Abstract: An implantable electrode device designed for heart stimulation and/or cardioversion/defibrillation in connection with a pacemaker or a defibrillator. The electrode device comprises a large-surface area indifferent reference electrode pole permanently implanted in the atrial septum and in electrical communication with a pacemaker or defibrillator. The electrode pole is made from biocompatible metal braiding and has a tube like opening. The electrical communication is positioned from the pacemaker/defibrillator via the right atrium of the heart through the indifferent electrode pole into the left atrium via the opening. Thus allowing electrical pulses to be delivered to the electrode pole and stimulating the heart.

Abstract: A medical electrical lead having an elongated lead body and a fixation helix extending along a generally helical axis, mounted around the outer circumference of the lead body. The fixation helix has a free end spaced from and extending from the lead body for less than the circumference of the lead body. The lead body includes an additional component which provides a rotation stop extending from the outer circumference of the lead body and provides stop surface generally perpendicular to the axis of the helix.

Abstract: A medical implantable lead to be inserted into a human or animal body and attached to an organ inside the body for monitoring and/or controlling the function of the organ has a header in a distal end, a fixation arrangement and an electrode arranged in the header. The fixation arrangement attaches the distal end of the lead to the organ and the electrode is arranged to transmit or receive electrical signals to or from the organ. The lead also has a connector in a proximal end that includes a connector pin and is adapted to be connected to a monitoring and/or controlling device, and an inner coil, which extends inside an outer casing of the lead and is adapted to transmit electrical signals between the monitoring and/or controlling device and the electrode. The inner coil is attached to the connector pin. The inner coil extends through a bore inside the connector pin and is attached to the connector pin in its proximal end. A method for manufacturing such a lead is also provided.

Abstract: In a device (1) for the defibrillation of a heart (2) with an implantable cardiac pacemaker and defibrillator (3), the defibrillation electrode (4) is arranged on the stimulation electrode (5), with the stimulation electrode enclosing the defibrillation electrode. In order to be able to remove the defibrillation electrode without a complicated operation if a defect in the defibrillation electrode (4) occurs during use, it can be moved relative to the stimulation electrode (5) and can be retracted and replaced relative to the implanted stimulation electrode (5) from its position of use, for which the stimulation electrode (5) can be detached or separated from the cardiac pacemaker (3) or its plug (9) provided on this pacemaker.

Abstract: An implantable battery powered leadless pacemaker or biostimulator is provided that may include any of a number of features. One feature of the biostimulator is that it safely operates under a wide range of MRI conditions. One feature of the biostimulator is that it has a total volume small enough to avoid excessive image artifacts during a MRI procedure. Another feature of the biostimulator is that it has reduced path lengths between electrodes to minimize tissue heating at the site of the biostimulator. Yet another feature of the biostimulator is that a current loop area within the biostimulator is small enough to reduce an induced current and voltage in the biostimulator during MRI procedures. Methods associated with use of the biostimulator are also covered.

Abstract: A medical electrical lead includes a proximal connector including a rotatable portion and first and second co-radial conductors coupled to the rotatable portion and extending distally from the rotatable portion. An actuation member is coupled between an electrode and the first and second conductors such that rotating the rotatable portion of the proximal connector transmits torque through the co-radial first and second conductors to the actuation member and results in both rotational and linear motion of the electrode.

Abstract: Various configurations of systems that employ leadless electrodes to provide pacing therapy are provided. In one example, a system that provides multiple sites for pacing of myocardium of a heart includes wireless pacing electrode assemblies that are implantable at sites proximate the myocardium using a percutaneous, transluminal, catheter delivery system. Also disclosed are various configurations of such systems, wireless electrode assemblies, and delivery catheters for delivering and implanting the electrode assemblies.

Abstract: A system of an autonomous intracardiac capsule and its implantation accessory. The autonomous capsule (10) includes a tubular body (12) with an anchoring screw (14) for penetrating the wall of a cavity of the heart, and at least one coupling finger (20, 22) radially projecting outwards. The implantation accessory (26) includes a lead body (28) with a sheath (30, 32) of deformable material supporting on the distal side a helical guide (36, 52), for guiding and driving by rotation the capsule. This helical guide is integral with the lead body, and its inner diameter is homologous to the outer diameter of the cylindrical body of the capsule so the latter can be housed it in, the coupling fingers protruding between the coils of the guide. The helix direction of the helical guide (36) is opposite to that of the anchoring screw (14). The helical guide is resiliently compressible in axial direction, and its helix pitch (38) is increased in the free distal end portion (40).

