WO2006076437A2

WO2006076437A2 - Lacrimal stent

Info

Publication number: WO2006076437A2
Application number: PCT/US2006/000991
Authority: WO
Inventors: Andrew Harrison; Dave Hultman; David Wulfman
Original assignee: Regents Of The University Of Minnesota
Priority date: 2005-01-11
Filing date: 2006-01-11
Publication date: 2006-07-20
Also published as: WO2006076437A3

Abstract

This document discusses, among other things, a stent having an inflatable membrane around an inner cylinder. The membrane is deployed by introducing a fluid between the membrane and the inner cylinder. An outer surface of the membrane conforms to a cavity or orifice. A lumen of the inner cylinder provides a conduit for fluids traversing the length of the stent.

Description

LACRIMAL STENT

TECHNICAL FIELD

This document pertains generally to an inflatable stent, and more particularly, but not by way of limitation, to a lacrimal stent.

BACKGROUND

Ordinary silicone stents used with dacryocystorhinostomy and other ophthalmological surgical procedures are unsatisfactory. For example, with dacryocystorhinostomy, typical problems include high failure rate due to granulomatous inflammation associated with silicone intubation, punctual erosion and slitting of canalicuili. In general, problems include increased risk of infection, patient discomfort, chronic tearing, and poor fit.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of substantially similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

Fig. 1 illustrates a stent with a deflated membrane positioned in an orifice.

Fig. 2 illustrates a stent with an inflated membrane positioned in an orifice.

Fig. 3 A illustrates a device at a time prior to everting the membrane. Figs. 3B, 3C and 3D illustrate a method of everting a membrane of the stent shown in Fig. 3 A.

Fig. 3E illustrates a stent with an everted membrane. Figs. 4A, 4B and 4C illustrate a method of inflating the membrane of a stent.

Figs. 5 A and 5B illustrate a sectional view of a stent in a deflated state and in an inflated state. Figs. 6A and 6B illustrate a sectional view of a stent in a deflated state and in an inflated state.

Fig. 7 illustrates a stent with a deflated membrane having a rolled end. Fig. 8 illustrates a membrane configured for an overlapping joint with an adjacent structure.

Figs. 9, 10 and 11 illustrate alternative treatment of the membrane end. Fig. 12A illustrates an end view of a stent having a fluted membrane. Fig. 12B illustrates a detailed view of a fluted membrane. Figs. 13 A and 13B illustrate views of a stent having two membranes coupled at a midpoint.

Figs. 14A and 14B illustrate views of a stent having two membranes separated by a gap.

Figs. 15A and 15B illustrate an introducer with a stent in a deflated state and in an inflated state. Figs. 16 A, 16B and 16C illustrate sectional views of a method for inflating and placing a stent using an introducer that couples with a lumen of the stent.

Fig. 17 includes a sectional view of an introducer coupled to a stent having a stub.

DETAILED DESCRIPTION

The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, which are also referred to herein as "examples," are described in enough detail to enable those skilled in the art to practice the invention. The embodiments may be combined, other embodiments may be utilized, or structural or procedural changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one. In this document, the term "or" is used to refer to a nonexclusive or, unless otherwise indicated. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

Fig. 1 illustrates a schematic of an inflatable stent 300A having a semirigid tubular core surrounded by an inflatable membrane or balloon structure. In the example illustrated, orifice 22 represents a lacrimal sac-nasal mucosa anastomosis (LSNMA) in structure 20 between tear sac 26 and nose 24. Orifice 22 is surgically formed using a diamond burr, bone punch or other tool, and as illustrated, may have regular or irregular wall dimensions.

Membrane 310A, in various examples, has a tubular shape and is formed of a flexible inert material such as silicone and is either extensible or inextensible. In one example, membrane 310A includes an elastic material such as rubber or latex. As shown in Fig. 2, after positioning stent 300A within orifice 22 with the medial portion in the space of the anastomosis, membrane 310A is inflated with fluid at region 324 A using an external pump. A fluid-tight seal is provided between stent 300A and membrane 310A and the seal is provided by locking collar 21 at one end and locking collar 23 at the other end. In one example, the locking collar includes an o-ring or other structure having elastic properties to stretch over the membrane 310A and the tubular stent and exert a tension force. In various examples, the locking collar is formed integral with the membrane or the stent. In one example, the locking collar is a discrete component formed separately from the membrane or stent. Region 324A can be inflated with a fluid such as saline or other inert liquid or gas. Stent 300A is retained in orifice 22 by membrane 31 OA which conforms to the walls. Stent 300A can be removed by deflating membrane 310A. In one example, the present subject matter includes a stent having a conformal external balloon and a lumen of predetermined diameter. As shown in Fig. 2, membrane 310A is inflated sufficiently to engage the walls of orifice 22 without necessarily forming a fluid-tight seal. With continued bone or tissue growth, the dimensions of orifice 22 may change over time and the level of inflation of membrane 31 OA is selected to accommodate such changes.

