Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/12—Surgical instruments, devices or methods for ligaturing or otherwise compressing tubular parts of the body, e.g. blood vessels or umbilical cord
  • A61B17/12022—Occluding by internal devices, e.g. balloons or releasable wires
  • A61B17/12131—Occluding by internal devices, e.g. balloons or releasable wires characterised by the type of occluding device
  • A61B17/12181—Occluding by internal devices, e.g. balloons or releasable wires characterised by the type of occluding device formed by fluidized, gelatinous or cellular remodelable materials, e.g. embolic liquids, foams or extracellular matrices
  • A61B17/12186—Occluding by internal devices, e.g. balloons or releasable wires characterised by the type of occluding device formed by fluidized, gelatinous or cellular remodelable materials, e.g. embolic liquids, foams or extracellular matrices liquid materials adapted to be injected
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/01—Introducing, guiding, advancing, emplacing or holding catheters
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/12—Surgical instruments, devices or methods for ligaturing or otherwise compressing tubular parts of the body, e.g. blood vessels or umbilical cord
  • A61B17/12022—Occluding by internal devices, e.g. balloons or releasable wires
  • A61B17/12099—Occluding by internal devices, e.g. balloons or releasable wires characterised by the location of the occluder
  • A61B17/12109—Occluding by internal devices, e.g. balloons or releasable wires characterised by the location of the occluder in a blood vessel
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/12—Surgical instruments, devices or methods for ligaturing or otherwise compressing tubular parts of the body, e.g. blood vessels or umbilical cord
  • A61B17/12022—Occluding by internal devices, e.g. balloons or releasable wires
  • A61B17/12099—Occluding by internal devices, e.g. balloons or releasable wires characterised by the location of the occluder
  • A61B17/12109—Occluding by internal devices, e.g. balloons or releasable wires characterised by the location of the occluder in a blood vessel
  • A61B17/12113—Occluding by internal devices, e.g. balloons or releasable wires characterised by the location of the occluder in a blood vessel within an aneurysm
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
  • A61L29/14—Materials characterised by their function or physical properties, e.g. lubricating compositions
  • A61L29/16—Biologically active materials, e.g. therapeutic substances
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0021—Catheters; Hollow probes characterised by the form of the tubing
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0043—Catheters; Hollow probes characterised by structural features
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0043—Catheters; Hollow probes characterised by structural features
  • A61M25/005—Catheters; Hollow probes characterised by structural features with embedded materials for reinforcement, e.g. wires, coils, braids
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0067—Catheters; Hollow probes characterised by the distal end, e.g. tips
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0067—Catheters; Hollow probes characterised by the distal end, e.g. tips
  • A61M25/0068—Static characteristics of the catheter tip, e.g. shape, atraumatic tip, curved tip or tip structure
  • A61M25/0069—Tip not integral with tube
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/01—Introducing, guiding, advancing, emplacing or holding catheters
  • A61M25/0105—Steering means as part of the catheter or advancing means; Markers for positioning
  • A61M25/0108—Steering means as part of the catheter or advancing means; Markers for positioning using radio-opaque or ultrasound markers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/01—Introducing, guiding, advancing, emplacing or holding catheters
  • A61M25/09—Guide wires
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B2017/00831—Material properties
  • A61B2017/00955—Material properties thermoplastic
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/12—Surgical instruments, devices or methods for ligaturing or otherwise compressing tubular parts of the body, e.g. blood vessels or umbilical cord
  • A61B17/12022—Occluding by internal devices, e.g. balloons or releasable wires
  • A61B2017/1205—Introduction devices
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M25/00—Catheters; Hollow probes
  • A61M25/0021—Catheters; Hollow probes characterised by the form of the tubing
  • A61M2025/0042—Microcatheters, cannula or the like having outside diameters around 1 mm or less

Definitions

• This application relates to detachable tip catheters, including a detachable, biocompatible tip microcatheter having a thermoplastic sleeve.
• Microcatheters including neuromicrocatheters, are generally microtubes inserted into the body through a blood vessel such as the femoral artery and have a variety of uses (see, e.g., U.S. Patent Nos. 6,306,124 and 6,454,738). Microcatheters have a distal and a proximal end where, typically, at or near the very distal end, a marker band is employed to permit the clinician to visualize the microcatheter positioning during in vivo use.
• the marker band typically comprises a metal or metal alloy ring such as platinum, nitinol and/or gold rings which can be visualized via fluoroscopy.
• Microcatheters are typically used to embolize the neurovasculature such as in treating arteriovenous malformations (AVMs), aneurysms, and the like in a relatively non-invasive manner.
• AVMs arteriovenous malformations
• aneurysms and the like in a relatively non-invasive manner.
