Patent Application
20110218602
The present invention relates to medical apparatus and methods. More specifically, the present invention relates to implantable medical leads and methods of manufacturing such leads.
Implantable pulse generators, such as pacemakers, defibrillators, implantable cardioverter defibrillators (“ICD”) and neurostimulators, provide electrotherapy via implantable medical leads to nerves, such as those nerves found in cardiac tissue, the spinal column, the brain, etc. Electrotherapy is provided in the form of electrical signals, which are generated in the pulse generator and travel via the lead's conductors to the electrotherapy treatment site.
Patients may benefit from electrotherapy treatments to be proposed in the future. However, current conventional lead manufacturing technology has generally limited the extent to which leads can be reduced in size and the elements or features that can be carried on leads.
There is a need in the art for a lead having a configuration that allows the lead to have a reduced size and which is capable of supporting elements or features in a variety of configurations. There is also a need in the art for a method of manufacturing such a lead.
Disclosed herein is an implantable medical lead. In one embodiment, the lead may include a longitudinally extending body, a helical anchor and a lead connector end. The longitudinally extending body may include a distal end, a proximal end, a braid-reinforced inner tubular layer extending between the proximal and distal ends, and an outer tubular layer extending between the proximal and distal ends. The braid-reinforced inner tubular layer may extend through the outer tubular layer in a coaxial arrangement. The helical anchor electrode may be operably coupled to a distal end of the braid-reinforced inner tubular layer. The lead connector end may be operably coupled to the proximal end of the body and include a pin contact operably coupled to a proximal end of the braid-reinforced tubular layer. Rotation of the pin contact relative to the lead connector end may cause rotation of the braid-reinforced inner tubular layer within the outer tubular layer, and the resulting rotation of the braid-reinforced inner tubular layer may cause rotation of the helical anchor electrode.
Another implantable medical lead is also disclosed herein. In one embodiment, the lead includes a longitudinally extending body having a distal end, a proximal end, and a braid-reinforced tubular layer extending between the proximal and distal ends. The braid-reinforced tubular layer may include a braid arrangement imbedded in a polymer wall material. The braid arrangement may include first and second conductors and first and second ribbons. The conductors and ribbons may be helically cross wound with each other such that the conductors do not cross each other and the ribbons do not cross each other.
Also disclosed herein is a method of assembling an implantable medical lead. In one embodiment, the method includes: providing a first longitudinally extending tubular liner including an outer circumferential surface; providing a first braid arrangement over the outer circumferential surface of the first longitudinally extending tubular liner, wherein the first braid arrangement includes first and second conductors and first and second ribbons, wherein the conductors and ribbons of the first braid arrangement are helically cross wound with each other such that the conductors do not cross each other and the ribbons do not cross each other; reflowing or molding (e.g., liquid injection mold (“LIM”)) a first polymer material over the first braid arrangement and outer circumferential surface of the first longitudinally extending tubular liner such that the braid arrangement is substantially imbedded in the polymer material and the polymer material substantially adheres to the outer circumferential surface, resulting in a first braid-reinforced tubular layer; and electrically connecting the first conductor to an electrode.
While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following Detailed Description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
An implantable medical lead 10 is disclosed herein. In one embodiment, the implantable medical lead 10 includes a tubular body 50 having one, two or more tubular layers 125, 135 each reinforced with a conductor/fiber braid arrangement 115 imbedded in the polymer material 162 forming the walls of the tubular layers 125, 135. The conductor/fiber braid arrangement 115 may be one, two or more helically wound conductors 100, 105, 110 woven with one, two or more helically wound fiber strips 165. In one embodiment, the braid arrangement 115 is such each conductor crosses the strips or ribbon 165, but does not cross itself or any other conductor. Similarly, each strip or ribbon 165 crosses the conductors, but does not cross itself or any of the strip or ribbon.
Such braid-reinforced layers 125, 135 offer the ability to manufacture lead bodies 50 have substantially reduced diameters, substantial improvement with respect to torque and flexibility consistency and capabilities, reduced manufacturing costs, and the ability to support a large number of electrodes and sensors in a large variety of configurations. Also, such braid-reinforced layers 135 may be used to replace the common helically wound central coil as a mechanism for extending/retracting a helical anchor electrode 85 and, in doing so, offer an anchor extension/retraction mechanism that provides one-to-one torque.