Abstract: An implantable lead may have a distal assembly including a coupler and a fixation helix secured to the coupler. The coupler may include a helical groove that is configured to accommodate the fixation helix. The helical groove may facilitate attaching the fixation helix to the coupler by threading the fixation helix into the helical groove. A weld may provide a secondary attachment between the fixation helix and the coupler.

Abstract: An active fixation implantable medical lead may include an electrode base that is configured to accommodate an extraction stylet that may be used if the fixation helix is not otherwise easily retracted. An extraction tool may be used in combination with the extraction stylet in extraction techniques designed for retraction of a fixation helix.

Abstract: A system for the endocardial stimulation/defibrillation of the left ventricle. This system includes a generator (60) and an endocardial lead having a distal end (30) which extends into the right ventricle (14). The lead includes anchor (32) for coupling the distal end to the interventricular septum (20). The lead body carries on it a stimulating and/or defibrillation electrode (38) (64, 66). A microcable (42) extends into the lead body and beyond, with an intermediate portion (56) crossing from one side of the interventricular septum (20) to the other, and an active free portion (58) that emerges in the left ventricle (16). The microcable is coupled to the generator, to produce an electric field (62) between, on one hand, the stimulation electrode (38) or defibrillation electrode (64, 66) of the lead body and, on the other hand, a bare region of the active free portion (58) of microcable (42).

Abstract: A medical implantable lead of the kind being adapted to be implanted into a human or animal body for monitoring and/or controlling of an organ inside the body has a penetrating fixation element in a distal end, which is adapted to penetrate into the tissue of the organ to fixate the lead such that a distal end of the lead will be in contact with the organ. The lead also has an electrode member to receive and/or transmit electrical signals from and/or to the organ. The lead has in a distal portion a movable member, which is displaceable in an axial direction of the lead and is actuated by a resilient member to be, in an initial state, maximally protruded in a distal direction in relation to the lead and which comprises a radiopaque material for forming of a first indication marker.

Abstract: A medical implantable lead is adapted to be implanted into a human or animal body for monitoring and/or controlling of an organ inside the body, and has in a distal end, a combined fixation means and electrode member in form of a helix, which is rotatable in relation to the lead and extendable out from the distal end by rotation of a tubular torque transferring member. The helix is electrically connected to a connector in the proximal end by at least one electrically conducting wire, which is formed as an electrically conducting coil, which is separate from the tubular torque transferring member and that includes one or more individual wires each having an electrically conducting wire core and a surrounding electrically insulating layer. The tubular torque transferring member has no electrically conducting function to or from the helix.

Abstract: A method, system, and apparatus are provided for an electrode assembly comprising a plurality of electrodes for use with an implantable medical device for conducting an electrical signal between the implantable medical device and a target tissue. The electrode assembly includes a helical member and first and second electrodes formed upon the helical member. The first and second electrodes are adapted to deliver the electrical signal. The electrode assembly also includes a first conductive element formed upon the helical member and operatively coupled to the first electrode. The electrode assembly also includes a second conductive element formed upon the helical member and operatively coupled to the second electrode.

Abstract: An implantable medical device that includes an elongated body having a proximal end and a distal end, a helical fixation member extending from the distal end of the elongated body, the helical fixation member including a distal tip for affixing the distal end of the elongated body at an implant site, and a tracking member extending from the distal end of the elongated body, through the helical fixation member and outward from the distal tip of the helical fixation member for tracking along an implant pathway during implantation of the implantable medical device.

Abstract: A lead assembly includes a nerve stimulation lead and at least one anchoring unit. The nerve stimulation lead includes electrodes disposed at a distal end that are electrically coupled to terminals disposed at the proximal end by a plurality of conductive wires. The at least one anchoring unit includes at least one elongated member and at least one fastener. The at least one elongated member extends along at least a portion of the nerve stimulation lead with a distal end of the at least one elongated member extending outwards from the nerve stimulation lead in proximity to the distal end of the nerve stimulation lead. The at least one fastener is attached to the distal end of the at least one elongated member and is configured and arranged for anchoring the at least one elongated member against a bony structure or against soft tissue abutting a bony structure.

