Abstract:
Embodiments are directed to eluting coils having a relaxed coiled state and a straightened state that may be deployed at a fixed location within a patient&#39;s body and may accurately dispense and distribute fluids and or dissolvable substances at site specific locations of the body. Some embodiments of eluting elements are configured to be subsequently retrieved from a delivery site.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. section 119(e) from U.S. Provisional Application Ser. No. 60/642,892, titled “Eluting Coils and Methods of Deploying and Retrieving”, filed Jan. 10, 2005, by John L. Wardle, which is incorporated by reference herein in its entirety. This application is also related to U.S. patent application Ser. No. 10/386,260, filed Mar. 10, 2003, by John L. Wardle, titled “Surgical Coils and Methods of Deploying” which is also incorporated by reference herein in its entirety. 

   BACKGROUND 
   Systemic drug delivery is often ill-suited to the treatment of conditions occurring at one or more discrete sites within a patient&#39;s body, because it involves the delivery of the medication to sites other than the target site. Systemic agent delivery also requires the infusion of large doses of the medication to assure the delivery of a therapeutic dose to the target site, thereby creating the possibility of deleterious effects. Another problem of systemic administration is the inevitable fluctuations of drug concentrations that it produces. The dosage that can be delivered to the target site may be limited by the need to minimize unwanted effects in other parts of a patient&#39;s body. Furthermore, systemic delivery exposes the medication to possible degradation and elimination by the action of other bodily organs. 
   Conventional methods of drug therapy, as discussed above, often result in blood levels of the cytotoxic agent that are dangerous for the patient. Even with local administration of these agents, one must consider that blood flow of vessels as well as other transport mechanisms may dilute the local concentration of the therapeutic agent by a wash-out effect. The need remains, therefore, for systems and methods for localized delivery of therapeutic agents, including toxic therapeutic agents, which may be concentrated and localized intramurally within the affected tissue or vessel. 
   There is general need in many branches of medicine for improved localized internal delivery of substances including therapeutic agents and drugs and diagnostic agents into the walls of ducts, organs and vessels. In particular, there is need for effective systems and methods of delivery into tissue and into cells themselves within organs, ducts, tracts and vessels of the body via percutaneous and luminal access. Problems remain however in the exact method by which the local administration of drugs or therapeutic agents can be achieved. The problem is further complicated where it is desirable to deliver drug in relatively small amounts and the delivery device must be sufficiently small, biocompatible, impermeable and drug non-reactive. There is also a need in some circumstances for retrieval systems and methods of delivery devices which may be implemented at the conclusion of treatment embodiments or portions thereof. 
   SUMMARY 
   Some embodiments include eluting coils that can accurately dispense and distribute fluids and or dissolvable substances in site specific locations of a patient&#39;s body. Some embodiments of eluting coils may be configured to be subsequently retrieved from a delivery site. 
   Some embodiments include an eluting coil, having an elongate element with a longitudinal axis formed into a coiled enclosed configuration with an overlapped portion. Sections of the elongate element make contact with adjacent sections of the elongate element in the overlapped portion. The overlapped portion has a circumferential overlap of at least 300 degrees and has a pre-stressed configuration to ensure surface contact between overlapped portions of the elongate element. Some of these embodiments include a pre-stress of the pre-stressed configuration which is substantially constant around the coil. Some of these embodiments include a surface of the elongate element that has at least one reservoir with a channel. Some of these embodiments include stand-off members on at least a portion of the surface of the elongate element that are configured to produce a controlled eluting gap between coils segments when the elongate element is in a coiled configuration. Some of these embodiments include an elongate element having an interlocking configuration that may include a longitudinal groove in a first surface of the elongate element and a longitudinal ridge, configured to mate with the longitudinal groove on a second surface opposite the first surface. The interlocking configuration may be configured to create an eluting gap between adjacent coils of overlapped portions the elongate element in a coiled configuration. Some of these embodiments may include a tail member for removal after deployment. 
