Electrode configuration for medical devices

Abstract

An example apparatus includes an elongate housing, first and second electrodes, and signal generating circuitry. The housing may be implanted within a single first chamber of a heart. The first electrode extends distally from the distal end of the elongate housing. A distal end of the first electrode is penetrable into wall tissue of a second chamber of the heart. The second electrode extending from the distal end of the elongate housing is configured to flexibly remain in contact with the wall tissue of the first chamber without being penetrated by the second electrode through the wall tissue of the first chamber. A signal generating circuit may be within the elongate housing and coupled to the first electrode and the second electrode. The signal generation circuitry may deliver cardiac pacing to the second chamber via the first electrode and cardiac pacing to the first chamber via the second electrode.

Description

[0001] This application is a divisional application of Medtronic Corporation's PCT international patent application, filed on June 17, 2020, with application number 202080041658.0 (international application number PCT / US2020 / 038096), entitled "Electrode Configuration for Medical Devices". Technical Field

[0002] This disclosure relates to medical devices, and more specifically to electrodes of medical devices. Background Technology

[0003] Various types of implantable medical devices (IMDs) have been implanted to treat or monitor one or more conditions in patients. These IMDs may be suitable for monitoring or treating conditions or functions related to the heart, muscles, nerves, brain, stomach, endocrine organs, or other organs and their associated functions. These IMDs may be associated with leads for positioning electrodes in desired locations, or they may be leadless, with the electrodes integrated into and / or attached to the device housing. These IMDs may have the ability to wirelessly transmit data to another device implanted in the patient or another instrument positioned outside the patient, or both.

[0004] A cardiac pacemaker is an intramural device (IMD) configured to deliver cardiac pacing therapy to restore a more normal heart rhythm. Such IMDs sense the electrical activity of the heart and deliver cardiac pacing via electrodes based on the sensed electrical activity. Some pacemakers are implanted at a distance from the heart and coupled to one or more leads that extend into the heart via a blood vessel to position the electrodes relative to the heart tissue. Some pacemakers are sized to be fully implanted in one of the heart chambers and may include electrodes integrated into or attached to the device housing instead of leads. Some pacemakers provide bichatral functionality by sensing and / or stimulating the activity of both the atria and ventricles, or provide other multichatral functionality. A pacemaker may provide multichatral functionality via leads extending into the respective heart chambers, or multiple pacemakers may provide multichatral functionality by being implanted in the respective chambers. Summary of the Invention

[0005] Generally, this disclosure relates to the configuration of electrodes in a device having a housing sized for implantation within a single chamber of the heart. More specifically, this disclosure relates to the configuration of electrodes that allows a single device implanted in one chamber to sense cardiac pacing and / or deliver cardiac pacing to more than one chamber. The ability of a single device implanted in one chamber to sense cardiac pacing and / or deliver cardiac pacing to more than one chamber avoids the need for leaded devices or multiple smaller devices to provide this functionality, thus reducing the amount of material implanted in the patient. In some cases, multiple devices may also require the implementation of energy-intensive communication schemes to coordinate their activities to provide dual-chamber functionality.

[0006] In some instances, the device includes a first electrode configured to penetrate the wall tissue of the heart chamber in which the device is implanted and to enter the wall tissue of another heart chamber. In addition to the first electrode, the device includes a second electrode configured to maintain consistent contact with the wall tissue of the chamber in which the device is implanted without penetrating the wall tissue. The electrode may be connected to a distal end of the device.

[0007] The second electrode can be configured, for example, to elastically deform toward the distal end of the device housing to accommodate differences in tissue surface and / or changes in the distance between the distal end of the device and the wall tissue during the cardiac cycle. The second electrode can be spring-biased toward a stationary configuration, and when elastically deformed, the spring bias can cause the second electrode to move away from the distal end of the device. In this way, elastic deformation and spring bias can maintain consistent contact between the second electrode and the wall tissue of the chamber in which the device is implanted.

[0008] The ability of the electrode to elastically deform to change the distance from which it extends from the device can at least partially help maintain contact between the tissue surface and the electrode without needing to penetrate the tissue of the first chamber. Thus, the device is not limited to a specific distance from which the electrode extends to achieve sufficient contact. Instead, the device can be positioned at different distances from the tissue surface, and the second electrode can maintain contact with the wall tissue as the heart moves. Because the second electrode has the ability to maintain contact with the wall tissue surface while another electrode is positioned in the wall tissue of another chamber, a single device can simultaneously provide pacing to two different chambers.

[0009] In one example, the device includes an elongated housing, a first electrode, a second electrode, and a signal generation circuitry system. The elongated housing extends from a proximal end to a distal end and is configured to be fully implanted within a first chamber of the heart, the first chamber having wall tissue. The first electrode extends distally from the distal end of the elongated housing, wherein the distal end of the first electrode is configured to penetrate into the wall tissue of a second chamber of the heart, separate from the first chamber. The second electrode extends distally from the elongated housing, wherein the second electrode is separate from the first electrode and is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue. The signal generation circuitry system is located within the elongated housing, coupled to the first and second electrodes, and configured to deliver cardiac pacing to the second chamber via the first electrode and to the first chamber via the second electrode.

[0010] In another example, a method includes delivering a cardiac pacing device to the heart, wherein the device includes an elongated housing extending from a proximal end of the housing to a distal end of the housing and is fully implanted within a first chamber of the heart having wall tissue. The device includes a first electrode extending distally from the distal end of the elongated housing, wherein the distal end of the first electrode penetrates into the wall tissue of a second chamber of the heart, separate from the first chamber. The device includes a second electrode extending distally from the elongated housing, wherein the second electrode is separate from the first electrode, and wherein the second electrode is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber. Delivering the cardiac pacing includes delivering the cardiac pacing via the first electrode to the second chamber and delivering the cardiac pacing via the second electrode to the first chamber.

[0011] In another example, the device includes an elongated housing, a first electrode, a second electrode, and a signal generation circuitry system. The elongated housing extends from a proximal end to a distal end, defining a longitudinal axis, and is configured to be fully implanted within the atrium of the heart. The first electrode extends distally from the distal end of the elongated housing and includes a helix, wherein as the helix rotates about the longitudinal axis, the distal end of the first electrode is configured to penetrate into the wall tissue of the heart's ventricle, and the distance between the distal end of the elongated housing and the wall tissue of the first ventricle decreases. The second electrode extends from the distal end of the elongated housing, wherein the second electrode is separate from the first electrode, and wherein the second electrode is configured to elastically deform toward the elongated housing through the atrial wall tissue as the distance between the distal end of the elongated housing and the atrial wall tissue decreases to flexibly maintain contact with the atrial wall tissue without penetrating the atrial wall tissue, and wherein the second electrode is more peripheral relative to the longitudinal axis than the first electrode. The signal generation circuit system is located within an elongated housing, coupled to a first electrode and a second electrode, and configured to deliver cardiac pacing to the ventricle via the first electrode and to the atrium via the second electrode.

[0012] This disclosure is intended to provide an overview of the subject matter described herein. It is not intended to provide an exclusive or exhaustive explanation of the methods and systems described in detail in the following drawings and specification. Attached Figure Description

[0013] Details of one or more embodiments of this disclosure are set forth in the following figures and description. Other features, objects, and advantages of this disclosure will become apparent from the description, figures, and claims.