Abstract: A medical implantable lead adapted to be implanted into a human or animal body for monitoring and/or controlling of an organ inside the body has a fixation in a distal end, which is adapted to fix a distal end of the lead to the organ, an electrode member in the distal end adapted to be in contact with tissue of the organ and receive and/or transmit electrical signals from and/or to the organ, and at least one electrically conducting coil, which includes one or more electrically conducting helical wires and that is adapted to connect the electrode member in the distal end with a monitoring and/or controlling device in a proximal end of the lead. One or more of the individual wires of the coil has a wire core that is provided with a surrounding electrically insulating layer, which in turn is provided with a surrounding electrically conducting shield layer, and the coil is close lapped such that electrically conducting shield layers of adjacent loops of the coil are in electrical contact with each other.

Abstract: Devices and methods are described for treating maladies such as atrial fibrillation. The devices and methods, in some implementations, include one or more rings formed of one or more windings. The rings provide mechanical pressure against an adjacent tissue, e.g., the tissue of a vessel, and the pressure works to inhibit the propagation of electrical signals along the vessel. The windings may be formed of a ribbon. Delivery systems are also provided.

Abstract: A leadless intra-cardiac medical device (LIMD) includes an electrode assembly configured to be anchored within a first wall portion of a first chamber of a heart. The electrode assembly includes an electrode main body having a first securing helix, an electrode wire segment extending from the body, and a first segment-terminating contact positioned on the electrode wire segment. The device further includes a housing assembly configured to be anchored within a second wall portion of a second chamber of the heart. The housing assembly includes a body having a second securing helix, a housing wire segment extending from the body, and a second segment-terminating contact positioned on the housing wire segment. The device also includes a connector block that electrically connects the electrode wire segment to the housing wire segment by retaining the first and second segment-terminating contacts.

Abstract: An assembly for introducing a leadless intra-cardiac medical device includes a sheath having an internal passage, wherein the sheath is configured to be maneuvered into the heart of the patient. A housing may be retained within the internal passage, wherein the housing is configured to be pushed out of the sheath, the housing having a first anchoring member configured to anchor the housing to a first implant location within the heart. The assembly may also include an electrode trailing the housing within the internal passage, wherein the electrode is also configured to be pushed out of the sheath. The electrode has a second anchoring member configured to anchor the electrode to a second implant location within the heart. A conductive wire connects the housing to the electrode, wherein movement of the housing out of the sheath causes the electrode to follow the movement to a distal end of the sheath.

Abstract: This invention relates to an implantable lead, which comprises a conductor; an electrode assembly, arranged at a distal end of the lead, and comprising a housing defining an internal cavity; a helical guide spring arranged in a proximal portion of the cavity and having several spaced turns, and a fixation assembly, which is rotatable relative to the housing, and which includes a shaft extending into the cavity from a proximal end of the housing; and an extendable helical fixation element attached to the shaft at a distal end thereof and protruding beyond the distal end thereof. The fixation assembly has an interaction portion, which interacts with the helical guide spring for causing longitudinal movement of the fixation element when the shaft is rotated.

Abstract: A system for therapeutically stimulating a His bundle includes an implantable pulse generator and a multi-polar medical electrical lead. The generator is configured for subcutaneous implantation and to generate a pacing stimulus. The lead includes a connector assembly, a flexible tubular body, a distal tip assembly and coil conductors. The body extends intravascularly from the generator to a location proximate the His bundle and includes a proximal end, a distal end, and a longitudinal lumen. The tip assembly includes an electrode, a fixation helix, and a shank portion. The helix extends to a location proximate the His bundle and is operable as an electrically isolated electrode. The shank portion extends within the lumen and includes a receptacle for receiving a stylet tip. The conductors extend longitudinally through the lumen and are coupled to the electrode and the helix. One or both of the conductors defines a stylet lumen.

Abstract: A device and method for providing stimulation to an inferior nodal extension of a heart. The method includes providing a lead comprising an electrode, positioning the electrode proximate an inferior nodal extension of a heart, and effecting at least one of activation, deactivation, or modulation of the electrode to provide stimulation to the inferior nodal extension.

Abstract: An implantable lead may have a distal assembly including a coupler, a fixation helix secured to the coupler and a housing in which the fixation helix and the coupler are disposed. The distal assembly may include an annular seal that is disposed between the coupler and the housing and that provides an at least substantially fluid-tight seal between the coupler and the housing.

