The present application relates to an implantable pulse generator (IPG) that is implantable through a routine procedure and which receives continuous operating power from an external power supply in a first mode of operation and from a separately implanted power supply module in a second mode of operation.
Implantable stimulation devices deliver electrical stimuli to nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and Deep Brain Stimulators (DBS) to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc. The description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227. However, the present invention may find applicability with any Implantable Pulse Generator (IPG) or in any IPG system.
As shown in
As shown in
Communication on link 42 can occur via magnetic inductive coupling between a coil antenna 44 in the external controller 40 and the IPG 10's telemetry coil 32 as is well known. Typically, the magnetic field comprising link 42 is modulated, for example via Frequency Shift Keying (FSK) or the like, to encode transmitted data. For example, data telemetry via FSK can occur around a center frequency of fc=125 kHz, with a 129 kHz signal representing transmission of a logic ‘1’ bit and 121 kHz representing a logic ‘0’ bit. However, transcutaneous communications on link 42 need not be by magnetic induction, and may comprise short-range RF telemetry (e.g., Bluetooth, WiFi, Zigbee, MICS, etc.) if antennas 44 and 32 and their associated communication circuitry are so configured. The external controller 40 is generally similar to a cell phone and includes a hand-held, portable housing.
External charger 50 provides power to recharge the IPG's battery 14 should that battery be rechargeable. Such power transfer occurs by energizing a charging coil 54 in the external charger 50, which produces a magnetic field comprising transcutaneous link 52, which may occur with a different frequency (f2=80 kHz) than data communications on link 42. This magnetic field 52 energizes the charging coil 30 in the IPG 10, which is rectified, filtered, and used to recharge the battery 14. Link 52, like link 42, can be bidirectional to allow the IPG 10 to report status information back to the external charger 50, such as by using Load Shift Keying as is well-known. For example, once circuitry in the IPG 10 detects that the battery 14 is fully charged, it can cause charging coil 30 to signal that fact back to the external charger 50 so that charging can cease. Like the external controller 40, external charger 50 generally comprises a hand-holdable and portable housing.
External controller 40 and external charger 50 are described in further detail in U.S. Patent Application Publication 2015/0080982. Note also that the external controller 40 and external charger 50 can be partially or fully integrated into a single external system, such as disclosed in U.S. Pat. Nos. 8,335,569 and 8,498,716.
As described above, the electrical stimulation that the IPG 10 is capable of delivering is highly customizable with respect to selected electrodes, electrode current amplitude and polarity, pulse duration, pulse frequency, etc. Due to uncertainties in the location of electrodes with respect to neural targets, the physiological response of a patient to stimulation patterns, and the nature of the electrical environment within which the electrodes are positioned, it is challenging to determine the stimulation parameters that might provide effective stimulation therapy for a particular patient. Thus, in order to determine whether the IPG 10 is capable of delivering effective therapy, and, if so, the stimulation parameters that define such effective therapy, the patient's response to different stimulation parameters is typically evaluated during a trial stimulation phase prior to the permanent implantation of the IPG 10.
As shown in
During the trial stimulation phase, the proximal ends of the leads 18 including the electrode terminals 20 are ultimately coupled to an external trial stimulator (ETS) 70, which, as its name implies, is external to (i.e., not implanted in) the patient. An external cable box assembly 340 is used to facilitate the connection between the leads 18 and the ETS 70. Each external cable box assembly 340 includes an external cable box 342 (which has a receptacle similar to connector block 22 for receiving the lead), a trial stimulation cable 344, and a male connector 346, which is plugged into a port 72 of the ETS 70. Once connected to the leads 18, the ETS 70 can then be affixed to the patient in a convenient fashion for the duration of the trial stimulation phase, such as by placing the ETS 70 into a belt worn by the patient (not shown).
The ETS 70 essentially mimics operation of the IPG 10 to provide stimulation to the implanted electrodes 16. This allows the effectiveness of stimulation therapy to be verified for the patient, such as whether therapy has alleviated the patient's symptoms (e.g., pain). Trial stimulation using the ETS 70 further allows for the determination of a particular promising stimulation program for the patient to use once the IPG 10 is later implanted into the patient. Although not shown, the ETS 70 typically contains a battery within its housing along with stimulation and communication circuitry.