• Neurovascular embolization devices include intravascular compositions which solidify in vivo so as to permanently occlude blood flow to cerebral aneurysms and cerebral arteriovenous malformations.
• Suitable intravascular compositions include, by way of example only, cyanoacrylates which polymerize in vivo to form a solid mass as well as solutions of a biocompatible, water insoluble polymer dissolved in a nonaqueous solvent such as dimethyl sulfoxide (“DMSO”) whereupon introduction into the vasculature, the DMSO dissipates and the polymer precipitates in the aqueous based blood composition.
• Such intravascular compositions further comprise a contrast agent to assist in visualization of the formed mass.
• a solid mass is formed from an embolic agent, such as for example an embolic liquid, delivered in situ to the embolization site.
• the embolic agent in the form of a prepolymer such as a cyanoacrylate prepolymer or a polymeric solution such as an Onyx® fo ⁇ nulation (available from ev3 Neurovascular, Irvine, CA and comprises ethylene vinyl alcohol copolymer, DMSO and tantalum) is ejected distally from the microcatheter tip and forms a solid mass at this distal point.
• An aspect of at least one of the embodiments described herein includes the realization that it is advantageous to provide microcatheters which can be safely removed from the patient in the event that they become trapped in the vasculature for any reason, while minimizing the potential deleterious effects caused by such complications. It is further advantageous to provide microcatheters which can maintain a high burst strength so as to inhibit the microcatheters from separating or bursting during the injection of the embolic agent, as well as a low retraction force for removal of the microcatheter in the event of reflux either before and/or after delivery of the embolic agent.
• a method for using microcatheter can comprise advancing a microcatheter into the patient, the microcatheter comprising an elongate flexible tubular body having a proximal end, a distal end and at least one lumen extending axially there through, a tip body having a proximal end and a distal end and a lumen extending axially there through, and a thermoplastically fitted sleeve covering a distal end of the tubular body and a proximal end of the tip body.
• the method can further comprise placing the tip body at the vascular site, delivering the embolic agent through the lumen of the tubular body and the lumen of the tip body, and detaching the tip body from the tubular body by applying a retraction force to the tubular body, the tip body remaining with the embolic agent.
• a microcatheter for delivering embolic agent to a vascular site within a patient can comprise an elongate flexible tubular body having a proximal end, a distal end and at least one lumen extending axially there through, a tip body having a proximal end and a distal end and a lumen extending axially there through, and a thermoplastically fitted sleeve covering a portion of both the tubular body and tip body, wherein the sleeve is frictionally engaged with both the tubular body and tip body, and the tip is detachable from one of the tubular body and tip body by application of a retraction force.
• Figure IA is a side elevation view of a microcatheter according to one embodiment.
• Figure IB is an enlarged view of a tip detachment portion of the microcatheter of Fig. IA.
• Figure 2D is a schematic view of an arteriovenous malformation.
• Figure 2E is a schematic view of a positioning method using the microcatheter of Fig. IA to treat the arteriovenous malformation.
• Figure 3 is a schematic view of the microcatheter tubular body, the tip body, and the thermoplastic sleeve of Figure IA.
• Figure 4 is a schematic view of the thermoplastic sleeve of Figure IA detachably engaged to the microcatheter tubular body.
• Figure 5 is a schematic view of the thermoplastic sleeve of Figure IA detachably engaged to the microcatheter tubular body and the tip body. Figure 5 also shows side holes in the tip body.
• Figure 6 is a schematic side view of a microcatheter according to another embodiment.
• Figure 7B is a perspective cross-sectional view of a sleeve according to another embodiment.
• Figure 7C is a perspective cross-sectional view of a sleeve according to another embodiment.
• Figure 8 is an enlarged cross-sectional view of the tip body of the microcatheter of Figure 6.
• Figure 9 is a chart illustrating the relationship between burst strength and detachment force for the microcatheter of Figure 6.
• Figure 10 is a cross-sectional view of a portion of a microcatheter according to another embodiment, including a thin-walled detachment portion.
• Figure 11 is a cross-sectional view of a portion of a microcatheter according to another embodiment, including a detachment ring.
• Figure 12 is a cross-sectional view of a portion of a microcatheter according to another embodiment with a separately manufactured detachable tip.
• Figure 13 is a cross- sectional view of a portion of a microcatheter according to another embodiment, showing a tip having side holes.
• Figure 14 is a perspective view of a portion of a microcatheter according to another embodiment, showing a catheter tip comprising gripping structures.
• Figure 15 illustrates is a schematic side view of a microcatheter according to another embodiment having a detachable tip, side holes, and marker bands.