[0014] Figure 1 This is a conceptual diagram illustrating an exemplary device implanted in a patient's heart according to one or more aspects of this disclosure.

[0015] Figure 2 This illustrates one or more aspects of this disclosure. Figure 1 A perspective view of an exemplary device.

[0016] Figure 3 This illustrates one or more aspects of this disclosure. Figure 1 and Figure 2 A functional block diagram of an exemplary configuration of an IMD.

[0017] Figure 4 It is implanted at the target implantation site. Figures 1 to 3 A conceptual diagram of the device.

[0018] Figure 5A , Figure 5B , Figure 5C and Figure 5DBased on one or more aspects of this disclosure Figures 1 to 4 Partial views of the device viewed from different perspectives.

[0019] Figure 5E Based on one or more aspects of this disclosure Figures 1 to 4 A cross-sectional view of the device, which is cut along the longitudinal axis of the device.

[0020] Figure 5F Based on one or more aspects of this disclosure Figures 1 to 4 A partial view of the device, and Figure 5G This is its end view.

[0021] Figure 6A , Figure 6B , Figure 6C and Figure 6D This is a partial view of another exemplary device according to one or more aspects of this disclosure, viewed from a different perspective.

[0022] Figure 7 This is a flowchart of an exemplary technique for deploying an apparatus having electrodes configured according to one or more aspects of this disclosure.

[0023] Figure 8 An exemplary first electrode including a steroid elution element is shown.

[0024] Figure 9A and Figure 9B Data from experiments are shown in which an IMD with a first electrode and a second electrode was implanted in the right atrium as described herein. Detailed Implementation

[0025] Generally, this disclosure relates to the configuration of electrodes in an implantable medical device (IMD) having a housing sized to be fully implanted into a single chamber of the heart. More specifically, this disclosure relates to the configuration of electrodes that allows a single device implanted in one chamber to sense cardiac pacing and / or deliver cardiac pacing to more than one chamber. In some instances, in addition to electrodes configured to penetrate into tissue in another chamber, the IMD may also include flexible electrodes, such as spring-based electrodes, configured to maintain contact with the tissue of the chamber in which the IMD is implanted without penetrating the tissue.

[0026] Figure 1This is a conceptual diagram illustrating an exemplary device 10 implanted in a patient's heart 12 according to one or more aspects of this disclosure. The device 10 is shown as being implanted in a target implantation region 2 within the right atrium (RA) of the patient's heart 12, such as the Koch triangle in the patient's heart 12, with the distal end of the device 10 pointing towards the left ventricle (LV) of the patient's heart 12. Although in Figure 1 In some instances, the distal end of device 10 points towards the LV, but in others, the distal end may point towards other targets, such as the interventricular septum of the heart 12. The target implantation region 2 may be located between the His bundle and the coronary sinus and may be adjacent to the tricuspid valve.

[0027] The device 10 includes a distal end 22 and a proximal end 24. The distal end 22 includes a first electrode 26 and a second electrode 28. The first electrode 26 extends from the distal end 22 and can penetrate the wall tissue of a first chamber (e.g., RA in the illustrated example) into the wall tissue of a second chamber (e.g., LV in the illustrated example). The second electrode 28 extends from the distal end 22 and is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber.

[0028] Figure 1 The configuration of electrodes 26 and 28 shown allows device 10 to sense cardiac signals and / or deliver cardiac pacing to multiple chambers of heart 12, such as the RA and ventricles in the illustrated example. In this way, the configuration of electrodes 26 and 28 facilitates the delivery of AV synchronous pacing via a single device 10 implanted within a single chamber (e.g., the RA). While in Figure 1 In the illustrated example, device 10 is implanted in the target implantation region 2 to sense and / or pace the RA and ventricles. However, devices with the electrode configuration according to embodiments of this disclosure can be implanted at any location in a variety of locations to sense and / or pace any two or more chambers of the heart 12. For example, device 10 can be implanted in region 2 or another region, and the first electrode 26 can extend into the tissue of the LV or interventricular septum (e.g., myocardial tissue) to facilitate, for example, delivery of AV synchronous pacing. Furthermore, devices with the electrode configuration according to embodiments of this disclosure can be implanted at any location in a variety of locations within the patient for sensing and / or delivery of treatment to other patient tissues.

[0029] Figure 2This is a perspective view showing device 10. Device 10 includes a housing 30 defining a hermetically sealed interior cavity. Housing 30 may be formed of a conductive material, including titanium or titanium alloys, stainless steel, MP35N (a non-magnetic nickel-cobalt-chromium-molybdenum alloy), platinum alloys, or other biocompatible metals or metal alloys, or other suitable conductive materials. In some instances, housing 30 is formed of a non-conductive material, including ceramics, glass, sapphire, silicone, polyurethane, epoxy resin, acetyl copolymer plastics, polyetheretherketone (PEEK), liquid crystal polymers, other biocompatible polymers, or other suitable non-conductive materials.

[0030] The housing 30 extends between the distal end 32 and the proximal end 34. In some instances, the housing may be cylindrical or substantially cylindrical, but may also be other shapes, such as prismatic or other geometries. The housing 30 may include, for example, a delivery tool interface member 36 located at the proximal end 24 for engagement with a delivery tool during implantation of the device 10.

[0031] During pacing and / or sensing, all or substantially all or a portion of the housing 30 may be used as an electrode 38, such as an anode. In some instances, the electrode 38 may surround a portion of the housing 30 at or near the proximal end 34. The electrode 38 may completely or partially surround the housing 30. Figure 2 Electrode 38 is shown as a single-band extension. Electrode 38 may also include multiple segments spaced apart at a distance along the longitudinal axis 40 of housing 30 and / or around the periphery of housing 30.

[0032] When the housing 30 is formed of a conductive material such as a titanium alloy, portions of the housing 30 may be electrically insulated by coatings of non-conductive materials such as parylene, polyurethane, silicone, epoxy resin, or other biocompatible polymers or other suitable materials. For portions of the housing 30 that do not have non-conductive materials, one or more discrete regions of the housing 30 having conductive materials may be exposed to define electrodes 38.

[0033] When the housing 30 is formed of a non-conductive material (such as ceramic, glass, or polymer material), a conductive coating or layer (such as titanium, platinum, stainless steel, or their alloys), the conductive material may be applied to one or more discrete regions of the housing 30 to form electrodes 38.

[0034] In some instances, electrode 38 may be a component mounted or assembled onto housing 30, such as a ring electrode. When housing 30 is made of a non-conductive material, electrode 38 may be electrically coupled to the internal circuitry of device 10 via conductive housing 30 or an electrical conductor. In some instances, electrode 38 is located near the proximal end 24 of housing 30 and may be referred to as a proximal housing-based electrode. Electrode 38 may also be located at other locations along housing 30, such as near the distal end 22 or at other locations along longitudinal axis 40.