The stimulation program executed by the ETS 70 can be provided or adjusted via a wired or wireless link 92 (wireless shown) from a clinician programmer 90. As shown, the clinician programmer 90 comprises a computer-type device, and may communicate wirelessly via link 92 using a communication head or wand 94 wired to the computer. Communication on link 92 may comprise magnetic inductive or short-range RF telemetry schemes as already described, and in this regard the ETS 70 and the clinician's programmer 90 and/or communication head 94 may include antennas compliant with the telemetry means chosen. Clinician programmer 90 may be as described in U.S. Patent Publication No. 2015/0360038. Note that the external controller 40 (
At the end of the trial stimulation phase, the leads 18 (or at least lead extenders that include a portion external to the body) are typically explanted and the relatively small percutaneous openings 306 are closed in a further, yet simple, surgical procedure. If trial stimulation proved ineffective for the patient, no further procedures are performed.
By contrast, if stimulation therapy proved effective, IPG 10 can be permanently implanted in the patient, which is often performed in a subsequent procedure after the trial leads 18 (or lead extenders) are explanted. (“Permanent” in this context generally refers to the useful life of the IPG 10). Permanent implantation involves creating a surgical pocket (e.g., in the buttocks) in which the IPG 10 is positioned, implanting permanent leads 18 using the same technique as described above, subdermally tunneling the proximal ends of the leads 18, including electrode terminals 20, to the pocket, and coupling the leads 18 to the connector blocks 22 in the IPG's header 24. The result is a fully-implanted stimulation therapy solution. The IPG 10 can be programmed with the stimulation parameters that were found to be effective during the trial stimulation phase. Subsequently, the stimulation parameters can be modified wirelessly using either the external controller 40 or the clinician programmer 90.
While this trial stimulation approach can be effective, the inventors have recognized certain drawbacks. A first is that because the leads 18 extend through percutaneous openings 306 during the trial stimulation phase, there is some risk of infection. While proper bandaging and antibiotics can help mitigate this risk, it is not prudent to continue with the trial stimulation phase for an extended period of time. Therefore, the duration of the trial period is typically limited to several days (e.g., 10-14 days), a substantial portion of which time the patient is recovering from the lead implantation procedure. As a result, there is not much time during which the patient can evaluate the effectiveness of various stimulation parameters under “normal” circumstances. In other words, even though it may be desirable in some cases to extend the trial stimulation phase, the need to close the openings 306 may cut the experimental period short, thus forcing a premature decision whether to proceed with implantation of the IPG 10.
A further drawback is that the trial stimulation phase requires two procedures within a short time period. The leads 18 are implanted and then, several days later, the patient undergoes an additional procedure to explant the leads, which can be difficult on the patient.
This has caused the inventors to consider solutions that can either extend the trial stimulation period or even eliminate the requirement of a multi-step implantation procedure.
The inventors realize that traditional external trial stimulation techniques as described earlier (
Accordingly, the inventors disclose a convertible stimulator system that allows for trial stimulation to occur in a fully implanted solution (i.e., a solution that does not require leads to pass outside of the body through openings such as 306) for an essentially unlimited duration followed by “conversion” of the convertible stimulator to a more traditional system through the implantation and connection of a separate power supply module, if desired. The convertible stimulator includes a lead portion and an electronics module in an integrated package, and it is initially completely implanted without the separate power supply module. As will be described below, the electronics module preferably has a diameter that is similar to that of the lead portion such that the entire convertible stimulator can be easily injected and/or subdermally tunneled to facilitate implantation of the convertible stimulator without any additional risk or inconvenience as compared to the lead implantation procedure described above.
In order to meet these size restrictions, the convertible stimulator preferably does not include an internal battery, although it may include a very small capacity battery or capacitor acting as an internal power source to provide power for a limited duration. The convertible stimulator is instead provided continuous power from a field produced by an external charger device, which may take the form of a powering patch, prior to the implantation and connection of the separate power supply module. A coil or other antenna arrangement in the convertible stimulator picks up and rectifies this field to provide power to stimulating electronics in the convertible stimulator, and also to recharge the small battery or capacitor if present.
