Minimally invasive lead system for vagus nerve stimulation

A system including two neurostimulation leads can be used for stimulating a select region of a nerve within a nerve bundle. For example, two leads can be used to stimulate a select region of the vagus nerve located within a patient's carotid sheath. The first neurostimulation is positioned within the carotid sheath and the second neurostimulation lead is positioned external to the carotid sheath. Each of the first and second neurostimulation leads includes at least one electrode defining an electrode array about the select region of the nerve. The electrode array, and more particularly, the different possible electrode vector combinations provided by the first and second neurostimulation leads facilitate steering of stimulation current density fields as needed or desired between the electrodes to effectively and efficiently treat a particular medical, psychiatric, or neurological disorder.

TECHNICAL FIELD

The present invention is directed to systems and methods for stimulating a region of a nerve within a nerve bundle. More particularly, the present invention is directed to systems and methods for stimulating a region of the vagus nerve within the carotid sheath.

BACKGROUND

The use of nerve stimulation for treating and controlling a variety of medical, psychiatric, and neurological disorders has seen significant growth over the last several decades, including for treatment of heart conditions, epilepsy, obesity, and breathing disorders, among others. For example, modulation of the autonomic balance with neural stimulation has been shown to be possible and have positive clinical benefits, such as protecting the myocardium from further remodeling and predisposition to fatal arrhythmias following a myocardial infarction (MI).

SUMMARY

Example 1 is a system for stimulating a select region of a patient's vagus nerve located within the patient's carotid sheath from a location adjacent the vagus nerve, the system including: a first neurostimulation lead adapted to be deployed at a location adjacent the select region of the vagus nerve within the carotid sheath, the first lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end, at least one conductor extending within the lead body from the proximal end towards the distal end, and at least one electrode operatively coupled to the at least one conductor and located on the distal portion, the at least one electrode adapted to deliver an electrical pulse to the vagus nerve; a second neurostimulation lead adapted to be deployed at a stimulation site external to the carotid sheath, the second lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end, the distal portion configured to wrap around and contact an external surface of the carotid sheath, a conductor extending within the lead body from the proximal end towards the distal end, and at least one electrode operatively coupled to the at least one conductor located on the distal portion such that when the distal portion is in contact with the external surface of the carotid sheath, the at least one electrode is oriented in a direction towards the vagus nerve; and a pulse generator adapted to send and receive a signal for selectively applying an electrical stimulation to one or more electrodes located on the first and/or second leads.

In Example 2, the system according to Example 1, wherein the distal portion of the second neurostimulation lead comprises a pre-formed spiral, wherein when the second lead is implanted, the spiral is configured to be helically wrapped around the external surface of the carotid sheath such that the at least one electrode is oriented towards the vagus nerve and placed into contact with the carotid sheath, wherein the at least one electrode is adapted to deliver an electrical pulse through the carotid sheath to the vagus nerve.

In Example 3, the system according to any one of Examples 1-2, wherein the distal portion of the second neurostimulation lead comprises a cuff electrode including a resilient cuff having an inner surface and at least one electrical contact located on the inner surface of the resilient cuff, wherein the cuff electrode is configured to be wrapped around the external surface of the carotid sheath such that the at least one electrode contact is oriented towards the vagus nerve and placed into contact with the carotid sheath, wherein the at least one electrode contact is adapted to deliver an electrical pulse through the carotid sheath to the vagus nerve.

In Example 4, the system according to any one of Examples 1-3, wherein the distal portion of the first neurostimulation lead comprises a pre-formed shape configured to orient at least one of the plurality of electrodes in a direction towards the vagus nerve and to stabilize and secure the distal portion of the lead within the carotid sheath at the stimulation site.

Example 5 is a system for stimulating a select region of a patient's vagus nerve located within the patient's carotid sheath from a location adjacent the vagus nerve, the system including: a first neurostimulation lead adapted to be deployed at a location within a region of the patient's internal jugular vein adjacent the select region of the vagus nerve located within the carotid sheath, the first lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end, at least one conductor extending within the lead body from the proximal end towards the distal end, and at least one electrode operatively coupled to the at least one conductor and located on the distal portion, the at least one electrode adapted to deliver an electrical pulse to the vagus nerve; a second neurostimulation lead adapted to be deployed at a stimulation site external to the carotid sheath, the second lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end, the distal portion configured to wrap around and contact an external surface of the carotid sheath, a conductor extending within the lead body from the proximal end towards the distal end, and at least one electrode operatively coupled to the at least one conductor located on the distal portion such that when the distal portion is in contact with the external surface of the carotid sheath, the at least one electrode is oriented in a direction towards the vagus nerve and the first neurostimulation lead located within the internal jugular vein; and a pulse generator adapted to send and receive a signal for selectively applying an electrical stimulation to one or more electrodes located on the first and/or second leads.