Figs. 3 A, 3B, 3C, 3D and 3E illustrate a sequence of forming an example of the present subject matter. Fig. 3 A includes a sectional view of device 290 from which stent 300B is formed, hi Fig. 3A, device 290 includes cylinder 305 contiguous (or integral) with tubular membrane 310B. The example illustrated is fabricated of molded silicone however, other materials and fabrication methods are also contemplated, hi addition to molding, the stent can be fabricated by casting or by blowing. Cylinder 305 includes a bore or lumen 307. hi addition, an end of membrane 310B includes reinforcement flange 315A having opening 317. As illustrated, the wall thickness of the tubular membrane 310B is less than that of cylinder 305. Flange 315A, like locking collar 21 and locking collar 23, includes structure to provide a fluid-tight seal. hi Fig. 3B, a portion of device 290 is positioned within a lumen of tubular guide or external sleeve 350 and conical mandrel 360 is inserted into opening 317. Flange 315A is deformed and a portion of membrane 31OB proximate flange 315 A is expanded to a larger diameter, hi Fig. 3 C, mandrel

360 is removed and flange 315A is everted onto end 354 of sleeve 350. End 356 of sleeve 350 is sealed and fluid pressure is applied to interior of sleeve 350 using pump 358. Pump 358, in various examples, includes a gas or air pump or other source of air pressure. In one example, lumen 307 is sealed during application of the fluid pressure. Device 290 is extracted from sleeve 350 by relative motion in the direction indicated by arrow 362 resulting in the configuration illustrated in Fig. 3D. Membrane 310B is everted upon extraction of device 290. In Fig. 3E, flange 315A is removed from sleeve 350 and allowed to contract onto cylinder 305. hi the example illustrated, flange 315A is positioned near, or flush with, a first end of cylinder 305, fold 320 is formed at a second end of cylinder 305, and membrane 310B is everted. Fig. 3E illustrates that cylinder 305 is located within the lumen of tubular membrane 310B. In one example, stent 300B is approximately 1 centimeter diameter and approximately 2 centimeters long, however dimensions greater or smaller are also contemplated.

Figs. 4A, 4B and 4C illustrate a method of inflating membrane 310B of stent 300B. Hole 322 traverses cylinder 305 on a bias and terminates on adjacent walls of cylinder 305. In Fig. 4A, needle 42 of syringe 40 is positioned in hole 322 and membrane 310B is in a deflated state. In Fig. 4B, fluid from syringe 40 is injected into region 324B located between membrane 310B and cylinder 305. In Fig. 4C, needle 42 is extracted from hole 322 and region 324B remains pressurized. In the figure, hole 322 is sealed by a plug or is sealed by virtue of a combination of the material selected for cylinder 305 and the bias alignment. In one example, hole 322 is formed prior to everting membrane 310B. In various examples, needle 42 penetrates cylinder 305 or abuts cylinder 305. In one example, the fluid-tight seal between cylinder 305 and membrane

310B is provided by a self-sealing septum. The septum, in various examples, includes polytetrafluorethylene (PTFE), rubber or silicone. A needle penetrates the septum to fill or access the fluid under the membrane. In one example, cylinder 305 is fabricated of material that functions as a self-sealing septum. Membrane 31 OB can be deflated by releasing the fluid pressure in region

324B. Pressure can be released by opening the seal on hole 322 or by breaching the impervious wall of membrane 310B. In one example, a vacuum is used to remove fluid from region 324B.

In one example, membrane 310B and cylinder 305 are co-formed by molding. In the stent of Figs. 5A and 5B, membrane 310C and cylinder 305 are separately formed and assembled. Both ends of membrane 310C are terminated with flange 315B. Impervious or sealed joints are formed between flange 315B and end 306A and end 306B of cylinder 305. In the figure, hole 322 terminates on a wall of lumen 307. When inflated, a positive fluid pressure exists in region 324C defined by the deflection of membrane 31OC and cylinder 305. In the example illustrated, stent 300C includes lumen 307 and co-axial holes in flanges 315B of membrane 310C. In one example, a first end of membrane 310C includes a single flange 315B and the second end of membrane 310C is closed. In one example, the membrane inflates to form a single region. In one example the membrane includes two or more segments that can be individually or separately inflated. Figs. 6A and 6B illustrates sectional views of stent 300D having two separately inflatable regions 324D and 324E. Membrane 310D is everted and includes fold 320, flange 315C and reinforcement 31 IB.

