Patent Application
20060241715
Implanted medical devices that incorporate external electrical connections, for example, implanted cardiac rhythm management devices that include a leadless electrode on the outer surface of an implanted pulse generator device.
Implantable medical devices, such as cardiac rhythm management devices, commonly include implanted pacemakers and defibrillator units. These devices include sensing, signal processing and control circuitry, together with a power supply protectively housed in a hermetically sealed case or can in combination with one or more conductive electrical leads designed to connect to the patient's heart muscle tissue. To maintain the integrity of the components in the sealed case, provision must be made for sealed passage of electrical conductors to the exterior for connection to the leads and ultimately to the tissue of interest. This has been typically accomplished by using connector blocks and associated feedthrough conductors located external to the implanted pulse generator housing or case which, themselves, typically are placed within a sealed lead connector structure of medical grade polymer material.
Button or similar leadless or “indifferent” sensing electrodes have also been provided on the outer surface of the lead connector portion of pulse generator cases or housing, each connected by an independent wire conductor between the electrode and the feedthrough system. These external leadless pulse generator electrodes and connecting conductors can be relatively expensive to manufacture and assemble. For instance, these electrode devices have been machined (a relatively expensive process) from medical grade stainless steels or titanium and thereafter wired to a feedthrough terminal. Wire conductive connectors have also been used between feedthrough terminals and corresponding connector blocks in the pulse generator lead/connecting portion with received and connect with the other external leads.
What is needed is a medical device including an external leadless electrode and feedthrough connection system that overcomes these and other shortcomings.
An implantable medical device, such as a pulse generator, includes a housing that has a header and an outer casing having internal circuitry therein. The implantable device further includes an external electrode wrapped around at least an outer portion of the housing, and a plurality of interconnect members electrically coupled with the external electrode and the internal circuitry. The pulse generator is optionally coupled with one or more lead assemblies.
Several options are possible for the medical device, including, but not limited to, the options as follows. For instance, the external electrode, such as a thin, flexible electrode, can be wrapped around two or three sides of the device, allowing for multi sided access to the external electrode. One example of the flexible electrode is a sheet metal electrode wrapped around the housing.
In another embodiment, an implantable medical device includes a header for receiving leads therein, where the header includes an electrode mounting portion with two or more sides. The device further includes at least one electrode flexibly formed around at least a portion of the electrode mounting portion, and an interconnect electrically coupling the at least one external electrode with circuitry within the device. The electrode is optionally coupled with the housing of the device, for example, by retention features, such as, but not limited to, crimped features, snap fit features, or interference fit.
A method is further described herein that includes wrapping an external electrode around at least a portion of a housing of a pulse generator, coupling the external electrode with the housing, coupling the external electrode with at least one interconnect an internal circuitry.
Several options are possible for the method, including, but not limited to, the options as follows. For instance, the electrode can be wrapped around one or more sides of the housing, and/or the header of the pulse generator. In another option, the electrode can be coupled with the housing in a number of different ways, such as interference fit, snap fit, forming crimp(s) in the electrode, etc.
These and other embodiments, aspects, advantages, and features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description and referenced drawings or by practice thereof. The aspects, advantages, and features are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents.
In the drawing figures wherein like reference characters depict like parts throughout the same:
a illustrates a perspective view of a portion of an implantable pulse generator device constructed in accordance with at least one embodiment;
b illustrates an exploded perspective view of an implantable pulse generator device constructed in accordance with at least one embodiment;
a illustrates a portion of a pulse generator device constructed in accordance with at least one embodiment;
b illustrates a portion of a pulse generator device constructed in accordance with at least one embodiment;
a illustrates a perspective view of an external electrode constructed in accordance with at least one embodiment; and
b illustrates a side view of an external electrode constructed in accordance with at least one embodiment.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope is defined by the appended claims.
a and 1b illustrate one example of an implantable medical device, for instance, an implantable pulse generator device 10, that allows for signals to be sent and/or received from tissue, for example, signals to and from a heart. The implantable pulse generator device 10 includes an outer housing 11 having an optional lead connector portion 12, and a casing 14. The housing 11 is defined in part by one or more planes 13 (
The lead connector portion 12, or the header, allows for elongate leads to be mechanically and electrically coupled therein. The lead is, for example, an elongate structure that includes electrodes disposed therealong. Electrodes disposed along the lead can be disposed in, on, along, or near tissue to be sensed or paced, such as a heart. The lead connector portion 12 is, in one option, generally fabricated from medical grade polymer material, which includes a number of openings 34 therein. The openings 34 allow for the optional leads to be inserted and retained therein. The openings 34 contain electrical connections which allow for the lead to be electrically coupled with various circuitry within the casing 14.