In Example 6, the system according to Example 5, wherein the distal portion of the second neurostimulation lead comprises a pre-formed spiral, wherein when the second lead is implanted, the spiral is configured to be helically wrapped around the external surface of the carotid sheath such that the at least one electrode is oriented towards the vagus nerve and placed into contact with the carotid sheath, wherein the at least one electrode is adapted to deliver an electrical pulse transvascularly through the carotid sheath to the vagus nerve.

In Example 7, the system according to any one of Examples 5-6, wherein the distal portion of the second neurostimulation lead comprises a cuff electrode including a resilient cuff having an inner surface and at least one electrical contact located on the inner surface of the resilient cuff, wherein the cuff electrode is configured to be wrapped around the external surface of the carotid sheath such that the at least one electrode contact is oriented towards the vagus nerve and placed into contact with the carotid sheath, wherein the at least one electrode contact is adapted to deliver an electrical pulse transvascularly through the carotid sheath to the vagus nerve.

In Example 8, the system according to any one of Examples 5-7, wherein the distal portion of the first neurostimulation lead comprises a pre-formed shape configured to orient at least one of the plurality of electrodes in a direction towards the vagus nerve and to stabilize and secure the distal portion of the lead within the carotid sheath at the stimulation site.

Example 9 is a method for stimulating a portion of a patient's vagus nerve located within a carotid sheath, the method including: implanting a first neurostimulation lead within the carotid sheath at a location adjacent the vagus nerve, the first lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end, at least one conductor extending within the lead body from a proximal end towards the distal end, and at least one electrode operatively coupled to the at least one conductor located on the distal portion and adapted to deliver an electrical pulse to the vagus nerve; positioning a second medial electrical lead external to the carotid sheath at a position adjacent the vagus nerve and the first neurostimulation lead, the second neurostimulation lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end and configured to contact an external surface of the carotid sheath, and at least one electrode located on the distal portion such that when the distal portion is in contact with the external surface of the carotid sheath, the at least one electrode is oriented in a direction towards the vagus nerve and the first neurostimulation lead located within the carotid sheath; selecting an electrode vector for stimulating the vagus nerve; and delivering the electrical stimulation pulse to the vagus nerve.

In Example 10, the method according to Example 9, wherein the step of implanting the first neurostimulation lead within the carotid sheath at a location adjacent the vagus nerve comprises implanting the first neurostimulation lead at a location within the internal jugular vein.

In Example 11, the method according to any one of Examples 9-10, further including the step of evaluating one or more electrode vectors between two or more electrodes located on the distal portions of the first and second neurostimulation leads against a predetermined stimulation threshold value.

In Example 12, the method according to any one of Examples 9-11, wherein the step of positioning the second neurostimulation lead external to the carotid sheath further comprises wrapping the distal portion around an outer circumference of the external sheath such that the at least one electrode is oriented towards the vagus nerve and the first neurostimulation lead, and is in contact with an external surface of the carotid sheath.

In Example 13, the method according to any one of Examples 9-12, wherein the distal portion of the second neurostimulation lead comprises a pre-formed spiral having the at least one electrode located thereon and wherein the step of positioning the second neurostimulation lead external to the carotid sheath further comprises helically wrapping the pre-formed spiral of the distal portion around an outer circumference of the carotid sheath such that the at least one electrode is oriented towards the vagus nerve and the first neurostimulation lead, and is in contact with an external surface of the carotid sheath.

In Example 14, the method according to any one of Examples 9-13, wherein the distal portion of the second neurostimulation lead further comprises a cuff including the at least one electrode located on an internal surface of the cuff and wherein the step of positioning the second neurostimulation lead external to the carotid sheath further comprises engaging the cuff around an outer circumference of the carotid sheath such that the at least one electrode is oriented towards the vagus nerve and the first neurostimulation lead, and is in contact with an external surface of the carotid sheath.

In Example 15, the method according to any one of Examples 9-14, wherein the distal portion of the first medical electrical lead comprises an expandable stent-like structure and the at least one electrode is located on an external surface of the expandable stent-like structure, wherein the step of implanting the first neurostimulation lead within the carotid sheath at the location adjacent the vagus nerve comprises: delivering the first neurostimulation lead to an intravascular location within an internal jugular vein such that the distal portion including the expandable stent-like structure is adjacent the vagus nerve; orienting the at least one electrode located on the external surface of the expandable stent-like structure in a direction towards the vagus nerve; and expanding the expandable stent-like structure such that it contacts and engages a wall of the internal jugular vein securing and stabilizing the lead within the vessel.

