Miniature balloon catheter method and apparatus

Abstract

A miniaturized balloon catheter assembly includes a cannula and an inflatable tubular balloon constructed of a silastic tubing detachably mounted on the cannula for performing a surgical procedure in a human vessel in response to pressure therein. In one embodiment, the balloon is detachable mounted with the detachability being responsive to pressure. For example, the balloon elastically grips the cannula and there is a small metallic C-shaped spring mounted about the balloon and cannula. In another embodiment, a valve, such as a pinhole in the silastic material for example, is included in the balloon which opens only after the pressure within the balloon exceeds a predetermined amount. According to a method of the invention, the cannula and the attached balloon are inserted into a small vessel and the balloon is pressurized therethrough. The balloon is partially inflated to allow fluid flow in the vessel to position the balloon at a desired location. The balloon is further inflated to fix the balloon in position against the walls of the vessel. Pressure is thereafter increased in the balloon to activate a desired procedure within the vessel. In the first embodiment the desired procedure is to withdraw the cannula from the affixed balloon as the increased pressure lubricates the connection between the balloon and the cannula. The C-spring and the silastic balloon cooperate to close off the opening into the balloon left by the retracted cannula and thereby leave the balloon in position in the vessel. In the second embodiment, the desired procedure is for the increased pressure to open the pin-hole and disperse a fluid into the vessel from the balloon. There are alternate embodiments for performing the above methods and the methods can be combined.

I claim: 
     
       1. A miniaturized balloon catheter assembly for use in small vessels comprising: a cannula having proximal and distal ends including an attaching means at the proximal end thereof for attaching to a source of pressurized fluid and having a small outer diameter for insertion into small vessels;   an inflatable balloon including a means forming a mouth at a proximal end thereof mounted on an external surface of the cannula at the distal end of the cannula to be in fluid communication therewith, the cannula and balloon together adapted to be carried by the fluid in a vessel to desired locations therein, whereupon attachment of the cannula fluid source of pressurized fluid and introduction of amounts of pressurized fluid flow inflate the balloon to fix it in position against the wall of said vessel at a desired location; and,   a balloon-retaining means responsive to a predetermined further amount of pressure to initiate a desired procedure within the small vessels, said balloon-retaining means including a resilient contracting member surrounding said means forming said mouth for holding said means forming said mouth on said external surface of said cannula, said resilient contracting member being constructed to have a specific predetermined internal size when in a contracted state for: contracting with a uniform predetermined tension about said means forming said mouth when said means forming said mouth is mounted on said cannula to hold said balloon on said cannula upon said balloon being inflated to fix it in position against the wall of said vessel at said desired location, expanding in response to said predetermined further amount of pressure in said balloon to release said cannula from said mouth, and thereafter contracting toward said specific predetermined internal size to close said balloon mouth and thereby retain said inflated balloon fixed in position against said wall.   
     
     
       2. A miniaturized balloon catheter as in claim 1 wherein said balloon is of an elastomeric silastic material. 
     
     
       3. A miniaturized balloon catheter assembly as in claim 1 wherein said cannula and said balloon are normally of approximately the same diamter and attachment of the inflatable portion of the cannula is achieved by expanding the means forming a mouth, and extending it over the adjacent end of the cannula. 
     
     
       4. A minaturized balloon catheter as in claim 3 wherein said resilient contracting member is a C-shaped spring. 
     
     
       5. A miniaturized balloon catheter as in claim 4 wherein the inner diameter of said balloon is approximately 0.011 inch and its outer diameter is approximately 0.024 inch while said C-shaped spring has an inner diameter of approximately 0.018 inch when it is in a non-expanded condition. 
     
     
       6. A miniaturized balloon catheter as in claim 1 wherein said resilient contracting member does not wrap about said means forming said mouth more than once. 
     
     
       7. A diagnostic and therapeutic method for carrying out procedures in small vessels by utilizing a miniaturized balloon catheter assembly including a resilient cannula adapted for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels and an inflatable balloon having a mouth at the proximal end thereof mounted on the end of the cannula in fluid communication therewith comprising the steps of: inserting the distal end of said cannula into the mouth of said inflatable balloon;   attaching said inflatable balloon to said resilient cannula with a resilient contracting member by surrounding a portion of said inflatable balloon near said mouth with said resilient contracting member and thereby contracting said balloon onto said resilient cannula, said resilient contracting member having a predetermined internal size when in a fully contracted state for: contracting about said balloon portion to hold said balloon on said cannula with a uniform tension when said balloon is mounted on said cannula and for contracting toward said predetermined internal size to close said balloon mouth when said balloon is not mounted on said cannula;   inserting the balloon catheter assembly into a small vessel;   attaching the cannula to a source of pressurized fluid and pressurizing the balloon portion to partially inflate the balloon portion to permit the balloon portion and attached cannula to be directed by the fluid flow within the vessel to the desired location;   further inflating the balloon portion to fix the balloon portion in position;   increasing the fluid pressure inside the balloon portion to expand said resilient contracting member; and   withdrawing said cannula from said mouth to allow said resilient contracting member to contract and thereby close said balloon mouth to retain said inflated balloon fixed in position.   
     
     
       8. The invention in accordance with claim 7 wherein said resilient contracting member is a C-shaped spring. 
     
     
       9. A miniaturized balloon catheter as in claim 8 wherein the inner diameter of said balloon is approximately 0.011 inch and its outer diameter is approximately 0.024 inch while said C-spring has an inner diameter of approximately 0.018 inch when it is in a non-expanded condition. 
     
