature sensors.

[0026] FIGS. 11A and 11B are views of example containment devices for controlling cold slurry and/or its cooling effect from outside the patient's body.

[0027] FIGS. 12A and 12B are views of example warm fluid removal devices for removing melted cold slurry from a treatment area.

[0028] FIGS. 13A-13C are views of an example guide for deploying a cold slurry containment device.

[0029] FIGS. 14A and 14B show a fenestrated cannula with balloons in retracted and expanded states.

[0030] FIG. 15 shows various opening designs for a fenestrated cannula and the resulting shapes of balloons expanded therethrough with slurry.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a cold slurry being injected into a patient. A cold slurry delivery device 100 having a cannula is inserted through the patient's skin and advanced to a location at or near a target tissue 105 (shown in phantom line). A cold slurry 110 is then delivered. Heat from the target tissue 105 is transferred to the cold slurry 110, which in turn lowers the temperature of the target tissue 105. After delivery, an area affected by the cold slurry 110 expands to a size larger than the initial delivery site (shown in the figure as arrows radiating outwardly from the delivered cold slurry 110 and dashed circles of increasing size).

[0032] FIG. 1 further shows an approach for controlling the cooling effect of the cold slurry 110. A deployment device 115 having an application cannula 120 is inserted through the patient's skin. At the distal end of the application cannula 120, there is a controlling end 125. The deployment device 115 is advanced until the controlling end 125 is at a location between the target tissue 105 and an adjacent (surrounding) tissue 135. The controlling end 125 includes a balloon 130. While the balloon 130 is shown having a linear shape, it can have any shape, such as a ring that encircles the target tissue 105. The balloon 130 is filled with air to create a barrier between the adjacent tissue 135 and the spreading cold slurry 110. The balloon 130 limits heat transferring from the adjacent tissue 135 to the cold slurry 110.

[0033] The approach provides several benefits. By acting as a temperature barrier, the balloon 130 can slow down the melting process, thereby prolonging the usefulness of the cold slurry 110. The balloon 130 can further help keep the target tissue 105 cold and thus, increase the effectiveness of the cold slurry treatment. By acting as a temperature barrier, the balloon 130 also protects the adjacent tissue 135 from being adversely affected or damaged by the cold. For example, FIG. 2 shows the balloon 130 placed between the cold slurry 110 and a nerve 140. The balloon 130 limits the cooling effect of the cold slurry 110 on the nerve 140. Beneficially, this lowers the possibility of damaging the nerve 140.

[0034] FIG. 3 shows another application of the balloon 130. The balloon 130 filled with air or fluid is placed next to a blood vessel 150. The balloon 130 exerts pressure on the blood vessel 150 causing it to constrict and limit blood flow 155, as shown. By reducing the amount of warm blood flowing into a treatment area, the balloon 130 can slow down the melting process, thereby prolonging the usefulness of cold slurry. The balloon 130 can further help keep a target tissue cold and thus, increase the effectiveness of the cold slurry treatment.

[0035] FIG. 4 shows an example cold slurry delivery device 200. The device 200 includes an application cannula 205 that is open at its distal end and defines an outlet 210. A controlling end 215 includes an outer balloon 220 disposed around the outlet 210. The application cannula 205 is in fluid communication with the interior volume of the outer balloon 220. The application cannula 205 includes a fluid delivery cannula 225. The application cannula 205 and the fluid delivery cannula 225 share a common longitudinal axis and can be said to be coaxial aligned.

[0036] The fluid delivery cannula 225 is open at its distal end defining a fluid outlet 230. The controlling end 215 further includes an inner balloon 235 disposed around the fluid outlet 230. The fluid delivery cannula 225 is in fluid communication with an interior volume of the inner balloon 235, which is labeled 240 in the figure. The inner balloon 235 is located inside the outer balloon 220. As shown, the inner balloon 235 occupies a portion of the interior volume of the outer balloon 220 leaving a space or gap 245 between an outer wall of the inner balloon 235 (which is labeled 250 in the figure) and an inner wall of the outer balloon 220 (which is labeled 255 in the figure).