Reinforcement 31 IB, in the example illustrated, includes a wall section thicker than that of inflatable portions 31 IA and 311 C. In one example, reinforcement 31 IB includes a rigid member that restricts the inflation forces present in an adjacent region. In one example, stent 300D is placed in a separating wall and portions 31 IA and 311C are positioned on either side of the separating wall.

In various examples, a sealed joint between the membrane and the cylinder is reinforced by a flange or other structure formed at an end of the membrane. Figs. 1, 9, 10 and 11 illustrate examples of portions of membranes having a reinforced end. In Fig. 7, stent 300E includes everted membrane 310E having a rolled flange 315D or coiled end. In one example, an adhesive is used to stabilize rolled flange 315D and resist uncoiling. In one example, an elastic or rigid o-ring is provided to reinforce an end of membrane 310E. In one example, membrane 310E includes an invested o-ring or other structure.

In the figure, stent 300E is devoid of a lumen in cylinder 305 however, in other examples, cylinder 305 includes one or more lumens traversing the length of stent 300E. Fig. 9 illustrates a half section view of stent 300G having solid cylinder 305 and membrane 310G having reinforcement flange 315C and fold 320. Flange 315C is in contact with an end wall of cylinder 305, however, in other examples, flange 315C is in contact with the side wall of cylinder 305. Fig. 10 illustrates a half section view of stent 300H having solid cylinder

305 and membrane 310H having reinforcement flange 315E and fold 320. Flange 315E includes a hem in contact with the side wall of cylinder 305. Fig. 10 illustrates a first and second hole 322 each terminating on the side wall of cylinder 305 and on opposing end walls. Membrane 31OH can be inflated or deflated using either hole 322 while the unused hole 322 is closed. Fig. 11 illustrates a portion of a half section view of stent 300J having solid cylinder 305 and membrane 31 OJ having reinforcement flange 315F. Flange 315F includes a double hem in contact with the side wall of cylinder 305. Fig. 8 illustrates a partial half section view of stent 300F having formed membrane 310F surrounding cylinder 305. Membrane 310F includes a bulbous portion that, when inflated, engages structure associated with orifice 22 (Fig. 1). Membrane 310F can be formed by varying the wall thickness of portions of the membrane, varying the durometer or by placement or removal of reinforcement members.

In one example, the membrane has a radially uniform wall thickness or cross-section. In one example, the cross-section of the membrane is tailored for a particular application. Figs. 12A and 12B illustrate examples of a fluted membrane surrounding cylinder 305. Fig. 12A includes an end section view of an inflated membrane 310K of stent 300K. Membrane 310K includes four separate chambers 330 that, when inflated, engage structure of orifice 22. In the figure, the material used for membrane 310K has an elasticity that varies across the surface. In various examples, the wall thickness, durometer and other parameters of membrane 310K is varied to form chambers 330. Fig. 12B illustrates a partial view of stent 300L having reinforcement spline 332 disposed on a surface of membrane 310L. Spline 332 precludes inflation over the covered area. In one example, spline 332 is formed by co-extrusion.

When inflated, membrane 310L forms a plurality of regions 324F each separated by non-inflated regions 326. Multiple lumens are provided by the plurality of regions 324F, as well as the non-inflated regions 326. hi one example, hole 322 is configured to allow inflation of one particular region while other areas of membrane 310L remain deflated.

In one example, the stent includes a single membrane affixed at one end of the cylinder. Li one example, the stent includes two or more membranes, each affixed at different positions about the cylinder. Figs. 13 A, 13B, 14A and 14B illustrate examples of two membranes on a cylinder.

Fig. 13 A illustrates stent 300M having membrane 310M and membrane 310N, each affixed to opposite ends of cylinder 305. Li the figure, membrane 31 OM and membrane 31 ON are each partially inflated and each are coupled to cylinder 305 by folds 320. Li Fig. 13B, membrane 310M and membrane 3 ION are deflated and are elastically coupled to cylinder 305. As shown, membrane 31 OM is terminated with a plain end and membrane 31 ON includes a hemmed end atop a portion of membrane 31OM. Other reinforcement treatments are also contemplated, including, for example, a double folded interlocking hem.