     
       10. The invention in accordance with claim 7 wherein the balloon includes an opening in it distal end and expels fluid therethrough downstream of the balloon portion during and after said cannula is withdrawn from said mouth. .Iadd. 
     
     
       11.  In a miniaturized balloon catheter assembly adapted for use in diagnostic and therapeutic procedures in connection with small vessels comprising; a cannula having means at a proximal end for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels, an inflatable tubular balloon having a mouth portion and mounted at the distal end of the cannula in fluid communication therewith, the cannula and balloon adapted to be carried by the fluid in the vessel to a desired location therein, whereupon introduction of an amount of pressurized fluid flow from the source of pressurized fluid will inflate the balloon to fix it in position, activation means responsive to a further amount of pressure to initiate a desired procedure within the small vessel at the desired location, said balloon being detachably mounted at the distal end of said cannula; the subassembly of a sealing means which, when the cannula and balloon are positioned at the desired location in the human vessel, seals the mouth portion of the balloon, said sealing means including elastomeric self-sealing plug material positioned in the mouth of the inflatable balloon adjacent to the end of the cannula, an expandable circumferential band on the outer surface of the inflatable balloon in concentric position with respect to the plug material therein, said subassembly further comprising a pin having a passageway therethrough and one end mounted at the distal end of the cannula with the passageway therein in communication with the passageway through the cannula and the other end of the pin positioned through a small opening in the self-sealing plug material into fluid communication with the inflatable balloon on the side of the plug material distal from the cannula and when in that position expanding the circumferential band, so that when the balloon is detached from the distal end of the cannula the pin is removed from the plug material, whereupon the elastomeric self-sealing plug material and the expandable circumferential band will close the opening in the plug material and the mouth portion of the balloon to retain the balloon in inflated condition. .Iaddend. .Iadd.12. The subassembly of claim 11 wherein said expandable circumferential band comprises a single strand element which does not   
     
     
        extend about said plug material a plurality of times. .Iaddend. .Iadd.13. A miniaturized balloon catheter assembly adapted for use in diagnostic and therapeutic procedures in connection with small vessels comprising; a cannula having means at a proximal end for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels, an inflatable tubular balloon having a mounth means constructed of self-sealing material for forming an opening into said balloon through which said balloon can be inflated, but which can be closed to maintain said balloon in an inflated state, said balloon being mounted at the distal end of the cannula in fluid communication therewith, said cannula extending into the mouth means of said balloon so that said balloon can be inflated and deflated via said cannula, the cannula and balloon adapted to be carried by the fluid in the vessel to a desired location therein, whereupon introduction of an amount of pressurized fluid flow from the source of pressurized fluid will inflate the balloon to fix it in position and a further amount of pressure will initiate a desired procedure within the small vessel at the desired location, said balloon having a sealing means thereon so that when the cannula and balloon are positioned in the desired location in the human vessel the cannula can be detached from the balloon whereupon the sealing means will seal the mouth portion of the balloon, said sealing means including a circumferential expandable-band means on the outer surface of the mouth means of said inflatable balloon tending to hold the balloon mouth means onto said cannula, said expandable-band means comprising a single strand element which does not extend about said mouth means a plurality of times, said expandable-band means and said mouth means having the joint function of responding to a sufficient amount of pressurized fluid passing through the cannula into the inflatable balloon to inflate the balloon to a desired amount by detaching the cannula from the balloon for removal of the cannula from the balloon mouth means, and responding to a decreased pressure in said balloon after said cannula has been removed by closing the opening in said mouth means of the balloon to retain the balloon in an inflated condition. .Iaddend. .Iadd.14. A diagnostic and therapeutic method for carrying out procedures in small vessels by utilizing a miniaturized balloon catheter assembly including a resilient cannula adapted for attachment to a source of pressurized fluid and having a small outer diameter for insertion into small vessels and an inflatable balloon having a mouth means constructed of self-sealing material for forming an opening into said balloon, through which said balloon can be inflated, but which can be closed to maintain said balloon in an inflated state, said balloon being mounted on the end of the cannula in fluid communication therewith, said method comprising the steps of: inserting the distal end of said cannula into the mouth means of said inflatable balloon so that said balloon can be inflated and deflated via said cannula;   attaching said inflatable balloon to said resilient cannula with a resilient contracting member by surrounding said mouth means with said resilient contracting member and thereby contracting said balloon onto said resilient cannula, said resilient contracting member comprising a single strand element which does not extend about said mouth means a plurality of times, said contracting member contracting about said balloon portion to hold said balloon on said cannula with a uniform tension when said balloon is mounted on said cannula to close said opening when said balloon is not mounted on said cannula;   inserting the balloon catheter assembly into a small vessel;   attaching the cannula to a source of pressurized fluid and pressurizing the balloon portion to partially inflate the balloon portion to permit the balloon portion and attached cannula to be directed by the fluid flow within the vessel to the desired location;   further inflating the balloon portion to fix the balloon portion in position;   increasing the fluid pressure inside the balloon portion to expand said resilient contracting member; and   withdrawing said cannula from said mouth means to allow said resilient contracting member to contract and thereby close said balloon mouth means to retain said inflated balloon fixed in position. .Iaddend.