   Some embodiments of eluting coils for deployment within a body of a patient include a resilient elongate element having an inside surface, an outside surface, a pre-stressed non-coiled configuration in a restrained state and a coiled configuration in a relaxed state with the outside surface disposed adjacent the inside surface in an overlapped portion thereof. At least one dissolvable agent reservoir is disposed on the elongate element. In addition, at least one conduit having a pre-determined cross section is disposed in fluid communication between the dissolvable agent reservoir and an outside portion of the coiled configuration of the resilient elongate element in the relaxed state. Some of these embodiments include a resilient elongate element with a pre-stress of a substantially constant radius of curvature along a length of the resilient elongate element. Some of these embodiments include at least one stand-off member on a surface of the resilient elongate element and the at least one conduit comprises a controlled gap formed by the stand-off member between the inside surface and outside surface of the resilient elongate element in overlapped portions of the coiled configuration in the relaxed state. Some of these embodiments include a conduit formed from at least one channel disposed on a surface of the resilient elongate element. 
   Some embodiments of a method of deploying an eluting coil include providing an eluting coil for deployment within a body of a patient. The eluting coil includes a resilient elongate element having an inside surface, an outside surface, a pre-stressed non-coiled configuration in a restrained state and a coiled configuration in a relaxed state with the outside surface disposed adjacent the inside surface in an overlapped portion thereof. At least one dissolvable agent reservoir is disposed on the elongate element. At least one conduit having a pre-determined cross section is disposed in fluid communication between the dissolvable agent reservoir and an outside portion of the coiled configuration of the resilient elongate element in the relaxed state. The resilient elongate element of the eluting coil is disposed in a restrained state. A distal end of an elongate delivery member is disposed adjacent a target site within a patient&#39;s body and the resilient elongate element is moved along the elongate delivery member. The resilient elongate element is deployed from a distal end of the elongate delivery member and allowed to achieve a relaxed coiled configuration. 
   Some embodiments of a method of retrieving an eluting coil include providing an eluting coil deployed within a body of a patient in a relaxed coiled configuration. The eluting coil includes a resilient elongate element having an inside surface, an outside surface, a pre-stressed non-coiled configuration in a restrained state and a coiled configuration in a relaxed state with the outside surface disposed adjacent the inside surface in an overlapped portion thereof. At least one dissolvable agent reservoir is disposed on the elongate element. At least one conduit having a pre-determined cross section is disposed in fluid communication between the dissolvable agent reservoir and an outside portion of the coiled configuration of the resilient elongate element in the relaxed state. A tail member is disposed at an end of the resilient elongate element configured to facilitate removal of the eluting coil after deployment thereof. A retrieval device is advanced into the patient&#39;s body until a distal end of the retrieval device is disposed adjacent the eluting coil. A retraction element of the retrieval device is coupled to the tail member and the resilient elongate element is withdrawn into the retrieval device. 
   These features of embodiments will become more apparent from the following detailed description when taken in conjunction with the accompanying exemplary drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrate a perspective view of an eluting coil having features of the disclosure. 
       FIG. 2  is an elevational view of an eluting coil having features of the disclosure. 
       FIG. 3  shows a perspective view of an eluting coil similar to that of  FIGS. 1 and 2  in a straightened configuration. 
       FIG. 4  is an enlarged view, in perspective, of the encircled portion  4  of  FIG. 3  showing surface reservoirs and channels. 
       FIG. 5  illustrates a perspective view of an alternative embodiment of an eluting coil in a straightened configuration. 
       FIG. 6  is an enlarged view, in perspective, of the encircled portion  6  of  FIG. 5  showing surface protrusions on the elongate member. 
       FIG. 7  is an elevational view of an eluting coil having an embodiment of a self-aligning coil configuration. 
       FIG. 8  is a transverse cross sectional view of the eluting coil of  FIG. 7  taken along lines  8 - 8  of  FIG. 7  illustrating an interlocking groove, raised ridge and eluting channel on the elongate element of the eluting coil. 
       FIG. 9  shows a perspective view of an alternative embodiment of an eluting coil with an integrated retrieval tail. 
