Expandable cannula
DCFirst Claim
1. A cannula comprising a longitudinally extending tubular sheath having a main passage, a variable volume chamber connected with said sheath and disposed adjacent to one end portion of said sheath, said one end portion of said sheath and said variable volume chamber being insertable into body tissue, said variable volume chamber being expandable under the influence of fluid pressure from a contracted condition to an extended condition in which said variable volume chamber projects outward of a side surface of said sheath when said one end portion of said sheath and said variable volume chamber are disposed in body tissue to retard withdrawal of said one end portion of said sheath from body tissue when said one end portion of said sheath is disposed in body tissue, a plurality of wires which are enclosed by said sheath and extend along an inner side of said sheath, and a conduit which is enclosed by said sheath and extends along an inner side of said sheath to said variable volume chamber, said conduit being disposed between adjacent wires of said plurality of wires, said conduit being adapted to be connected in fluid communication with a source of fluid pressure to enable said conduit to conduct fluid pressure to said variable volume chamber to effect expansion of said variable volume chamber from the contracted condition to the extended condition when said one end portion of said sheath and said variable volume chamber are disposed in body tissue.
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Abstract
Cannulas for surgical and medical use expand along their entire lengths. The cannulas are inserted through tissue when in an unexpanded condition and with a small diameter. The cannulas are then expanded radially outwardly to give a full-size instrument passage. Expansion of the cannulas occurs against the viscoelastic resistance of the surrounding tissue. The expandable cannulas do not require a full depth incision, or at most require only a needle-size entrance opening. In one embodiment of the invention, the cannula has a pointed end portion. In this embodiment of the invention, the cannula includes wires having cores which are enclosed by jackets. The jackets are integrally formed as one piece with a sheath of the cannula. The cannula may be expanded by inserting members or by fluid pressure. The cannula is advantageously utilized to expand a vessel, such as a blood vessel. An expandable chamber may be provided at the distal end of the cannula.
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Citations
45 Claims
- 1. A cannula comprising a longitudinally extending tubular sheath having a main passage, a variable volume chamber connected with said sheath and disposed adjacent to one end portion of said sheath, said one end portion of said sheath and said variable volume chamber being insertable into body tissue, said variable volume chamber being expandable under the influence of fluid pressure from a contracted condition to an extended condition in which said variable volume chamber projects outward of a side surface of said sheath when said one end portion of said sheath and said variable volume chamber are disposed in body tissue to retard withdrawal of said one end portion of said sheath from body tissue when said one end portion of said sheath is disposed in body tissue, a plurality of wires which are enclosed by said sheath and extend along an inner side of said sheath, and a conduit which is enclosed by said sheath and extends along an inner side of said sheath to said variable volume chamber, said conduit being disposed between adjacent wires of said plurality of wires, said conduit being adapted to be connected in fluid communication with a source of fluid pressure to enable said conduit to conduct fluid pressure to said variable volume chamber to effect expansion of said variable volume chamber from the contracted condition to the extended condition when said one end portion of said sheath and said variable volume chamber are disposed in body tissue.
- 19. A cannula comprising a longitudinally extending tubular sheath having a main passage, a variable volume chamber connected with said sheath and disposed adjacent to one end portion of said sheath, a plurality of wires which are enclosed by said sheath and extend along an inner side of said sheath, surface means disposed on said one end portion of said sheath and on end portions of said wires for piercing body tissue, and a conduit which is enclosed by said sheath extends along an inner side of said sheath to said variable volume chamber, said conduit being adapted to be connected in fluid communication with a source of fluid pressure to enable said conduit to conduct fluid pressure to said variable volume chamber to effect expansion of said variable volume chamber from the contracted condition to the extended condition when said one end portion of said sheath and said variable volume chamber are disposed in body tissue.
- 23. A cannula comprising a longitudinally extending tubular sheath formed of a material capable of being expanded from a contracted condition in which a longitudinally extending passage through the tubular sheath has a relatively small cross sectional size to an expanded condition in which the passage has a relatively large cross sectional size, a plurality of wires enclosed by said sheath, said wires being disposed in a longitudinally extending array along an inner side of said sheath, said longitudinally extending array of wires having a relatively small cross sectional size when said sheath is in the contracted condition and a relatively large cross sectional size when said sheath is in the expanded condition, said wires having longitudinal central axes which are disposed in a parallel relationship when said sheath is in the contracted condition and when said sheath is in the expanded condition, and a flexible portion is connected with said sheath and is expandable outward of an outer side surface of said sheath to engage body tissue when said sheath is in the expanded condition.
- 30. A cannula comprising a longitudinally extending tubular sheath formed of a material capable of being expanded from a contracted condition in which a longitudinally extending passage through the tubular sheath has a relatively small cross sectional size to an expanded condition in which the passage has a relatively large cross sectional size, a plurality of wires enclosed by and connected with said sheath, said wires being disposed in a longitudinal extending array along an inner side of said sheath, said longitudinally extending array of wires has a relatively small cross sectional size when said sheath is in the contracted condition and a relatively large cross sectional size when said sheath is in the expanded condition, a flexible portion is connected with said sheath and is expandable under the influence of fluid pressure to engage body tissue when said sheath is in the expanded condition, and a fluid conduit enclosed by and connected with said sheath and extending along an inner side of said sheath to said flexible portion, said conduit being effective to conduct fluid pressure to said flexible portion to effect expansion of said flexible portion, said conduit being spaced a first distance from a longitudinal central axis of said sheath when said sheath is in the contracted condition and being spaced a second distance from the longitudinal central axis of said sheath when said sheath is in the expanded condition, said second distance being greater than said first distance, said conduit being disposed between adjacent wires in said longitudinally extending array of wires when said sheath is in the contracted condition and when said sheath is in the expanded condition.
- 36. A cannula comprising a longitudinally extending tubular sheath formed of a material capable of being expanded from a contracted condition in which a longitudinally extending passage through the tubular sheath has a relatively small cross sectional size to an expanded condition in which the passage has a relatively large cross sectional size, a plurality of wires enclosed by said sheath, said wires being disposed in a longitudinally extending array along an inner side of said sheath, said longitudinally extending array of wires having a relatively small cross sectional size when said sheath is in the contracted condition and a relatively large cross sectional size when said sheath is in the expanded condition, a flexible portion connected with said sheath and expandable outward of an outer side surface of said sheath to engage body tissue when said sheath is in the expanded condition, and surface means disposed on said sheath and on said wires for piercing body tissue when said sheath is in the contracted condition.
Specification