United States Patent
`Fischell et al.
`
`19)
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,768,507
`Sep. 6, 1988
`
`[54]
`
`[75]
`
`[73]
`
`[21]
`
`[22]
`
`INTRAVASCULAR STENT AND
`PERCUTANEOUS INSERTION CATHETER
`SYSTEM FOR THE DILATION OF AN
`ARTERIAL STENOSIS AND THE
`PREVENTION OF ARTERIAL RESTENOSIS
`
`Inventors: Robert E. Fischell, Silver Spring,
`Md.; Tim A. Fischell, Palo Alto,
`Calif.
`
`Assignee: MedInnovations, Inc., Dayton, Md.
`
`Appl. No.: 93,110
`
`Filed:
`
`Aug, 31, 1987
`
`Related U.S. Application Data
`Continuation of Ser. No. 832,216, Feb. 14, 1986, aban-
`doned.
`
`Innt. C14 vos eecscccsetesesseesteceesseensenrserssees A61B 17/00
`WLS. CD. ceecccsesecsseseceserereseneeee 128/303 R; 128/341
`
`Field of Search...............00+ 128/303 R, 341, 343,
`128/345, 334 R, 348.1; 623/1
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3/1985 Dotter 0...cee 128/303 R X
`4,503,569
`4,553,545 11/1985 Maasset al. ou... ceesssseereee 128/341
`
`Primary Examiner—Michael H. Thaler
`Attorney, Agent, or Firm—Howard W.Califano
`
`ABSTRACT
`(57]
`This invention is in the field of percutaneous insertion
`catheters that are used for placing a coil spring stent
`into a vesselofa living body for the purposes of enhanc-
`ing luminal dilation, preventing arterial restenosis and
`preventing vessel blockage resulting from intimal dis-
`section following balloon and other methodsofangio-
`plasty. The stent can also be used for the maintaining
`patency of many different ducts or vessels within a
`living body.
`
`6 Claims, 3 Drawing Sheets
`
`
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 1
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 1
`
`

`

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`US. Patent—Sep. 6, 1988 Sheet1 of3 4,768,507
`
`
`
`
`
`FIG. 1B
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`
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`FIG. 1€
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 2
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`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 2
`
`

`

`
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`US. Patent—Sep. 6, 1988 Sheet 2 of 3 4,768,507
`
`
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`
`
`FIG. 8
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 3
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`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 3
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`

`

`2a
`
`a2
`
`a we 2, we
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`a£= > 3
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`
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`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 4
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`