Should stimulation therapy as provided by the convertible stimulator prove ineffective, the convertible stimulator may be explanted at a convenient later time not dictated by considerations of infection risk due to percutaneous openings, which again are not present in the disclosed technique. Conversely, should stimulation therapy prove effective, the convertible stimulator can continue to be used by the patient for stimulation during an extended trial period or even beyond, although such stimulation will require use of the continuous external charger. Should it eventually be decided that stimulation therapy is effective enough to warrant conversion to a more traditional system (i.e., a system that does not require the use of a continuous external power supply), the separate power supply module can be implanted and coupled to the convertible stimulator at a convenient time for the patient and clinician. Because the convertible stimulator is designed to accommodate such a conversion and the power supply module can be small (especially if it employs a rechargeable power supply), the “conversion” procedure simply involves the creation of a pocket to accommodate the power supply module and the connection of the power supply to the electronics module (which is initially implanted at a site that can accommodate subsequent conversion, e.g., in the buttocks). Eventual conversion of the convertible stimulator through the connection of the implanted power supply (while not strictly required) can convenience the patient, who will no longer need to ensure that power is continuously applied to the convertible stimulator.
An example of a convertible stimulator 100 as described above and as implanted in a patient's tissue 5 is shown in
The electronics module 104 of the convertible stimulator 100 has a generally cylindrical shape with rounded edges to ensure patient comfort. The electronics module 104 is formed of a biocompatible material such as titanium, a ceramic material, or an epoxy, and, in the example shown, has a slightly larger diameter (DEM) than that of the lead portion 102 (DL). The difference in diameter in the illustrated example is not required and, in other embodiments, the electronics module 104 may have the same diameter as the lead portion 102. In any event, the largest diameter of any portion of the convertible stimulator 100 is preferably small enough to enable it to pass within a standard gauge (e.g., 14 gauge) needle or at least to be easily subdermally tunneled. For example, the electronics module 104 may have a diameter of 1.6 mm or less and the lead portion 106 may have a diameter of 1.5 mm or less. The length of the electronics module 104 may be approximately 1-2 inches or less and is generally dictated by the size of the electrical components that are housed within the electronics module 104, which components are described below. The short length of the electronics module improves MM compatibility. Although the electronics module 104 has been described as having a cylindrical shape, in an alternative embodiment, the electronics module 104 may have an oblong (e.g., oval) cross section.
One or more electrical contacts 120 are positioned on the exterior portion of the electronics module 104. While two ring-type contacts are shown, different numbers and types of contacts might also be used. As described in detail below, the contacts 120 are coupled to circuitry within the electronics module 104 and provide a connection point to establish electrical power and communication between such circuitry and electrical components within the separate power supply module if and when the convertible stimulator 100 is connected to such a separate power supply module. It will be understood that if the housing of the electronics module 104 is formed of a conductive material, the contacts 120 are isolated from the housing by an insulating material.
An optional stylet channel 180 extends through the convertible stimulator 100 from the proximal end of the electronics module 104 through the distal end of the lead portion 102. This channel enables the insertion of a stylet to stiffen the lead portion 102 of the convertible stimulator 100 during implantation. A typical implantation of the convertible stimulator 100 involves implantation of the lead portion 102 through a standard gauge needle (with a stylet inserted and in a manner that mirrors the lead implantation procedure described in the background section above) followed by the subdermal tunneling of the electronics module 104 to a suitable location for the possible subsequent implantation of the power supply module (e.g., the buttocks).
