Impedance-based verification of implantable medical device delivery

Abstract

A device for delivering an implantable medical device (IMD) includes an elongated member and a deployment chamber configured to accommodate the IMD, the deployment chamber defining a distal opening for deploying the IMD outside of the deployment chamber. The device includes: a first electrode, the first electrode positioned inside the deployment chamber during intravascular navigation; a second electrode; and an impedance detection circuit system, the impedance detection circuit system configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of a patient's fluid or tissue. The device also includes a processing circuit system, the processing circuit system configured to determine an impedance of the path based on the signal and control a user interface to indicate when the impedance of the path indicates that at least one of the IMD or the distal opening is in a fixed configuration relative to a target site of the patient.

Description

Technical Field

[0001] The present disclosure generally relates to medical delivery devices configured to deliver implantable and / or insertable medical devices to a target site within the human body. Background Art

[0002] Various medical devices for delivering therapy and / or monitoring physiological conditions have been used clinically or proposed to be used for clinical use in patients. Examples include medical devices that deliver therapy to the heart, muscle, nerve, brain, stomach or other organs or tissues or patients and / or monitor conditions associated with the heart, muscle, nerve, brain, stomach or other organs or tissues or patients. Some medical devices can use one or more electrodes to deliver therapeutic electrical signals to such organs or tissues and / or one or more electrodes to sense the intrinsic electrical signals generated by such organs or tissues in the patient's body. Similarly, some medical devices can additionally or alternatively include one or more other sensors for sensing the physiological parameters of the patient.

[0003] For example, some medical devices can act as a pacemaker or cardioverter-defibrillator that provides therapeutic electrical signals to the heart. The therapeutic electrical signal can include a pulse for pacing or an electric shock for cardioversion or defibrillation. In some instances, the medical device can sense the intrinsic depolarization of the heart, and thus control the delivery of the therapeutic signal based on the sensed depolarization. When an abnormal heart rhythm (such as bradycardia, tachycardia or fibrillation) is detected, one or more appropriate therapeutic electrical signals can be delivered to restore or maintain a predetermined (e.g., relatively more normal) heart rhythm. For example, in some cases, an implantable medical device can deliver a pacing stimulus to the patient's heart when tachycardia or bradycardia is detected, and / or deliver a cardioversion or defibrillation shock to the heart when fibrillation is detected.

[0004] In some instances, a medical device may utilize one or more medical leads or other sensors with one or more electrodes to deliver therapeutic electrical signals or sense. For example, an electrode or sensor may be carried at a distal portion of a lead, wherein a proximal portion of the lead may be coupled to a medical device housing containing a circuit system (such as a signal generating and / or sensing circuit system). Alternatively, an implantable medical device may function without a lead, such that the implantable medical device includes one or more electrodes on its external housing to deliver therapeutic electrical signals to a patient and / or sense the patient's intrinsic electrical signals. For example, a leadless cardiac device (such as a leadless pacemaker) may sense the intrinsic depolarization and / or other physiological parameters of the heart and / or deliver therapeutic electrical signals to the heart. A leadless cardiac device may be positioned inside or outside the heart, and in some instances, may be anchored to the wall of the heart by a fixing mechanism. A leadless cardiac device may be delivered to the heart percutaneously and / or transvascularly using a device containing a catheter. Summary of the invention

[0005] Various aspects of the present disclosure relate to methods and structures related to a delivery device for delivering an implantable medical device (IMD), the IMD being configured to verify that the delivery device and / or the IMD is defining one or more fixed configurations relative to a target site of a patient. The fixed configuration may include a spatial arrangement of the delivery device, the IMD, and / or the tissue of the target site that indicates that the IMD is effectively fixed to the target site. The fixed configuration may include a first fixed configuration that is tested (and may be defined and verified therein) before the IMD is deployed (and fixed) to the target site. The first fixed configuration may include a spatial relationship of the delivery device relative to the tissue of the target site, wherein the spatial relationship facilitates the fixed element of the IMD to achieve the desired fixation to the target site. For example, the first fixed configuration may involve a delivery device that orients the deployment port in a predetermined manner relative to the surface of the target site. Additionally or alternatively, the fixed configuration may include a second fixed configuration that is tested (and may be defined and verified therein) after the deployment and fixation of the IMD associated with the IMD achieving a threshold amount of fixation. For example, a threshold amount of fixation can involve a threshold number of fixation elements secured to tissue at a target site, wherein a component of the IMD (e.g., an electrode) is brought into a threshold level of contact against the target site or a threshold amount of fixation can involve a threshold number of turns of a single distal screw inserted into tissue at the target site.

