Patent Application
20060247576
The present invention is directed to a device and method for delivering a fluid-based agent to a selected site within the body and, more particularly, for delivering a fluid-based agent such as a pharmaceutical agent, diagnostic agent or preventative agent in a body lumen.
A challenging problem in the treatment of patients is the delivery of a fluid-based agent to only a selected local site within the body. For example, it is commonly desirable to achieve an effective concentration of a therapeutic or preventative agent at only a selected local site within a body lumen. The amount of an agent needed to effectively treat a disease in a particular organ can oftentimes only be achieved by establishing blood levels that can produce damaging side effects on other internal organs and healthy tissue. For example, therapy administered to prevent blood coagulation at one site can produce unwanted bleeding at other sites.
Devices and methods are known for delivering fluid-based agents locally into the body. For example, percutaneous transluminal coronary angioplasty balloon dilation catheters have been formed with drug coatings. These devices can be bulky and limit blood flow. There are also stents that include a polymer sheath with an incorporated controlled release drug. Such stents are less than fully satisfactory due to the size of the sheath and its limited compatibility with certain drugs.
There are known devices for delivering fluid-based agents in vessels that include an element having a portion that is preformed in a permanent coil shape as exemplified in U.S. Pat. No. 5,523,092 to Hanson et al. The disclosed device includes a delivery sheath having a diameter larger than the diameter of the coil, making the device intrusive inside the body. Other known devices such as disclosed in U.S. Pat. No. 5,603,694 to Brown et al. include an element that transforms from a coil shape to a more linear shape, for example, when heated by a heat source or manipulated by a guide wire inside the element while the element is inside the body. Such devices are also less than fully satisfactory in that the required heating of the element to remove the coil shape and enable removal of the element from the body, makes such devices complicated to operate inside the body. Also, depending on the transformation temperature of the element, the required heating cause the shape transformation can damage human tissue.
Thus, there is a need for a device and method for delivering a fluid-based agent in a lumen in a mammalian body that (i) can deliver the agent directly to substantially only the selected location, thereby reducing the amount of the agent that needs to be delivered such as to achieve a desired effect, (ii) reduces side effects on other internal organs and healthy tissue, (iii) is small sized and, thus, relatively less intrusive and less restrictive to blood flow than some known devices, and (iv) does not require an external heat source or guide wire to operate in the lumen.
The present invention is a device and method suitable for delivering a fluid-based agent into a lumen within a mammalian body that satisfies the above needs. The device is particularly suitable for delivering a fluid-based agent directly into a wall of a lumen. The lumen can be in a vessel or any other tissue that contains or transports fluid in the body. The fluid-based agent can be a therapeutic agent, a preventative agent or a diagnostic agent.
The device comprises a housing including an elongated bore, and a delivery element. The delivery element includes a proximal portion, a distal portion and a wall. The wall defines a fluid passage extending between the proximal portion and the distal portion. The wall also defines a plurality of apertures in fluid communication with the fluid passage at the distal portion.
The housing is selectively movable relative to the delivery element between a position in which the distal portion is disposed in the bore, and a position in which the distal portion is disposed extended from the bore. The bore is sized such that the distal portion assumes a constrained shape in the bore.
The distal portion self-expands to a different shape exteriorly of the bore. The distal portion self expands preferably to a helical shape. The diameter of the expanded distal portion increases such that the apertures are proximate to the wall of the lumen. Preferably, the apertures are in direct contact with the wall.
The present device can deliver a therapeutic agent, preventative agent or a diagnostic agent directly to the wall of the lumen, producing important advantages. Particularly, the device (i) reduces the amount of the agent needed to achieve a desired effect, (ii) reduces side effects on other tissue, and (iii) is small sized.
The distal portion of the delivery element is preferably formed of a superelastic material, which can be superelastically constrained when inside the bore of the housing and transform to the helical shape outside the bore. This transformation can be repeated without producing plastic deformation of the distal portion. The housing has a small diameter because the delivery element can be introduced into the body in a straightened shape and not in a preformed coil shape. The superelastic material is preferably capable of forming stress-induced martensite at temperatures near mammalian body temperature and recovering to the non-stressed shape in direct response to release of the applied stress. Accordingly, the present device does not require a heat source or a straightening element inside the element to transform the shape of the distal portion inside of the body, thus making the device simple to use.
These and other features, aspects and advantages of the present invention will become better understood from the following description, appended claims and accompanying drawings, in which:
The present invention is a device and method for delivering a fluid-based agent in a lumen within a mammalian body. The lumen can be any natural tissue conduit that contains or transports body fluids. For example, the lumen can be in a vessel of the cardiovascular system such as a vein or artery, a bile duct, or a fluid conduit in the intestinal tract, urinary system or respiratory system. The device can be used in humans as well as in animals.
As used herein, the term “fluid-based agent” means any liquid or liquid-based agent. For example, fluid-based agents can include liquids, liquid suspensions, liquid emulsions, gels, suspensions, liquid mixtures and liquid/solid mixtures.
The present invention is particularly suitable for delivering therapeutic agents, preventative agents and diagnostic agents directly to body tissue. The tissue is typically the wall of a vessel or an organ at a selected delivery site. The selected site can be a diseased or healthy section of the fluid conduit.