For a general discussion of an embodiment of a lead 10 including a body having at least one tubular layer reinforced with the conductor/fiber braid arrangement, reference is made to
As shown in
As illustrated in
As shown in
As illustrated in
As indicated in
In one embodiment, the tip electrode 75 or helical anchor electrode 85 may be in electrical communication with the pin contact 55 via a first helically routed electrical conductor 100 (see
For a detailed discussion regarding a lead body 50 employing the conductor/fiber braid arrangement 115 disclosed herein, reference is made to
As shown in
In one embodiment, the liner layers 130 and 140 may be formed of polytetrafluoroethylene PTFE or another polymer material having similar properties. Each liner layer 130 and 140 may have a wall thickness of between approximately 0.001″ and approximately 0.005″. In one embodiment, the braid-reinforced layers 125 and 135 may each be formed of a conductor/fiber braid arrangement 115 (see
In some embodiments, the layers 125 and 135 may both be braid-reinforced with the braid arrangement 115. However, in other embodiments, only one of the layers 125 and 135 may be braid-reinforced with the braid arrangement 115, the other non-braid-reinforced layer being simply a layer of SPC or other similar polymer material. For example, in one embodiment, the innermost layer 135 may be braid-reinforced with the braid arrangement 115 and the outermost layer 125 may not employ the braid arrangement 115. Conversely, in another embodiment, the outermost layer 125 may be braid-reinforced with the braid arrangement 115 and the innermost layer 135 may not employ the braid arrangement 115.
For a discussion of an example braid arrangement 115, reference is now made to
As can be understood from
As can be understood from
Since the ribbon 165 acts as a spacer between the conductors 100, conductors 100 with or without individual electrical insulation jackets may be employed in the braid arrangement 115. As can be understood from
As can be understood from
As can be understood from
The configuration of the braid-reinforced layers 125 and 135 readily lends itself to the efficient coupling of the electrical conductors 105 and 110 to their respective electrodes 80 and 82. For example, as can be understood from
As can be understood from
As indicated in
Due to the innermost assembly layer 155 and outermost assembly layer 160 being coaxially rotatably relative to each other, in some embodiments, the innermost assembly layer 155 may serve in place of the helically coiled central conductor commonly found in active fixation leads and which are commonly used to extend/retract the helical active fixation anchors of such leads. The configuration of the innermost assembly layer 155 offers several advantages over the traditional helically coiled central conductor. For example, unlike the traditional helically coiled central conductor, the innermost assembly layer 155, due to its configuration/construction, offers a one-to-one torque transfer when used as the mechanism for extending/retracting the helical anchor 85.
A discussion of an embodiment of the lead tubular body 50 employing the innermost assembly layer 155 as the mechanism for rotatably extending/retracting the helical active fixation anchor 85 will now be given with respect to
As can be understood from
As indicated in
As can be understood
In one embodiment, the coupling of the shank 225 to the innermost liner layer 130 in combination with the configuration of the header assembly 235 (see
A variety of implantable medical leads 10 may be configured as described herein. For example, the lead 10 may be a cardiac lead (both high and low voltage), a multi-polar lead (both cardiac and neurologic), an MRI compatible lead, and an “intelligent” lead such as those intelligent leads that incorporate active components, such as sensors, integrated circuits, MEMS devices or drug delivery mechanisms.
The construction of a lead body 50 may be done on an individual basis or on a continuous basis. When the lead body 50 is manufactured on an individual basis, the conductors 100, 105, 110 and ribbon 165 may be braided together on a standard braiding machine to assemble the braid arrangement 115, which can then be stored on a spool until it is ready to be pulled as a whole or completed braid arrangement 115 onto a liner layer 130, 140 of the lead body 50 during the assembly process.
Prior to winding the braid assembly 115, the braid pattern, inside diameter and pitch may be determined according to the type of lead 10 being constructed, such as LV, high or low voltage. In some embodiments, the pitch may be varied at certain points along the length of the lead body 50 to impart different flexibility and torque characteristics at the certain points along the lead body 50.
Once the braid assembly 115 is braided, the braid assembly 115 may be stored on a large spool. When it is time to assemble a specific lead tubular body 50, the specific length of braid assembly 115 may be removed from the spool as needed for the specific length of the lead tubular body 50 being assembled. This specific length of braid assembly 115 may then be pulled over an innermost liner layer 130, which, as discussed above, may be PTFE or other applicable polymer materials. Once the braid assembly 115 extends about the outer circumferential surface 215 of the innermost liner layer 130, SPC (which is also known as OPTIM™ and will act as the wall material 162) may be reflowed or molded (e.g., LIM) about the braid assembly 115 and innermost liner layer 130 enclosed within the braid assembly 115. Specifically, in one embodiment employing reflowing, a SPC tube 162 may be pulled over the combined braid assembly 115 and liner layer 130. A fluorinated ethylene propylene (“FEP”) jacket is then pulled over the SPC tube 162, the braid 115, and liner 130 and then subjected to reflow conditions to form the inner layer assembly 155. The FEP jacket is then removed from the resulting inner layer assembly 155.