[0006] The system can verify these fixed configurations by providing an electrical signal between two electrodes to the fluid and / or tissue at the target site of the patient and then identifying and analyzing the impedance of the provided electrical signal. For example, before deploying the IMD, the system can send an electrical signal to the fluid and / or tissue in an electrical path between a first electrode positioned inside the deployment chamber that houses the IMD and a second electrode positioned outside the deployment chamber. Then, the system can identify the impedance of the signal between the two electrodes. The system can be configured to identify that the delivery device defines a first fixed configuration when the impedance of this signal rises above a predetermined threshold (e.g., as a result of the electrical signal defining a path through tissue with a higher resistance indicating that the delivery port is fully pressed against the tissue at the target site). Similarly, the system can be configured to identify that the IMD defines a second fixed configuration when the impedance of this signal is stable (such as during a pull test (where the IMD is slightly pulled after the fixation element may have been fixed to the target site)). For example, the system can be configured to identify when the impedance of the signal obtains some harmonics (such as a double-peaked feature or a relatively "noisy" slope) when the IMD is not in the second fixed configuration. Additionally or alternatively, the system can identify the amount of lag between the voltage and current across the electrodes (e.g., the amount by which the voltage leads / lags the current) to identify a phase waveform of one or more impedance electrical signals, and therein determine whether the deployment chamber and / or IMD defines a first or second fixed configuration based on whether the phase waveform is noisy or clean. Further, the system can be configured to perform a fast Fourier transform (FFT) algorithm on the impedance signal to isolate frequency components that can indicate whether the deployment chamber or IMD defines a fixed configuration. The system can then identify to the clinician whether the delivery device and / or IMD defines a first fixed configuration, a second fixed configuration, or neither.

[0007] In some instances, an implantable medical device delivery system includes an elongated member configured to navigate an intravascular system of a patient. The delivery system also includes an expansion chamber connected to a distal portion of the elongated member and configured to accommodate at least a portion of an implantable medical device (IMD). The expansion chamber defines a distal opening configured to expand the IMD outside the expansion chamber at a target site in the patient's body. When the elongated member navigates the intravascular system, the delivery system also includes a first electrode positioned inside the expansion chamber. The delivery system also includes a second electrode. The delivery system also includes a signal generation circuit system configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of the patient's fluid or tissue. The delivery system also includes a processing circuit system configured to determine an impedance of the path based on the signal and control a user interface to indicate when the impedance of the path indicates that at least one of the IMD or the distal opening is in a fixed configuration relative to the target site of the patient.

[0008] In other examples, an implantable medical device delivery system includes an elongated member configured to navigate the intravascular system of a patient. The delivery system also includes an expansion chamber connected to the distal portion of the elongated member and configured to accommodate at least a portion of an implantable medical device (IMD). The expansion chamber defines a distal opening configured to expand the IMD outside the expansion chamber at a target site in the patient's body. The delivery system also includes a first electrode fixed to the inner surface of the expansion chamber. The delivery system also includes a second electrode, which is fixed to the outer surface of the expansion chamber or the elongated member. The delivery system also includes a signal generation circuit system, which is configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of the patient's fluid or tissue. The delivery system also includes a processing circuit system, which is configured to determine the impedance of the path based on the signal and control the user interface to indicate when the impedance of the path indicates that the distal opening is in a fixed configuration relative to the target site of the patient.

[0009] In other examples, an implantable medical device delivery system includes an implantable medical device (IMD) configured to be fixed to a target site in a patient's body by a plurality of fixing elements extending distally from a distal tip of a housing of the IMD. The delivery system also includes a first electrode fixed to the distal tip of the housing. The delivery system also includes a second electrode fixed to an outer surface of a proximal portion of the housing. The delivery system also includes a signal generating circuit system configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of a fluid or tissue of the patient. The delivery system also includes a processing circuit system configured to determine an impedance of the path based on the signal and control a user interface to indicate when the impedance of the path indicates that the IMD is in a fixed configuration relative to the target site of the patient.