Abstract: An implantable medical lead has at least one electric conductor running along a lead body and electrically interconnecting at least one electrode at the distal portion of the lead with at least one lead terminal at the proximal portion of the lead. The lead also has at least one closed channel running along at least a portion of the lead body. The closed channel contains an extracorporeally detectable detection substance. A rupture to the lead will cause the detection substance to leak out of the channel and outside of the lead body. Lead damage can be confirmed by the absence of or a reduced amount of said detection substance inside the lead.

Abstract: A lead for an implantable cardiac prosthesis, with protection against the thermal effects of MRI fields by terminating the lead head (10) with an electrically insulating tubular outer housing (28) and an anchoring mechanism. The tubular housing (28) carries an electrically isolated thermally conductive solid part in the outer region of its distal end forming a heat sink. The heat sink thermally conductive material is for example titanium, associated with an electrically insulating coating such as a diamond deposition. The anchor may be a projecting helical anchoring screw (20), axially extending the tubular housing, which is an electrically conductive active screw on at least one end portion.

Abstract: A stimulation electrode is produced having a porous film layer and being partially coated with an insulating parylene (polyparaxylylene) film, whose insulating film has a dielectric breakdown voltage of greater than 100 V. Parylene is deposited on the entire surface of a porous film coating and then partially removed again by plasma. After the partial removal of the parylene, this porous film still has a capacitance of greater than 15 mF/cm2 in a physiological NaCl solution at a frequency of 0.1 Hz. For the stimulation electrode, the transition from the insulating film to the porous film is formed so that the film thickness of the parylene film decreases continuously. In this way, a stimulation electrode having a porous film layer and being partially coated with an insulating parylene film is provided, whose electrode on the non-insulating parylene film-coated surface has a capacitance of greater than 15 mF/cm2 in a physiological NaCl solution at a frequency of 0.

Abstract: An implantable lead may include a housing and a laminate distal seal disposed across a distal end of the housing. A coupler and a fixation helix secured to the coupler may be disposed within the housing. The fixation helix may have a retracted position in which the fixation helix does not penetrate the laminate distal seal and an extended position in which the fixation helix has pierced the laminate distal seal and extends therethrough.

Abstract: Electrical medical leads having active fixation electrodes, particularly helix electrodes intended to be screwed into body tissue, e.g., the heart, are disclosed having selectively applied insulation to optimize exposed electrode surface area and dispose the exposed electrode surface area toward tissue that is less traumatized by injury caused by screwing in the fixation helix. In a preferred fabrication method, an outer helical surface is masked by contact with a masking tube while a dielectric coating is applied to the inner helical surface of the coil turns of the helix, and the masking tube is removed when the dielectric coating has set. In one variation, at least one aperture is formed through the masking tube sidewall exposing an area of the outer helical surface thereby interrupting the uninsulated outer helical electrode.

Abstract: An implantable lead for a medical device includes a lead body having a proximal end and a distal end, an electrical connector coupled to the proximal end of the lead body, an electrode coupled to the distal end of the lead body, and electrically conductive conductor coil extending between the proximal and the distal end of the lead body, the conductor coil wound in a first winding direction under tension. The lead body also includes a plastic ribbon wound around the conductor coil in a second winding direction opposite to the first winding direction without releasing the tension of the conductor coil.

Abstract: Tools and methods are particularly suited for certain cardiac conditions involving use of a catheter for pacing of the right and left ventricles from a lead in the right ventricle, e.g., to facilitate mechanically and/or electrically synchronous contractions for resynchronization. Certain aspects involve pacing and/or mapping by delivering pulses to a cardiac site useful for improving heart function as measured, e.g., by QRS width, fractionation, late LV activation timing, mechanical synchronicity of free wall and septal wall, effective throughput/pressure, or a combination thereof. In one embodiment, a catheter arrangement includes a fixation mechanism to attach the catheter arrangement to heart tissue, individually-addressable electrodes for providing pacing signals to the heart tissue, and an elongated structure that supports the fixation mechanism and the electrodes.

Abstract: A nerve stimulating drill bit is provided and can include a shank and a body attached to the shank. The body can include a plurality of flutes and a cutting tip. Further, a first conductor can extend through the shank and the body. The first conductor can be insulated and can provide a signal at the cutting tip. Further, the signal can be configured to provide nerve stimulation at the cutting tip of the nerve stimulating drill bit.