In some embodiments, a mandrel is used to dip or extrude the PTFE liner 130 onto the mandrel outer circumferential surface. The PTFE innermost liner layer 130 is left on the mandrel as the braid 115 is braided over the outer circumferential surface 215 of the innermost liner layer 130. The SPC wall material 162 is then reflowed or molded over the PTFE liner layer 130 and braid 115, imbedding the braid 115 in the wall material 162. The mandrel can then be pulled from the completed assembly or left in the completed assembly for the addition of additional elements of the lead. The completed assembly can be stored on a spool in lengths of, for example, 500′ or discrete lengths.
In multi-layer leads, the inner layer may be built as described above with respect to the mandrel process and stored on a spool or in discrete lengths, the mandrel for the inner layer being of a small diameter. A second or outer layer may then be assembled as described above with respect to the mandrel process, except the second mandrel is of a larger diameter as compared to the first mandrel. Once the second layer (i.e., outer layer) is completed, it may be pulled over the first layer (i.e., inner layer).
In some embodiments, the inner layer is assembled via any of the above described methods, and the outer layer assembly takes place by first pulling an outer PTFE layer over the assembled inner layer. The outer braid is then braided over the outer PTFE layer. The SPC wall material for the outer layer is then reflowed or molded over the outer braid and outer PTFE layer.
In one embodiment, the inner layer is a standard inner lead layer having, for example, a helical inner conductor coil surrounded by a PTFE liner. An outer layer with the imbedded braid, as described herein, could be pulled over the standard inner layer or assembled over the standard inner layer via any of the above-described methods.
At this point in the process, the conductor 100 may be laser ablated to expose the conductor 100 through the conductor insulation, if any, and the reflowed SPC wall material 162 to create a pathway that may be used to electrically couple the conductor 100 to the anchor electrode 85. A crimp slug may be applied to the exposed conductor 100 in preparation for electrically connecting the conductor 100 and electrode 85.
The shank 225 and its connected helical anchor electrode 85 may be inserted into the distal end of the inner layer assembly 155 and connected thereto. The crimp slug may then be laser welded to the helical anchor electrode 85 or the shank 225, which is electrically connected to the helical anchor electrode 85.
Generally speaking, a crimp slug may be attached to a conductor before or after the conductor insulation, if any, is removed. The form of a crimp slug may be open or closed, tubular or coiled, and/or circular. A conductor may be cut or left intact depending on the type of crimp slug used. This process may be repeated as many times as needed to attach the appropriate number of electrodes. Depending on where the electrode is located, the electrode may be a platinum band/ring, a half ring, a quarter ring, a coil, a helical active fixation anchor, and/or a sensor. The electrode may be attached to the crimp slug via laser welding.
After the electrode 85 has been attached to the crimp slug, any gaps around and under the electrode 85 are filled in with the appropriate material such as, OPTIM™, MedA, epoxy, etc. The proximal end of the conductor 100 and inner layer assembly 155 may then be coupled to respectively to the pin contact 55 and lead connector end 35.
Once the inner layer assembly 155 is completed, the construction of the outer layer assembly 160 may be begun. As with the inner layer assembly 155, the specific length of braid assembly 115 may be removed from the spool. This specific length of braid assembly 115 may then be pulled over an outermost liner layer 140, which, as discussed above, may be PTFE or other applicable polymer materials. Once the braid assembly 115 extends about the outer circumferential surface 195 of the outermost liner layer 140, SPC (which is also known as OPTIM™ and will act as the wall material 162) may be reflowed or molded (e.g., LIM) about the braid assembly 115 and outermost liner layer 140 enclosed within the braid assembly 115. Specifically, in one embodiment employing reflow, a SPC tube 162 may be pulled over the combined braid assembly 115 and liner layer 140. A FEP jacket is then pulled over the SPC tube 162, the braid 115, and liner 140 and then subjected to reflow conditions to form the outer layer assembly 160. The FEP jacket is then removed from the resulting outer layer assembly 160.
At this point in the process, the conductors 105, 110 may be laser ablated to expose the conductors 105, 110 through the conductor insulation, if any, and the reflowed SPC wall material 162 to create a pathway that may be used to electrically couple the conductors 105, 110 to the respective electrodes 80, 82. Crimp slugs may be applied to the exposed conductors 105, 110 in preparation for electrically connecting the conductors 105, 110 to their respective electrodes 80, 82.