• a microcatheter 10 (e.g. a neuromicrocatheter) can be useful for delivering embolic agents to vascular sites of patients.
• these vascular sites are located in the neurovasculature, and include AVMs and aneurysms.
• this technique can be used in any vessel in the body, and can be useful for embolizing any body lumen.
• Microcatheter 10 can comprise a distal end 12, a proximal end 14, and an elongate flexible tubular body 16 extending therebetween.
• the tip body 30 may optionally contain a plurality of lateral apertures or holes 38.
• the shape of the apertures 38 can be selected from round, elliptical, or other shapes.
• the embolic agent 42 can be a liquid embolic agent and can comprise of a number of materials. Suitable embolic agents 42 include those containing biocompatible polymers and prepolymers which polymerize in situ.
• the liquid embolic agent can also comprise a biocompatible solvent and a contrast agent.
• the contrast agent is water-insoluble.
• Onyx® a non-adhesive liquid embolic agent comprised of EVOH (ethylene vinyl alcohol) copolymer dissolved in DMSO (dimethyl sulfoxide) and suspended micronized tantalum powder to provide contrast for visualization under fluoroscopy. Further description of suitable embolic agent are described in U.S. Patents 5,667,767; 5,695,480; 6,051,607; 6,342,202; 6,531,111; and 6,562,317 all of which are incorporated by reference herein and made a part of this specification.
• the tip body 30 can be entrapped within the agent 42.
• the sleeve 26 can also be entrapped or partially trapped by the agent 42.
• the attending clinician can apply a retraction force to the tubular body 16.
• the thermoplastic sleeve 26 can either 1) remain attached to the tip body 30 (Fig. 2B); 2) remain attached to the tubular body 16 (Fig. 2C); or 3) break into two components thereby remaining partially attached to both the tubular body 16 and the tip body 30 (not shown).
• the microcatheter 10 can be used to treat an arteriovenous malformation (AVM).
• FIG 2D illustrates an example of an AVM
• Figure 2E illustrates how the microcatheter 10 can be moved to the AVM site to deliver embolic agent 42 to the site.
• the tip 30 can be detached through use of the sleeve 26 and a retraction force.
• the location of the sleeve 26 after application of the force can be influenced by the construction of how the sleeve 26 is engaged to the tip body 30 and the tubular body 16 (see Fig. 3).
• the engagement of the tip body 30 to the sleeve 26 and the engagement of the tubular body 16 to the sleeve 26 can be accomplished in variety of ways.
• the sleeve 26 can overlap with a distal end 34 of the tubular body 16 (see Fig. 4) and/or can overlap with a proximal end 36 of the tip body 30 (see Fig. 5).
• the amount of overlap can be a factor in determining the retraction force used for detaching the tip body 30.
• one or both attachments of the sleeve 26 to the tip body 30 or the tubular body 16 can be a butt joint (end to end), hi some embodiments, the distal end 34 and proximal end 36 can form a butt joint.
• One advantage of the microcatheters described herein is the ability to have a low and consistent detachment force while maintaining a high burst strength, hi addition to the use of the sleeve 26 to detachably engage the tip body 30 to the tubular body 16, this advantage can also be accomplished by the materials selected for the tubular body 16 and the sleeve 26, the overlap length of the sleeve 26 with the tubular body 16 and the tip body 30, and/or the construction of affixing the sleeve 26 to the tubular body 16 and the tip body 30.
• the tubular body 16 can be constructed of a variety of materials and in a variety of ways known in the art to optimize the burst strength.
• the tubular body 16 can be constructed of a material that is compatible with dimethylsulfoxide.
• the tubular body 16 can also contain zones with varying flexibility which can also be controlled by the methods of construction and materials employed. It can be desirable to have a more flexible zone at the distal end of the tubular body 34. Description of the construction of the zones can be found in U.S. Patent 5,843,050, which is hereby incorporated by reference and made a part of this specification.
• the tip body 30 can also be "biodegradable.”
• biodegradable/bioerodable and non-biodegradable materials are known which are useful for constructing microcatheter tips.
• the tip body 30 can be formed of a material which is biodegradable or bioabsorbable in situ. Biodegradable or bioabsorbable materials, or some combination thereof, can be used which allow for the biodegradation/bioabsorption in predetermined conditions.
• biocompatible-biodegradable materials are commercially available.
• the general criteria for selecting a polymer for use as a biomaterial is to match the mechanical properties and the time of degradation to the needs of the application.
• Polymeric substances which may be used are set forth in U.S. Patent No. 4,938,763.