Fig. 14A illustrates half sectional views of stent 300N having membrane 310P and 310Q, each affixed to opposite ends of cylinder 305. In the figure, membrane 31 OP and membrane 31 OQ are spaced apart along the length of cylinder 305. When inflated, as shown in Fig. 14B, membrane 310P and membrane 310Q form inflated regions 324G and 324H with cylinder 305. As shown, membrane 310P and membrane 310Q are terminated with plain ends and folds 320. Exemplary systems and methods for placing the stent relative to orifice

22 are illustrated in Figs. 15A, 15B, 16A, 16B, 16C and 17.

Fig. 15A illustrates introducer 405 coupled to deflated stent 300A shown in position for insertion in, for example, orifice 22. Fig. 15B illustrates introducer 405 coupled to inflated stent 300A. Introducer 405 includes retainer 440 and thruster 415. As shown in the section views of Figs. 16A and 16B, retainer 440 includes a finger grip portion coupled to hollow shaft 445. Shaft 445 terminates at end 450 and is configured for a friction fit within lumen 307 of stent 300A. Thruster 415 includes a finger grip portion coupled to slotted barrel 420 which terminates at face 425. Hollow shaft 445 is slidably coupled to barrel 420. Face 425 abuts an end wall of cylinder 305. Fluid line 480 is routed through shaft 445 and engages hole 322 of stent 300A.

To place stent 300A in orifice 22, end 450 is inserted into lumen 307. In one example, an end of fluid line 480 is coupled to hole 322. An operator manipulates introducer 405 and when properly positioned, applies fluid pressure to line 480. Fluid pressure delivered via line 480 inflates the membrane of stent 300A. In one example, hole 322 seals shut after removal of fluid line 480.

After inflation, the finger grip portion of retainer 440 is drawn towards the finger grip portion of thruster 415, as illustrated by arrows 442 and 417 of Fig. 16B. When drawn together, the relative motion of retainer 440 and thruster 415 serves to eject stent 300A from end 450. Fig. 16C illustrates inflated stent 300A decoupled from introducer 405. In the figure, fluid line 480 is partially withdrawn from hollow shaft 445. Introducer 405 can be used for deflating and removing stent 300A. For removal, fluid line 480 is coupled to hole 322 and end 450 is engaged with lumen 307. After deflating the membrane using fluid line 480, introducer 405 is extracted from orifice 22. In one example, an introducer engages an inside diameter portion of a lumen of the stent. In one example, an introducer engages a stub or other feature on a surface of the stent. Fig. 17 includes an illustration of stent 300P having stub 365 projecting from an end wall. Stub 365 includes a necked-in or weakened portion 367 configured to break under tensile or shear loading exerted by retainer 440 through receiver 460. In the example illustrated, fluid line 480 is routed in a space between retainer 440 and barrel 420. Following placement and inflation of stent 300P, an operator applies a tension or rotational force on retainer 440 which separates stub 365 from stent 300P. Stub 365 can extend from either or both ends of stent 300P.

Alternate Examples

Other examples are also contemplated. For example, a sealed joint between the membrane and the cylinder can be reinforced by a groove in the cylinder, a notch or by other structure formed at an end of the cylinder. A corresponding membrane includes a bulb that engages the groove, notch or other structure.

In one example, more than one region under the membrane can be inflated simultaneously by using a single manifold coupled to the different regions. hi one example, the membrane is formed of material having a variable durometer or wall thickness, hi such a case, the durometer or wall thickness is selected to provide a sealed joint at a particular portion of the membrane and allow flexibility at other portions of the membrane. For example, the durometer or thickness of the membrane may vary radially or longitudinally over the stent. hi one example, cylinder 305 is devoid of a lumen. Applications in addition to lacrimal surgery are also contemplated. For example, and without a lumen in cylinder 305, the present subject matter can be used to occlude septal defects in a heart, control urinary incontinence or treat an aortic aneurysm. In addition, a multiple lumen (such as a fluted design), can provide multiple channels for communicating different fluids or lines.

Another exemplary application includes treatment of conditions related to the ureter and the urethera. A typical ureter has a diameter of approximately 3 mm. A stent, according to the present subject matter, has an uninflated diameter of approximately 1 mm diameter and a length of approximately 5-10 mm. When inflated, the diameter is at least the full 3 mm of the ureter.

A typical urethra diameter is approximately 6 mm. A stent, according to the present subject matter has an uninflated diameter of approximately 4-5 mm and a length of approximately 1 cm. When inflated, the diameter is at least the full 6 mm of the urethra. Such a device can prove beneficial for treatment of an enlarged prostrate, also known as benign prostatic hypertrophy (BPH).

In one example, lumen 307 of cylinder 305 includes an open channel free of obstructions or other structure. In one example, lumen 307 is configured to receive a device such as a valve, a sensor or therapeutic device or agent.

