Dynamically compliant catheter

Abstract

A catheter enabling a reduced puncture hole size into the skin and blood vessel is disclosed. In one embodiment, the catheter has an elongate body having an expandable sheath extending at least a portion of its length. A pressure constraining sheath is positioned to surround the expandable sheath, at a selected region to prevent expansion of the inner sheath at the region of the constraining sheath. In one preferred use, the constraining sheath is positioned at the puncture hole. During use, the catheter increases in cross-section by an expandable sheath expanding from a first diameter to a second diameter. However, the outer sheath does not expand, maintaining a small diameter at the puncture site.

I claim:  
     
         1 . A catheter for passing a fluid into a patient's body, the catheter comprising: 
 an elongate body, a portion of which is radially expandable by the force of a fluid passed therethrough; and    an outer sheath positioned around at least a portion of the elongate body, the outer sheath capable of constraining the expansion of the expandable sheath.    
     
     
         2 . The catheter according to  claim 1 , wherein the outer sheath is at least 5 cm in length.  
     
     
         3 . The catheter according to  claim 1 , wherein the outer sheath has an outer diameter of at least 1 mm in size.  
     
     
         4 . The catheter according to  claim 1 , wherein a wall thickness of the outer sheath is at least 0.004 mm.  
     
     
         5 . The catheter according to  claim 1 , wherein the outer sheath is capable of withstanding a pressure of at least about 500 p.s.i. without expanding or distorting in the radial direction.  
     
     
         6 . The catheter according to  claim 1 , wherein the outer sheath is capable of withstanding a pressure of at least about 750 p.s.i. without expanding or distorting in the radial direction.  
     
     
         7 . The catheter according to  claim 1 , wherein the outer sheath is capable of withstanding a pressure of at least about 1000 p.s.i. without expanding or distorting in the radial direction.  
     
     
         8 . The catheter according to  claim 1 , wherein the outer sheath is capable of withstanding a pressure of at least about 1200 p.s.i. without expanding or distorting in the radial direction.  
     
     
         9 . The catheter according to  claim 1 , further comprising a backbone which can be located transmurally or intralumenally.  
     
     
         10 . The catheter according to  claim 9 , wherein the backbone is removable and replaceable in or out of the body.  
     
     
         11 . The catheter according to  claim 9 , wherein the backbone is at least 60 cm in length.  
     
     
         12 . The catheter according to  claim 9 , wherein the backbone comprises Ni-Ti shape-memory alloy.  
     
     
         13 . The catheter according to  claim 1 , wherein a portion of the elongate body is radially expandable by a twist and lock mechanism.  
     
     
         14 . The catheter according to  claim 1 , wherein a portion of the elongate body is radially expandable by direct control of a user.  
     
     
         15 . The catheter according to  claim 1 , wherein the outer sheath is made from a material selected from the group consisting of metals, plastics and composites.  
     
     
         16 . The catheter according to  claim 9 , further comprising an inner expandable sheath that extends the length of the catheter.  
     
     
         17 . The catheter according to  claim 16 , wherein the inner sheath surrounds the backbone.  
     
     
         18 . The catheter according to  claim 16 , wherein the inner sheath is radially expandable by the force of a fluid passed therethrough.  
     
     
         19 . The catheter according to  claim 18 , wherein the inner sheath is radially expandable in a controlled and repeatable manner.  
     
     
         20 . The catheter according to  claim 16 , wherein the inner sheath is radially expandable from one diameter to at least a second diameter, the second diameter being greater in size than the first diameter.  
     
     
         21 . The catheter according to  claim 20 , wherein the inner sheath has sufficient non-elastic material to provide a circumference related to the second diameter.  
     
     
         22 . The catheter according to  claim 21 , wherein the inner sheath is folded upon itself inside the outer sheath.  
     
     
         23 . The catheter according to  claim 16 , wherein the inner sheath is made from a material selected from the group consisting of metals, plastics and composites.  
     
     
         24 . The catheter according to  claim 23 , wherein the inner sheath comprises polymeric materials  
     
     
         25 . The catheter according to  claim 24 , where in the inner sheath comprises elastic.