• the following polymers are biocompatible as well as biodegradable:
• PGA-TMC poly(glycolide-co-trimethylene carbonate)
• PGA-LPLA poly(l-lactide-co-glycolide)
• LPLA-DLPLA poly(l-lactide-co-dl-lactide)
• PDO-PGA-TMC poly(glycolide-co-trimethylene carbonate-co-dioxanone)
• PHA polyhydroxyalkanoate class of biopolymers
• TephaFLEX polymer currently available from Tepha, Inc. Cambridge MA, USA.
• the sleeve 26 can be comprised of a thermoplastic material or a material that is heat-shrinkable.
• the thermoplastic selected is ideally complimentary to the tubular body 16 material and may be either filled or unfilled.
• the sleeve 26 can comprise more than one thermoplastic material.
• thermoplastic polyolefm elastomer TPE
• acrylic celluloid
• cellulose acetate ethylene-vinyl acetate
• EVAL ethylene vinyl alcohol
• fluoroplastics PTFE, FEP, PFA, CTFE, ECTFE, ETFE
• ionomers acrylic/PVC alloy; liquid crystal polymer (LCP); polyacetal (POM or Acetal); polyacrylonitrile (PAN or acrylonitrile); polyamide (PA or Nylon); polyaryletherketone (PAEK or Ketone); polybutadiene (PBD); polybutylene (PB); polycaprolactone (PCL); polychlorotrifluoroethylene (PCTFE); polyhydroxyalkanoates (PHAs); polyketone (PK); polyester; low density polyethylene (LDPE); linear low density polyethylene (LLDPE); polyethylene (PE); polyetherimide (PEI); polyethersulfone (PES); polysulfone; polyethylenechlorinates (
• the sleeve 26 can be filled or not filled with a radiopaque material, such as barium sulfate.
• the thermoplastic is a thermoplastic elastomer.
• the thermoplastic is a heat shrinkable polyolefm, such as polyethylene and in another embodiment the thermoplastic is a low density polyethylene and polyolefin elastomer (DuPont Engage®) blend.
• the ability to detach the tip body 30 from the tubular body 16 can be influenced by the construction of the microcatheter 10 and particularly, the construction of detachably engaging the sleeve 26 to the tip body 30 and the tubular body 16.
• the total length of the microcatheter 10 can generally be in the range of form about 150 cm to about 175 cm, although other ranges are also possible.
• the tubular body 16 can be selected to have an outside diameter within the range of from 0.5 mm to about 1.5 mm, although other diameters are also possible.
• the diameter of the central lumen 22 can be about 0.002 to about 0.005 inches larger than the outside diameter of the guidewire, if one is used.
• the tubular body 16 and tip body 30 can be provided as described above.
• the sleeve 26 can then be provided and detachably engaged to the tubular body 16 and the tip body 30 by applying a controlled temperature heat source for a designated time at the juncture of the sleeve 26 and the tubular body 16 and the tip body 30.
• the time that the heat source is applied, as well as the temperature, can influence the bond that forms between the sleeve 26 and the other components.
• the sleeve 26 can attach to the tubular body 16 and the tip body 26 by either a mechanical bond (force of the heat shrinking around the smaller microcatheter and tip body) or a fused bond (where the materials of the sleeve, the tubular body, and/or the tip body are melting together).
• the bond can be a weaker tensile strength bond to allow the tip body 30 to detach from the tubular body 16 upon application of a retraction force of about 10 to about 160 gram-force, preferably about 20 to 50 gram-force.
• the sleeve 26 can be attached to the tip body 30 and/or tubular body 16 by use of adhesives or solvents.
• the amount of overlap can be one factor in the retraction force required to separate the tip body 30 from the tubular body 16.
• this overlap can be from about 0.5 to about 5 mm. In some embodiments, the overlap can be about 2 to about 4 mm. Other overlap ranges are also possible.
• a kit comprising a microcatheter 10, or other microcatheter described herein, and a liquid embolic agent as described above can be provided.
• a microcatheter 110 can be similar to the microcatheter 10 described above. Therefore, similar components of the microcatheter 110 are referenced by the same reference numeral as the corresponding component in the microcatheter 10, incremented by one hundred.
• a tip detachment area can comprise a tubular body 116, a thermoplastically fitted sleeve 126, and a tip body 130.
• the thermoplastic sleeve 126 can be fitted over a distal end 134 of the tubular body 116 and proximal end 136 of the tip body 130, similar to sleeve 26 described above.
• the sleeve 126, or any sleeve described herein can be frictionally engaged with both the tubular body 116 and tip body 130 prior to detachment, and can form a tighter frictional engagement with the tubular body 116 than with the tip body 116. Once a retraction force is applied, the sleeve 126 can thus tend to remain on the tubular body 116, thus leaving the tip body 130 behind.
• the tubular body 116 can comprise a marker 132.