[0010] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the devices and methods described in detail in the following figures and descriptions. Details of one or more aspects of the disclosure are set forth in the following figures and descriptions. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A is a conceptual diagram illustrating an example therapy system including a leadless implantable medical device (IMD) that can be used to monitor one or more physiological parameters of a patient and / or provide therapy to the patient's heart.

[0012] Figure 1B is a conceptual diagram illustrating another example therapy system including an IMD coupled to a plurality of leads that can be used to monitor one or more physiological parameters of a patient and / or provide therapy to the patient's heart.

[0013] Figure 2A is a conceptual diagram illustrating an example delivery device including an elongated member, a deployment pod housing an example IMD, two electrodes, and circuitry configured to use impedance of an electrical signal between the two electrodes to determine whether one of the deployment pod or the IMD is defining a fixed configuration.

[0014] Figure 2B It is demonstrated through Figure 2A Conceptual illustration of a cross-sectional view of an elongated member of a delivery device.

[0015] Figure 2C It is shown Figure 2A Example first and second electrodes on a deployment module for verifying that the deployment module is defining a first fixed configuration and Figure 2AConceptual diagram of example first and second electrodes on an IMD for verifying whether the IMD is defining a second fixed configuration.

[0016] Figure 2D It is shown Figure 2A An example first electrode on a deployment module for verifying whether the deployment module is defining a first fixed configuration and Figure 2A Conceptual illustration of an example first electrode on an IMD for verifying whether the IMD is defining a second fixed configuration, wherein two first electrodes are configured for use with a common second electrode on a deployment module.

[0017] Figure 2E is shown by the first set of holes through the wall of the deployment compartment are fixed to Figure 2A Conceptual diagram of example first and second electrodes of an IMD that enables two electrodes to verify whether a deployment module is defining a first fixed configuration and whether the IMD is defining a second fixed configuration.

[0018] Figure 2F is shown to be fixed to the deployment compartment by a second set of holes through the wall of the deployment compartment and one or more ribs of the deployment compartment. Figure 2A Conceptual diagram of example first and second electrodes of an IMD that enables two electrodes to verify whether a deployment module is defining a first fixed configuration and whether the IMD is defining a second fixed configuration.

[0019] Figure 2G It is shown Figure 2F Conceptual illustration of a cross-sectional view of the deployment compartment, second electrode, and ribs.

[0020] Figure 2H The method for verifying whether the deployment module is defining the first fixed configuration is shown. Figure 2A Conceptual illustration of an example first electrode in a deployment capsule and a second electrode on the distal tip of the deployment capsule.

[0021] Fig.2I The method for verifying whether the deployment module is defining the first fixed configuration is shown. Figure 2A Conceptual illustration of an example first electrode of a metal can containing an IMD and a second electrode on an elongated member of a delivery device.

[0022] Figure 3 is a conceptual block diagram illustrating an example configuration of circuitry of a system including a delivery device configured to verify when a delivery device and / or an IMD defines one or more fixed configurations.

[0023] Figure 4A is a method of defining a first non-fixed configuration relative to a target site. Figure 2A Conceptual illustration of a side view of a delivery device.

[0024] Figure 4B is a method of defining a first fixed configuration relative to a target site. Figure 2A Conceptual illustration of a side view of a delivery device.

[0025] Figure 5A and 5B The second non-fixed configuration is respectively shown to be close to the target site and relative to the target site. Figure 2A Conceptual diagram of a view of the delivery device and IMD.

[0026] Figure 5C and 5D The second fixed configuration is respectively shown to be close to the target part and relative to the target part. Figure 2A Conceptual diagram of a view of the delivery device and IMD.

[0027] Figure 6 is a graph indicating example impedance data for a first fixed configuration.

[0028] Figure 7 is a graph indicating example phase data for a first fixed configuration.

[0029] Fig. 8A is a graph indicating example impedance data for a second non-fixed configuration.

[0030] Figure 8B is a graph indicating example impedance data for the second fixed configuration.

[0031] Fig. 9A is a graph indicating example phase data for a second non-stationary configuration.

[0032] Fig. 9B is a graph indicating example phase data for the second fixed configuration.

[0033] Fig. 10A is a graph indicating example FFT data for a second non-fixed configuration.

[0034] Fig. 10B is a graph indicating example FFT data for the second fixed configuration.

[0035] Fig.11 A flow chart depicts an example method of processing circuitry to verify that electrical signals indicate a delivery device and an IMD are defining one or more fixed configurations relative to a target site.