       FIG. 10  is an enlarged view, in perspective, of the encircled portion  10  of  FIG. 9  showing a retrieval hole. 
       FIG. 11  shows a perspective view of an alternative embodiment of an eluting coil with an attached retrieval tail. 
       FIG. 12  is an enlarged view, in perspective, of the encircled portion  12  of  FIG. 11  showing a retrieval loop. 
       FIG. 13  is an enlarged view, in perspective, of the encircled portion  13  of  FIG. 11  showing a retrieval loop attachment. 
       FIG. 14  is a perspective view of a retrieval device including a retrieval cannula and a retraction element in the form of a retrieval wire disposed within the retrieval cannula, with a distal end of the retrieval cannula disposed adjacent an eluting coil and a distal end of the retrieval wire coupled to a tail extension of a resilient elongate element of the eluting coil to retrieve the eluting coil. 
       FIG. 15  is an enlarged view, in perspective, of the encircled portion  15  of  FIG. 14  showing retrieval wire placed in a retrieval hole of the resilient elongate element of the eluting coil. 
       FIG. 16  is a perspective view of the retrieval wire and retrieval cannula with the resilient elongate element of the eluting coil being withdrawn into a distal port at a distal end of the retrieval cannula. 
       FIG. 17  is an enlarged view, in perspective, of the encircled portion  17  of  FIG. 16  showing the resilient elongate element of the eluting coil being withdrawn into the retrieval cannula. 
       FIG. 18  is a perspective view of a ratcheting delivery device configured to deliver and deploy eluting coils, with a thumb ring of the delivery device in a proximal retracted position. 
       FIG. 19  is a perspective view of the delivery device of  FIG. 18  with the thumb ring of the delivery device in an advanced distal position with an eluting coil being deployed from a distal end of a delivery sheath of the delivery device. 
       FIG. 20  is an enlarged view, in perspective, of the encircled portion  20  of  FIG. 19  showing a distal section of the delivery device. 
       FIG. 21  illustrates a sharpened distal tip of an eluting coil penetrating tissue during deployment. 
       FIG. 22  illustrates a schematic view of the eluting coil of  FIG. 21  in a further deployed configuration, the direction of deployment being indicated by the arrow. 
       FIG. 23  illustrates a schematic view of the eluting coil in a completely deployed state within tissue. 
   

   DETAILED DESCRIPTION 
     FIGS. 1-4  illustrate an embodiment of an eluting coil  10  having a resilient elongate element  12  shown in a relaxed coiled configuration with approximately 7 revolutions. The resilient elongate element has an inside surface  14  and an outside surface  16  with the outside surface  16  in contact with the inside surface  14  in an overlapped portion over approximately 6 revolutions of circumferential overlap (about 2160 degrees). Some embodiments of eluting coils may have overlapped portions with an angular overlap of about 300 degrees to about 2160 degrees. The resilient elongate element  12  has a transverse cross section with a substantially flattened configuration producing a ribbon-like configuration for the resilient elongate element  12 . The resilient elongate element also has a tissue penetrating point or tip  18  disposed at a distal end  20  of the resilient elongate element  12 . The resilient elongate element  12  also has a wedge shaped recess  22  disposed at a proximal end  24  of the resilient elongate element  12 . The relaxed coiled configuration of the eluting coil  10  includes a void or hole in the center thereof which may be disposed about target tissue of a patient upon deployment. Such tissue is mechanically captured by the deployed eluting coil  10  which may prevent movement or migration of the eluting coil  10  once it has been deployed. 
   The eluting coil  10  may be delivered to a target site in a patient&#39;s body (not shown) by methods disclosed in the incorporated application U.S. patent application Ser. No. 10/386,260, filed Mar. 10, 2003, by John L. Wardle, titled “Surgical Coils and Methods of Deploying” (&#39;260 Application). FIGS. 25-30 and the accompanying description of the &#39;260 application describe embodiments of a delivery device having a delivery member or sheath that may be used to deploy the eluting coil  10  to a target site within a patient&#39;s body. Other embodiments of the &#39;260 application may also be used. 