In Example 16, the method according to any one of Examples 9-15, wherein the step of implanting the first neurostimulation lead within the carotid sheath comprises delivering the first neurostimulation lead to an intravascular location within an internal jugular vein such that the distal portion is adjacent the vagus nerve and the at least one electrode is oriented in a direction towards the vagus nerve.

In Example 17, the method according to any one of Examples 9-16, wherein the step of implanting the first neurostimulation lead within the carotid sheath comprises implanting the distal portion of the first neurostimulation lead at a location adjacent the vagus nerve between the vagus nerve and an internal jugular vein.

Example 18 is a method for stimulating a portion of a patient's vagus nerve located within a carotid sheath, the method including: implanting a first neurostimulation lead within a patient's internal jugular vein located within the carotid sheath at a location adjacent the vagus nerve, the first lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal end, one or more of conductors extending within the lead body in a distal direction from a proximal end towards the distal end, and an expandable electrode coupled to the distal end of the lead body and operatively coupled to the one or more electrodes, the expandable electrode adapted to deliver an electrical pulse to the vagus nerve; positioning a second medial electrical lead external to the carotid sheath at a position adjacent the vagus nerve and the first neurostimulation lead, the second neurostimulation lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end and configured to contact an external surface of the carotid sheath, and at least one electrode located on the distal portion; electing an electrode vector for stimulating the vagus nerve and; stimulating the vagus nerve.

In Example 19, the method according to Example 18, further including the step of evaluating one or more electrode vectors between two or more electrodes located on the distal portions of the first and second neurostimulation leads against a predetermined stimulation threshold value.

In Example 20, the method according to any one of Examples 18-19, wherein the step of positioning the second neurostimulation lead external to the carotid sheath further comprises wrapping the distal portion around an outer circumference of the external sheath such that the at least one electrode is oriented towards the vagus nerve and the first neurostimulation lead and is in contact with an external surface of the carotid sheath.

In Example 21, the method according to any one of Examples 18-20, wherein the distal portion of the second neurostimulation lead comprises a pre-formed spiral having the at least one electrode located thereon and wherein the step of positioning the second neurostimulation lead external to the carotid sheath further comprises helically wrapping the pre-formed spiral of the distal portion around an outer circumference of the carotid sheath such that the at least one electrode is oriented towards the vagus nerve and the first neurostimulation lead and is in contact with an external surface of the carotid sheath.

In Example 22, the method according to any one of Examples 18-21, wherein the distal portion of the second neurostimulation lead further comprises a cuff including the at least one electrode located on an internal surface of the cuff and wherein the step of positioning the second neurostimulation lead external to the carotid sheath further comprises positioning the cuff around an outer circumference of the carotid sheath such that the at least one electrode is oriented towards the vagus nerve and the first neurostimulation lead and is in contact with an external surface of the carotid sheath.

In Example 23, the method according to any one of Examples 18-22, further including the step of transitioning the expandable electrode from a collapsed configuration suitable for delivery to an expanded configuration, wherein in the expanded configuration the expandable electrode contacts and engages a wall of the internal jugular vein securing and stabilizing the lead within the vessel.

Example 24 is a method for stimulating a portion of a patient's vagus nerve located within a carotid sheath, the method including: positioning a neurostimulation lead within the carotid sheath at a location adjacent the vagus nerve, the lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion having a distal end, at least one conductor extending within the lead body from a proximal end towards the distal end, and a plurality of electrodes operatively coupled to the at least one conductor located on the distal portion and adapted to deliver an electrical pulse to the vagus nerve; orienting at least one of the plurality of electrodes in a direction towards the vagus nerve; selecting an electrode combination for stimulating the vagus nerve; and delivering the electrical stimulation pulse to the vagus nerve.

In Example 25, the method according to Example 24, wherein the neurostimulation lead is implanted at a location within the internal jugular vein adjacent the vagus nerve.

In Example 26, the method according to Examples 24-25, wherein the neurostimulation lead is implanted at a location within the carotid sheath between the vagus nerve and the internal jugular vein.

In Example 27, the method according to Examples 24-26, further including the step of evaluating one or more electrode vectors between two or more electrodes located on the distal portion of the neurostimulation leads against a predetermined stimulation threshold value.

Example 28 is a system for stimulating a select region of a patient's vagus nerve located within the patient's carotid sheath from a location adjacent the vagus nerve, the system including: a neurostimulation lead adapted to be deployed at a location adjacent the select region of the vagus nerve within the carotid sheath, the lead including a lead body extending from a proximal end adapted to be coupled to a pulse generator to a distal portion including a distal end, a plurality of conductors extending within the lead body from the proximal end towards the distal end, and a plurality of electrodes located on the distal portion and operatively coupled to the plurality of conductors in a one to one manner such that each electrode is individually addressable, the at least one electrode adapted to deliver an electrical pulse to the vagus nerve; and a pulse generator adapted to send and receive a signal for selectively applying an electrical stimulation to one or more electrodes located on the first and/or second leads.