As can be understood from
In some embodiments, once the entire lead body is constructed via any of the above described methods, the entire lead body or portions thereof may be heat-set to assume a desired configuration that may, for example, allow passive fixation features to bias within a vein for LV implantation in the case of a CRT lead. Also, such heat-setting may be used for strain relief.
At this point, in one embodiment, the outer layer assembly 160 is pulled over the completed inner layer assembly 155 such that the outer circumferential surface 205 of the inner layer assembly 155 abuts against the inner circumferential surface 200 of the outer layer assembly 160. The crimp slugs of the respective conductors 105, 110 may then be laser welded to the respective electrodes 80, 82. After the electrodes 80, 82 have been attached to the crimp slugs, any gaps around and under the electrodes 80, 82 are filled in with the appropriate material such as, OPTIM™, MedA, epoxy, etc. The proximal end of the conductors 105, 110 and outer layer assembly 160 may then be coupled respectively to the ring contacts 60, 61 and lead connector end 35. In one embodiment, the resulting completed lead 10 may have a tubular body 50 with an braid-reinforced inner layer assembly 155 that is axially rotatable relative to an braid-reinforced outer layer assembly 160, thereby allowing the inner layer assembly 155 to be rotated via the pin contact 55 to cause the helical anchor electrode 85 to extend or retract at the lead distal end 70.
When the lead body 50 is manufactured on a continuous basis, the appropriate length of inner liner 130 may be selected depending on the type of lead 10 being constructed. The braid assembly 115 may then be braided over the outer circumferential surface 215 of the inner liner 130 in a continuous manner. If beneficial to the lead configuration and function, a variable pitch may be braided into the braid assembly 115 where desired during the braiding process. Once the braid assembly 115 is braided over the inner liner 130, the SPC wall material 162, crimp slugs, shank 225, anchor 85 and electrical connections may be completed as discussed above with respect to the individual basis discussion, thereby forming the inner layer assembly 155.
A braid assembly 115 is then braided onto the outer circumferential surface 195 of the outer liner layer 140. Once the braid assembly 115 is braided over the outer liner 140, the SPC wall material 162, crimp slugs, shank 225, anchor 85 and electrical connections may be completed as discussed above with respect to the individual basis discussion, thereby forming the outer layer assembly 160. The inner layer assembly 155 is then placed within the outer layer assembly 160 as discussed above with respect to the individual basis discussion, thereby forming the complete lead body 50. In one embodiment, the resulting lead body 50 has an inner braid-reinforced layer assembly 155 that is axially rotatable within an outer braid-reinforced layer assembly 160 to cause a helical anchor electrode 85 to extend/retract from the lead distal tip.
In some embodiments, the braid assembly 115 of the outer layer assembly 160 may be left exposed in certain selected discrete areas along the length of the lead body 50. These discrete areas of exposed braid assembly 115 may function as tissue in-growth locations where tissue may in-grow into the exposed braid assembly to facilitate chronic anchoring of the lead body 50 at the location of the implantation of the lead 10.
In some embodiments, one or more of the conductors 105 may instead be a tubular lumen extending distally from the lead proximal end. Such a lumen or lumens 105, although forming a portion of the braid assembly 115, may be used to transfer something other than current through the lead body 50. For example, such a lumen 105 of the braid assembly 115 may be used to deliver air, liquid, drugs, etc. from a proximal end of the lead to a location on the lead near the lead distal end.
In some embodiments, the helix anchor 85 at the lead distal end is not extendable/retractable relative to the lead distal end. Instead, the helix anchor 85 is fixed in an extended configuration and the entire lead body is rotated to imbedded the helix anchor 85 in cardiac tissue. Thus, in such fixed helix anchor embodiments, the inner layer of the lead body is not configured to rotate within the outer layer of the lead body.
The braid-reinforced layer assemblies 155, 160 used to form the lead tubular body 50 offer a number of advantages over known lead body configurations. For example, in some embodiments, the such braid-reinforced layer assemblies 155 may be substituted for helically wound central coils that are employed to extend/retract helical anchors; providing one-to-one torqueabilty, reduced manufacturing costs, and improved and more consistent flexibility as compared to leads employing the helically wound central coils known in the art.
The braid-reinforced layer assemblies 155, 160 allow greater flexibility in positioning an electrode along the lead body as the conductors of the assemblies 155, 160 are more readily located and accessible, as compared to lead configurations known in the art. As a result, the manufacturing of multi-electrode leads having, for example, 1-32 or more electrodes is made more feasible.
Since the conductors are imbedded in the material of the tubular wall, the French size made possible via the braid-reinforced layer assemblies 155, 160 may be substantially less than other leads commonly known in the art.
The leads disclosed herein are applicable to both cardiology applications and other medical areas, including neurological.
Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