Because the convertible stimulator 100 may lack an internal power source altogether, or may include only a small rechargeable battery or capacitor, an external powering device such as a powering patch 150 is used to provide continuous power to the convertible stimulator 100 prior to the connection of an implanted power supply module. As shown in
In one example, the magnetic field 130 produced by the patch 150 can comprise 80 kHz (fc). The magnetic field 130 is in turn received at a secondary coil 118 (
When the transistor 146 is in the closed position and the transistor 148 is in the open position, which occurs when the voltage at contact 120A, VBAT, is less than a predetermined threshold voltage, VT, VDC is passed to node 144 to provide the operating voltage, VOP, for the convertible stimulator 100. By contrast, when VBAT is greater than VT, the transistor 146 is in the open position and the transistor 148 is in the closed position such that VBAT is passed to node 144 to provide the operating voltage, VOP, for the convertible stimulator 100. The threshold voltage, VT, can be selected to be a value just above the fully depleted voltage value of a power source (described below) within the power supply module and can be programmed into the microcontroller 140, which generates the control signals that set the states of the transistors 146 and 148. In this manner, the operating power for the convertible stimulator 100 is provided from the received field 130 when the power supply module is not connected to the convertible stimulator 100 and is provided from the power supply module when it is connected (and is not fully depleted). Although the described embodiment defaults to the use of VBAT when it exceeds a threshold voltage, an alternate embodiment may default to the use of VDC when it exceeds the threshold voltage. In such an embodiment, the operating voltage may be derived from the field 130 generated by an external device even when the power supply module has been connected, which may occur, for example, each time a rechargeable battery in the power supply module is charged.
VOP can in one embodiment represent the sole power source for the convertible stimulator 100's circuitry, and therefore require the patch 150 (or alternate external power source) to be present and providing a magnetic field 130 or the power supply module to be connected via terminals 120 for any aspect of the convertible stimulator 100 to operate. Alternatively, the convertible stimulator 100 can as shown in dotted lines in
Preferably, the patch 150 can alter the strength of the magnetic field 130 it produces using telemetered feedback from the convertible stimulator 100. Thus, circuitry 156 includes a demodulator 174 for decoding data wirelessly received from the convertible stimulator 100; control circuitry (such as a microcontroller) 170 for interpreting such data; and drive and modulation circuitry 172. Drive and modulation circuitry 172 can set the strength of the AC current (Icoil) that will flow through the patch's coil 154 and hence the strength of the magnetic field 130 it produces. Data regarding how to set Icoil can come from telemetry circuitry in the convertible stimulator 100, which may transmit data to the patch 150 via Load Shift Keying (LSK) for example. As is known, LSK involves modulating the impedance of the coil 118 in the convertible stimulator 100 with data to be transmitted to the patch 150, which causes decodable perturbations in the magnetic field 130 the patch 150 produces. Convertible stimulator 100 thus includes LSK circuitry for this purpose, represented as a transistor 116 capable of selectively shorting both ends of the coil 118 together in accordance with the data to be transmitted. LSK circuitry may also selectively short both ends of the coil 118 to ground, as represented by transistor 114. Telemetry of data from an implantable medical device to an external charger via LSK is discussed further in U.S. Patent Application Publication 2015/0080982. While magnetic field 130 adjustments are desirable, for example to ensure that VDC is set to a proper level, it isn't strictly necessary that all embodiments of patch 150 have such capability, and instead continuous magnetic field 130 can be non-adjustable.
As discussed earlier, the patch 150 preferably also includes the ability to transmit data to the convertible stimulator 100 via drive and modulation circuitry 172. For example, at times when the patch 150 is used to change the stimulation program running in the convertible stimulator 100 (more on this below), data can be modulated on the magnetic field 130 using Frequency Shift Keying (FSK). In one example, the magnetic field 130 may be tuned to a center frequency (fc) of 80 kHz when not modulated with data and merely providing power, but may vary its frequency (e.g., f0=75 kHz; f1=85 kHz) when sending ‘0’ and ‘1’ data bits. Alternatively, data may be modulated on magnetic field 130 by various forms of amplitude or phase modulation. The convertible stimulator 100 may receive this data at an amplifier 110 connected to the receiving coil 118, which outputs the amplified data to demodulation circuitry 112, which in turn reports this data in digital form to a microcontroller 140 in the convertible stimulator 100. Such received data can include a stimulation program as discussed above, which informs stimulation circuitry 142 in the convertible stimulator 100 which electrodes 116 to stimulate and how to so stimulate them (e.g., frequency amplitude, duration, etc.). Stimulation circuitry 142 may be as described in U.S. Pat. Nos. 8,606,362 and 8,620,436 for example. While communications between an external device and the convertible stimulator 100 have been described in the context of communications via magnetic induction using the coil 118, the convertible stimulator 100 may also include a separate communications antenna that enables communications via other known short-range RF telemetry schemes (e.g., Bluetooth, WiFi, Zigbee, MICS, etc.).