The lead connector portion 12 further includes, in one example, an electrode mounting portion 17, and at least one external electrode 22, for example, a leadless or indifferent electrode, disposed along the electrode mounting portion 17. The external electrode 22 is, in one option, a thin, readily shaped electrode 22 with corresponding interconnect 24 (
The external electrode 22 is an electrode that, in one option, is wrapped around a portion of the header. The wrapped external electrode 22 covers the portion of the header, for example, by winding, folding, or coating a substantially non-rigid electrode around a portion of the header. In one example, the external electrode 22 is a thin and/or flexible member, such as sheet metal having a thickness and/or treatment allowing it to be wrapped or alternatively flexibly formed around a portion of the header. One example is illustrated in
The external electrode 22, in one example, includes features that allow for the electrode to be coupled, secured, or retained with the housing 11 (
The preformed or prewrapped electrode 22, shown in
The external electrode 22 is electrically isolated from the casing 14, in a number of different manners. For example, the header can be formed of various non-conductive materials including, but not limited to, polyurethane, or epoxy, and the external electrode 22 is coupled with the header. In another option, other insulative material and/or coating can be disposed between the external electrode 22 and the header and/or the casing.
As discussed above, the electrode 22 is disposed along or optionally coupled with the housing 11, which includes a casing 14, as shown in
a, 1b, 3, 5a and 5b, show part of the molded or filled medical grade polymer removed to illustrate the internal interconnects between certain components. These include a plurality of interconnection conductors as at 16 which may be ribbon conductors which connect a plurality of connector blocks, as at 18, with a plurality of corresponding external feedthrough terminals as at 20. The feedthrough terminal 20 may be in the form of protruding wire stubs or metal pads of conductive material compatible with the leads. The connector blocks 18, individual lead 16 and corresponding terminals 20 are insulated from each other, in at least one option.
a and 5b illustrate an alternative embodiment of a feed-through connection system including the leadless or indifferent electrode 22. In one example, the leadless or indifferent electrodes 22 are provided with separate leads 40, which are solid wire leads typically placed in a narrow channel provided along the upper surface of the lead connector portion 12 which may be thereafter filled with an amount of medical grade polymer, if desired.
As shown in
The conductors or interconnects 16 are in one option, in ribbon form, and are, in another option, manufactured of very thin gauge metal or foil such as a medical grade stainless steel or titanium. The external leadless electrodes are also manufactured of relatively thin gauge material. For example, the thickness for the material is from about 0.005 inches to about 0.025 inches and the width of the conductors is from about 0.020 inches to about 0.060 inches. In another example, the thickness of the material is about 0.020 inches.
The relatively thin gauge and/or flexible electrode 22 replaces a rather heavy gauge machined external button electrode, or the like. The use of the relatively thin gauge, readily shaped or wrapped metal electrodes for the leadless or indifferent electrodes eliminates the need for expensive machining which has been required for the early button-type electrodes. Furthermore, the electrode snaps on allowing for ease in manufacturability.
A method for forming an implantable device such as a pulse generator includes wrapping the external electrode 22 around at least a portion of a housing 11, such as wrapping or forming the external electrode 22 around the header. The wrapping or forming process can include the various embodiments discussed above. For example, although not so limited, the thin flexible electrode is wrapped around two or more sides of the housing, such as the header. In another option, the thin, flexible electrode is wrapped around three or more sides of the housing. For instances, the flexible electrode would be wrapped over at least a portion of a first major side, a top portion, and at least a portion of a second major side of the housing.
The external electrode 22 is also coupled with the housing 11, for example, by a snap fit and/or coupling at least one crimp of the external electrode with the housing 11. The external electrode 22 is electrically coupled with at least one interconnect, which is electrically coupled with internal circuitry of the device.
Once electrical connections are made to all of the corresponding feedthrough terminals, medical grade polymer is over-molded or backfilled in a layer which covers and preserves the connections while completing the desired outer shape of the structure, and assists with sealing the interconnect members. In this manner, the flexible interconnects are imbedded in the overlayer of medical grade polymer which is typically silicone or a medical grade polyurethane. The device is implanted and optionally coupled with a lead, for example, a lead that is implanted within a heart of a patient.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Although the use of the implantable device has been described for use with a lead in, for example, a cardiac stimulation system, the implantable device could as well be applied to other types of body stimulating systems. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