In various examples, the stent is fabricated of a biocompatible or non- biocompatible material. Biocompatible materials are conducive to implantation in humans or animals. Non-biocompatible materials are conducive to other applications, including for example, a bushing, gasket or other device for use with electrical equipment, a chemical, fluid or material handling manifold or system.

In one example, the stent is fabricated of a flexible or pliable material which is easily bendable. Suitable examples include polyimide, polyurethane, polylactic acid, silastic, silicone, latex and rubber. In various examples, the material used for the membrane differs from that of the cylinder.

In one example, the membrane is fabricated of extensible material, and consequently, the surface area of the inflated membrane is greater than the surface area of the deflated membrane. In one example, the membrane is fabricated of non-extensible material and thus, the surface area remains constant whether inflated (deployed) or deflated.

In one example, the present subject matter includes an inflatable external membrane around a central core or cylinder. The central core retains its shape and structural integrity whether the outer membrane is inflated or deflated. In various examples, the membrane is permeable or semi-permeable. In various examples, the membrane elutes a therapeutic or medicinal agent through the wall. In one example, the membrane is coated with a therapeutic or medicinal agent. In various examples, a locking collar is provided at one or more ends of the tubular stent or cylinder. According to one example, the locking collar includes a ring that cinches the membrane to an inner wall section of the stent. Accordingly, the membrane is positioned, and secured, over an end of the cylinder with a locking collar that is inserted into an open bore, or a recess, in the end. hi one example, the longitudinal position of the tube relative to the cylinder remains fixed, as illustrated in FIGS. 1, 2, and 4-17. Friction resulting from the elastic forces around the one or more joints between the tube and the cylinder precludes shifting of the tube relative to the cylinder. In an exemplary embodiment, the longitudinal position of the tube evolves during the eversion portion of the manufacturing process (as illustrated in FIG. 3) and remains fixed, or immovable, during implantation (dilation) and explantation (contraction).

Conclusion It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in which" are used as the plain-English equivalents of the respective terms "comprising" and "wherein." Also, in the following claims, the terms "including" and "comprising" are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising: a tube; and a cylinder disposed within a lumen of the tube and having an impervious joint between a distal end of the cylinder and a distal end of the tube; and wherein the tube includes an elastic membrane and wherein a longitudinal position of the tube relative to the cylinder remains fixed.

2. The apparatus of claim 1 wherein the tube is contiguous with the cylinder.

3. The apparatus of claim 1 wherein the tube has a uniform wall thickness.

4. The apparatus of claim 1 wherein the tube has a non-uniform wall thickness.

5. The apparatus of claim 1 further including a flange at a proximal end of the tube.

6. The apparatus of claim 5 wherein the flange is contiguous with the tube.

7. The apparatus of claim 1 wherein the cylinder has a bore and further wherein the tube has a wall thickness less than the wall thickness of the cylinder.

8. The apparatus of claim 1 wherein a proximal end of the tube is substantially flush with a proximal end of the cylinder.

9. The apparatus of claim 1 further including a medicinal coating on a surface of the tube.

10. The apparatus of claim 1 configured for insertion in at least one of a ureter and a urethera.

11. A method comprising: providing a tube having a thin wall section and a thick wall section, wherein the thin wall section is proximate a first end of the tube; everting a portion of the thin wall section; aligning the first end with the thick wall section; and forming an impervious joint between the first end and the thick wall section.

12. The method of claim 11 wherein providing includes molding.

13. The method of claim 11 wherein everting includes increasing a diameter of the first end.

14. The method of claim 13 wherein increasing includes inserting a mandrel into the first end.

15. The method of claim 11 wherein everting includes pressurizing the thin wall section.

16. The method of claim 15 wherein pressurizing includes introducing a gas.

17. The method of claim 11 wherein aligning includes positioning the first end proximate a second end of the tube.

18. A method comprising: forming an elastic tube, the tube having a first portion and a second portion, wherein the first portion is proximate the second portion and wherein a wall thickness of the first portion is thinner than that of the second portion; everting the first portion; and deforming the tube to longitudinally align the first portion relative to the second portion.

19. The method of claim 18 wherein everting the first portion includes stretching the first portion.

20. The method of claim 18 wherein everting the first portion includes stretching the first portion using a mandrel.

21. The method of claim 18 wherein everting the first portion includes: coupling an outer surface of the first portion on an exterior surface of a tubular guide; displacing the elastic tube relative to the tubular guide; and sealing the first portion onto an outer surface of the second portion.

22. The method of claim 21 wherein displacing includes applying a fluid pressure.