The patch 150 is preferably light weight and disposable, and may generally resemble an adhesive bandage in structure. It is contemplated that the magnetic field 130 will be continuously produced until the battery 152 in the patch 150 is depleted, at which time a new patch 150 would need to be affixed to the patient. Alternatively, the battery 152 may be replaceable in the patch 150, thus allowing the patch to be re-used.
Referring again to
Due to its preferably simple construction, the patch 150 may contain no user interface elements. Alternatively, the patch may include simple means for adjusting the stimulation therapy being provided by the convertible stimulator 100. For example, the electronics of the patch 150 may include depressible bubble contacts 158a and 158b that are used to increase and decrease the amplitude of stimulation being provided by the stimulation program (SP) the convertible stimulator 100 is currently running. Notice that bubble contact 158a may be larger than bubble contact 158b, thus providing the patient easy means to feel which of the two contacts is to be used for increasing and decreasing stimulation. Alternatively, other devices may be used to provide power and also the data necessary to adjust stimulation therapy, such as the external controller 40 (
While a light weight patch 150 is preferred that can be fixed in position on the patient's skin relative to the convertible stimulator 100, convertible stimulator 100 can alternatively be powered by other external charging devices. For example, the convertible stimulator 100 may be powered by more traditional external charging devices, such as the external charger 50 described earlier (
Each of the example electronics modules 104A and 104B includes a housing 101 that is formed of top and bottom “clamshell” portions 101A and 101B that are joined (e.g., welded or brazed) at a seam 103, although other methods of construction, including molding the convertible stimulator 100 as a single unit, are also possible. As shown, the coils 118A and 118B are positioned within the housing 101. It will be understood that if the housing portions 101A and 101B are formed of a conductive material, such as titanium, then they will attenuate the magnetic field 130 to some degree, and as such, the housing portions 101A and 101B may instead be formed of non-conductive materials, such as ceramic or epoxy, as described above.
The bottom portion of
Although the electronics module 104 and the lead portion 102 have been described as separate components that are fixed together to form an integrated unit, the different portions may also be initially formed as single component. For example, the various mechanical and electrical components may be positioned within a mold cavity and overmolded to create the convertible stimulator 100 as a single integrated unit. In such an embodiment, the electronics module 104 would not include a cavity 117, but rather the components would be encapsulated within a mold material. Regardless of the way in which the convertible stimulator 100 is constructed, because it is an integrated unit, the lead portion 102 may be provided in several different length options to accommodate the patient-specific distance between the desired locations of the electrodes 116 and the electronics module 104. Moreover, although the illustrated device includes electrodes arranged on a percutaneous lead portion 102, other electrode arrangements, such as a two dimensional arrangement of electrodes on a paddle style lead, may also be used.
Cavity 117 contains a printed circuit board (PCB) 107, which includes electronic components 105 that make up the circuitry described in
As illustrated in the cross-sectional view in the bottom portion of
While the example power supply modules include openings 202 that accommodate insertion of an electronics module 104 in a direction along the length of the power supply module, the openings 202 may alternatively be positioned to accommodate insertion of an electronics module in a direction along the width of the power supply module. Likewise, while the described power supply modules have included batteries 226, 226′ as the power source, it will be understood that other types of power sources, such as a supercapacitor, for example, may be used. While several example power supply modules have been described, it will be understood that different designs and functionality may be implemented. For example, the features of the described power supply modules may be combined and additional features may be added.
