Implantable biocompatible expander suitable for treatment of constrictions of body lumen

Abstract

An implantable biocompatible expander suitable for implantation into a urinary duct, comprises an elongated sinusoidal ring comprising at least two proximal prongs and at least two distal prongs, wherein the expander is resiliently deformable from a relaxed radially expanded orientation to a radially contracted orientation suitable for transluminal delivery through the urinary duct. The expander is configured to exert an outward radial force against a wall of the urinary duct when in-situ within the urinary duct. In particular, the expander is suitable for treatment of benign prostatic hyperplasia and configured for implantation into the prostatic urethra between, and substantially spanning the prostatic urethra between, the bladder neck and external sphincter.

1 . A method of treating benign prostatic hyperplasia in a patient, the method comprising:
 by transluminal delivery through the patient's urethra, positioning an expandable implant, in a contracted configuration, at a target location within the patient's prostatic urethra, the implant having at least three proximal prongs; and   at the target location, resiliently self-expanding the implant from the contracted configuration to effect dilation of the prostatic urethra while causing the at least three proximal prongs of the implant to sit within respective ones of the most lateral triangular recesses of the prostatic urethra.   
     
     
         2 . The method as claimed in  claim 1 , wherein each proximal prong is connected to longitudinal struts and said dilation of the prostatic urethra is effected by pressing those longitudinal struts against a wall of the prostatic urethra. 
     
     
         3 . The method as claimed in  claim 2 , comprising flexing one or more of the longitudinal struts to follow a wall shape of the prostatic urethra. 
     
     
         4 . The method as claimed in  claim 3 , comprising flexing one or more of the longitudinal struts to follow changes in the wall shape of the prostatic urethra. 
     
     
         5 . The method as claimed in  claim 2 , comprising spanning at least 50% of the length of the prostatic urethra by the longitudinal struts. 
     
     
         6 . The method as claimed in  claim 1 , wherein positioning the implant comprises locating the patient's verumontanum within an open area defined between adjacent longitudinal struts of the implant. 
     
     
         7 . The method as claimed in  claim 6 , wherein positioning the implant comprises positioning a distal prong of the implant distally with respect to the patient's verumontanum, that distal prong connecting said adjacent longitudinal struts. 
     
     
         8 . The method as claimed in  claim 7 , wherein said distal prong positioned distally with respect to the verumontanum also pushes against a median lobe of the prostatic urethra. 
     
     
         9 . The method as claimed in  claim 1 , wherein positioning the implant comprises positioning distal prongs of the implant such that when the implant is self-expanded, at least one of the distal prongs pushes against the transition zone of the patient's prostate gland to expand the lumen of the prostatic urethra at that location. 
     
     
         10 . The method as claimed in  claim 9 , wherein others of the distal prongs push against lateral lobes of the prostatic urethra. 
     
     
         11 . The method as claimed in  claim 1 , wherein the implant has a triangular cross-sectional shape and the method comprises orienting the implant to match that cross-sectional shape with a triangular cross-sectional shape of the prostatic urethra. 
     
     
         12 . The method as claimed in  claim 11 , wherein matching the cross-sectional shape of the implant with the cross-sectional shape of the prostatic urethra comprises aligning the at least three proximal prongs with the most lateral triangular recesses of the prostatic urethra. 
     
     
         13 . The method as claimed in  claim 11 , wherein matching the cross-sectional shape of the implant with the cross-sectional shape of the prostatic urethra comprises aligning at least three distal prongs of the implant with respective lobes of the prostatic urethra. 
     
     
         14 . The method as claimed in  claim 1 , wherein self-expanding the implant presses at least three distal prongs of the implant against walls of the prostatic urethra. 
     
     
         15 . The method as claimed in  claim 1 , wherein self-expanding the implant exerts an outward radial force against walls of the prostatic urethra. 
     
     
         16 . The method as claimed in  claim 15 , comprising exerting a greater outward radial force against the walls of the prostatic urethra at a proximal end and at a distal end of the implant than between those ends of the implant. 
     
     
         17 . The method as claimed in  claim 1 , wherein self-expanding the implant invaginates the implant into a wall of the prostatic urethra. 
     
     
         18 . The method as claimed in  claim 1 , comprising expanding the implant without a balloon. 
     
     
         19 . The method as claimed in  claim 1 , wherein positioning the implant at the target location comprises positioning a distal end of the implant at least 5 mm proximally from a neck of the patient's bladder. 
     
     
         20 . The method as claimed in  claim 1 , wherein positioning the implant at the target location comprises positioning a proximal end of the implant at least 5 mm distally from the patient's external urethral sphincter. 
     
     
         21 . The method as claimed in  claim 1 , comprising differentially flexing distal and proximal ends of the implant when at the target location. 
     
     
         22 . The method as claimed in  claim 21 , wherein differentially flexing the distal and proximal ends of the implant causes respective cross-sectional areas of the proximal and distal ends to vary relative to each other. 
     
     
         23 . The method as claimed in  claim 1 , wherein a radially-outwardly facing surface of the implant constitutes less than 10% of a total open area of the implant when the implant is self-expanded at the target location. 
     
     
         24 . A method of treating benign prostatic hyperplasia in a patient, the method comprising:
 by transluminal delivery through the patient's urethra, positioning an expandable implant, in a contracted configuration, at a target location within the patient's prostatic urethra by positioning a distal prong of the implant distally with respect to the patient's verumontanum; and   at the target location, resiliently self-expanding the implant from the contracted configuration to effect dilation of the prostatic urethra, accommodating the verumontanum within an open area defined between adjacent longitudinal struts of the implant that extend proximally from the distal prong.   
     
     
         25 . A method of treating benign prostatic hyperplasia in a patient, the method comprising:
 by transluminal delivery through the patient's urethra, positioning an expandable implant, in a contracted configuration, at a target location within the patient's prostatic urethra, the implant being a sinusoidal ring having at least three proximal prongs, at least three distal prongs and longitudinal struts that connect the proximal prongs to the distal prongs; and   at the target location, resiliently self-expanding the implant from the contracted configuration to effect dilation of the prostatic urethra by pressing the longitudinal struts against a wall of the prostatic urethra, each of the longitudinal struts spanning the wall of the prostatic urethra with inclination between the proximal prongs and the distal prongs.   
     
     
         26 . A method of positioning an expandable implant at a target location within a patient's prostatic urethra for treating benign prostatic hyperplasia in the patient, the method comprising:
 by transluminal delivery through the patient's urethra, positioning the expandable implant, in a contracted configuration, at the target location within the patient's prostatic urethra;   and, at the target location,   imaging the implant when positioning the implant;   orienting the implant, in dependence on said imaging, such that proximal prongs of the implant are aligned with respective most lateral triangular recesses of the prostatic urethra; and   resiliently self-expanding the implant from the contracted configuration to effect dilation of the prostatic urethra while causing the proximal prongs of the implant to sit within said respective recesses of the prostatic urethra.   
     
     
         27 . The method as claimed in  claim 26 , wherein imaging the implant is performed from within a hollow delivery device that delivers the implant to the target location. 
     
     
         28 . The method as claimed in  claim 27 , comprising illuminating a part of the prostatic urethra adjacent to a distal end of the delivery device.