• the marker 132 can be positioned such that it lies underneath the sleeve 126, thereby identifying a position of the sleeve 126 and tip body 130 prior to detachment of the tip body 130.
• FIG. 7B illustrates an alternative embodiment of a sleeve 126'.
• the sleeve 126' can be similar to the sleeve 126 described above, except the sleeve 126' can include an internal separation element 127.
• the internal separation element 127 can be designed to separate the distal end 134 and proximal end 136 of the tubular body 116 and tip body 130, respectively, while still allowing embolic agent to flow through the microcatheter.
• the separation described above can inhibit the distal end 134 and proximal end 136 from contacting one another and/or sticking or adhering to one another after heating of the thermoplastically fitted sleeve 126'.
• the separation element 127 can facilitate reduced detachment forces.
• the separation element 127 can be formed integrally with the sleeve 126', or can be attached or inserted separately.
• the separation element 127 can comprise a variety of materials, including but not limited to metal or plastic, and in some embodiments can be in the shape of a washer.
• FIG. 7C illustrates another alternative embodiment of a sleeve 126".
• the sleeve 126" can be similar to the sleeves 126' and 126" described above, except that the sleeve 126" can comprise two discrete components 128a and 128b.
• the components 128a and 128b can be mirror images of one another, and can be attached (e.g. adhered together or held together) to form the sleeve 126".
• the sleeve 126" can include separation elements 127 which can be used to separate the distal end 134 and proximal end 136 of the tubular body 116 and tip body 130.
• the tip body 130 can also comprise a marker 133.
• the marker 133 can be a radiopaque marker located along a portion of the tip body 130, and can be used to identify a position of the tip body 130 prior to and/or after detachment of the tip body 130 from the tubular body 116.
• Static burst strength generally describes an internal pressure (for example applied by embolic liquid within the catheter) which can cause radial bursting of the microcatheter.
• Static burst strength is that pressure at which the microcatheter' s tubular wall bursts. It is generally desired to have a high static burst strength, so as to limit the possibility of the microcatheter bursting during use. If the static pressure is raised high enough, this internal pressure can cause the microcatheter to burst, or break.
• Detachment force generally describes an axially applied tensile force required for detaching the tip body 130 from the tubular body 116.
• Detachment force can be applied by the user, for example by pulling proximally on a proximal end of the tubular body 116. It is generally desired to have a low detachment force, so as to limit the amount of force required to detach the tip body 130.
• a mechanism such as one of the sleeves described above can act to both inhibit bursting of the microcatheter 110, while facilitating detachment of the tip body 130.
• the sleeve 26, 126, 126', or 126" can allow for a desired detachment force while maintaining a high burst strength.
• the detachment force for maintaining a static burst strength between approximately 50 and 400 psi can range from approximately 20 to 40 gram-force while using the sleeve 126'.
• the sleeve 126' is thermoplastically fitted around the tubular body 116 to such a degree that the retraction force required for detachment increases (i.e. a tighter fit), so too will the amount of static pressure required to burst the microcatheter radially.
• the microcatheters 10 and 110 described above include thermoplastically fitted sleeves 26, 126, 126' and 126" which are used for detachably engaging the tubular bodies and tip bodies of the microcatheters.
• Thermoplastically fitted sleeves can provide an advantage over other types of structures or systems for detachably holding a tip body to a tubular body of a microcatheter.
• metallic sleeves e.g. metallic rings
• the adhesive used with such metallic rings could undesirably deteriorate, allowing the metallic ring to dislodge from the microcatheter and become an emboli in the patient's body.
• the adhesive is broken down before detachment. If the adhesive is broken down by the embolic agent itself, the procedure of detachment can become time-dependent and take longer than desired, or in some cases could be unpredictable in terms of the time required for detachment. Additionally, the retraction force needed to detach the tip body could vary, depending on the amounts of adhesive used, the consistency of the adhesive used, the application of the adhesive, etc. In contrast, the microcatheters described above have the advantage of utilizing a single retraction force to quickly, efficiently, and consistently detach the tip body from the tubular body of the microcatheter.
• the sleeves 26, 126, 126', and 126" described above can have length (e.g. axially along the inner lumen) to outer diameter ratios which provide a further advantage in inhibiting bursting of the microcatheters 10 or 110.
• the sleeve 126' can have a length to outer diameter ratio of approximately 8:1 at a distal end, and 9:1 at a proximal end. Other ratios are also possible.
• the length to outer diameter ratio is at least 6:1 or 7:1. Ratios for example as large as 8:1 or 9:1 can provide added stability to the microcatheter, and inhibit bursting by providing greater coverage or overlap along the tubular body 116 and tip body 130.