[0035] Each of the first electrode 26 and the second electrode 28 extends from the first end of the housing 30, which is fixedly attached to the housing 30 at or near the distal end 22, to the second end. Figure 2 In some examples, the second end is not attached to the housing 30 except via the first end (e.g., it is a free end). The first electrode 26 includes one or more coatings configured to define a first electroactive region 44, and the second electrode 28 includes one or more coatings configured to define a second electroactive region 46. In some examples, the first electroactive region 44 may be closer to the second end of the first electrode 26, for example, the distal end, than the second electroactive region 46 is to either end of the second electrode 28. Figure 2 In one example, the first electroactive region 44 includes the distal end of the electrode 26.

[0036] The first electrode 26 and the second electrode 28 can be formed of conductive materials such as titanium, platinum, iridium, tantalum, or alloys thereof. The first electrode 26 and the second electrode 28 can be coated with an electrically insulating coating, such as parylene, polyurethane, silicone, epoxy resin, or other insulating coating, to reduce the conductive active surface area of ​​the first electrode 26 and the second electrode 28, thereby defining a first electrically active region 44 and a second electrically active region 46. Defining the first electrically active region 44 and the second electrically active region 46 by covering the portions with an insulating coating can increase the impedance of the first electrode 26 and the second electrode 28, thereby reducing the current delivered during pacing pulses to capture cardiac tissue. Lower current consumption saves power to the device 10, such as one or more rechargeable or non-rechargeable batteries.

[0037] In some instances, the first electrode 26 and the second electrode 28 may have a conductive material coating on the first electroactive region 44 and the second electroactive region 46 to define the active region. For example, the first electroactive region 44 and the second electroactive region 46 may be coated with titanium nitride (TiN). The first electrode 26 and the second electrode 28 may be made of substantially similar materials, or they may be made of different materials from each other.

[0038] exist Figure 2In some instances, the first electrode 26 takes the form of a helix. In other instances, the helix is ​​an object with a three-dimensional shape, similar to a line uniformly wound in a single layer around a cylindrical or conical surface, such that if the surface were unfolded into a plane, the line would be a straight line. The second electrode 28 includes a ramp portion 29. Figure 5C The ramp portion can be configured as a partial spiral, such as a spiral that does not rotate completely around the circumference of a cylindrical or conical surface.

[0039] like Figure 2 As shown, the first electrode 26 can be a right-handed spiral, and the second electrode 28 can be a left-handed partially spiral (e.g., Figure 5A (As shown in more detail in -G), although in other instances, the handedness of the electrodes can be switched or the electrodes can have the same handedness with each other. Figure 2 In some examples, the helix and partial helix defined by the first electrode 26 and the second electrode 28, respectively, have the same pitch, although in other examples they may have different pitches. In some examples, one or both of electrodes 26 and 28 may have a shape other than a helix. For example, in some examples, the second electrode may have a ring shape (e.g., as shown in the image). Figure 6A -D (as shown). As another example, the first electrode configured to penetrate tissue in another chamber can be configured as one or more elongated darts, barbs, or serrations.

[0040] The size and shape of the first electrode 26 and the second electrode 28 can also be modified to enhance tissue contact between the first electroactive region 44 and the second electroactive region 46. For example, the first electrode 26 and the second electrode 28 may have a circular cross-section, or they may be made with a flatter cross-section (e.g., elliptical or rectangular) based on tissue contact specifications. The size and shape of the first electrode 26 and the second electrode 28 can also be determined by stiffness requirements. For example, stiffness requirements may vary based on anticipated implantation requirements, including the tissue in which the electrode is implanted or in contact, and how long the device 10 is intended to be implemented.

[0041] The distal end of the first electrode 26 may have a conical, hemispherical, or beveled distal tip with a narrow tip diameter, for example, less than 1 millimeter (mm), for penetration into and through tissue layers. In some instances, the distal end of the first electrode may be a sharp or angled tip or a sharp or beveled edge, but the sharpness may be constrained to avoid cutting actions that could cause lateral displacement of the distal end of the first electrode 26 and undesirable tissue trauma. In some instances, the first electrode 26 may have its maximum diameter at its base where it intersects with the distal end 32 of the housing. In such instances, the diameter of the first electrode 26 may decrease from the distal end 32 of the housing to the distal end of the first electrode 26.

[0042] The external dimensions of the first electrode 26 can be substantially straight and cylindrical, and in some instances, the first electrode 26 is rigid. In some instances, the first electrode 26 and the second electrode 28 can be flexible in the lateral direction and are non-rigid to allow some flexing with heart movement. In a relaxed state, when not subjected to any external force, the first electrode 26 and the second electrode 28 can be configured to maintain the distance between the first electroactive region 44 and the second electroactive region 46 and the distal end 32 of the housing.

[0043] The distal end of the first electrode 26 can pierce one or more tissue layers to position the first electrically active region 44 within a desired tissue layer, such as ventricular myocardium or interventricular septum. Therefore, the first electrode 26 extends from the distal end 32 of the housing by a distance corresponding to the intended pacing site depth and can have relatively high compressive strength along its longitudinal axis, which can be substantially similar to the longitudinal axis 40, to resist bending in the lateral or radial directions when longitudinal forces, axial forces, and / or rotational forces are applied, for example, to the proximal end 34 of the housing 30 to advance the device 10 into the tissue at the target implantation region 2. When the first electrode 26 is a helical electrode, the first electrode 26 can maintain spacing between its multiple windings by resisting bending in the lateral or radial directions. The first electrode 26 can be longitudinally non-compressible. However, the first electrode 26 can also be elastically deformable in the lateral or radial directions when subjected to lateral or radial forces, allowing for temporary flexing, for example, with tissue movement, but returning to its normal straight position when the lateral force decreases. In some instances, when the first electrode 26 is not exposed to any external force or is only exposed to a force along its longitudinal axis (which is substantially similar to longitudinal axis 40), the first electrode 26 maintains a straight, linear position as shown in the figure.

[0044] In some instances, the second electrode 28 or electrode 38 may be paired with the first electrode 26 to sense ventricular signals and deliver ventricular pacing pulses. In some instances, the second electrode 28 may be paired with electrode 38 or the first electrode 26 to sense atrial signals and deliver pacing pulses to the atrial myocardium 20 in the target implantation area 2. In other words, in some instances, electrode 38 may be paired with the first electrode 26 and the second electrode 28 at different times for either ventricular or atrial functional purposes. In some instances, the first electrode 26 and the second electrode 28 may be paired with each other with different polarities for both atrial and ventricular functional purposes.

[0045] In some instances, the second electrode 28 can be configured as an atrial cathode electrode for delivery of pacing pulses to atrial tissue at the target implantation site 2, in conjunction with electrode 38. The second electrode 28 and electrode 38 can also be used to sense atrial P waves for controlling atrial pacing pulses (delivered in the absence of sensed P waves) and for controlling atrial-synchronized ventricular pacing pulses delivered using the first electrode 26 as the cathode and electrode 38 as the return anode.

[0046] At the distal end 22, the device 10 includes a distal fixation assembly 42 comprising a first electrode 26, a second electrode 28, and a distal end 32 of the housing. The distal end of the first electrode 26 may be configured to rest within the ventricular myocardium of a patient, and the second electrode 28 may be configured to contact the atrial endocardium of a patient. In some instances, the distal fixation assembly 42 may include more or fewer electrodes than two. In some instances, the distal fixation assembly 42 may include one or more second electrodes along the distal end 32 of the housing. For example, the distal fixation assembly 42 may include three electrodes, such as the second electrode 28, configured for atrial function, and these three electrodes may be substantially similar to or different from each other. The spacing between the plurality of second electrodes 28 may be equal or unequal distances. The second electrodes 28 may be individually and selectively coupled to a sensing circuitry and / or pacing circuitry enclosed by the housing 30 to serve as an anode having the first electrode 26 or as an atrial cathode electrode, or they may be electrically shared and not individually selectable.