DETAILED DESCRIPTION

The neural stimulation systems and methods described herein according to the various embodiments can effectively and efficiently be used to treat and control a variety of disorders, such as medical, psychiatric, or neurological disorders, by modulation of autonomic balance. Employing a plurality of electrode bearing leads (e.g., two or more), portions of which are positioned adjacent a nerve trunk of interest, a multiplicity of electrode vector combinations are available to the system for adequately stimulating one or more selected portions of the nerve trunk at low stimulation thresholds and with minimal adverse side-effects.

FIG. 1shows a system2for stimulating a region of a patient's vagus nerve6located within the carotid sheath10. The carotid sheath10includes multiple layers of fascia wrapping the common carotid artery (not shown), the internal jugular vein (IJV)14, and the vagus nerve6. The system2includes a first neurostimulation lead18, a second neurostimulation lead22and an implantable medical device (IMD)26such as, for example, a pulse generator. According to various embodiments, the first neurostimulation lead18is located within the carotid sheath10and the second neurostimulation lead22is located external to the carotid sheath10. In the illustrated embodiment, the first neurostimulation lead18is disposed within the IJV14.

The IMD26is adapted to deliver neural stimulation pulses and includes, among other things, a neural stimulation circuit28. The neural stimulation circuit is adapted to send and receive a signal for selectively applying an electrical stimulation to the vagus nerve via the first and/or second neurostimulation leads18and22. In some embodiments, the neural stimulation circuit28includes a programmable memory for storing instructions on which the IMD26operates, a processor circuit to process sensed physiologic data or feedback and, in some embodiments, a therapy titration/adjustment circuit which receives the resulting physiologic feedback which can be representative of the efficacy of any applied therapy (e.g., stimulation pulses). Electrical stimulation generated by the IMD26(FIG. 1) can be delivered to a select region of the vagus nerve6via the first and/or second neurostimulation leads18and22.

The first and second neurostimulation leads18and22are coupled at their respective proximal ends30and34to the IMD26. The proximal ends30and34of each of the lead bodies38and42are configured to be operatively connected to the IMD26via a connector (not shown). The first and second neurostimulation leads18and22each include an elongated, insulative lead body38and42extending from their respective proximal ends30and34to a distal end50and54, respectively. Each of the lead bodies38and42is flexible and, in some embodiments, may have a circular cross-section. Alternatively, in other embodiments the lead bodies38,42(or portions thereof) may have non-circular (e.g., elliptical) cross-sectional shapes. In some embodiments, the lead bodies38and42can include multiple lumens. For example, the lead bodies38and42can include one or more lumens each configured to receive a conductor and/or a guiding element such as a guidewire or a stylet for delivery and/or implantation of the leads18and/or22.

According to various embodiments, each of the neurostimulation leads18and22can include a plurality of conductors including individual wires, coils, or cables extending within their respective lead bodies38and42from the proximal ends30,34towards the distal ends50,54of each of the lead bodies38and42, respectively. The conductors can be insulated and/or molded in place with an insulator such as silicone, polyurethane, ethylene tetrafluoroethylene, or another biocompatible, insulative polymer. In one exemplary embodiment, the conductors have a co-radial design. In this embodiment, each individual conductor is separately insulated and then wound together in parallel to form a single coil. In another exemplary embodiment, the conductors have a co-axial configuration. In still other embodiments, one or more of the conductors is a stranded cable conductor each routed through one of the aforementioned lumens in the lead body38,42. In general, the lead can include any combination of conductor types such as for, example, a combination of a coil conductor and a cable conductor.

According to further embodiments of the present invention, each conductor is adapted to be connected to an individual electrode, such as, for example, electrode60in a one-to-one manner allowing each electrode60to be individually addressable. Additionally, each electrode60of the neurostimulation leads18,22can be programmed by the IMD26to assume a positive (+) or negative (−) polarity to create a particular stimulation field when current, for example, is applied thereto. Thus, many different vector combinations of programmed anode and cathode electrodes can be used to deliver a variety of current density field waveforms to stimulate a selected region of the vagus nerve6without stimulating other nearby structures (e.g., muscles, other nerves, etc.).

According to various embodiments of the present invention, as illustrated inFIGS. 2A-2Cand3A-3C, the distal portions64and68of each of the first and second neurostimulation leads18and22are positioned adjacent to a region of the vagus nerve6located within the carotid sheath10. In many embodiments, each of the distal portions64and68include multiple electrodes (e.g. electrode60) located thereon. In embodiments including multiple electrodes, the electrodes may form one or more bipolar electrode pairs. In some embodiments, the electrodes can be ring or partial ring electrodes as are generally known in the art. In other embodiments, the electrodes can be stent electrodes, cuff electrodes or sheath electrodes.