• detachable tip catheters can be used to deliver an embolic agent.
• the components of the catheters illustrated in Figures 10-15 and described herein can, at least in some embodiments, be used with the catheters 10 and 110 described above.
• catheters are generally constructed according to known principles of catheter design and typically consist of a proximally-disposed rigid section, an intermediate semi-flexible section, and a distal flexible portion designed to facilitate negotiation of the small, tortuous vessels expected to be encountered during each particular medical application.
• the distal end of a catheter can contain one or more radiopaque markers to aid a clinician in visualization of the catheter location during a medical procedure.
• the radiopaque markers are positioned at fixed distances from the distal end of the catheter.
• one radiopaque marker can be optionally placed proximally adjacent to a tip detachment area in order to aid the clinician in visualizing the catheter and anatomical sequela of the medical procedure (e.g., embolization) and tip detachment.
• the predetermined tip detachment area may be, in essence, a weak or rigid portion of the catheter body. Put another way, the predetermined tip detachment area may be less resilient with applied force than the tubular body.
• This unibody construction can be similar to traditional catheter tip design except that the weak/rigid construction of the predetermined detachment point controls the location of breakage. This design improves upon existing unibody catheter tip construction in which the tip is substantially uniform and breakage occurs randomly along the catheter tip body, upon the application of excessive force.
• the catheter can deform while inserted into the patient, particularly in a microvasculature environment.
• the catheter can be relatively inflexible or flexible at the predetermined tip detachment area. Thus the catheter tip can selectively detach at this predetermined area due to the detachment area having a lower tensile strength than the adjacent tubing.
• Resilience properties of the predetermined detachment area such as elasticity (reversible deformation) or plasticity (non-reversible deformation) can be calculated to occur per unit force at a predetermined tubular body location largely based on the physicochemical properties of the materials and the conditions under which the catheter is used.
• the predetermined detachment area can be made of the same material as the catheter, but the detachment area is thinner than the adjacent portions of the catheter, providing a weakened point susceptible to breakage upon the application of an appropriate (e.g., retraction) force.
• the relative weakness of the detachment area, and the concomitant difference in thickness of the catheter wall can be modified in order to facilitate detachment (i.e., breakage) upon application of the desired amount of force.
• the detachment area will be at least 10%, 20%, 30%, 40%, 50%, 65%, or 80% thinner than the adjacent catheter wall.
• FIG 10 is a schematic illustration of a unibody catheter 210 having a detachable tip constructed according to the principles described above.
• the catheter 210 forms a tubular body consisting of substantially parallel walls 214 forming a lumen 212.
• the material of the catheter walls 214 are weakened at the detachment area 218. This weakening of the detachment area 218 can be a thinning of the catheter wall 214 material, a different (weaker or more rigid) material compared to the catheter wall 214 material.
• the detachable tip 216 can be the portion of the catheter 210 that is distal to the detachment area 218 and is detached with the breakage of the catheter 210 at the detachment area 218 upon application of predetermined force to the catheter 210.
• a marker 215 can be positioned just proximal to the detachment area 218 and preferably is positioned within 1 centimeter of the detachment area 218.
• Figure 12 shows one embodiment of a catheter 230 with a separate detachable tip 236.
• the distal catheter end is enlarged to form a flange 238 and the detachable tip 236 is fitted over the flange as an integral concentric coupling (i.e., in a sleeve- like fashion).
• the distal catheter end does not contain a flange or other specialized receiving structure (i.e., has substantially the same outer diameter as the adjacent portion of the distal catheter).
• FIG. 14 illustrates a detachable tip 256 with side grips 257.
• the side grips 257 can be used for mechanical removal via a guidewire looped around the end of the detachable tip 256.
• the side grips 257 can be protrusions or invaginations designed to further anchor the tip 256 in an embolic polymer when tip detachment is desired, as described herein.
• the side grips can also be used to aid in the mechanical retrieval of the tip once it has been detached from the catheter.
• the design of the grips can add no function apart from decorative to give the medical device an aesthetically pleasing design.
• the tip can be formed of a material which is biodegradable or bioabsorbable in situ.
• Biodegradable or bioabsorbable materials, or some combination thereof, may be used which allow for the biodegradation/bioabsorption in predetermined conditions.
• biocompatible-biodegradable materials are commercially available.
• a general criteria for selecting a polymer for use as a biomaterial is to match the mechanical properties and the time of degradation to the needs of the application.
• Polymeric substances which can be used are set forth in U.S. Patent No. 4,938,763.