[0037] To use the cold slurry delivery device 200, the application cannula 205 is inserted through the patient's skin and the controlling end 215 is advanced to a location at or near a target tissue in much the same manner as described above with reference to FIG. 1. In this example, the outer balloon 220 and the inner balloon 235 are inserted into the patient's body in their uninflated state. The outer balloon 220 is filled with air that is supplied through the application cannula 205. The inner balloon 235 is filled with a cold slurry 260 that is supplied through the fluid delivery cannula 225. The air filling the gap 645 between the inner balloon 235 and the outer balloon 220 acts an insulator and protects the surrounding tissue from damage. The inner balloon 235 can also be filled with a fluid, gel, inorganic aerogel, foam or other thermal insulator.

[0038] FIG. 5 shows another example of the cold slurry delivery device 200 for delivering a cold slurry. This example is similar to the one described above with reference to FIG. 4 with the addition of a fluid return cannula 265. The fluid return cannula 265 is housed within the application cannula 205 together with the fluid delivery cannula 225, as shown. The fluid return cannula 265 removes cold slurry from the inner balloon 235 that is no longer at the desired temperature. Replenishing the old cold slurry with fresh cold slurry in this manner can accommodate for the eventually melting of cold slurry. This approach is particular useful for a treatment that requires a long period of cooling.

[0039] FIG. 6 shows an example balloon 300 for delivering cold slurry. The balloon 300 has a first chamber 305 and a second chamber 310, as shown. The first chamber 305 is filled a cold slurry (or other cooling fluid) and faces a target tissue 315. The second chamber 310 is filled with air (or other gas) and faces an adjacent tissue 320, which is near the target tissue 315. This configuration allows the balloon 300 to cool the target tissue 315 while protecting the adjacent tissue 320 from the cooling effect of the cold slurry. Examples of the balloon can have any shape in addition to the linear and spherical examples described above with reference to FIGS. 1-5. For example, FIG. 2 shows the balloon 130 having a length (L) greater than its width (W) and having a concave shape. The point of concavity is defined by a point along an axis offset and parallel to a longitudinal axis 165. As another example, FIG. 7 shows a balloon 350 with several projecting arms or balusters 355.

[0040] Other examples of the balloon can have a number of chambers that can be opened or closed to control the shape of the balloon. For example, FIG. 8 shows a balloon 400 with four compartments 405a-405d (generally 405). The compartments 405 can be filled with various fluids or gasses of varying temperatures. The balloon 400 has a length (L) greater than its width (W).

[0041] FIG. 9 shows a cold slurry temperature monitor 500 for measuring the temperature of the cold slurry. The cold slurry temperature monitor 500 can be a standalone device or incorporated with the cold slurry delivery device 100, 200 (of FIGS. 1 and 5) or the deployment device 115 (of FIG. 1). As shown, for example, the cold slurry temperature monitor 500 extends from an application cannula 505 (e.g., the cannula of the cold slurry delivery device 100). The cold slurry temperature monitor 500 can move between an extended position, which is shown in the figure, and a retracted position. In the retracted position, the cold slurry temperature monitor 500 is shielded within the application cannula 505. This helps with inserting the cold slurry temperature monitor 500 through the patient's skin and advancing the monitor 500 to a location at or near the cold slurry.

[0042] In the example shown, the cold slurry temperature monitor 500 includes at a temperature sensor 510 at its distal tip. Without limiting the principles of the invention, the temperature sensor 510 can be a forward infrared (FIR) sensor. As shown, the cold slurry temperature monitor 500 can be moved to intermediate positions between the retracted and extended positions. These intermediate positions together with the extended position correspond to different locations within the cold slurry, which are labelled in figure A through E. By moving the cold slurry temperature monitor 500 to the intermediate positions and the extended position, a temperature gradient (or temperature thru depth) of the cold slurry can be determined. The temperature gradient, in turn can, can be used to assess, for example, the capacity (capability) for the cold slurry to cool the target tissue.