In some embodiments, as shown inFIG. 2A, the distal portion64of the first neurostimulation lead18can be located within the carotid sheath10adjacent the vagus nerve6. In one embodiment, as shown, the first neurostimulation lead18can be located within the carotid sheath at a location between the IJV14and the vagus nerve6. The distal portion64of the lead18can be subcutaneously tunneled to a position adjacent the select region of the vagus nerve6located within the carotid sheath10. The distal portion64can be secured at the desired location using sutures or other securing means to prevent dislodgment of the distal portion64portion of the lead.

In other embodiments, as shown inFIG. 2B, the distal portion64of the first neurostimulation lead18can be located within the IJV14at a location adjacent the selected region of the vagus nerve6. The distal portion64can be delivered intravascularly to the site within the IJV14. The electrode(s)60located on the distal portion64of the lead18are adapted to transvascularly deliver an electrical pulse across the vessel wall72of IJV14to an electrode on a second lead to stimulate the selected region of the vagus nerve6.

The distal portion64of the first neurostimulation lead18can be stabilized and secured within the IJV14by a variety of techniques. In some embodiments, the distal portion64of the first neurostimulation lead18can include a pre-formed bias76that is adapted to contact and exert a lateral or radial force on the vessel walls72of the IJV14to stabilize and secure the distal portion within the IJV14. The-pre-formed bias76can be used to orient any electrodes60located on the distal portion64of the lead18in a direction towards the vagus nerve6. In some embodiments, the pre-formed bias76is adapted to transition from a collapsed configuration suitable for delivery to an expanded configuration in which the pre-formed bias portion contacts and engages the vessel walls72of the IJV14securing and stabilizing the distal portion64in the IJV14. The pre-formed bias76can include any one of a spiral shape, an S-curve, a sinusoidal curve and the like.

In one embodiment, as shown inFIG. 2B, the pre-formed bias76has a spiral shape. In other embodiments, as will be described in greater detail below, the distal portion64can include a stent-like member for securing and stabilizing the distal portion64in the IJV14.

According to various embodiments, as shown inFIGS. 2A and 2B, the distal portion68of a second neurostimulation lead22is located external to the carotid sheath10adjacent to the select region of the vagus nerve6and the distal portion64of the first neurostimulation lead18located within the carotid sheath10. The distal portion68of the second neurostimulation lead22also includes one or more electrodes60and is configured to be wrapped around an outer circumference80of the carotid sheath10. The distal portion68is wrapped around the outer circumference80of the carotid sheath10such that the one or more electrodes60located thereon are oriented in a direction towards the vagus nerve6located within the carotid sheath10. In some embodiments, the distal portion68is wrapped around the outer circumference80of the carotid sheath10such that the one or more electrodes60are oriented towards the vagus nerve6and are in contact with an external surface84of the carotid sheath10. The one or more electrodes60are adapted to deliver an electrical pulse across the wall88of the carotid sheath10to the vagus nerve6located within.

In some embodiments, the distal portion68can have a pre-formed spiral shape elastically biased such that the distal portion68wraps around and engages the external surface84of the carotid sheath10when implanted. In one embodiment, an inner diameter of the pre-formed spiral is slightly less than an outer diameter of the carotid sheath10such that when the distal portion68is placed around the external circumference80of the carotid sheath10, the elastic bias causes the distal portion68to engage the carotid sheath10, securing and stabilizing the distal portion68of the lead22about the carotid sheath10such that the electrode(s) is placed into contact with an external surface88of the carotid sheath. In other embodiments, sutures may optionally be used to secure the distal portion68of the lead22in place around the outer circumference of the carotid sheath10, either by themselves or in combination with the pre-formed elastically biased shape discussed above. In other embodiments, the distal portion68can include a cuff or sheath electrode adapted to wrap around and engage the external surface84of the carotid sheath10, as will be described in greater detail below.

In some embodiments, as shown inFIG. 2C, the second neurostimulation lead22may be disposed within the carotid sheath10. In the illustrated embodiment, the second neurostimulation lead22is disposed within the IJV14. In some embodiments, the second neurostimulation lead22may be disposed within the carotid sheath10but exterior to the IJV14. The first neurostimulation lead18and the second neurostimulation lead22may be positioned relative to each other such that the vagus nerve6extends between the first neurostimulation lead18and the second neurostimulation lead22. Electrodes60located on the first neurostimulation lead18and the second neurostimulation lead22are adapted to deliver an electrical pulse therebetween to stimulate a selected region of the vagus nerve6.