   The resilient material of the resilient elongate element  12  is configured to resist deformation from the relaxed coiled configuration shown in  FIGS. 1 and 2  and spring back to the relaxed coiled configuration when released from a restrained configuration, such as a straightened configuration, as shown in  FIG. 3 . The resilient elongate element  12  of eluting coil  10  and all eluting coil embodiments discussed herein may be made from a variety of materials including those that exhibit either great elasticity or shape memory properties. Suitable materials for fabrication include but are not limited to nickel titanium alloys (Nitinol), stainless steel, Elgiloy, MP35N or other high strength biocompatible materials. In addition to these materials eluting coils can be made from absorbable materials such as magnesium alloy which besides being absorbable has the added advantage that it does not interfere with magnetic resonance imaging (MRI). 
     FIG. 2  illustrates the geometry of some embodiments of eluting coils where a first surface of each circumferential overlap, or portion thereof, is in direct contact with a second surface of its neighboring overlap or portion of the resilient elongate element  12 . Direct contact of the overlapping surfaces  14  and  16  ensures that there is no unintended free space between contacting surfaces  14  and  16 . In some embodiments, the resilient elongate element  12  has a pre-stress with a constant curvature R along a length of the resilient elongate element  12 . When the resilient elongate element  12  of the eluting coil  10  is ejected from a delivery device in a restrained non-coiled configuration, such as a straightened or substantially straightened configuration, the resilient elongate element will tend to spring back to the coiled configuration of the relaxed state of the resilient elongate element  12 . In the relaxed coiled configuration, all layers of overlap tend to assume an unstressed state of constant radius of curvature R. As the resilient elongate element is deployed from a distal end of a delivery sheath or member, the distal end  20  begins to curl and assume a relaxed configuration. When the distal end  20  and the first revolution of the coil  10  enter a target site, the coil will be able to assume an unstressed state and assume a radial position R As subsequent layers of circumferential overlap are ejected from the delivery device the resilient elongate element  12  coils upon itself. The first overlap layer  26  will assume radius at rest of R+T and the sixth layer  28  will have a resulting radius of R+6T. The result is that as all layers are not allowed to assume the fully unstressed state of radius R. As such, compression forces, expansion forces or both cause the adjacent overlap layers of the resilient elongate element  12  to contact one another. 
   The surfaces  14  and  16  may be configured so as to provide a three dimensional drug eluting surface or reservoir, the modification could be as simple as a bead blast texture or more sophisticated techniques can be used as described in the following embodiments.  FIGS. 3-4  illustrate an embodiment of resilient elongate element  12  of eluting coil  10  in a non-coiled restrained state with a straightened configuration. The elongate element  12  is shown with the distal end  20  extended opposite the proximal end  24 . A plurality of axially consecutive longitudinal dissolvable agent reservoirs  30  and channels  32  are cut into the outside surface  16  elongate element  12 . The reservoirs  30  and channels  32  are shown covering a substantial portion of outer surface  16 , but any suitable portion of outer surface  16  or inner surface  14  could be used for such reservoirs  30  or channels  32 . When the resilient elongate element  12  shown in  FIGS. 3 and 4  is allowed to assume a relaxed coiled configuration, the reservoirs  30  and channels  32  cut into the outer surface  16  are pressed against the inner surface  14  such that the reservoirs  30  are sealed from an outside portion of the eluting coil  10  and a top portion of the channels are sealed to form a conduit in fluid communication between the respective reservoirs  30  and outside portion of the eluting coil  10 . As shown in more detail in  FIG. 4 , the channels  32  may extend across a plurality of reservoirs  30  to a lateral edge  34  of the resilient elongate element  12 . For some embodiments of eluting coils  10 , some of the reservoirs or dissolvable agent depots  30  may be exposed when the resilient elongate element  12  of the eluting coil  10  is in a coiled configuration in a relaxed state. The exposure of such reservoirs  30  allows for initial delivery of a high dose of agent over a short period upon initial deployment of the eluting coil  10 . The non-exposed or encapsulated reservoirs  30  will deliver agent from a dissolvable matrix over a course of time determined by the transverse cross section of the channels or conduits  32  and capacity of reservoirs  30 . 