[0036] Fig.12 Depicted is a flow chart of an example method for a clinician to deploy an IMD to a target site while verifying that a delivery device and the IMD are defining one or more fixed configurations relative to the target site. DETAILED DESCRIPTION

[0037] Various aspects of the present disclosure relate to methods and systems for delivering an implantable medical device (IMD) to a target site in a patient's body and verifying an effective fixed configuration of the delivery device and the IMD relative to the target site. Once the IMD is navigated to the target site with a fixation element on or near the distal end of the IMD, the IMD can be fixed to the target site. The delivery device can include a navigable elongated member (e.g., a catheter), an expansion chamber at the distal end of the elongated member, and a verification system configured to verify when the delivery device and / or IMD defines one or more fixed configurations relative to the target site. For example, various aspects of the methods and systems disclosed herein relate to providing an electrical signal to a patient's fluid and / or tissue between electrodes of the system, and analyzing the impedance of the delivered electrical signal to verify when the delivery device and / or IMD defines a fixed configuration relative to the target site.

[0038] The delivery device and / or IMD may include a first electrode and at least a second electrode contained in the deployment chamber of the delivery device during intravascular navigation. Further, the delivery device and / or IMD may include a circuit system configured to deliver electrical signals to fluids and / or tissues (and then analyze) between the two electrodes. For example, the first electrode may be fixed to the inner surface of the deployment chamber (e.g., the surface facing the IMD), and the second electrode may be fixed to the outer surface of the deployment chamber (the surface facing the vascular system), and the circuit system may be configured to provide electrical signals to fluids and tissues between the two electrodes. The circuit system may be configured therein to monitor the impedance of the electrical signal provided across the electrodes, and identify when the signal rises above a threshold value. In the case where the IMD includes a distally extending fixation element of the IMD, the IMD is deployed from the deployment chamber at an angle substantially at right angles to the surface of the tissue site, which can improve the ability of the fixation element to fix the IMD to the tissue. Therefore, when the circuit system is configured to detect the impedance of the electrical signal provided across the distal port of the deployment chamber, it can functionally provide an indication of when the delivery device defines an effective deployment arrangement. The circuit system may be configured to provide an indication to the clinician (eg, using a user interface of the system) as to when the delivery device defines such a fixed configuration.

[0039] Similarly, the IMD may include a first electrode fixed to the distal tip of the IMD and a second electrode close to the distal tip. In some instances, the first electrode of the delivery device may be the first electrode of the IMD. In such instances, the second electrode of the delivery device may be a second electrode of the IMD fixed to the IMD at a location close to the distal tip of the IMD, or the second electrode may be fixed to the deployment receptor at a location close to the distal tip of the IMD. In other instances, the delivery device may include two discrete electrodes and the IMD may include two discrete electrodes, so that the entire system includes two groups of electrodes, each group of electrodes verifying one of the fixed configurations. The circuit system of the IMD may be configured to provide an electrical signal to the fluid and tissue between the first electrode on the distal tip and the second electrode close to the first electrode. The circuit system may be configured therein to monitor the impedance of the electrical signal provided across the electrodes, and identify whether the signal incorporates any harmonics over time and during the pressure test. In the case where the IMD includes a therapeutic element on its distal tip (e.g., an electrode configured to provide therapy or sensing to a patient), the ability of the IMD to provide therapy using this therapeutic element is improved when the IMD presses the therapeutic element squarely and firmly into the patient's tissue. Thus, configuring the circuit system to detect when the impedance of the electrical signal provided by the electrode on the distal tip includes harmonics can functionally provide an indication of when the IMD has not been deployed so that the therapeutic element on its distal tip is squarely and firmly pressed into the tissue at a target site. The circuit system can be configured to provide an indication to the clinician as to when the IMD has not identified impedance with such harmonics and defined an effective fixed configuration therein.

[0040] Figure 1A 1 is a conceptual diagram illustrating an example therapy system 10A that can be used to monitor one or more physiological parameters of a heart 12 of a patient 14 and / or provide therapy to a heart 12 of a patient 14 using one or more medical devices delivered using a delivery device of the present disclosure. The patient 14 is typically, but not necessarily, a human patient. The therapy system 10A includes an implantable medical device (IMD) 16A communicatively (e.g., wirelessly) coupled to an external device 18. The IMD 16A can be an implantable leadless pacemaker that provides electrical signals to the heart 12 via one or more electrodes (not shown in FIG. 1 ) on its external housing. Additionally or alternatively, the IMD 16A can sense electrical signals associated with depolarization and repolarization of the heart 12 via electrodes on its external housing. In some instances, the IMD 16A provides pacing pulses to the heart 12 based on the electrical signals sensed within the heart 12. For example, IMD 16A may be a Micra pacing system (TPS) commercially available from Medtronic Public Limited Company of Dublin, Ireland. TM device.