`

`1
`
`4,768,507
`
`INTRAVASCULAR STENT AND PERCUTANEOUS
`INSERTION CATHETER SYSTEM FOR THE
`DILATION OF AN ARTERIAL STENOSIS AND
`THE PREVENTION OF ARTERIAL RESTENOSIS
`
`This is a continuation of co-pending application Ser.
`No. 832,216, filed on 2-14-86, now abandoned.
`
`BACKGROUNDOF THE INVENTION
`
`In the last decade there has been increasing use of
`percutaneoustransluminal balloon angioplasty for the
`opening of stenoses of the peripheral and coronary
`arteries. In this procedure the uninflated balloon at the
`tip of the catheter is advanced into the narrowed por-
`tion ofthe arterial lumen. Theballoonis then inflated so
`as to push the stenotic plaque outward thereby enlarg-
`ing the luminal diameter and improvingdistal perfusion.
`Theballoon is then deflated and the catheter is with-
`drawn from the body.Initially the blood flow at that
`point is typically improved to a significant degree.
`However, within six months, restenosis, defined as a
`loss of more than 50% oftheinitial enlargment ofarte-
`rial diameter, occurs in approximately 30% of cases. It
`would therefore be of great value if a means could be
`devised to retain patency (i.e. opening) of the artery so
`that adequate blood flow would be maintained.
`The concept of placing a coil spring intravascular
`stent within an artery is not new. In the September-
`October 1969 edition of Investigative Radiology, C. T.
`Dotter reported the insertion of 6 coil spring intravas-
`cular stents in the arteries of dogs. Three of these
`springs which were covered with silicone rubber oc-
`cluded within 24 hours. Twooutof three, bare stainless
`steel wire springs remained patent at 24 years. Dotter
`also described a “pusher-catheter” of equal diameter
`with the spring outer diameter which was used to place
`the springs within the artery.
`In more recent work, D. Maaset al in the September
`1984 edition of Radiology described improvedstainless
`steel coil spring intravascular stents that were implanted
`in 65 dogs and 5 calves. A 100% success rate was re-
`ported using bare, heat treated steel alloy springs that
`were torqued to a reduced diameter and inserted with a
`special device designed for that purpose.
`Neither Dotter nor Maas atall were able to perform
`a percutaneousprocedureforthe stent insertion. Dotter
`describes a “‘pusher-catheter” that was of equal diame-
`ter to the outside diameterof the coil spring. Maaset.al.
`used a 7 mm diameter special insertion device that ap-
`plied torque to the coil spring to reduce its diameter to
`7 mm;i.e., the deployed outside diameter was greater
`than 7 mm.Since the largest practical outside diameter
`for percutaneousdelivery is less than 4 mm, the device
`and methods used by Maas et al are not practical for
`percutaneousinsertion.
`The results of Dotter i.e. 2 of 3 patent arteries at the
`end of 24 years using comparatively small (3.5 mm)
`diameter coil are probably not good enough forclinical
`applications. The results of Maas et al were very good,
`but these were for inside diameters greater than 7 mm.
`Whatis really needed and not described by either
`Dotter or Maas et al or anyoneelse is a safe and simple
`method for percutaneoustransluminalinsertion of a coil
`spring stent whoseinsertion device structure allows an
`insertion catheter of outer diameter less than 4 mm.
`Another requirement of the insertion device is that it
`maintains the reduced diameter of the coil spring stent
`
`10
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`15
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`20
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`25