   Eluting coils  10  may be configured to be delivered to a target site in a patient&#39;s body with a wide range of agents, such as bioactive agents including drugs, antibiotic agents, growth factors, anti-inflammatory agents and the like disposed in a dissolvable matrix within reservoirs  30 , channels  32  or both. Dissolvable matrix components may include, but are not limited to, lipid materials, gelatins and the like.  FIG. 4  shows a dissolvable agent reservoir  30  with a dissolvable agent  36  disposed therein. Generally, some or all of the reservoirs  30  may have some dissolvable agent  36  disposed within them prior to deployment of the eluting coil  10 . When the resilient elongate element  12  of the eluting coil  10  is ejected from the delivery device the overlapping surfaces will encapsulate and contain the reservoirs  30  and channels  32  as discussed above. Thereafter, the dissolvable agent will come in contact with body fluids via the conduits formed by the channels and the dissolvable agent will be delivered from the reservoirs  30  to a region outside the eluting coil  10  through the conduits formed by the encapsulated channels  32 . 
   Reservoirs  30  may be formed into one surface  14  or  16  of the resilient elongate element  12 , or may extend completely through the resilient elongate element  12 . Channels  32  may be cut to a specific depth and width in order to provide a path or conduit for controlled release of the dissolvable agent  36 , such as a bioactive agent, from the connected reservoir(s)  30  to tissue of a target site. The channels  32  may also contain the dissolvable agent  36 . This embodiment of the eluting coil  10  provides a means for a broad spectrum of release profiles to be tailored to the requirements of a particular bioactive agent and may also be used to enable the delivery of multiple compounds simultaneously. For example, different zones of the surfaces  14  or  16  of the resilient elongate element  12  may be loaded with different agents, such as drugs or other biologically active agents. For example, some embodiments may include anti-inflammatory agents and therapeutic agents on a single eluting coil  10 . For such embodiments, different agents may be separated into different reservoirs  30 , or may be combined together into the same reservoir or reservoirs  30 . 
   In addition, different zones or portions of the resilient elongate element  12  of the eluting coil  10  may be configured with varying reservoir  30  and channel  32  profiles. Different surfaces  14  and  16 , including reservoirs  30  or channels  32  thereof, of the resilient elongate element  12  of the eluting coil  12  may also be loaded with different agents disposed within a dissolvable agent matrix. Also, two or more components of a multi-component drug or other agent that need to be combined in order to react or otherwise be activated may be placed on opposite surfaces  14  and  16  of the resilient elongate element  12  of the eluting coil  10 . In such a configuration, the two or more components will then be combined or otherwise communicated with each other and activated when the eluting coil  10  is deployed and the opposing surfaces  14  and  16  make contact. 
     FIGS. 5-6  illustrate another embodiment of a resilient elongate element  40  of an eluting coil  10  in a restrained straightened state with some features that are common with the previous resilient elongate element embodiment  12 . The resilient elongate element  40  has a series of surface protrusions or stand-off members  42  that are configured to create a space between overlapping surfaces  14  and  16  of the eluting coil  10  when deployed. The controllable gap or conduit created as a result of the stand-off members  42  will be substantially equal to the height of the stand-off members  42  when the resilient elongate element  40  is disposed in a coiled relaxed configuration. Inside surface  14  or outside surface  16  of the resilient elongate element  40  of the eluting coil  10  may be coated with a bioactive agent in a dissolvable matrix  36 . A bioactive agent disposed in a dissolvable matrix  36  may also be disposed on inner portions of the resilient elongate element  40  between stand-off members in a dissolvable agent depot or reservoir  43 , as shown in  FIG. 6 . For such an embodiment, a space or gap (such as the gap indicated by arrows  49  in the embodiment shown in  FIG. 8  below) created by the stand-off members  42  between adjacent surfaces  14  and  16  of the resilient elongate element  40  in a relaxed coiled state or configuration will provide a controlled leak path or conduit for the bioactive agent in the dissolvable matrix  36  to reach an outside portion of the resilient elongate element  40  when in a relaxed coiled configuration. 