• the following polymers are biocompatible as well as biodegradable:
• PGA-TMC poly(glycolide-co-trimethylene carbonate)
• PDO-PGA-TMC poly(glycolide-co-trimethylene carbonate-co-dioxanone)
• PHA polyhydroxyalkanoate class of biopolymers
• TephaFLEX polymer currently available from Tepha, Inc. Cambridge MA, USA.
• a biodegradation region can be engineered into a wide variety of biocompatible polymers.
• Hydrolytically unstable linkages can be manufactured into biocompatible polymers, such as including functional groups containing esters, anhydrides, orthoesters, and amides.
• Enzymatic substrate sites, hydrolysis site, or other chemically (or bio-chemically) breaking sites can be incorporated into a biocompatible polymeric backbone otherwise having desired physico-chemical properties.
• Environmental degradation sites such as light or temperature sensitive sites, can also be used. For example, one can employ a chemical moiety which is degraded upon exposure to light, and fiber optic light may be used as the light source for such degradation in situ.
• the tip can be formed of a material which is DMSO dissolvable, allowing it to degrade during a procedure using Onyx thereby lowering the detachable tip tensile strength.
• the detachable tip can also contain one or more biologically active moieties, such as a therapeutic moiety.
• a biologically active moiety including a therapeutically active moiety
• the composition of the detachable tip can be selected for a desired pharmacokinetic or sustained duration drug delivery in addition to any therapeutic delivery incident to the catheter use.
• Bioly active moieties may or may not be therapeutically effective. Although a biological activity can occur locally, this can be solely to inhibit, for example, a later condition from developing or as a prophylactic measure. Thus, any individual patient may or may not show therapeutic benefit, as the benefit may be the prevention of a harmful inflammatory response, for example.
• Microtubules are necessary for cytoskeletal and therefore cellular growth or division. By inhibiting cellular cytoskeletal growth, one may inhibit inflammatory or other unwanted cellular activity. One may inhibit microtubule growth by preventing inhibiting the tubule formation or by inhibiting the tubule deconstruction.
• Various microtubule inhibitors include anti-cancer compounds (taxanes and the vinca alkaloids, for example) as well as other synthetic antitubulin or microtubule inhibitors.
• FIG 15 is a schematic side view illustrating a microcatheter 260 in accordance with one embodiment.
• the microcatheter 260 can comprise a tubular body 262, a detachable tip 264, and means 266 coupling the tip 264 to the tubular body 262.
• Means 66 can be adapted be able to detach the tip 264 from the tubular body 262.
• the tubular body 262 can include a proximal portion 268 which is closer to an operator of the microcatheter 260, a distal portion 270, and a lumen (not shown) extending from the proximal portion 268 to the distal portion 270.
• the tubular body 262 can have a substantially uniform wall forming the lumen.
• Detachment means 266 can be designed to be breakable to detach tip 264 from the tubular body 262 for most in vivo applications of the microcatheter 260.
• the detachment means 26 can be breakable upon application of a force of about 10 to 160 gram-force.
• the detachment means can be designed to be breakable by electrical means.
• the detachment means 266 can be an extension of the tubular body 264 and constructed from the same material of the tubular body 262.
• the detachment means 266 can include a side wall that has a thickness smaller than the wall thickness of the tubular body 64.
• the detachment means 66 can be constructed from a different material from that making the tubular body 62.
• a marker or marker band 274 can be provided on the distal portion 270 of the tubular body 262.
• the marker band 274 can be disposed immediately proximal to the detachment means 266 to assist an operator to visualize the location of the detachable tip 264 and/or the detachment zone 266 inside the vascular system.
• the marker band 274 can be made of a radiopaque metal which can be identified by for example X-ray imaging. Since the marker band 274 is disposed on the tubular body 262, it remains on the tubular body 272 after the tip 264 is detached from the tubular body 62. As a result, the marker band 274 or the radiopaque metal can be removed out of the patient with the tubular body 62 after delivery of the fluid agent, thus minimizing or eliminating damages to the patient.
• a second marker or marker band 276 can be provided on the tip 264.
• the additional marker band 276 can be disposed immediately proximal to the distal end of the tip 264 and thus remains at the site of delivery after the tip 264 is detached from the tubular body 262.
• a solid mass can be formed from the embolic agent in situ.
• the additional marker band 276 can be embedded in the solid mass at the embolization site and does not enter the systemic fluid of the treated vascular, which is otherwise detrimental to the patient.
• the attachment means can comprise a flange structure adapted to couple the tip body to the tubular body.
• the tip body can be made of a material that is biodegradable.
• Example 1 Use of Detachable Biodegradable Tip
• embolizing refers to a process wherein a material is injected into a blood vessel, typically to plug the vessel to stop unwanted blood flow.
• materials and methods for embolizing are set forth in U.S. Patent No. 5,695,480, herein incorporated by reference in its entirety and made a part of this specification.