[0043] FIG. 10 shows another example of the cold slurry temperature monitor 500 having multiple sensors 515a-e (generally 515) spaced along the length of the monitor 500. Each of the sensors 515 measures a different location within the cold slurry. For example, sensor 515c measures the temperature of the cold slurry at the location labelled C in FIG. 9. In this way, a temperature gradient of the cold slurry can be determined without having to move the cold slurry temperature monitor 500.

[0044] FIG. 11A shows the cold slurry delivery device 100 of FIG. 1 delivering a cold slurry to the target tissue 105 underneath the patient's skin (which is shown in phantom line). A containment device 600 is applied over the patient's skin to control the spread of the cold slurry and/or its cooling effect from outside the patient's body. The containment device 600 has an opening 605 that defines a containment zone 610 within which the cold slurry and/or its cooling effect is substantially confined. The opening 605 is surrounded by a pressure surface 615 for applying pressure around the containment zone 610. As shown, the containment device 600 is applied with the opening 605 placed over the target tissue 105 and the pressure surface 615 over the surrounding tissue 135 (which is shown in phantom line).

[0045] In a convenient example of the containment device 600, the pressure surface 615 is a hollow inside and can expand when filled a fluid or gas, such as air. Force is exerted by pumping air/fluid into the pressure surface 615 causing it to expand and press against the patient's skin. The target tissue 105 experiences little or no pressure because of the opening 605. The surrounding tissue 135, on the other hand, experiences positive pressure. This positive pressure limits the spread of cold slurry and/or its cooling effect from the target tissue 105 to the surrounding tissue 135. Additionally, the pressure exerted can constrict blood vessels in the surrounding tissue 135 and limit warm blood from flowing into the treatment area.

[0046] The exerted pressure can be reduced or removed by pumping air/fluid out of the pressure surface 615 causing it to deflate. In a convenient example, the pumping of air/fluid into and out of the pressure surface 615 is done automatically. For example, air/fluid is pumped into the pressure surface 615, such that the containment device 600 applies pressure at or near the start of a cold slurry treatment. After a pre-determined amount of time, the air/fluid is pumped out of the pressure surface 615 relieving pressure from the containment device 600 at or near the end of the cold slurry treatment.

[0047] Shown in FIG. 11B, the pressure surface can be divided into segments 620 (shown as a first segment 620a and a second segment 620b). The segments 620 can be, for example, concentric rings. The segments 620 can be filled, individually, such that the pressure exerted pressure by each segment is different. For example, the first segment 620a closest to the opening 605 is filled so that the pressure exerted against the patient's skin is greater that the pressure exerted by the second segment 620b. The difference in pressure applied by the containment device 600 can help control the migration of cold slurry. Additional, the different pressures can facilitate tissue contouring.

[0048] In another example of the containment device, the pressure surface is solid. When a force is exerted against the containment device, the target tissue experiences little or no pressure because of the opening. The surrounding tissue, on the other hand, experiences positive pressure. This positive pressure limits the spread of cold slurry and/or its cooling effect from the target tissue to the surrounding tissue. Additionally, the pressure exerted can constrict blood vessels in the surrounding tissue and limit warm blood from flowing into the treatment area.

[0049] The solid pressure surface can be divided into segments, for example, concentric rings. The segments can be added or removed to make the size of the opening and, in turn, the containment zone bigger or smaller. The segments can also be added or removed to make the size of the pressure surface bigger or smaller and thus change the area over which pressure is applied.

[0050] In the examples shown, the containment device 600 has a circular shape with the opening 605 centrally located and the pressure surface 615 concentric with the opening 605. Further, the pressure surface 615 is a substantially planer surface, as shown. The containment device 600 can be of any shape suitable for applying pressure to a part of the patient's body. For example, the containment device 600 can be rectangular, triangular or other regular shape. The containment device 600 can also have an irregular shape that is adapted to conform to a part of the patient's body being treated. For the example, the containment device 600 can be concaved to saddle, for example, the patient's stomach. The concavity of the containment device 600 is defined in the context of the device in use.