Abstract: A lead delivery system for delivering a neurostimulation lead to a patient's internal jugular vein using a percutaneous stick. The system comprises a neurostimulation lead adapted to stimulate a vagus nerve from the internal jugular vein. The lead includes a proximal end, a distal end, a generally spiral shaped retaining structure interposed between the proximal and distal ends and configured to retain the lead in the internal jugular vein, an electrode coupled to the retaining structure, and a side port interposed between the retaining structure and the proximal end. The side port provides access to a lumen extending from the distal end to the side port. A guidewire is sized to fit within the side port and lumen and reduce a force exerted by the retaining structure against the internal jugular vein, thereby allowing rotation of the lead and orientation of the electrode by applying a torque to the lead.

Abstract: An implantable medical device that includes an elongated body having a proximal end and a distal end, a helical fixation member extending from the distal end of the elongated body, the helical fixation member including a distal tip for affixing the distal end of the elongated body at an implant site, and a tracking member extending from the distal end of the elongated body, through the helical fixation member and outward from the distal tip of the helical fixation member for tracking along an implant pathway during implantation of the implantable medical device.

Abstract: A lead system has an elongate body, an active fixation assembly movable relative to the elongate lead body, including a non-stationary electrode. The lead system further includes a non-stationary electrode member and an electrical interconnect electrically connected between the non-stationary electrode member and the stationary electrode member. The electrical interconnect provides a reliable electrical interconnection between the stationary electrode and the non-stationary electrode, while allowing the non-stationary electrode to move relative to the stationary electrode.

Abstract: Implantable medical leads with magnetic shielding and methods of shielding implantable leads from magnetic fields during medical procedures such as magnetic resonance imaging (MRI) are disclosed. An exemplary implantable medical lead includes a helically coiled inner electrode conductor wire, a helically coiled outer electrode conductor wire disposed radially about the inner electrode conductor wire, and at least one layer of insulation that electrically isolates the inner and outer electrode conductor wires. The inner electrode conductor wire can have a hollowed, multifilar configuration including six or more co-radially wound wire filars. The outer electrode conductor wire is electrically isolated from the inner electrode conductor wire, and may have either a single or double filar configuration.

Abstract: An implantable active fixation cardiac lead is disclosed that includes an elongated lead body having opposed proximal and distal end portions and having an interior lumen extending therethrough, an axially rotatable extendable and retractable fixation helix operatively associated with the distal end portion of the lead body, a rotatable in-line quadripolar connector assembly operatively associated with the proximal end portion of the lead body and including an elongated rotatable pin electrode having opposed proximal and distal end portions, and an elongated torque transmitting conductor coil extending through the interior lumen of the lead body and having a proximal end portion connected to the distal end portion of the rotatable pin electrode and a distal end portion connected to the rotatable fixation helix, to facilitate manual activation of the fixation helix.

Abstract: An electrical lead for a cardiac device includes a body having a distal end sized for insertion through a catheter, first and second electrodes extending through the body, with each electrode terminating in a tip having proximal and distal ends and arranged to extend to an area of cardiac tissue. The tips include a fully insulated portion on the proximal and distal ends measuring in a range between 5 percent and 40 percent of the lengths of the tips, and further include an uninsulated intermediate section. The tip of the second electrode includes a helical section surrounding the first electrode and has an insulated portion on an inwardly facing portion surface facing toward the first electrode. The tip of the second electrode also includes a fully insulated portion on the proximal and distal ends measuring in the same or similar percentage range.

Abstract: The lead includes a helical fixation member coupled to the distal end of the lead body. The helical fixation member has at least one internal reservoir and a plurality of elution ports in fluid communication with the internal reservoir. A therapeutic agent composition is disposed within the internal reservoir. Additionally, the helical fixation member includes a sealed distal end to prevent coring of the cardiac tissue.

Abstract: A helical fixation element of an implantable medical lead. The fixation element has at least one blood drainage channel running along at least a tissue-penetrating portion of the helix windings of the fixation element. The channel guides, during penetration and anchoring of the fixation element and the lead in a tissue, blood leaking from the tissue away from the vicinity of the fixation element, thereby reducing the size of a fibrin clot formed around the fixation element. The capture threshold for stimulating the tissue is therefore reduced.

Abstract: A medical electrical lead for transvascularly stimulating a nerve, muscle or other tissue from an adjacent vessel is described. The lead includes an expandable distal portion having one or more spirals for securing and stabilizing the lead within the vessel.