In other embodiments of the present invention, as shown inFIGS. 3A-3C, the distal portion64of the first neurostimulation lead18includes a stent-like member90. The stent-like member90is adapted to transition from a collapsed configuration suitable for delivery to an expanded configuration. The distal portion64of the first stimulation lead18including the stent-like member90can be delivered intravascularly to a location within the IJV14adjacent the selected region of the vagus nerve6in a collapsed configuration. The stent-like member90is then transitioned from its collapsed configuration to an expanded configuration in which the stent-like member90contacts and engages the wall72of the IJV14. In the expanded configuration, the stent-like member90contacts and engages the walls72of the IJV14securing and stabilizing the distal portion64of the lead18within the IJV14at a location adjacent a select region of the vagus nerve6.

In one embodiment, as shown inFIG. 3A, one or more electrodes60are located on an outer surface92of the stent-like member90. The stent-like member90can be rotated during the implantation procedure such that at least one of the electrodes60located on its outer surface92is oriented in a direction towards the vagus nerve6.

In still other embodiments, as shown inFIGS. 3B and 3C, the stent-like member90can be a stent electrode adapted to transvascularly deliver an electrical pulse across the wall72of the IJV14to the vagus nerve6. In further embodiments, the stent electrode90can be selectively insulated so as to shield other areas of the vagus nerve6and surrounding anatomy from undesired stimulation. In one embodiment, for example, the stent electrode90can be insulated on an inner surface. In another embodiment, the stent electrode90can be operatively coupled to more than one conductor extending within the lead18such that one or more regions of the stent electrode90can be used to electrically stimulate the vagus nerve6.

In other embodiments, as shown inFIG. 3B, the distal portion68of the second neurostimulation lead22can include a cuff electrode94. The cuff electrode94is positioned around the carotid sheath10such that it is adjacent the select region of the vagus nerve6to be stimulated and the stent-like electrode90located within the carotid sheath10. The cuff electrode94is formed of a resilient material and has one or more electrical contacts96located on its inner surface98. The nerve-cuff electrode94is sufficiently resilient such that it wraps around and engages an external surface84of the carotid sheath10such that the one or more electrodes located on an internal surface of the cuff94are placed into contact with an external surface84of the carotid sheath10. One or more conductors extending within the lead22are coupled to the nerve-cuff electrode94to transvascularly deliver an electrical pulse across the wall88of the carotid sheath10via the one or more electrical contacts96to the vagus nerve6. In some embodiments, the stent-like electrode90located within the IJV14can have a negative polarity and the nerve-cuff electrode94can have a positive polarity, acting as a return electrode.

In some embodiments, as illustrated, the first and second neurostimulation leads18and22are positioned such that the cuff electrode94is axially adjacent the stent-like member90. In some embodiments, the first and second neurostimulation leads18and22are positioned such that the cuff electrode94is disposed cranial or caudal to the stent-like electrode90in order to provide a longitudinal vector between one or more electrodes on the first neurostimulation lead18and one or more electrodes on the second neurostimulation lead22.

In still other embodiments, the distal portion68of the second neurostimulation lead22can include a sheath electrode102, as shown inFIG. 3C. The sheath electrode102is positioned around the carotid sheath10such that it is adjacent the select region of the vagus nerve6to be stimulated and the stent-like electrode90located within the carotid sheath10. Like the cuff electrode94, described above, the sheath electrode102is formed of a resilient material and has one or more electrical contacts104located on its inner surface108. The sheath electrode102is sufficiently resilient such that it wraps around and engages an external surface84of the carotid sheath10. One or more conductors extending within the lead22are coupled to the sheath electrode102to transvascularly deliver an electrical pulse across the wall88of the carotid sheath10via the one or more electrical contacts104to the vagus nerve6. However, unlike the cuff electrode94, the sheath electrode102has an overall length l oriented along a longitudinal axis x that is greater than a length m of the stent electrode90located within the carotid sheath10. In some embodiments, the sheath electrode102is placed around an outer circumference80of the carotid sheath10such that its proximal and distal ends110and112extend beyond the proximal and distal ends116and120of the stent-like electrode90located within the carotid sheath10in order to provide a longitudinal vector. In one embodiment, for example, the sheath electrode can have an overall length ranging from about 5 mm to about 25 mm. In some embodiments, the stent electrode90located within the IJV14can have a negative polarity and the sheath electrode102can have a positive polarity, acting as a return electrode.

In one embodiment, the sheath electrode102includes a long band electrode coupled to an inner surface of the sheath electrode102where it is adapted to contact the carotid sheath10. The long band electrode can range in length from about 3 mm to about 10 mm, and may provide a larger radius as a return electrode in order to capture the nerve. A long band electrode may also potentially lower the pacing threshold.