[0051] As shown, the opening 605 and pressure surface 615 are axially aligned, i.e., sharing a common axis. In other examples, the axis of the opening 605 and axis of the pressure surface 615 are offset a distance. This non-axial example of the containment device 600 can be useful in applications where it is desirable to bias the containment of cold slurry more or less to one side of the target tissue 105.

[0052] The containment device 600 can be made out plastic, polymer, rubber or other material suitable for applying pressure to a part of the patient's body. The containment device can be used manually, for example, a clinician presses (e.g., by way of a handle on the containment device) the device 600 against the patient's skin. Use of the containment device 600 can also be facilitated with straps or clamps for wrapping the containment device 600 around a part of the patient's body.

[0053] FIG. 12A shows the cold slurry delivery device 100 of FIG. 1 delivering a cold slurry to the target tissue 105 underneath the patient's skin. Heat from the target tissue 105 is transferred to the cold slurry 110, which in turn lowers the temperature of the target tissue 105 to a first temperature T1. After delivery, the cold slurry 110 spreads out and affects an area larger than the initial delivery site (shown in the figure as arrows radiating outwardly from the delivered cold slurry 110 and dashed circles of increasing size). As the cold slurry 110 spreads out, it melts and lowers the temperature of the surrounding tissue 135 to a second temperature T2, which is warmer than the first temperature T1.

[0054] A warm fluid removal device 700 removes the resulting warm fluid from the treatment area. The warm fluid removal device 700 has a distal end 705 that is positioned a distance away for the target tissue 105 and within the surrounding tissue 135. The warm fluid removal device 700 further includes a proximal end 710 that is coupled to a vacuum pump 715. The vacuum pump 715 provides the suction to remove the warm fluid from the treatment area.

[0055] The vacuum pump 715 is operatively coupled to a controller 720 for operating the vacuum pump 715. The controller 720 can operate the vacuum pump 715 continuously such that warm fluid is constantly removed. The controller 720 can operate the vacuum pump 715 intermittently such that warm fluid is drawn off at pre-determined intervals. In a convenient example, the controller 720 monitors the temperature of the target tissue 105 using a temperature probe (e.g., one similar to the cold slurry temperature monitor 500 described above with reference to FIGS. 9 and 10). When the temperature of the target tissue 105 rises above the first temperature T1, the controller 720 responds by operating the vacuum pump 715 and removing the warm fluid from the treatment area.

[0056] FIG. 12B shows another example warm fluid removal device 750 for removing warm fluid from a treatment area. Generally, the warm fluid removal device 750 has a hoop-like shape. As shown, the warm fluid removal device 750 is U-shaped with an open end 755 facing the target tissue 105. The warm fluid removal device 750 further has a plurality of holes 760 defined along its length through which warm fluid is removed from the treatment area (shown as arrows). The warm fluid removal device 750 can include an open distal end 765 to further enhance removal of the warm fluid from the treatment area. In a convenient example, the warm fluid removal device 750 has a non-operating mode and an operating mode. In the non-operating mode, the warm fluid removal device 750 is substantial linear in shape. In the non-operating mode, the warm fluid removal device 750 can be readily inserted through the patient's skin, advanced to the tissue surrounding the target tissue, and removed from the patient.

[0057] In the operating mode, the warm fluid removal device 750 is U-shaped with the open end 755 facing the target tissue 105 as shown in FIG. 12B. The warm fluid removal device 700 can be mechanically actuated between the non-operating mode and operating mode with a tension wire, for example. In another example, the warm fluid removal device 750 is made for a shape memory alloy, such as nitinol.

[0058] The warm fluid removal device 750 further includes a proximal end 770 that is coupled to a vacuum pump 775. The vacuum pump 775 provides the suction to remove the warm fluid of the treatment area. The controller 781 can operate the vacuum pump 775 continuously such that warm fluid is constantly removed. The controller 720 can operate the vacuum pump 775 intermittently such that warm fluid is drawn off at pre-determined intervals. In a convenient example, the controller 780 monitors the temperature of the target tissue 105 using a temperature probe (e.g., one similar to the cold slurry temperature monitor 500 described above with reference to FIGS. 9 and 10). When the temperature of the target tissue 105 rises above the first temperature T1, the controller 780 operates the vacuum pump 775 to remove the warm fluid from the treatment area.