Abstract: This document discusses, among other things, a lead body extending longitudinally along a lead axis, a driver axially displaceable relative to the lead body, and a driven member coupled to the lead body and displaceable away from the lead axis. The driven member at least partially defines an expandable passage having at least one internal dimension. The driver is displaceable into the expandable passage and has at least one outer dimension that is larger than the at least one internal dimension of the expandable passage. An example method includes disposing a first member having a first cross-section in a lead assembly having a lead axis, an expandable passage, and a displaceable member proximate the expandable passage. The method further includes urging the first member into the expandable passage in the lead assembly, and urging the displaceable member away from the lead axis to expand the expandable passage.

Abstract: A delivery system for implanting a leadless cardiac pacemaker into a patient is provided. The cardiac pacemaker can include a docking or delivery feature having a through-hole disposed on or near a proximal end of the pacemaker for attachment to the delivery system. In some embodiments, the delivery catheter can include first and second tethers configured to engage the delivery feature of the pacemaker. The tethers, when partially aligned, can have a cross-sectional diameter larger than the through-hole of the delivery feature, and when un-aligned, can have a cross-sectional diameter smaller than the through-hole of the delivery feature. Methods of delivering the leadless cardiac pacemaker with the delivery system are also provided.

Abstract: An implantable medical device that includes an elongated body having a proximal end and a distal end, a helical fixation member extending from the distal end of the elongated body, the helical fixation member including a distal tip for affixing the distal end of the elongated body at an implant site, and a tracking member extending from the distal end of the elongated body, through the helical fixation member and outward from the distal tip of the helical fixation member for tracking along an implant pathway during implantation of the implantable medical device.

Abstract: Methods, devices and assemblies for anchoring implanted medical electrical leads employed in the stimulating and/or sensing of signals in tissue are disclosed. The devices include a lead anchoring clip having a central hub portion, an anchoring portion for coupling to tissue and a lead engagement mechanism that couples the clip to a medical electrical lead.

Abstract: Methods and apparatus for storing data records associated with a medical monitoring event in a data structure. An implanted device obtains data and stores the data in the data record in a first data structure that is age-based. Before an oldest data record is lost, the oldest data record may be stored in a second data structure that is priority index-based. The priority index may be determined by a severity level and may be further determined by associated factors. The implanted device may organize, off-load, report, and/or display a plurality of data records based on an associated priority index. Additionally, the implanted device may select a subset or composite of physiologic channels from the available physiologic channels based on a selection criterion.

Abstract: An implantable medical lead configured for active fixation in the vasculature of a patient includes an elongated lead body having a central lumen and a distal tip. Disposed within the central lumen are a fixation helix and an elongated member, such as a lead coil, coupled to the fixation helix. The elongated member is adapted to rotate the fixation helix, thereby causing it to advance or retract within the central lumen of the lead body. The lead body includes a window along a portion of its length through which the fixation helix may be affixed to a blood vessel of the patient's vasculature.

Abstract: A lead having an extendable and retractable fixation mechanism has a rotating terminal pin at the terminal end which rotates the fixation mechanism at the distal end. As the terminal pin is rotated, the fixation mechanism is extended or retracted from the distal end of the lead. A threaded collar allows for the fixation mechanism to smoothly extend and retract from the lead, and allows for a 1:1 turn ratio between the terminal pin and the fixation mechanism. A fluoroscopic ring disposed at the distal end of the lead provides information during the implantation process.

Abstract: A leadless cardiac pacemaker having a radial fixation mechanism is provided. The cardiac pacemaker can include fixation mechanism separate from a pacing electrode and having a diameter equal to or less than the outer diameter of the pacemaker. The fixation mechanism can allow the pacemaker to be inserted into tissue with less than 2 rotations of the pacemaker to place the pacing electrode in contact with the tissue. In some embodiments, the fixation mechanism can comprise a plurality of hooks or protrusions positioned near a distal portion of the pacemaker. The fixation mechanism(s) can be configured to penetrate the endocardium of the patient and reside mostly within the myocardium. Methods of delivering the leadless cardiac pacemaker into the heart are also provided.

Abstract: The invention includes a implantable medical electrical lead for electrical stimulation of body tissue that includes at least one electrode; a lead body; and at least one modifiable portion, wherein the at least one modifiable portion has a first configuration and a second configuration, wherein the first configuration exists when axial tension is exerted on the at least one modifiable portion, and wherein the second configuration exhibits a greater resistance to movement of the lead within the body tissue than does the first configuration. Kits, and systems and methods of using the lead are also included.