Systems and methods for variable stiffness tethers

Abstract

Described herein are devices and methods for guide elements configured with variable stiffness, with one or more flexible portions and one or more stiff portions. The flexible portion is be used as a tensioning element of a cinchable implant to tighten or compress tissues while the stiff portion is used to facilitate the insertion or withdrawal of portions of the implant or instruments acting on the implant. The guide element is further configured to be separated or severed between the flexible and stiff portions so that a flexible portion is left within the body as part of the implant, while the stiff portion is withdrawn from the body after implantation is completed.

1 . A tether-anchor assembly comprising:
 a tether comprising a rigid proximal portion and a flexible distal portion releasably attached the rigid proximal portion; and   a tissue-piercing anchor comprising an eyelet, wherein the flexible distal portion of the tether is coupled to the eyelet.   
     
     
         2 . The tether-anchor assembly of  claim 1 , wherein the anchor is fixedly coupled to said flexible distal portion of said tether via a knot assembly. 
     
     
         3 . The tether-anchor assembly of  claim 1 , wherein the flexible portion has a first torsional stiffness and the rigid portion has a second torsional stiffness that is higher than the first torsional stiffness. 
     
     
         4 . The tether-anchor assembly of  claim 1 , wherein the force required to cause the rigid portion to yield in a compression test is greater than the force required to cause the flexible portion to yield in a compression test. 
     
     
         5 . The tether-anchor assembly of  claim 1 , wherein the proximal portion comprises a first portion and a second portion, wherein the first portion is more rigid than the second portion. 
     
     
         6 . A tether, comprising:
 a core element having a distal portion and a proximal portion;   wherein said proximal portion is located in a tubular sheath, said sheath having a higher torsional stiffness than said core element; and   wherein said distal portion is configured to be used as a tensioning element and detachable from said proximal portion of said core element.   
     
     
         7 . The tether as in  claim 6 , wherein said sheath is made from a biodegradable material. 
     
     
         8 . The tether as in  claim 6 , wherein said sheath is made from a non-biodegradable material. 
     
     
         9 . The tether as in  claim 6 , wherein said distal portion is in the range of from about 5 cm to about 30 cm in length. 
     
     
         10 . The tether as in  claim 6 , wherein said sheath is slidably disposed along longitudinal axis of said core element. 
     
     
         11 . A tether, comprising:
 a core element having a distal portion and a proximal portion;   wherein said proximal portion is coated with a material to increase proximal torsional stiffness of said core element; and   wherein said distal portion is configured to be used as a tensioning element and detachable from said proximal portion of said core element.   
     
     
         12 . A method of using a tether having a flexible distal portion and a rigid proximal portion, comprising:
 advancing said tether to a predetermined location;   advancing a surgical device over said tether;   detaching said distal portion from said proximal portion; and   proximally withdrawing said proximal portion.   
     
     
         13 . The method as in  claim 12 , wherein detaching said distal portion further comprises advancing a cutting device over said tether and cutting said distal portion from said proximal portion. 
     
     
         14 . The method as in  claim 12 , further comprising positioning a plurality of anchors along said distal portion. 
     
     
         15 . The method as in  claim 14 , further comprising attaching the plurality of anchors to cardiac tissue.