[0047] The second electrode 28 is configured to flexibly maintain contact with the wall tissue (e.g., RA endocardium) of the heart chamber in which the device 10 is implanted, regardless of variations in the tissue surface or the distance between the distal end 32 of the housing 30 and the tissue surface, which may occur as the wall tissue moves during the cardiac cycle.

[0048] To maintain flexible contact with the wall tissue, the second electrode 28 can be flexible and configured to have spring-like properties. For example, the second electrode 28 can be configured to elastically deform, for example, toward the distal end 32 of the housing 30, but can be spring-biased toward a stationary configuration, and when elastically deformed, the spring bias can cause the second electrode to move away from the distal end 32 of the housing 30. In this way, elastic deformation and spring bias can maintain consistent contact between the second electrode and the wall tissue of the chamber in which the device is implanted.

[0049] As described herein, flexibly maintaining contact generally refers to the ability of the electrode to move relative to the housing 30. For example, the electrode can be configured to elastically deform as described above. In some instances, the electrode may be additionally attached to the housing 30 by means of a mechanism such as a spring or a connector, or may include a mechanism such as a spring or a connector that allows movement of the electrode relative to the housing 30. In such instances, the electrode itself does not need to be deformable.

[0050] Figure 3 This is a functional block diagram illustrating an exemplary configuration of device 10. (Example...) Figure 3 As shown, the device 10 includes electrodes 26 and 28, which can be positioned relative to each other. Figure 1 and Figure 2 As described. For example, as relative to Figure 1 and Figure 2 As described, the first electrode 26 may be configured to extend from the distal end 32 of the housing 30 and may penetrate the wall tissue of the first chamber (e.g., RA) into the wall tissue of the second chamber (e.g., LV). The second electrode 28 extends from the distal end 32 of the housing 30 and is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber by the second electrode.

[0051] exist Figure 3 In the illustrated example, device 10 includes a switching circuit system 50, a sensing circuit system 52, a signal generation circuit system 54, a sensor 56, a processing circuit system 58, a telemetry circuit system 60, a memory 62, and a power supply 68. The various circuit systems may be programmable or fixed-function circuit systems, or may include programmable or fixed-function circuit systems configured to perform functions attributed to their respective circuit systems. Memory 62 may store computer-readable instructions that, when executed by the processing circuit system 58, cause device 10 to perform various functions. Memory 62 may be a storage device or other non-transitory medium. Figure 3 The components of the device 10 shown can be housed within the housing 30.

[0052] Signal generation circuitry 54 generates an electrical stimulation signal, such as a cardiac pacing pulse. Switching circuitry 50, coupled to electrodes 26, 28, and 38, may include one or more switch arrays, one or more multiplexers, one or more switches (e.g., a switch matrix or other set of switches), one or more transistors, or other circuitry. Switching circuitry 50 is configured to direct the stimulation signal from signal generation circuitry 54 to a selected combination of electrodes 26, 28, and 38 having selected polarities, for example, to selectively deliver pacing pulses to the RA, ventricle, or interventricular septum of the heart 12. For example, to pace one or both ventricles, switching circuitry 50 may couple a first electrode 26 penetrating into the wall tissue of the ventricle or interventricular septum to signal generation circuitry 54 as a cathode, and couple one or both of a second electrode 28 or electrode 38 to signal generation circuitry 54 as an anode. As another example, in order to enable RA pacing, the switching circuit system 50 can couple a second electrode 28, which is flexibly kept in contact with the RA endocardium, to the signal generation circuit system 54 as a cathode, and couple one or both of the first electrode 26 or electrode 38 to the signal generation circuit system 54 as an anode.

[0053] The switching circuit system 50 can also selectively couple the sensing circuit system 52 to selected combinations of electrodes 26, 28, and 38, for example, to selectively sense the RA or ventricular electrical activity of the heart 12. The sensing circuit system 52 may include filters, amplifiers, analog-to-digital converters, or other circuitry configured to sense cardiac electrical signals via electrodes 26, 28, and 38. For example, the switching circuit system 50 may couple each of the first electrode 26 and the second electrode 28 (in combination with electrode 38) to a corresponding sensing channel provided by the sensing circuit system 52 to sense ventricular or atrial cardiac electrical signals, respectively. In some instances, the sensing circuit system 52 is configured to detect events within the cardiac electrical signals, such as depolarization, and provide their indication to the processing circuit system 58. In this way, the processing circuit system 58 can determine the timing of atrial and ventricular depolarization and control the delivery of cardiac pacing, such as AV-synchronized cardiac pacing, based on this timing. The processing circuit system 58 may include one or more of the following: a microprocessor, a controller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a discrete logic circuit system, or any other processing circuit system configured to provide functionality attributable to the processing circuit system 58, which may be embodied herein as firmware, hardware, software, or any combination thereof.

[0054] Sensor 56 may include one or more sensing elements that convert patient physiological activity into electrical signals to sense values ​​of corresponding patient parameters. Sensor 56 may include one or more accelerometers, optical sensors, chemical sensors, temperature sensors, pressure sensors, or any other type of sensor. Sensor 56 may output patient parameter values, which can be used as feedback to control the sensing and delivery of treatment by device 10.

[0055] The telemetry circuit system 60, under the control of the processing circuit system 58, supports the device 10 and the external programmer. Figure 3 Wireless communication between the device 10 and another computing device (not shown). The processing circuitry system 58 of the device 10 can receive updates of operating parameters from the computing device and provide collected data, such as sensed cardiac activity or other patient parameters, via the telemetry circuitry system 60. The telemetry circuitry system 60 can communicate via radio frequency (RF) communication technology, for example, via an antenna (not shown).

[0056] Power source 68 delivers operating power to various components of device 10. Power source 68 may include a rechargeable or non-rechargeable battery and power generation circuitry to generate operating power. Recharging can be accomplished via near-side inductive interaction between an external charger and a sensing charging coil within device 10.

[0057] Figure 4 This is a conceptual diagram of the device 10 implanted at the target implantation area 2. A first electrode 26 can be inserted, causing a helical engagement between the tissue and the first electrode 26. When the first electrode 26 engages with the tissue, it penetrates into the tissue at the target implantation area 2 and advances through the atrial myocardium 20 and central fibrous tissue 16 to locate the first electrically active region 44 within the ventricular myocardium 14, as shown below. Figure 4 As shown. In some instances, the first electrode 26 penetrates into the interventricular septum. In some instances, the first electrode 26 does not completely penetrate the endocardial or epicardial surface of the ventricle.

[0058] In some instances, longitudinal force is provided by manual pressure applied to the proximal end 34 of the housing via an advance tool to pierce cardiac tissue at the target implantation area 2. In some instances, actuation of the advance tool causes the device 10 and the first electrode 26, configured as a helix, to rotate about a longitudinal axis 40. Rotation of the helix about the longitudinal axis 40 advances the first electrode 26 through the atrial myocardium 20 and the central fibrous body 16 to position the first electrically active area 44 within the ventricular myocardium 14, as... Figure 4 As shown.