     FIGS. 7-8  illustrate an embodiment of eluting coil  10  which has a resilient elongate element  44  that is configured as an interlocking eluting coil  10  when deployed.  FIG. 8  shows a transverse cross sectional view of the eluting coil  10  which shows a raised longitudinal ridge  46  disposed on an outer or first surface  16  of the resilient elongate element  44 . The longitudinal ridge  46  is configured to mate and interlock with a longitudinal groove  48  extending longitudinally along a second or inner surface  14  of the elongate element. An interlocking engagement between the raised longitudinal ridge  46  and longitudinal groove  48  is configured such that the engagement prevents the remainder of the overlap surfaces  14  and  16  from contacting. For such a configuration, a controllable gap or space indicated by arrows  49  is created. The controllable gap between adjacent sections of the resilient elongate element  44  functions as a conduit between an inner portion of the eluting coil  10  and an outside portion of the eluting coil  10  when the coil is in a coiled relaxed state. 
   Reservoirs, such as reservoirs  30  discussed above may be disposed on one or both of the surfaces  14  and  16  of the resilient elongate element  44  with the controllable gap providing a conduit between the reservoirs and an outside portion of the coil  10 . Also, one or more surfaces  14  and  16  of the resilient elongate element  44  may be coated with the bioactive agent in a dissolvable matrix with the space or gap between surfaces of the resilient elongate element  44  providing a controlled leak path or conduit for the bioactive agent to an outside portion of the eluting coil  10  in a coiled relaxed state. Although the embodiment shown in  FIGS. 7 and 8  includes one raised longitudinal ridge  46  and one longitudinal groove  48  on an opposite surface of the resilient elongate element  44 , the resilient elongate element  44  may include multiple raised longitudinal ridge elements and mating longitudinal grooves. 
     FIGS. 9-13  illustrate alternate embodiments of eluting coils which can be removed from the treatment site after deployment if necessary. These eluting coil embodiments include an extension tail that is configured to be coupled to by a device that may then be used to apply a retractive force upon the deployed eluting coil. The extension tail may be an integral part of the resilient elongate element of the eluting coil itself or be a separate attached feature or element. 
     FIGS. 9 and 10  illustrate an eluting coil  50  that may have features, dimensions and materials similar to or the same as those of the eluting coil  10  discussed above. Eluting coil  50  also includes a tail extension  52  formed integrally with a proximal end  54  of a resilient elongate element  56  of the eluting coil  50 . The tail extension includes a hole  58  disposed at a proximal end  60  of the tail extension  52  in order to facilitate capture and retrieval of the eluting coil  50  after deployment thereof. The proximal end  60  of the tail extension may include radiopaque material or otherwise be configured to be radiopaque in order to facilitate visualization of the hole  58  of the tail extension  52  under X-ray or fluoroscopy during a retrieval procedure. The tail extension embodiment  52  shown in  FIGS. 9 and 10  has a substantially straight configuration in a relaxed state in order to extend away from the eluting coil  50  and facilitate location and coupling of the tail extension  52 . In use, the proximal end  60  of the tail extension  52  may be placed just under the surface of the skin of a patient in order to avoid infection and make the tail extension  52  easy to relocate or access. However, under some circumstances, such as where only short term implantation is necessary, the tail extension  52 , the proximal end  60  of the tail extension  52  or both may be deployed so as to breach through the surface of the skin of the patient. 