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`30
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`45
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`35
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`2
`during insertion and allowsthe coil to expand to a diam-
`eter greater than the diameterofthe arterial lumenafter
`removal of the insertion catheter.
`To makethe intravascular stent (IS) safe for human
`use even in small diameter coronaryarteries, it is neces-
`sary for the spring material to be biocompatible and
`non-thrombogenic. The greatest success by Dotter and
`Maaset al was with bare metal coil springs. However,
`no investigation to date has described use of these stents
`in either human subjects or in animal coronaryarteries.
`Furthermore, Dotter quotes an article which states that
`“It appears that success or failure of an arterial substi-
`tute in dogs bears no direct relationship to the results
`one will obtain when a similar substitute is used clini-
`cally for the peripheral arteries”. Hence one must be
`concerned with the human biocompatability of the ma-
`terial used for the IS.
`Manyarticles such as “ULTI Carbon Goretex: A
`New Vascular Graft” by R. Debski et al in the May-
`June 1983 edition of Current Surgery describe the supe-
`rior non-thrombogenic characteristics of ultra low-tem-
`perature isotropic (ULTI) carbonas such a blood com-
`patible material. The use of carbon as a blood compati-
`ble material for humans is well known among those
`skilled in the art of vascular grafts and prosthetic heart
`valves. However, no investigator of IS devices has ever
`described the use. of carbon coated coil springs or car-
`bon coated polytetrafluoroethylene (PTFE) covered
`coil springs to solve the problem of thrombosis of small
`diameter IS devices in humans.
`It should be noted that nothing in the prior art de-
`scribes the use of a coil spring stent for the prevention
`of arterial blockage due to intimal dissection (tearing
`awayofthe intima layer) following balloon angioplasty.
`There is appproximately a 30% incidenceof radiologi-
`cally detectable intimal dissection following routine
`percutaneous
`transluminal:
`coronary
`angioplasty
`(PTCA). In many of these cases this is not a problem.
`Vessel wall healing and remodeling typically restores a
`smooth luminal contour with good vessel patency
`within several weeks following the angioplasty. In a
`small but significant subset of these patients, the intimal
`dissection may be severe, resulting in a high risk of
`vessel closure within 24 hours following PTCA. These
`patients will typically sustain some degree of myocar-
`dial infarction despite further aggressive attempts at
`revascularization,
`including coronary artery bypass
`surgery.
`
`SUMMARYOF THE INVENTION
`
`Thus it is an objective of the present invention to
`utilize a coil spring intravascular stent (IS) for the pre-
`vention of arterial restenosis.
`A second objective of the inventionis to utilize an IS
`to further enlarge the luminal diameter after successful
`percutaneous transluminal angioplasty.
`Another objective is to provide a percutaneoustran-
`sluminal catheter meansfor placing the IS at the appro-
`priate place within the artery.
`Still another objective is to describe a method for
`percutaneousinsertion of intravascularstents.
`Still another objective is to provide a means and
`method for preventing arterial blockage due to intimal
`dissection following balloon or other types of angio-
`plasty.
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 5
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 5
`
`