[0059] As the first electrode 26 advances into the tissue, the distance between the second electrode 28 and the atrial endocardium 18 decreases until the second electrode 28 contacts the surface of the atrial endocardium 18 and can press against the surface of the atrial endocardium, thereby engaging the cardiac tissue with the second electrically active region 46. The second electrode 28 is maintained in contact with the atrial endocardium 18 by the first electrode 26, for example, the first electrode 26 prevents the second electrode 28 from retracting from the surface of the atrial endocardium 18. As described herein, the second electrode 28 is also configured to flexibly maintain contact with the atrial endocardium 18. In some embodiments, the second electrode may be oriented toward the distal end 32 of the housing 30 ( Figure 2 It has an elastic deformation and a spring bias that pushes the second electrode distally from the distal end 32. In some instances, the first electrode 26 may be the only fixed feature of the device 10. The distance by which the first electrode 26 extends from the housing 30 can be selected such that the first electroactive region 44 reaches an appropriate depth in the tissue layer to reach the target pacing and sensing site, in this case, in the ventricular myocardium 14, without penetrating all the way into the adjacent ventricle.

[0060] In some pacing applications, the target implantation region 2 is along the atrial endocardium 18, essentially the lower part of the AV junction and His bundle. The first electrode 26 may have a length that penetrates the atrial endocardium 18 in the target implantation region 2, passes through the central fibrous body 16, and enters the ventricular myocardium 14 without penetrating the surface of the ventricular endocardium. In some instances, when the full length of the first electrode 26 is fully advanced into the target implantation region 2, the first electrically active region 44 rests within the ventricular myocardium 14, and the second electrode 28 is positioned in close contact with the atrial endocardium 18. In various instances, the first electrode 26 may extend from the distal end 32 of the housing by approximately 3 mm to 12 mm. In some instances, the first electrode 26 may extend from the housing 30 by at least 3 mm, and in various instances at least 3 mm but less than 20 mm, less than 15 mm, less than 10 mm, or less than 8 mm. The diameters of the first electrode 26 and the second electrode 28 may be less than 2 mm and may be 1 mm or less, or even 0.6 mm or less.

[0061] Figure 5A , Figure 5B , Figure 5C and Figure 5D These are partial views of the device 10 as observed from different perspectives. Figure 5AThis is a partial view of the distal end 22 of the device 10, including the distal end fixation assembly 42. The housing 30 includes a head 80. In some instances, the head 80 may be separable from or integral with the housing 30, and may be made of the same or different material as the housing 30. The distal end 32 of the housing (e.g., the head 80) defines a recess 82 (e.g., a recessed channel) to receive at least a portion of the second electrode 28 when it elastically deforms toward the housing 30. When the second electrode 28 is partially or completely deformed into the recess 82, the second electroactive region 46 may maintain contact with the tissue surface.

[0062] In some instances, the second electrode 28 can maintain contact with the tissue as the degree of deformation of the second electrode 28 toward the housing 30 changes. The second electrode 28 can be spring-biased to an undeformed position, and deformation of the second electrode 28 proximally toward the distal end 32 of the housing 30 can result in a spring force pointing distally from the housing 30, which causes the second electrode 28, and more specifically, the second electrically active region 46, to press against the cardiac tissue. For example, the deformation of the second electrode 28 can vary with cardiac activity. At least in part due to the change in the deformability of the second electrode 28, for example, during the cardiac cycle, the second electrically active region 46 can maintain consistent contact with the tissue and provide pacing to the heart.

[0063] Figure 5B This is a conceptual diagram of a partial view of an apparatus 10 according to one or more aspects of this disclosure, wherein the recess 84 is shown in cut-out form. Figure 5C and Figure 5D This is a conceptual diagram of a partial side perspective view of the device 10 according to one or more aspects of this disclosure. (See diagram below.) Figure 5B As shown, the attachment end 86 of the second electrode 28 is attached to the head 80 and connected (e.g., electrically connected) to the feedthrough. At the opposite end of the second electrode 28, the free-floating end 88 of the second electrode 28 bends rearward toward the device 10 and is movable into the recess 84 when the second electrode 28 deforms. For example, when the free-floating end 88 is pushed into the recess 84 due to the deformation of the second electrode 28 with heart movement, the second electroactive region 46 can remain in contact with the tissue.

[0064] As discussed herein, the first electrode 26 and the second electrode 28 can have different helical shapes. For example, the helix of the first electrode 26 can be a right-handed helix. The first electrode 26 can be inserted, for example, in a manner similar to rotating and advancing a threaded screw, such that the tissue engages with the helix of the first electrode 26. A portion of the helix of the second electrode 28 can be a left-handed helix. As the distance between the second electrode 28 and the tissue decreases due to the right-handed rotation of the first electrode 26, the tissue will gradually contact the ramp portion 29 of the second electrode 28 (in a manner similar to advancing along a ramp). Figure 5C(as shown in the figure), and the slope shape of the slope portion 29 will gradually deform toward the shell 30, for example, by compression.

[0065] Due to this configuration of the second electrode 28, in some instances, having the first electrode 26 and the second electrode 28 have the same rotational orientation may cause difficulties in tissue insertion. For example, if the second electrode 28 is also right-handed, the blunter end (in...) Figure 5C The portion 29 (shown as the left side of the ramp portion 29) will first contact the endocardial tissue. The blunt end of the second electrode 28 can grip the tissue and restrict rotation, rather than the ramp gradually deforming towards the housing 30. This restriction of rotation of the second electrode 28 can reduce the contact between the second electrically active region 46 and the tissue of the patient's heart 12.

[0066] In some instances, the first electrode 26 includes a helix with a first pitch, and the ramp portion 29 of the second electrode 28 is a partial helix with a second pitch. The first pitch of the helix of the first electrode 26 may be the same as, substantially similar to, or different from the second pitch of the partial helix of the second electrode 28. In some instances, the second electrode 28 may be more peripheral relative to the longitudinal axis 40 than the first electrode 26. In some instances, the first electrode 26 is located within the internal space defined by the second electrode 28 and is substantially concentric with the second electrode 28.

[0067] Figure 5E This is a conceptual diagram showing a cross-sectional view of the apparatus 10 according to one or more aspects of the present disclosure, taken along its longitudinal axis. Figure 5E A distal fixing assembly 42 is shown, comprising a first electrode 26, a second electrode 28, a head 80 having a recess 84, and a housing 30. The first electrode 26 is connected (e.g., electrically) to a first feedthrough 90. An attachment end 86 of the second electrode 28 is connected (e.g., electrically) to a second feedthrough 92. At the opposite end of the second electrode 28, a free-floating end 88 of the second electrode 28 can be compressed into the recess 84 by deformation. The first feedthrough 90 and the second feedthrough 92 are electrically coupled to a circuit system within the housing 30, such as a switching circuit system 50, a sensing circuit system 52, and / or a signal generation circuit system 54. Figure 3 ).