• materials for embolization can be purchased from ev3 Neurovascular Inc., Irvine, CA, USA. Examples include Onyx® embolic compositions sold as Onyx® 18, 20, 34 and 500 HD embolic compositions.
• embolizing materials set forth in US 6,454,738 can be delivered to the site of the aneurysm via a catheter.
• embolic agent As noted above, one commercially available embolic agent is Onyx® and its associated kit, the Onyx® Liquid Embolic System sold by ev3 Neurovascular, Inc. (MicroTherapeutics, Inc., Irvine, California, USA).
• the embolic Onyx® compositions in the kits can be non-adhesive liquid embolic agents comprised of EVOH (ethylene vinyl alcohol) copolymer dissolved in DMSO (dimethyl sulfoxide) and suspended micronized tantalum powder to provide contrast for visualization under fluoroscopy.
• EVOH ethylene vinyl alcohol
• DMSO dimethyl sulfoxide
• the Onyx® embolic agents can be both biologically active agents as well as contain a diagnostic or imaging agent.
• Onyx® 18 or 34 kits can include a 1.5 ml vial of Onyx® embolic agent, a 1.5 ml vial of DMSO, one DMSO-compatible delivery syringe, and two Onyx® syringes.
• Onyx® 18 or 34 can be delivered by slow controlled injection through a microcatheter into the aneurysm or other vascular site under fluoroscopic control.
• the DMSO solvent can dissipate into the blood, causing the EVOH copolymer and suspended tantalum to precipitate in situ into a spongy, coherent embolus.
• the Onyx® 18 or 34 can immediately form a skin as the polymeric embolus solidifies from the outside to the inside, while filling more distally in the vascular site. Final solidification of this material can occur within five minutes.
• a microcatheter having a predetermined tip detachment area as disclosed herein can be used to deliver the Onyx® embolic agent.
• a marker band Located proximal to the detachment area, or within the detachment area, can be a marker band.
• This band which can be around or in the tubular body, can be continuous or discontinuous.
• the microcatheter tubular body can be of uniform elasticity and plasticity except for a region approximately 1 cm from the distal end (e.g. the tip body of a unibody-constructed catheter).
• the tip bodies 30 described herein can be between 1-10 cm in length, preferably between 1-6 cm in length, and even more preferably between 1-3 cm in length. Other ranges are also possible.
• the diameter of the microcatheter tubular body at 1 cm from the distal end can, for example, be between about 0.5 mm and about 1.5 mm. Other diameters and ranges are also possible. Additionally, at a distance, for example, of about 1- 10 cm from a distal end of the distal tip the microcatheter body can contain a predetermined detachment area of lower plasticity and elasticity. Optionally this region can be biodegradable.
• the catheter in Example 1 can be used, wherein the predetermined tip detachment area is a separate tip fitted over the distal end of the catheter as a sleeve, as illustrated in Figure 12.
• the separate tip can be comprised of a biocompatible, biodegradable polymer.
• the biodegradable polymer can contain enzymatic degradation sites which, in the presence of a suitable enzyme, degrade the tip to bioabsorbable constituents.
• a tip as shown in Figure 14, with grippable elements can be removed from the catheter.
• a guidewire or other mechanical element can be used to stabilize or retrieve the tip having grippable elements.
• the tip can then be inhibited from migrating in the systemic circulation or embedding in the vasculature.
• the tip so stabilized can be kept at its in situ location for local deployment of any other moiety, such as an imaging agent or biologically active moiety, if the tip has suitable delivery properties as described herein or known in the art.
• active agents such as biologically active agents
• a distal tip can further comprise an additional detectable label or imaging reagent.
• the practitioner can observe the degradation or subsequent absorption by suitable label detection (e.g., florescent labels detected via light sensor) or imaging viewing (e.g., a contrast agent which can be distinguished from the embolic agent).
• a catheter can have a predetermined tip detachment area at, for example, 10 mm from the distal end.
• the tip portion of the catheter body (or, a separate tip) can be biodegradable and can act as a sustained release delivery vehicle for biologically active moieties.
• the catheter can be used to selectively deliver an anti-cancer chemotherapeutic agent to a specific location within a patient's body where a tumor is located.
• the tip can be deployed at a location proximate to the tumor.
• the tip can contain a dosage of a second antitumor biologically active agent to be released over a selected duration.
• the catheter and compositions described above can also be used in other embolic situations such as in the embolization of AVM's, in the embolization of blood vessels feeding into malignant and non-malignant tumors such as fibroid tumors, treating blood vessels involved in abdominal aortic aneurysms (AAA), and the like.
• AVA abdominal aortic aneurysms

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