Medical Device for Fluid Flow and Method of Forming Such Device

Abstract

A medical device which defines a lumen for flowing a bodily fluid from an upstream end of the device to a downstream end thereof is disclosed. The device has a luminal wall ( 14 ) that extends between the upstream and downstream ends and defines the lumen within which the fluid flows. The wall exhibits a succession of protuberances spaced from each other along the length of the device. Each protuberance has a flank facing upstream ( 54 ) and a flank facing downstream ( 64 ), the flank facing upstream extending into the fluid flow so that a radially outermost part of the flow of fluid from the upstream to the downstream end of the device impinges on the upstream flank and is thereby caused to reverse its flow, and flow upstream from the upstream flank to the downstream flank of the next adjacent protuberance upstream, creating micro-vortices between two adjacent protuberances.

1 . A method of producing a medical device for implantation in a human or animal body, comprising:
 providing a medical device including a wall defining a lumen;   forming a succession of protuberances in the wall, each protuberance having a flank facing upstream and a flank facing downstream, the flank facing upstream extending into fluid flowing into the lumen so that a radially outermost part of a fluid flow from the upstream to the downstream end of the device impinges on the upstream flank and is thereby caused to reverse its flow and flow upstream from the upstream flank to the downstream flank of an adjacent protuberance upstream, creating micro-vortices between adjacent protuberances.   
     
     
         2 . The method of  claim 1 , wherein the providing step comprises extruding an extruded section that includes the wall. 
     
     
         3 . The method according to  claim 2 , wherein the forming step includes forming the protuberances during extrusion of the extruded section. 
     
     
         4 . The method according to  claim 2 , wherein the forming step includes forming the protuberances subsequent to extrusion of the extruded section. 
     
     
         5 . The method according to  claim 1 , wherein the forming step includes forming the protuberances by using at least one rotating forming tool. 
     
     
         6 . The method according to  claim 1 , wherein the forming step includes forming the protuberances by using two counter-rotating forming tools. 
     
     
         7 . The method according to  claim 1 , further comprising inverting the medical device prior to forming the protuberances and/or a succession of micro-protuberances. 
     
     
         8 . The method according to  claim 7 , wherein a laser is used to form the protuberances and/or micro-protuberances. 
     
     
         9 . The method according to  claim 1 , wherein the forming step comprises attaching a foil bearing the protuberances and/or a succession of micro-protuberances to the wall. 
     
     
         10 . A medical device for implantation in a human or animal body, comprising:
 an elongated member that extends from a first opening to a second opening to permit blood flow therethrough, the elongated member defining a longitudinal axis extending through the first and second openings and having an inner surface and an outer surface cincturing the longitudinal axis,   the inner surface including a plurality of protrusions and indentations adjacent to each other, the protrusions and indentations extending along the longitudinal axis and being exposed to the longitudinal axis,   each of the plurality of protrusions and indentations disposed so that each protrusion forms a curved surface that circumscribes the longitudinal axis and is positioned generally transversely thereto, the curved surface being disposed between a first indentation and a second indentation spaced apart along the longitudinal axis.   
     
     
         11 . The medical device according to  claim 10 , wherein the protrusions comprise cusps and the indentations comprise troughs. 
     
     
         12 . The medical device according to  claim 11 , wherein the first trough has, in a cross-section taken along the length of the member, a first radius of curvature and the second trough has, in a cross-section taken along the length of the member, a second radius of curvature. 
     
     
         13 . The medical device according to  claim 12 , wherein the first radius of curvature is generally equal to the second radius of curvature. 
     
     
         14 . The medical device according to  claim 12 , wherein the first radius of curvature is not equal to the second radius of curvature. 
     
     
         15 . The medical device according to  claim 12 , wherein at least one of the cusps comprises, in a cross-section taken along the length of the member, a third radius of curvature. 
     
     
         16 . The medical device according to  claim 15 , wherein each of the first and second radii of curvature comprises a plurality of fourth radii of curvature. 
     
     
         17 . The medical device according to  claim 16 , wherein each of the length of the plurality of fourth radii of curvature is about 0.1 times the length of at least one of the first and second radii. 
     
     
         18 . The medical device according to  claim 10 , wherein at least one of the protrusions extends in a radial direction towards the longitudinal axis over a protrusion distance of about 0.05 times that of a radial distance from the outer surface of the member to the longitudinal axis. 
     
     
         19 . The medical device according to  claim 18 , wherein each of at least two protrusions adjacent to each other along the longitudinal axis includes an inflection point defining a peak of the protrusion so that a separation distance between the two peaks of the at least two adjacent protrusions along the longitudinal axis is about 2 times to about 6 times the protrusion distance. 
     
     
         20 . The medical device according to  claim 19 , wherein each of at least three adjacent protrusions includes an inflection point defining a peak of the protrusion so that a separation distance between adjacent peaks of the at least three protrusions is generally equal to a separation distance between other adjacent peaks of the at least three protrusions. 
     
     
         21 . The medical device according to  claim 20 , wherein the protrusions and indentations include a generally sinusoidal configuration. 
     
     
         22 . The medical device according to  claim 20 , wherein a flow of a fluid in the elongated member is laminar as indicated by a Reynolds number for the flow condition through the elongated member where the fluid is adapted to simulate blood and having an average density of about 1.05 g/cm3 and an average viscosity of about 1/30 poise. 
     
     
         23 . The medical device according to  claim 22 , wherein the Reynolds number is less than about 2000. 
     
     
         24 . The medical device according to  claim 23 , wherein the Reynolds number is less than about 200. 
     
     
         25 . The medical device according to  claim 24 , wherein the Reynolds number is less than about 1. 
     
     
         26 . The medical device according to  claim 22 , further comprising a stent structure coupled to the outer surface of the elongated member. 
     
     
         27 . The medical device according to  claim 26 , wherein the stent comprises a plurality of stent cylinders connected by a plurality of connectors. 
     
     
         28 . The medical device according to  claim 19 , wherein each of at least three adjacent protrusions includes an inflection point defining a peak of the protrusion so that a separation distance between adjacent peaks of the at least three protrusions is not equal to a separation distance between other adjacent peaks of the at least three protrusions. 
     
     
         29 . The medical device according to  claim 10 , wherein the protrusions and indentations comprise a series of undulations. 
     
     
         30 . The medical device according to  claim 29 , wherein the series of undulations comprises, in a cross-section taken along the longitudinal axis of the member, a sinusoidal surface. 
     
     
         31 . The medical device according to  claim 29 , wherein the series of undulations comprises, in a cross-section taken along the longitudinal axis of the member, a sawtooth surface. 
     
     
         32 . A method of reducing thrombogenicity in blood contacting surfaces, comprising:
 providing an elongated member of a synthetic material having a proximal opening, a distal opening and an inner surface surrounding a longitudinal axis extending through the openings;   flowing a fluid through the member, the fluid having average physical characteristics of mammalian blood; and   generating a plurality of vortices in sequence on the inner surface along the direction of fluid flow as the fluid moves from the proximal opening to the distal opening.