[0068] Figure 5F This is a partial view of the apparatus 10 according to one or more aspects of this disclosure, and Figure 5G This is its end view. In some instances, the first electrode 26 may be damaged in the insertion area where the first electrode 26 enters the tissue, typically in... Figure 5F and Figure 5GThe term "X" indicates an insertion region. For example, the first electrode 26 may damage the endocardial tissue of the atrium penetrated by the first electrode 26. As the first electrode 26 advances into the patient's tissue, the insertion region X penetrated by the first electrode 26 may ultimately be located at the intersection of the first electrode 26 and the housing 30. In some instances, the second electrode 28 may be configured and positioned on the device 10 such that the second electrically active region 46 is positioned away from the insertion region X, for example, as far away from the insertion region X as possible. In some instances, the portion Z of the second electrically active region 46 of the second electrode 28 that contacts the patient tissue, or the longitudinal midpoint of the second electrically active region 46, may be approximately 180° relative to the longitudinal axis of the device 10 and the first electrode 26 and the insertion region X. In some instances, how far the first electrode 26 is inserted into the tissue may depend at least in part on the relative positioning of regions X and Z.

[0069] In some instances, the dimensions of the first electrode 26 and the second electrode 28, such as size and shape (e.g., the length of the coil, the number of windings, the spacing between the windings, and the size and shape of the electroactive region), can be determined at least in part based on the relative positioning of regions X and Z. For example, the dimensions of the first electrode 26 and the second electrode 28, as well as their attachment to the housing 30, can be selected such that the insertion region X is opposite or substantially opposite to region Z of the second electroactive region 46.

[0070] Figure 6A , Figure 6B , Figure 6C and Figure 6D This is an illustration of a partial view of the distal fixing component 100 of another exemplary device according to one or more aspects of this disclosure, viewed from different angles. Figure 6A and Figure 6B A top perspective view is provided, and Figure 6C and Figure 6DA side perspective view is provided. Except for the differences described herein, the distal fixation assembly 100 may be identical or substantially similar to the distal fixation assembly 42. The distal end fixation assembly 100 includes a first electrode 102, a second electrode 104, and a housing 116. The second electrode 104 extends from a first end 106 to a second end 108, having an electroactive region 110 between the first end 106 and the second end 108. The housing 116 includes a head 112 having a recess 114 (e.g., a recessed channel) for receiving the second electrode 104. The first end 106 and the second end 108 are attached (e.g., anchored) to the housing 116. Either the first end 106 or the second end 108 (or both) is connected (e.g., electrically connected) to a feedthrough. The recess 114 receives the second electrode 104 when tissue contact deforms the second electrode 104. The electroactive region 110 of the second electrode 104 will remain in contact with the tissue, while the remaining portions of the second electrode 104 extending from the first end 106 and the second end 108 are pushed into the recess 114.

[0071] Figure 7 This is a flowchart of an exemplary method 200 for deploying the device. Reference will be made to device 10 simultaneously. Figure 1 To describe Figure 7 The technique, although those skilled in the art will understand, can be performed with reference to another implantable medical lead or other medical device.

[0072] according to Figure 7 An exemplary method 200 includes inserting a device 10 of an elongated housing 30 extending from a proximal end of the housing to a distal end of the housing into a single first chamber of the heart, the first chamber having wall tissue (202). For example, by rotation of the device 10 and a first electrode 26 about a longitudinal axis 40, the first electrode 26 is advanced to penetrate the wall tissue of the first chamber into the wall tissue of a second chamber, wherein the first electrode 26 extends distally from the distal end 32 of the elongated housing 30 through the wall tissue of the first chamber into the wall tissue of the second chamber (204). In some instances, advancing the first electrode 26 includes positioning the distal end of the first electrode 26 within the ventricular myocardium of a patient.

[0073] The second electrode 28 extends from the distal end 32 of the elongated housing 30, flexibly maintaining contact with the wall tissue of the first chamber without penetrating the wall tissue (206). In some instances, flexibly maintaining contact with the wall tissue of the first chamber using the second electrode 28 includes contacting the patient's atrial endocardium 18. In some instances, flexibly maintaining contact with the wall tissue of the first chamber using the second electrode 28 includes deforming the second electrode 28 toward the elongated housing 30 through the wall tissue of the first chamber as the distance between the distal end of the elongated housing 30 and the wall tissue of the first chamber decreases. In some instances, the recess 82 receives at least a portion of the second electrode when the second electrode 28 elastically deforms back toward the elongated housing 30. In some instances, a spring bias of the second electrode 28 causes the second electrode 28 to move away from the housing and into uniform contact with the wall tissue of the first chamber. Exemplary method 200 also includes delivering cardiac pacing from a signal generation circuit system 54 within an elongated housing 30 to a second chamber via a first electrode 26 and to a first chamber (208) via a second electrode 28.

[0074] Inflammation in patient tissues can be caused by interactions with the IMD. For example, penetration of the tissue by the first electrode and / or contact between the tissue and the second electrode can lead to tissue inflammation. Inflammation in patient tissue near the electrodes may result in a higher threshold for stimuli delivered to the tissue to activate or capture it. A higher capture threshold can, in turn, increase the energy consumption of the IMD associated with stimulus delivery.

[0075] In some instances, IMDs as described herein (such as IMD 10, 42, and 100) may include one or more steroid elution elements. Steroids can reduce inflammation in patient tissues resulting from interactions with the IMD. The steroid elution element may be configured to elute one or more steroids to tissues near the element over time. In some instances, the one or more steroid elution elements include one or more monolithic controlled-release devices (MCRDs).

[0076] In some instances, the IMD includes one or both of a first steroid elution element and a second steroid elution element, the first steroid elution element being configured to elute one or more steroids to tissue near a first electrode, and the second steroid elution element being configured to elute one or more steroids to tissue near a second electrode. For example, such as Figure 6B As shown, the IMD 100 includes a steroid elution element 118 at the distal end of the housing 116, for example, included in, attached to, or formed on the head 112. The steroid elution element 118 is configured to elute one or more steroids to tissue near the second electrode 104.

[0077] Figure 8An exemplary first electrode 302 including a steroid elution element 304 is shown. The steroid elution element 304 is configured to elute one or more steroids to tissue in proximity to the first electrode 302. In the illustrated example, the steroid elution element 304 is disposed within a channel or lumen of the first electrode 302. The steroid can be eluted through a distal opening 306 of the channel or lumen. In some embodiments, the first electrode 302 may be porous, and the steroid can additionally or alternatively be eluted through these pores. In some embodiments, the steroid elution element 304 may additionally or alternatively be formed on the outer surface of the first electrode 302.

[0078] Figure 9A and Figure 9B Data from experiments are shown, in which an IMD with a first and second electrode was implanted in the right atrium as described herein. More specifically, Figure 9A The capture thresholds of first electrodes penetrating the ventricular myocardium are shown as varying over time, some of which have steroid elution elements (SE) and some lack steroid elution elements (NSE). Figure 9B The capture threshold over time is shown for second electrodes in contact with the atrial endocardium, some of which have a steroid elution element (SE) and some lack a steroid elution element (NSE). Figure 9A and Figure 9B It can be seen that steroid elution elements can limit the increase in the capture threshold over time, whereas this increase may occur for electrodes lacking steroid elution elements. This increase may be more pronounced in second electrodes lacking steroid elution elements that contact the atrial endocardium.