As generally illustrated inFIGS. 2A-2Band3A-3C, electrical stimulation generated by the IMD26(FIG. 1) can be delivered to a select region of the vagus nerve6using any combination of the various embodiments of the distal portions64and68of the neurostimulation leads18and22, described above. Each of the leads18and22includes one or more electrodes60,90,94and/or102located on their respective distal portions64and68, forming an electrode array (including inter-lead and intra-lead electrode configurations) around the selected region of the vagus nerve6. The electrode array positioned around the selected region of the vagus nerve6, and more specifically, the numerous electrode vector combinations (FIG. 4) provided by the first and second neurostimulation leads18and22facilitate steering of stimulation current density fields as needed or desired between the electrodes to effectively and efficiently treat a particular medical, psychiatric, or neurological disorder. The different combinations of electrodes60,90,94and/or102are used to change the shape of the current density field in and around the selected region of the vagus nerve6. By using appropriate stimulation parameters (as determined by the IMD26(FIG. 1) itself or a physician or other caregiver by way of an external programmer) and electrode locations within the array, a neural stimulation system2(FIG. 1) can induce action potentials in the selected region of the vagus nerve6that result in the desired treatment effect. In addition, the stimulation current density fields may be steered between two or more electrodes60,90,94and/or102(i.e., an electrode vector) which result in low stimulation thresholds and a minimization of stimulation side-effects.

FIG. 4shows various electrode vector combinations that can be generated by the distal portions64and68of the two leads18and22when placed adjacent a select region of a patient's vagus nerve6located within the carotid sheath10, as described in detail above according to the various embodiments of the present invention. The polarity and location of the electrodes60,90,94and/or102chosen to deliver the stimulation current and the parameters of the stimulation current (e.g., amplitude, frequency, burst frequency, duty cycle, or pulse width, etc.) may be based on a status of the one or more sensed physiologic responses, a desire for low stimulation thresholds, the particular disorder the stimulation is meant to treat, or a desire to minimize or abate stimulation side-effects. Additionally, the numerous electrode vector combinations may facilitate the physician or the IMD26to recurrently select one or more electrode combinations which optimize or provide an acceptable balance of one or a combination of physiologic feedback responses, a minimal degree of stimulation side-effects, or a low stimulation threshold parameter, among other things.

FIG. 5is a block diagram outlining a method200for stimulating a select region of a patient's vagus nerve6located within a carotid sheath10using two neurostimulation leads18and22. According to various embodiments, the method200includes the step of implanting a first neurostimulation lead18within the carotid sheath10such that its distal portion64is positioned adjacent (or near) to the select region of the vagus nerve6(Blocks204aand204b). In one embodiment, the distal portion64of the first neural stimulation lead18including one or more electrodes60is implanted within IJV14located within the carotid sheath10at a location adjacent the select region of the vagus nerve6(Block204a). In another embodiment, the distal portion64of the first neural stimulation lead18including one or more electrodes60located thereon is implanted within the carotid sheath10at a location adjacent the select region of the vagus nerve6(Block204b). The first neurostimulation lead18can be implanted within the carotid sheath10using a variety of techniques including surgical dissection, endoscopy or transvascular delivery techniques under fluoroscopy or other standard visualization techniques.

The method200outlined inFIG. 5also includes positioning a second neurostimulation lead external to the carotid sheath10at a location adjacent the select region of the vagus nerve6and the first neural stimulation lead18(Block208). More particularly, the distal portion68of the second neural stimulation lead22including one or more electrodes60is positioned external to the carotid sheath at a location adjacent the distal portion64of the first neurostimulation lead18and the vagus nerve6located within the carotid sheath10or the in the IJV14. In some embodiments, as described in greater detail above, the distal portion68is configured to engage the external surface of the carotid sheath such that when the distal portion68is in contact with the carotid sheath at least one electrode60is oriented in a direction towards the vagus nerve6and the distal portion64of the first neurostimulation lead18. For example, in some embodiments, the distal portion68of the second neural stimulation lead22can be helically wrapped around the carotid sheath.

Once the two leads and their respective distal portions64,68have been positioned adjacent to the select region of the vagus nerve6, one or more electrode vectors established between two or more sets of electrodes located the distal portions of the first and second neurostimulation leads18and22are evaluated for stimulating the vagus nerve (Block212). The electrode vectors are evaluated against a predetermined stimulation threshold for their ability to stimulate the vagus nerve and produce a desired response. An electrode vector for stimulating the vagus nerve6is then selected using the data generated during the evaluation step, and the vagus nerve6is then stimulated (Blocks216and220).