`

`3
`
`4,768,507
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`4
`1. A pair ofpliers is used to hold the most distal por-
`tion of the IS 10 into the most distal spiral groove
`26 of the inner core 22.
`2. The spring IS 10 is then pulled and twisted apply-
`ing torque to its most proximal end so that the
`spring IS 10 is forced into the spiral grooves 26.
`3. A pliers wide enough to hold all turns of the IS 10
`in place except the most proximal turn and the most
`distal turn is then applied at the center of the IS 10
`to hold it in the spiral grooves 26.
`A needle nose pliers is then used to force the most
`proximal turn of the IS 10 into the core groove 28.
`5. The conical interior surface 34 of the cylindrical
`handle 32 is then fed over the most distal turn of the
`IS 10 asit sits in the most distal groove 26 of the
`core 22.
`6. As the handle 32 is moved in the proximal direc-
`tion, the broad pliers holding the central portion of
`the IS 10 in place is simultaneously moved in the
`proximal direction until the entire IS 10 is covered
`by the interior surface of the handle 32 and the
`outer cylinder 24.
`7. The handle 32is then pulled in a proximal direction
`until the distal end of the cylinder 24 lies just over
`the last turn of the IS 10 which occurs when the
`cylinder handle 32 and the core handle 36 are sepa-
`rated by a distance D as shownin FIG.4.
`In this manner, a coil spring IS 10 whose unrestrained
`(i.e. free) diameter can be between 1.1 to 5.0 times larger
`than its diameter when stored on the core 22 can be
`placed at the distal end of the insertion catheter 20.
`Deployment of the spring IS 10 within a recently
`dilated occlusion is accomplishedin the following steps:
`1. By conventional means, a guiding catheter (not
`shown)is placed percutaneously into the femoral
`artery and its distal end is advanced to thesite
`where the IS 10 is to be released.
`2. Under fluoroscopic control, the insertion catheter
`20 is advanced through the guiding catheter until
`the center of the IS 10 is positioned at the center of
`the recently dilated stenosis.
`3. While holding the core handle 36 firmly against the
`body so that it does not move, the outer cylinder
`handle 32 is move proximally so as to decrease to
`zero the distance D of FIG.4:
`4. All turns of the IS 10 except the most proximal turn
`are then expanded outward to engagethe interior
`surface of the recently dilated stenosis.
`5. The core 22 and the outer cylinder 24 are then
`pulled out of the body together which leaves the
`coil spring IS 10 in its desired place in the artery.
`An angioplasty balloon could then be expanded
`within the IS 10 so as to morefirmly imbed the spring
`into the stenotic plaque. The balloon and guiding cathe-
`ters would of course be removed from the body after
`they were used for their intended purposes.
`Thecoil spring used in this manner would:
`1. Prevent restenosis of the occlusion.
`2. Increase the lumen diameter by constantly apply-
`ing an outward radial force to the plaque, and
`3. Hold in place any intima layer torn from the steno-
`sis during balloon dilation which might otherwise
`tend to block blood flow in that artery.
`The materials of the core 22, core handle 36, outer
`cylinder 24 and outercylinder handle 32 might be PVC
`or some other comparatively strong plastic. The IS 10
`might be fabricated from a stainless spring steel or an
`alloy oftitanium such as Ti-6A1-4V. The outside diame-
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIGS.1A, 1B and 1C are cross-sectional views show-
`ing respectively the shape of the plaque within an arte-
`rial wall, (A) before balloon dilation, (B) immediately
`after balloon dilation, and (C) at several monthsafter
`dilation.
`FIG.2 is a cross-sectional view of an IS in the form
`of a coil spring placed in a position to prevent restenosis
`and/or provide additional dilation of the plaque.
`FIG.3 is a cross-sectional view ofthe distal end of an
`insertion catheter for inserting theIS.
`FIG.4 is a cross-sectional view of the proximal end
`of the insertion catheter.
`FIG.5 is a cross-sectional view of a wire coated with
`ULTIcarbon.
`FIG.6 is a cross-sectional view of a wire enclosed by
`PTFEand coated with ULTI carbon.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`FIGS. 1A, 1B and 1Care cross-sectional views of an
`arterial wall AW surrounding a plaque P which forms
`an arterial stenosis or narrowing.It is well knownin the
`art to utilize percutaneous transluminal balloon angio-
`plasty to dilate the stenosis of FIG. 1A by expanding a
`balloon that is placed within the narrowed lumen. The
`result immediately after balloon dilation is shown in
`FIG.1B. However,in approximately 30% ofall balloon
`procedures, there is a restenosis of the artery as illus-
`trated in FIG. 1C.
`If however, a coil spring intravascular stent (IS) 10 is
`placed at the dilation site immediately after balloon
`dilation in a position as shown in FIG.2, the resistance
`of the IS 10 to deformation by inwardly directed radial
`pressure can preclude restenosis of the artery. Further-
`more,if the constrained diameter of that IS 10 as shown
`in FIG.2 is less then the free diameterof the coil spring
`IS 10, then additional dilation may occur following the
`insertion of the IS 10. Furthermore,if the intima layer
`was torn (i.e. dissected) during balloon dilation, the IS
`10 can hold that intima layer in place and prevent subse-
`quent blockage of the artery which can result from the
`effect of blood flow causing the torn intima to comeoff
`the wall of the dilated stenosis.
`FIG. 3 showsthe distal end of the insertion catheter
`20 which consists of an inner core 22 and an outercylin-
`der 24. The core 22 has a rounded andtapered front end
`23 and spiral grooves 26 into which the coil spring IS 10
`is placed. The core 22 has a back groove 28 which
`contains the most proximal coil of the coil spring IS 10
`which is prevented from springing radially outward by
`the flange 30.
`FIG.4 is a cross-sectional view of the proximal end
`of the insertion catheter 20. A cylindrically shaped
`cylinder handle 32 is molded onto the outer cylinder 24.
`Similarly, a cylindrically shaped core handle 36 is
`molded onto the core 22. A conically shaped interior
`surface 34 of the cylinder handle 32 is used to help guide
`the cylinder handle 32 over the IS 10 as it is mounted on
`the distal end of the insertion catheter 20. The distance
`D in FIG.4 is initially set to be slightly greater than the
`length of the IS 10 at the distal end of the insertion
`catheter 20.
`.
`The spring IS 10 is loaded onto the distal end of the
`core in the following manner:
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`350
`
`55
`
`65
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 6
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 6
`
`