[0079] It should be understood that the various aspects disclosed herein may be combined in combinations other than those specifically presented in the specification and drawings. It should also be understood that, depending on the example, certain actions or events of any process or method described herein may be performed in a different order, and may be added, combined, or omitted entirely (e.g., all described actions or events may not be necessary for performing the technique). Furthermore, although some aspects of this disclosure are described for clarity as being performed by a single module or unit, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0080] In one or more instances, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, functionality may be stored on a computer-readable medium in the form of one or more instructions or code and may be executed by a hardware-based processing unit. The computer-readable medium may include non-transitory computer-readable media, which corresponds to tangible media such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0081] Additionally, it should be noted that the system described herein is not limited to the treatment of human patients. In alternative instances, the system can be implemented in non-human patients, such as primates, canines, equines, pigs, and felines. These other animals may undergo clinical or research treatments that may benefit from the subject matter of this disclosure.

[0082] The instructions can be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), or other equivalent integrated or discrete logic circuit systems. Therefore, the term "processor" as used herein can refer to any of the foregoing structures or any other physical structure suitable for implementing the described techniques. Furthermore, the techniques can be fully implemented in one or more circuit or logic elements.

[0083] Example 1: An apparatus comprising: an elongated housing extending from a proximal end to a distal end of the housing, the elongated housing being configured to be fully implanted within a first chamber of a heart having wall tissue; a first electrode extending distally from the distal end of the elongated housing, wherein the distal end of the first electrode is configured to penetrate the wall tissue of the first chamber into the wall tissue of a second chamber of the heart separated from the first chamber; a second electrode extending from the distal end of the elongated housing, wherein the second electrode is separate from the first electrode and wherein the second electrode is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber; and a signal generation circuit system within the elongated housing, the signal generation circuit system being coupled to the first electrode and the second electrode, wherein the signal generation circuit system is configured to deliver cardiac pacing to the second chamber via the first electrode and to the first chamber via the second electrode.

[0084] Example 2: According to the device of Example 1, wherein the distal end of the first electrode is configured to penetrate into the ventricular myocardium of the patient, and wherein the second electrode is configured to flexibly maintain contact with the atrial endocardium of the patient.

[0085] Example 3: The apparatus according to Example 1 or 2, wherein the first electrode includes a helix.

[0086] Example 4: The apparatus according to Example 3, wherein the second electrode includes a ramp portion configured as a partial helix.

[0087] Example 5: According to the apparatus of Example 4, wherein the first pitch of the helix of the first electrode and the second pitch of the partial helix of the second electrode are substantially similar.

[0088] Example 6: The apparatus according to Example 4 or 5, wherein one of the helix of the first electrode and the partial helix of the second electrode is right-handed, and the other of the helix of the first electrode and the partial helix of the second electrode is left-handed.

[0089] Example 7: The device according to any one of Examples 1 to 6, wherein the elongated housing defines a longitudinal axis, and the second electrode is more peripheral relative to the longitudinal axis than the first electrode.

[0090] Example 8: The apparatus according to any one of Examples 1 to 7, wherein the first electrode is located in the internal space defined by the second electrode and is substantially concentric with the second electrode.

[0091] Example 9: The apparatus according to any one of Examples 1 to 8, wherein the second electrode extends from a first end to a second end, wherein the first electrode includes one or more coatings configured to define a first electroactive region, and the second electrode includes one or more coatings configured to define a second electroactive region, and wherein the first electroactive region is closer to the distal end of the first electrode than the second electroactive region is closer to either end of the second electrode.

[0092] Example 10: The apparatus according to any one of Examples 1 to 9, wherein the second electrode is configured to elastically deform toward the elongated housing via the wall tissue of the first chamber as the distance between the distal end of the elongated housing and the wall tissue of the first chamber decreases, so as to maintain contact with the wall tissue of the first chamber without the second electrode penetrating the wall tissue of the first chamber.

[0093] Example 11: The device according to Example 10, wherein the distal end of the elongated housing defines a recess to receive at least a portion of the second electrode when the second electrode elastically deforms toward the elongated housing.

[0094] Example 12: The device according to any one of Examples 1 to 3 or 7 to 11, wherein the second electrode extends from a first end to a second end, and the first end and the second end are attached to the elongated housing.

[0095] Example 13: The device according to any one of Examples 1 to 11, wherein the second electrode extends from a first end attached to the elongated housing to a free second end that bends rearward toward the elongated housing.

[0096] Example 14: The device according to any one of Examples 1 to 12, wherein the length of the first electrode is in the range of about 3 mm to about 12 mm.

[0097] Example 15: The device according to any one of Examples 1 to 14 further includes a third electrode extending from the distal end of the elongated housing, wherein the third electrode is substantially similar to the second electrode.

[0098] Example 16: A method comprising: delivering a cardiac pacing device to a heart, wherein the device includes an elongated housing extending from a proximal end of the housing to a distal end of the housing and fully implanted within a first chamber of the heart having wall tissue, wherein the device includes: a first electrode extending distally from the distal end of the elongated housing, wherein the distal end of the first electrode penetrates the wall tissue of the first chamber into the wall tissue of a second chamber of the heart separate from the first chamber of the heart; and a second electrode extending from the distal end of the elongated housing, wherein the second electrode is separate from the first electrode, and wherein the second electrode is configured to flexibly maintain contact with the wall tissue of the first chamber without penetrating the wall tissue of the first chamber, and wherein delivering the cardiac pacing comprises: delivering the cardiac pacing to the second chamber via the first electrode; and delivering the cardiac pacing to the first chamber via the second electrode.

[0099] Example 17: According to the method of Example 16, wherein the distal end of the first electrode penetrates into the ventricular myocardium of the patient, and wherein the second electrode is flexibly kept in contact with the atrial endocardium of the patient.

[0100] Example 18: The method according to Example 16 or 17, wherein the first electrode comprises a helix.

[0101] Example 19: The method according to Example 18, wherein the second electrode includes a ramp portion configured as a partial helix.

[0102] Example 20: According to the method of Example 19, wherein the first pitch of the helix of the first electrode and the second pitch of the partial helix of the second electrode are substantially similar.

[0103] Example 21: The method according to Example 19 or 20, wherein one of the helix of the first electrode and the partial helix of the second electrode is right-handed, and the other of the helix of the first electrode and the partial helix of the second electrode is left-handed.

[0104] Example 22: The method according to any one of Examples 16 to 21, wherein the elongated housing defines a longitudinal axis, and the second electrode is more peripheral relative to the longitudinal axis than the first electrode.

[0105] Example 23: The method according to any one of Examples 16 to 22, wherein the first electrode is located in the internal space defined by the second electrode and is substantially concentric with the second electrode.

[0106] Example 24: The method according to any one of Examples 16 to 23, wherein the second electrode extends from a first end to a second end, wherein the first electrode includes one or more coatings configured to define a first electroactive region, and the second electrode includes one or more coatings configured to define a second electroactive region, and wherein the first electroactive region is closer to the distal end of the first electrode than the second electroactive region is closer to either end of the second electrode.

[0107] Example 25: According to any one of Examples 16 to 24, wherein the second electrode elastically deforms toward the elongated housing through the wall tissue of the first chamber as the distance between the distal end of the elongated housing and the wall tissue of the first chamber decreases, so as to maintain contact with the wall tissue of the first chamber without the second electrode penetrating the wall tissue of the first chamber.