The convertible stimulator 100 may in one embodiment be designed to be compatible with multiple power supply modules (such as power supply modules 200, 200′, 200″ and 200′″) to enable a patient to select the appropriate power supply module for their needs. For example, a patient that determines during an extended trial period (i.e., in which the convertible stimulator 100 acts independently) that the type of therapy they find effective is energy intensive, may be best served by a power supply module with a rechargeable battery, such as power supply modules 200′ or 200″. Conversely, a patient that determines during an extended trial period that the type of therapy they find effective is not energy intensive, may prefer a power supply module with a non-rechargeable battery, such as power supply module 200.
The external charger 50 is used to charge (or recharge) the battery 226′. A battery 26 in the external charger 50 provides operational power for the charger 50 and energy for the production of a magnetic charging field 52. Specifically, and as described above with respect to
The power supply module 200″ can also communicate data back to the external charger 50 using Load Shift Keying (LSK) modulation circuitry 224. LSK modulation circuitry 224 receives data to be transmitted back to the external charger 50 from the power supply module's microcontroller 250, and then uses that data to modulate the impedance of the charging coil 230. The coil 230's impedance is modulated via control of transistor 214, which shorts both ends of the coil 230 to ground. Impedance modulation could alternatively be accomplished by shorting both ends of the coil 230 together. The change in impedance is reflected back to coil 54 in the external charger 50, which interprets the reflection at LSK demodulation circuitry 74 to recover the transmitted data. This means of transmitting data from the power supply module 200″ to the external charger 50 is useful to communicate data relevant to charging of the battery 226′, such as the battery level, whether charging is complete and the external charger can cease, and other pertinent charging variables. However, because LSK works on a principle of reflection, such data can only be communicated from the power supply module 200″ to the external charger 50 during periods in which the external charger 50 is active and is producing a magnetic charging field 52.
The external controller 40 is used to send and receive data to/from the power supply module 200″ and, ultimately, the convertible stimulator 100. For example, the external controller 40 can send programming data such as therapy settings to the convertible stimulator 100 to dictate the therapy the convertible stimulator 100 will provide to the patient. Also, the external controller 40 can act as a receiver of data from the convertible stimulator 100, such as various data reporting on the convertible stimulator's status. The external controller 40 is powered by a battery (not shown), but could also be powered by plugging it into a wall outlet, for example.
Wireless data transfer between the power supply module 200″ and the external controller 40 preferably takes place via inductive coupling in generally the same way as described above with respect to the IPG 10. When data is to be sent from the external controller 40 to the power supply module 200″ via FSK link 42, coil 44 is energized with alternating current (AC), which generates a magnetic field, which in turn induces a voltage in the power supply module's telemetry coil 232. The generated magnetic field is FSK modulated (20) in accordance with the data to be transferred. The induced voltage in coil 232 can then be FSK demodulated (230) at the power supply module 200″ back into the telemetered data signals. Data telemetry in the opposite direction via FSK link 42 from the power supply module 200″ to the external controller 40 occurs similarly.
Data that is received from the external controller 40 or that is transmitted to the external controller 40 is communicated between the power supply module's microcontroller 250 and the convertible stimulator's microcontroller 140 over a communications bus that is established through the connection of the contacts 120C and 220C as shown. Connection of the contacts 120C and 220C may cause the convertible stimulator 100 to deactivate its own internal demodulation circuitry 112, which otherwise remains active such that the convertible stimulator 100 can communicate with an external device such as the external controller 40 in the absence of a power supply module that includes data telemetry functionality.
The external controller 40 typically comprises a user interface similar to that used for a portable computer, cell phone, or other hand held electronic device. The user interface typically comprises touchable buttons and a display, which allows the patient or clinician to send therapy programs to the convertible stimulator 100, and to review any relevant status information reported from the convertible stimulator 100.
The disclosed convertible stimulator provides the benefits of a fully implanted IPG that is externally powered during an extended trial period (or permanently, if desired) as well as the benefits of a more traditional internally-powered system through the subsequent connection of a separately-implanted power supply module.
While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.
This is a non-provisional of U.S. Provisional Patent Application Ser. No. 62/317,059, filed Apr. 1, 2016, to which priority is claimed, and which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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62317059 | Apr 2016 | US |