`

`4,768,507
`
`5
`ter of the unrestrained coil spring IS 10 might vary from
`2 to 12 mm depending on the lumen diameter into
`whichit is implanted. The wire diameter might be be-
`tween 0.1 and 0.5 mm. The outer diameter of the outer
`cylinder 24 would be less than 4 mm. Thelength of the
`IS 10 would be between 5 and 25 mm depending upon
`the length of the dilated stenosis into which it would be
`placed.
`Decreased thrombogenicity can be achieved by coat-
`ing the outside of the coil with a non-thrombogenic
`material such as ULTI carbon. An enlarged cross sec-
`tion of such a wire is shownin FIG.4. The metallic core
`is shown as 40 and the coating is shown as 42. Coating
`thickness might be as thin as 0.01 mm oras thick as 0.1
`mm.
`
`6
`position covering said spiral groove of said inner
`core member to a second position exposing the
`spiral groove of said inner core member, wherein
`cooperation of the spiral groove of said inner core
`member with the inner surface of said hollow
`sheathing cylinder formsa spiral cavity adapted to
`contain a coil stent when said sheathing cylinder is
`in said first position; and,
`a coil stent held in a radially compressed state within
`said spiral cavity by exerting a radial outward force
`on said sheathing cylinder when said sheathing
`cylinderis in its first position, and is released from
`said spiral cavity and expandable byits intrinsic
`mechanical properties to a larger diameter when
`said sheathing is in its second position without the
`FIG. 5 shows another enlarged cross section of the
`requirementofrelative axial rotation between the
`wire of the IS 10 in which the metallic core 40 is first |
`inner core member and the outer sheathing cylin-
`covered by a plastic layer 44 such as PTFE and then
`der.
`coated with a nonthrombogenic coating 46 such as
`2. The apparatus of claim 1, wherein said inner core
`ULTIcarbon. Theplastic coating would typically be
`member further comprises a flange means, adapted to
`between 0.05 and 0.5 mm and the non-thrombogenic
`frictionally engage the proximal end of said coil stent.
`coating might have a thickness between 0.01 and 0.5
`3. The apparatus of claim 2, wherein said flange
`mm.
`means comprises:
`Althoughthis intravascular stent mightfind its great-
`a back groove cut into the surface of said inner core
`est application as a means to enhance balloon angio-
`memberand adapted to contain the proximal end of
`plasty in humansit could also be used to successfully
`said coil stent; and,
`provide permanentdilation and patency of other ducts
`a flange located adjacent to said back groove and
`and vessels within a living human or animal body. For
`adapted to prevent radial movementof said coil
`example, this coil spring intravascular stent 10 could
`stent whichis frictionally engaged.
`also be used to maintain long term patencyofureters or
`-4, The apparatus of claim 1, wherein said inner core
`fallopian tubes. In every use, the fact that wire diameter
`member comprises a rounded and tapered distal end.
`would be typically 1/10 the coil spring pitch length i.e.,
`5. The apparatus of claim 1, further comprising a
`only 10% of the lumeninterior surface is actually in
`control meansof movingthedistal end of said sheathing
`contact with a foreign material. Therefore, normal body
`cylinder from said first position to said second position
`cells could grow over the coils of such springs. Thus,
`relative to the distal end of said inner core member and
`the normal characteristics of the interior lining of such
`deploying said coil stent without the requirement of
`ducts or vessels would be only minimally compromised.
`axial rotation of the outer sheathing cylinderrelative to
`Various other modifications, adaptations, and alterna-
`the inner core member.
`tive designsare, of course, possible in light of the above
`6. The apparatusof claim 5, wherein the proximal end
`teachings. Therefore, it should be understood at this
`of said sheathing cylinder and said inner core member
`time that within the scope of the appendedclaims, the
`extend external to said living body, and wherein said
`invention may be practiced otherwise than as specifi-
`control means comprises a first handle operably cou-
`cally described herein.
`Whatis claimed is:
`pled to a proximal portion of said sheathing cylinder,
`and a second handle operably coupled to a proximal
`1. A stent insertion apparatus comprising: an inner
`portion of said inner core member, wherein movement
`core member having distal and proximal ends and a
`of said first handle toward said second handle causes
`spiral groove formed onits outer surface;
`movement of the distal ends of said sheathing cylinder
`a hollow outer sheath cylinder having distal and
`from said first position to said second position relative
`proximal ends and having an inner surface slidably
`30
`to said inner core memberso as to release said coil stent.
`mounted around said inner core member and mov-
`*
`*
`*
`*
`*.
`able relative to said inner core memberfromafirst
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`35
`
`65
`
`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 7
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`Petitioner Edwards Lifesciences Corporation - Exhibit 1010 - Page 7
`
`