[0108] Example 26: According to the method of Example 25, the distal end of the elongated housing defines a recess to receive at least a portion of the second electrode when the second electrode elastically deforms toward the elongated housing.

[0109] Example 27: The method according to any one of Examples 16 to 18 or 22 to 26, wherein the second electrode extends from a first end to a second end, and the first end and the second end are attached to the elongated housing.

[0110] Example 28: The method according to any one of Examples 16 to 26, wherein the second electrode extends from a first end attached to the elongated housing to a free second end that bends rearward toward the elongated housing.

[0111] Example 29: A device comprising: an elongated housing extending from a proximal end of the housing to a distal end of the housing and defining a longitudinal axis, the housing being configured to be fully implanted within the atrium of the heart; a first electrode extending distally from the distal end of the elongated housing and including a helix, wherein, as the helix rotates about the longitudinal axis, the distal end of the first electrode is configured to penetrate the wall tissue of the atrium and enter the wall tissue of the ventricle of the heart, and the distance between the distal end of the elongated housing and the wall tissue of the first ventricle decreases; and a second electrode extending from the distal end of the elongated housing, wherein the second electrode is separate from the first electrode, wherein... The second electrode is configured to elastically deform toward the elongated housing via the atrioventricular wall tissue as the distance between the distal end of the elongated housing and the atrioventricular wall tissue decreases, so as to flexibly maintain contact with the atrioventricular wall tissue without penetrating the atrioventricular wall tissue by the second electrode, and wherein the second electrode is more peripheral relative to the longitudinal axis than the first electrode; and a signal generation circuit system, the signal generation circuit system being located within the elongated housing and coupled to the first electrode and the second electrode, wherein the signal generation circuit system is configured to deliver cardiac pacing to the ventricle via the first electrode and to the atrium via the second electrode.

[0112] Various examples have been described. These embodiments and other examples are within the scope of the appended claims.

Claims

1. An apparatus comprising: An elongated shell extends from the proximal end of the shell to the distal end of the shell and defines a longitudinal axis, the shell being configured to be fully implanted into the first chamber of the heart; A first electrode extends distally from the distal end of the elongated housing and includes a helix, wherein, as the helix rotates about the longitudinal axis, the distal end of the first electrode is configured to penetrate the wall tissue of the first chamber and enter the wall tissue of the second chamber of the heart as the distance between the distal end of the elongated housing and the wall tissue of the first chamber decreases. The second electrode extends from the distal end of the elongated housing at a first end of the second electrode, bends along the periphery of the distal end of the elongated housing while tilting distally away from the distal end of the elongated housing toward a second end of the second electrode, the second electrode includes an end portion extending from the distal end of the elongated housing at a second end of the second electrode, and the second electrode also includes an electroactive region located near the second end of the second electrode; The signal generation circuit within the elongated housing is coupled to the first electrode and the second electrode, wherein the signal generation circuit is configured to deliver cardiac pacing to the second chamber via the first electrode and to deliver cardiac pacing to the first chamber via the second electrode.

2. The apparatus according to any of the preceding claims, characterized in that, The second electrode includes a second electrode member that extends from the distal end of the elongated housing at a first end and bends along the periphery of the distal end of the elongated housing while tilting distally toward the second end of the second electrode member away from the distal end of the elongated housing. The second electrode also includes an electroactive region located near the second end of the second electrode member.

3. The apparatus according to any of the preceding claims, characterized in that, The second electrode component is formed in the form of an end wall.

4. The apparatus according to any of the preceding claims, characterized in that, The second electrode defines a ramp portion extending from the distal portion of the housing.

5. The apparatus according to any of the preceding claims, characterized in that, As the device advances into the wall tissue, the wall tissue gradually contacts the ramp portion of the second electrode.

6. The apparatus according to any of the preceding claims, characterized in that, The second electrode defines a portion of the spiral.

7. The apparatus according to any of the preceding claims, characterized in that, One of the helix of the first electrode and the partial helix of the second electrode is right-handed, and the other of the helix of the first electrode and the partial helix of the second electrode is left-handed.

8. The apparatus according to any of the preceding claims, characterized in that, The electroactive region of the second electrode is configured for non-penetrating contact with the wall tissue of the first chamber of the heart.

9. The apparatus according to any of the preceding claims, characterized in that, The second electrode is configured to elastically deform toward the elongated housing through the wall tissue of the first chamber as the distance between the distal end of the elongated housing and the wall tissue of the first chamber decreases, so as to maintain contact with the wall tissue of the first chamber without the second electrode penetrating the wall tissue of the first chamber.

10. An apparatus comprising: An elongated shell extends from the proximal end of the shell to the distal end of the shell and defines a longitudinal axis, the shell being configured to be fully implanted into the first chamber of the heart; A first electrode extends distally from the distal end of the elongated housing and includes a helix, wherein, as the helix rotates about the longitudinal axis, the distal end of the first electrode is configured to penetrate the wall tissue of the first chamber. The second electrode includes: a ramp extending from the distal end of the elongated housing and inclined distally away from the distal end of the elongated housing; an end portion extending from the ramp to the distal end of the elongated housing; and an electrically active region spaced distally from the distal end of the elongated housing.

11. The apparatus according to any of the preceding claims, characterized in that, The ramp bends along the periphery of the distal end of the elongated shell, while sloping distally away from the distal end of the elongated shell.

12. The apparatus according to any of the preceding claims, characterized in that, The end portion includes an end wall positioned relative to the proximal portion of the ramp.

13. The apparatus according to any of the preceding claims, characterized in that, As the device advances into the wall tissue, the wall tissue gradually contacts the slope.

14. The apparatus according to any of the preceding claims, characterized in that, The ramp defines a portion of the spiral.

15. The apparatus according to any of the preceding claims, characterized in that, One of the helix of the first electrode and the partial helix of the second electrode is right-handed, and the other of the helix of the first electrode and the partial helix of the second electrode is left-handed.

16. The apparatus according to any of the preceding claims, characterized in that, The electroactive region of the second electrode is configured for non-penetrating contact with the wall tissue of the first chamber of the heart.

17. The apparatus according to any of the preceding claims, characterized in that, The second electrode is configured to elastically deform toward the elongated housing through the wall tissue of the first chamber as the distance between the distal end of the elongated housing and the wall tissue of the first chamber decreases, so as to maintain contact with the wall tissue of the first chamber without the second electrode penetrating the wall tissue of the first chamber.

18. The apparatus according to any of the preceding claims, characterized in that, The first electrode is configured to penetrate into the wall tissue of the second chamber of the heart as the distance between the distal end of the elongated housing and the wall tissue of the first chamber decreases; and The device further includes a signal generation circuit within the elongated housing, the signal generation circuit being coupled to the first electrode and the second electrode, wherein the signal generation circuit is configured to deliver cardiac pacing to the second chamber via the first electrode and to deliver cardiac pacing to the first chamber via the second electrode.

19. The apparatus according to any of the preceding claims, characterized in that, The housing includes a head that forms the distal end of the housing.

20. The apparatus according to any of the preceding claims, characterized in that, The head is formed of a different material than the other part of the shell.

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