     FIGS. 11-13  illustrate an eluting coil  62  that may have features, dimensions and materials similar to or the same as those of the eluting coil  10  discussed above. Eluting coil  62  also includes a tail extension  64  that is a separate element from the resilient elongate element  66  of the eluting coil  62 . The tail extension  64  includes a loop of a flexible element, such as suture material, that extends through a hole  68  in a proximal end  70  of the resilient elongate element  66 . The tail extension includes a loop  72  disposed at a proximal end of the tail extension  64  in order to facilitate coupling to the tail extension  64  and capture and retrieval of the eluting coil  62  after deployment thereof. The loop  72  of the tail extension  64  may include radiopaque material or otherwise be configured to be radiopaque in order to facilitate visualization of the loop  72  of the tail extension  64  under X-ray or fluoroscopy during a retrieval procedure. Just as with eluting coil embodiment  50  discussed above, the proximal end of the tail extension  64  may be placed just under the surface of the skin of a patient in order to avoid infection and make the tail extension  64  easy to relocate or access. However, under some circumstances, such as where only short term implantation is necessary, the tail extension  64 , the proximal end of the tail extension  64  or both may be deployed so as to breach through the surface of the skin of the patient. 
     FIGS. 14-17  illustrate a removal or retrieval method and device that may be employed to remove an eluting coil  50  after deployment, and in particular, after deployment within tissue of the body of a patient.  FIGS. 14 and 15  show a perspective view of a retrieval device  80  coupled to eluting coil  50 . The retrieval device  80  includes a retrieval cannula  82  and a retraction element in the form of a retrieval wire  84  disposed within the retrieval cannula  82 . A distal end  86  of the retrieval cannula  82  is disposed adjacent eluting coil  50 . A hooked distal end  88  of the retrieval wire  84  is disposed through or otherwise coupled to hole  58  the tail extension  52  of the resilient elongate element  54  of the eluting coil  50  to retrieve the eluting coil  50 . The retrieval cannula is configured as an elongate hollow member that may be made from a high strength material such as stainless steel or the like. A distal section  87  of the retrieval cannula  82  may have an optional flattened or oblong transverse cross section in order to better accommodate the flattened transverse cross section or ribbon-like configuration of some resilient elongate element embodiments. In addition, the flattened or oblong transverse cross section may also be useful for tissue penetration during deployment or positioning within tissue of a patient while minimizing trauma to the tissue surrounding the retrieval cannula  82  during tissue penetration. 
   In some embodiments of methods of retrieval of a deployed eluting coil  50 , the retrieval process begins with identifying or locating the proximal end  60  of the tail extension  52 . Once located, the hooked distal end  88  of a retrieval wire  84  it placed through the hole  58  (or a loop  72  of an embodiment of an eluting coil  62  as shown in  FIGS. 11-13 ) as shown in  FIG. 15 . The proximal end of the retrieval wire  84  is the back loaded or withdrawn into the cannula  82 . The proximal end of the retrieval wire  84  may held stationary while the distal end  86  of the cannula  82  is advanced distally until the distal end  86  contacts the resilient elongate element  54  of the eluting coil  50 . The cannula  82  may then be held stationary and the retrieval wire  84  is pulled or withdrawn proximally, as indicated by arrow  90 , shown in  FIG. 16 , which in turn pulls the resilient elongate element  54  of the eluting coil  50  into the cannula  82  and uncoils the eluting coil  50  and imparts a restrained non-coiled configuration on the resilient elongate element  54  as the resilient elongate element  54  is withdrawn into the cannula  82 . 
     FIGS. 16 and 17  show a perspective view of the retrieval wire  84  and retrieval cannula  82  with the resilient elongate element  54  of the eluting coil  50  being withdrawn into a distal port  88  disposed at the distal end  86  of the retrieval cannula  82 . The retrieval wire  84  and resilient elongate element  54  are being withdrawn into the retrieval cannula along a direction indicated by arrow  90 . 
     FIGS. 18-23  illustrate an embodiment of a delivery device  138  and methods of using the delivery device  138  for deployment of eluting coils  140 .  FIG. 18  is a perspective view of an embodiment of a delivery device  138  having an elongate delivery sheath  142  with a proximal end  144  a distal end and a delivery actuator  148  secured to the proximal end  144  of the delivery sheath  142 . The delivery sheath  142  is an elongate hollow tube having a sharpened distal tip  150  shown in  FIG. 20 . The delivery sheath  142  has an interior lumen  152  which is configured to constrain a resilient elongate element  154  of an eluting coil  140  and allow the constrained resilient elongate element  154  to be advanced through the lumen  152  of the delivery sheath  142  to a deployment site. The eluting coil  140  and resilient elongate element  154  may have features, dimensions and materials which are similar to or the same as those of any of the eluting coil or resilient elongate element embodiments discussed herein. For the configuration shown, the delivery sheath  142  can be made from any suitable high strength metal, composite or polymer. 