The device 20 according to the present invention is shown in
The housing 22 has a outer diameter D2 which is typically about 0.007 inches to about 0.02 inches, which is smaller than the diameter of the lumen 12 as defined by the inner diameter D3 of the wall 12. For example, the lumen 12 can typically have an inner diameter of from about 0.08 inches to about 1 inch for vessels. Small vessels typically have a lumen diameter of from about 0.08 inches to about 0.25 inches. The housing 22 outer diameter can be varied depending on the size of the lumen in which the device 20 is used. The housing 22 has a sufficient length such that the proximal end extends outside of the body during use of the device 20 so that a user can manipulate the device 20. Accordingly, the housing 22 length can be varied depending on the distance between the point of entry of the device 20 into the body and the delivery site of the fluid-based agent.
The housing 22 can be formed of a suitable biocompatible material including metals such as stainless steel, and non-metallic materials such as polymers. The housing 22 has sufficient strength to constrain the delivery element 24 in the constrained condition in the bore 28 so that the delivery element 24 does not assume the recovered shape prior to being located at the treatment site. In addition, the housing 22 is capable of bending during advancement in body lumens to enable placement of the device 20 in tortuous fluid conduits.
The delivery element 24 includes a proximal portion (not shown), a distal portion 30, and a wall 32 defining a fluid passage 34 (
The distal portion 30 of the delivery element 24 is preferably comprised of a shape memory alloy that can be constrained in the constrained (straightened) shape inside the bore 28 of the housing 22, and then self-expand so as to assume a recovered shape when extended from the bore 28. The proximal portion of the delivery element 24 can be formed of a different material than the distal portion 30 as the proximal portion does not undergo the same shape transformation during use in the body lumen. The materials selected for the distal portion 30 and the proximal portion are preferably materials that are biocompatible and can remain in the body lumen during delivery of the fluid-based agent without damage to body organs and tissue, and also exhibit passive chemical behavior.
The shape memory material comprising the distal portion 30 of the delivery element 24 is preferably a superelastic material that can accomplish a shape change without having to undergo a temperature change as required for thermoelastic shape memory materials. Superelastic materials form stress-induced martensite when mechanically stressed at a temperature at least above As (austenite start), and preferably above Af (austenite finish). The material is preferably a superelastic material having a large non-linear elastic range and capable of large strains without the occurrence of permanent deformation. Superelastic materials can be deformed substantially reversibly by 8% and more, by the application of mechanical stress and stress release. These properties enable the housing 22 to have a small bore 28 size.
Suitable superelastic materials for forming the distal portion 30 include, for example, binary Ni—Ti, and Ni—Ti alloys including elemental additions such as V, Fe, Nb, Co, Cr and Zr. Ni—Ti alloys are available that have an Ms temperature at near mammalian body temperature (about 35°-40° C.) and do not require heating by a heat source to cause a shape change when inside the body. The shape change between the constrained state and the recovered state is achieved by stress release. These alloys are also characterized as having a low modulus and high austenitic yield strength. Other suitable superelastic materials include copper-based alloys consisting essentially of Cu, Al and Zn; Cu, Al and Ni; and Cu and Zn.
The distal portion 30 is superelastically constrained in a first position of the housing 22 shown in
The housing 22 is movable relative to the delivery element 24 in the direction B (toward the proximal end) between the first position shown in
A fluid-based agent is introduced into the fluid passage 34 of the delivery element 24 at the proximal end of the device 20 and caused to flow to the distal portion 30. The agent can be introduced into the fluid passage 34 using a conventional fluid supply source by pumping, injection or gravity flow. The delivery pressure of the agent into the fluid passage 34 can be varied to control the rate of dispensing through the apertures 36 in the distal portion 30.
The fluid-based agent can be a therapeutic agent, a diagnostic agent, a preventative agent or-another suitable agent as will be understood by those skilled in the art with reference to the disclosure herein. For example, suitable agents include anticoagulants such as heparin, agents which inhibit platelet formation, agents which effect platelet metabolic function, vascular cell growth promoters, vasodilators, cholesterol lowering substances, antibodies, dyes and markers.
A method of delivering a fluid-based agent in a body lumen in a mammalian body comprises introducing the device 20 into the body and into a selected lumen 10 with the housing 22 in the first position shown in
After an effective amount of the agent is dispensed in the lumen, the distal portion 30 is retracted into the bore 28 of the housing 22 and transforms to the first shape shown in
The effective amount of the agent is dependent on the type of agent delivered and the recommended dose of the agent. For example, a therapeutically effective amount of a therapeutic agent to treat a disease or condition can be delivered using the device 20. Preventative agents can be delivered in effective amounts to prevent the onset or progression of a disease or other undesirable state.
Thus, the present device can deliver fluid-based agents such as therapeutic and preventative agents directly to walls of fluid conduits such as vessels and organs. Diagnostic agents such as radioactive isotopes can also be delivered directly to the wall. In the preferred application, the device reduces the amount of the agent needed to achieve a desired effect because the agent substantially diffuses directly into the wall and does not enter into the fluid stream in the lumen. Consequently, the agent is delivered substantially to the selected site and is not carried to other internal organs and healthy tissue, thus reducing side effects of the agent.
In addition, the device 20 is small sized due to the use of the superelastic delivery element 30 and the small sized housing 22. Consequently, the device 20 is less restrictive to the flow of blood and other fluids as compared to larger known devices. The small size of the device 20 also makes it relatively easy to maneuver in lumens. Furthermore, the device 20 is relatively simple to use because it does not require the simultaneous manipulation of a guide wire and/or a heating device to cause the delivery element 24 to change shape.
The present invention has been described in considerable detail with reference to certain preferred embodiments thereof, however, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein.
This application is a continuation of U.S. patent application Ser. No. 08/968,756, filed on Oct. 20, 1997, the entire contents of which is hereby incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 08968756 | Oct 1997 | US |
| Child | 11423368 | Jun 2006 | US |