In still other embodiments of the present invention a single lead system300, as shown inFIG. 6, can be used to stimulate a region of the vagus nerve6. According to various embodiments, the system300includes a neurostimulation lead118coupled at its proximal end120to an IMD126via a connector (not shown). The neurostimulation lead118can have many or all of the same features of the leads18and22, discussed above according to the various embodiments.

According to various embodiments of the present invention, as illustrated inFIGS. 7A-7C, the distal portion164of the lead118can be positioned adjacent to a region of the vagus nerve6located within the carotid sheath10. In many embodiments, the distal portion164can include multiple electrodes (e.g. electrode160) located thereon. In embodiments including multiple electrodes, the electrodes may form one or more bipolar electrode pairs. In some embodiments, the electrodes can be ring or partial ring electrodes as are generally known in the art. In other embodiments, the electrodes can be stent electrodes, cuff electrodes or sheath electrodes.

In some embodiments, as shown inFIG. 7A, the distal portion164of the neurostimulation lead118can be located within the carotid sheath10at a location between the IJV14and the vagus nerve6. In one embodiment, the distal portion164of the lead118can be subcutaneously tunneled to a position adjacent the select region of the vagus nerve6located within the carotid sheath10. The distal portion64can be secured at the desired location using sutures or other securing means to prevent dislodgment of the distal portion164portion of the lead. In still another embodiment, the distal portion164of the lead118can include a nerve cuff (not shown) adapted to be placed around the vagus nerve6.

In other embodiments, as shown inFIG. 7B, the distal portion164of the first neurostimulation lead118can be located within the IJV14at a location adjacent the selected region of the vagus nerve6. The distal portion164can be delivered intravascularly to the site within the IJV14. The electrode(s)160located on the distal portion64of the lead18are adapted to transvascularly deliver an electrical pulse across the vessel wall72of IJV14to stimulate the selected region of the vagus nerve6.

The distal portion164of the first neurostimulation lead118can be stabilized and secured within the IJV14by a variety of techniques. In some embodiments, the distal portion164of the first neurostimulation lead118can include a pre-formed bias176that is adapted to contact and exert a lateral or radial force on the vessel walls72of the IJV14to stabilize and secure the distal portion within the IJV14. The-pre-formed bias176can be used to orient any electrodes160located on the distal portion164of the lead118in a direction towards the vagus nerve6. In some embodiments, the pre-formed bias176is adapted to transition from a collapsed configuration suitable for delivery to an expanded configuration in which the pre-formed bias portion contacts and engages the vessel walls72of the IJV14securing and stabilizing the distal portion164in the IJV14. The pre-formed bias176can include any one of a spiral shape, an S-curve, a sinusoidal curve and the like. In one embodiment, as shown inFIG. 7B, the pre-formed bias76has a spiral shape. In other embodiments, the distal portion164can include a stent-like member for securing and stabilizing the distal portion64in the IJV14, as described in detail above in reference toFIG. 3A.

In other embodiments, the distal portion164of the lead118can be located external to the carotid sheathl8adjacent to the select region of the vagus nerve6. In one embodiment, the distal portion164of the lead118is configured to be helically wrapped around an outer circumference surface80of the carotid sheath10. The distal portion164is wrapped around the outer circumference80of the carotid sheath10such that the one or more electrodes160located thereon are oriented in a direction towards the vagus nerve6located within the carotid sheath10. In some embodiments, the distal portion164is wrapped around the outer circumference80of the carotid sheath10such that the one or more electrodes160are oriented towards the vagus nerve6and are in contact with an external surface84of the carotid sheath10. The one or more electrodes160are adapted to transvascularly deliver an electrical pulse across the wall88of the carotid sheath10to the vagus nerve6located within.

In some embodiments, the distal portion164can have a pre-formed spiral shape elastically biased such that the distal portion164wraps around, engages and applies a compressive force to the external surface84of the carotid sheath10when implanted. In one embodiment, an inner diameter of the pre-formed spiral is slightly less than an outer diameter of the carotid sheath10such that when the distal portion164is placed around the external circumference80of the carotid sheath10, the elastic bias causes the distal portion164to engage the carotid sheath10, securing and stabilizing the distal portion164of the lead22about the carotid sheath10. In other embodiments, sutures may optionally be used to secure the distal portion164of the lead118in place about the outer circumference of the carotid sheath10, either by themselves or in combination with the pre-formed elastically biased shape discussed above. In other embodiments, the distal portion164can include a cuff or sheath electrode adapted to wrap around and engage the external surface84of the carotid sheath10, as described in greater detail above in reference toFIGS. 3B and 3C.

Once the distal portion164is positioned and secured at a location adjacent to the region of the vagus nerve6, electrical stimulation generated by the IMD126(FIG. 6) can be delivered to a select region of the vagus nerve6using any combination of electrodes located on the distal portion164of the lead118forming an intra-lead electrode array.