   Suitable metals for construction of the delivery sheath  142  may include stainless steel, Nitinol, MP35N and the like. The delivery actuator  148  has an elongate cylindrically shaped body portion  156  with a proximal flange  158  and a distal flange  160 . The body portion  156  has an internal bore  162  that is sized to accept a cylindrical actuator  164  in sliding relation to the body portion  156 . A thumb ring  166  is disposed at a proximal end  168  of the cylindrical actuator  164  to facilitate the grip of an operator of the delivery device  138 . The body portion  156  and cylindrical actuator  164  can be made from a variety of suitable medical grade materials, including metals, composites and polymers. Specifically, polymers such as ABS plastic, PVC, polycarbonate and the like may be used. 
   An eluting coil  140  being deployed from a distal end  146  of the delivery sheath  142  into tissue  170  of a target tissue site is shown in  FIGS. 21-23 . The resilient elongate element  154  of eluting coil  140  may include the pre-stressed self-forming embodiment shown, wherein the resilient elongate element  154  returns to a relaxed coiled configuration, that is the configuration in a relaxed state, as the resilient elongate element  154  exits the distal end  146  of the delivery sheath  142  and the constraint of the delivery sheath  142  is removed. The eluting coil  140  is shown mechanically capturing a portion of tissue  172  of the target tissue site as it encircles the tissue. 
   Embodiments of delivery device  138  shown in  FIG. 18  may use low profile delivery sheaths in the form of hollow needles with sharpened distal ends to deliver eluting coils to a target tissue site. The delivery sheath  142  is a straight tube with a distal tissue penetrating point  150  and is stiffer than an eluting coil  140  to be delivered therethrough. The geometry of the distal point of the delivery sheath  142  can be important in some embodiments. The distal point  150  needs to easily penetrate tissue while also providing clearance for the surgical coil  140  as it is being delivered without substantial restriction to assume the relaxed geometry of the surgical coil  140 . For some delivery sheath  142  embodiments, the distal point can have an angle of about 25 degrees. 
   Delivery sheath  142  may have an internal profile that can slidably receive an elongate element  154  of an eluting coil  140  along their full length and will straighten them out into a restrained substantially straight configuration in doing so. Eluting coil  140  may be pre-loaded into the delivery sheath  142  prior to use. The maximum number of eluting coils  140  that a delivery sheath  142  can accommodate is limited by its length, however, some applications may require only a single eluting coil  140  be used. In a delivery device  138  having a multiple eluting coil  140  configuration, eluting coils  140  may be stacked end to end within the delivery sheath  142 . 
   In one embodiment of use, the distal end  146  of the delivery sheath  142  is placed at a target site, a thumb ring  166  of the cylindrical actuator  164  is then moved distally as shown in  FIG. 19  which pushes an advancing ribbon (not shown) which in turn pushes the most proximal eluting coil which then ejects the most distal eluting coil from the device  138  as shown in  FIG. 20 . 
   There are varieties of techniques that can be employed with these low profile delivery devices  138  to access target sites. The delivery sheath  142  can be used in the same manner as a hypodermic needle is for drug delivery (direct incision). Alternatively they can be placed within the working channel of an endoscope or cannula. All methods allow the physician to completely or partially implant a coil in tissue at an anterior or posterior location. 
   With regard to the above detailed description, like reference numerals used therein refer to like elements that may have the same or similar dimensions, materials and configurations. While particular forms of embodiments have been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the embodiments of the invention. Alternate embodiments may include the combination of various features of different embodiments. For example, some or all of the features of the embodiments shown in  FIG. 4  may be combined with some or all of the features of the embodiments shown in  FIG. 8 . Accordingly, it is not intended that the invention be limited by the forgoing detailed description.