[0059] The warm fluid removal device 700 of FIG. 12A (or 650 of FIG. 12B) and the cold slurry delivery device 100 of FIG. 1 can be operated together, for example, using the controller 720, to replenish old cold slurry with fresh cold slurry. Replenishing cold slurry can occur intermittently such that warm fluid is drawn off and cold slurry is delivered at pre-determined intervals.

[0060] In a convenient example, the controller 720 monitors the temperature of the target tissue 105 using a temperature probe (e.g., one similar to the cold slurry temperature monitor 500 described above with reference to FIGS. 9 and 10). When the temperature of the target tissue 105 rises above the first temperature T1, the controller 720 responds by operating the warm fluid removal device 700 to remove warm fluid from the treatment area; and by operating the cold slurry delivery device 105 to deliver cold slurry to the target tissue 105. This configuration is particular useful for cooling tissue for an extended period of time.

[0061] In a convenient example, any one of the devices described above can be deployed using a guide. FIGS. 13A-13C show an example of the guide 800 to use with the deployment device 115 of FIG. 1. The guide 800 includes a working channel 805 for housing the application cannula 120 and the balloon 130. The working channel 800 is inserted through the patient's skin and advanced towards the treatment area. At the treatment area, the deployment device 115 is pushed out of the working channel, as shown in FIG. 13B. The balloon 130 is then be inflated with a fluid or a gas, such as air, as shown in FIG. 13C, and used to control the cold slurry and/or its cooling effects, as described above. When the treatment is done, the balloon 130 is deflated and pulled back into the working channel 805. The guide 800 is then withdrawn from the patient's body. The guide 800 can have one or more working channels to control the function of the balloon or a collection of balloons.

[0062] In various embodiments, fenestrated needles or cannulas are provided with one or more mini or micro balloons that, when filled with a therapeutic cold fluid or slurry, drastically increase surface area through which the cannula can transfer heat from surrounding tissue. The balloons may be modeled after intestinal villi for example and may be deployed from a single needle or cannula as shown in FIGS. 14A and 14B or through an array of needles or cannulas. The expansion and retraction of the balloons can be dependent on a differential in wall pressure when slurry or cold solution flows through the cannula or needle.

[0063] An exemplary fenestrated needle or cannula is shown in FIGS. 14A and 14B. The fenestrated cannula 1401 may be constructed of a relatively rigid or inflexible material compared to the balloon 1407 material. Balloons 1407 formed of a relatively flexible or expansible material are present in a series of openings 1403 in the rigid cannula 1401. The cannula 1401 may have a solid tip to allow pressure to build within a lumen 1405 of the cannula as slurry or fluid is added. As fluid or slurry is added and pressure within the lumen 1405 builds, the relatively flexible balloons 1407 expand outwardly through the openings 1403 as shown in FIG. 14B. The resulting expanded balloons, filled with cold slurry, drastically increase the surface area for thermal interaction with surrounding tissue. Once fluid or slurry flow ceases, the expanded balloons 1407 retract back within the openings 1403 as shown in FIG. 14A, allowing for ease of insertion and removal of the cannula.

[0064] The micro or mini balloons of fenestrated cannulas may be a variety of different shapes as shown in FIG. 15. The left column of FIG. 15 illustrates the shape of various openings in fenestrated cannula embodiments of the invention and the right column shows a corresponding balloon shape one a balloon is expanded through an opening of the shape shown in the left column. For example, a rigid material such as that of the cannula itself may be used to divide the opening as shown in FIG. 15. By dividing the opening in two or in quarters, a balloon expanding therethrough will form two or four separate expanded members. In certain embodiments, the flexibility of the balloon material within an opening may be varied as shown in FIG. 15 to cause the expanded balloon to take on different shapes. For example, concentric rings of varying flexibility may result in an oblong expanded balloon which may be advantageous for certain treatments.