[0041] IMD 16A can include circuitry within the hermetically sealed housing of IMD 16A. IMD 16A can also include a power supply and / or memory for circuitry 28. Circuitry 28 can be configured to provide functions belonging to IMD 16A as described herein. For example, as described in more detail below, circuitry 28 of IMD 16A can include circuitry configured to provide electrical signals across electrodes to verify that delivery device and / or IMD 16A are defining an effective fixed configuration during the deployment procedure. These electrical signals can include sinusoidal waveforms and / or pulses. Processing circuitry 28 can include one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry and any combination of such components.

[0042] For example, circuitry 28 may include processing circuitry, stimulation circuitry, telemetry circuitry, sensing circuitry, etc. The stimulation circuitry may generate and deliver electrical stimulation under the control of the processing circuitry. For example, in operation, the processing circuitry may access the memory to load a therapy program into the stimulation circuitry, where the stimulation parameters of the therapy program may include voltage amplitude, current amplitude, pulse rate, pulse width, duty cycle, or a combination of electrodes (e.g., where the electrodes are fixed to IMD 16A). Further, the stimulation circuitry may communicate with the signal generation circuitry (e.g., Figure 3 There is some overlap in the signal generating circuit system 124).

[0043] The telemetry circuit system can be configured to use a radio frequency protocol or an inductive communication protocol for wireless communication. The telemetry circuit system can include, for example, one or more antennas configured to communicate with an external device 18. The processing circuit system can transmit operating information (such as sensing information) through the telemetry circuit and receive a therapy program or therapy parameter adjustment. Moreover, in some instances, the IMD 16A can communicate with other implantable devices (such as stimulators, control devices, or sensors) through the telemetry circuit. The sensing circuit system can be configured to sense one or more parameters of the patient 14. For example, the sensing circuit system can use the electrodes of the IMD 16A to sense the parameters of the heart 12. Based on the sensed values ​​of the sensing circuit system, the processing circuit system can use the telemetry circuit system to provide information or use the stimulation circuit system to provide therapy related to the sensed values. Further, as described herein, the processing circuit system can use the telemetry circuit system to send fixed instructions or non-fixed instructions to various user interfaces for clinicians.

[0044] IMD 16A may include a fixation element (e.g., a set of fixation tines) to secure IMD 16A to patient tissue. The fixation element of IMD 16A may be positioned near the distal end of IMD 16A such that the fixation element is configured to extend a distal opening of a deployment bay of a delivery device prior to and / or while deploying IMD 16A using a delivery device. Figure 1A In the example of FIG1 , IMD 16A is positioned completely inside heart 12 near the inner wall of right atrium 20 to provide right atrium 20 pacing. In other examples, IMD 16A may be positioned at any other location outside or inside heart 12. For example, IMD 16A may be positioned outside or inside right ventricle 22, left atrium 24, and / or left ventricle 26, respectively (e.g., to provide right ventricular, left atrium, and left ventricular pacing). Further, although in Figure 1A A single IMD 16A is shown in FIG. 1 , but system 10A may include additional IMDs that are similar to or different from IMD 16A.

[0045] Depending on the location of the implant, IMD 16A may include other stimulation functions. For example, IMD 16A may provide atrioventricular node stimulation, fat pad stimulation, vagus nerve stimulation, or other types of electrical stimulation. In other examples, IMD 16A may be a monitor that senses one or more parameters of heart 12 (e.g., electrical activity, mechanical activity, and / or blood pressure) and may not provide any stimulation functions. In some examples, system 10A may include multiple leadless IMDs 16A to provide stimulation and / or sensing at various locations.

[0046] As mentioned above, IMD 16A can be delivered and deployed to its target site using a delivery device as described herein. IMD 16A can be substantially completely contained within a deployment chamber of the delivery device such that a fixation element of IMD 16A is adjacent to a distal opening of the deployment chamber. After the attachment of IMD 16A is secured to the target site (e.g., by a device such as a Figure 1A ), the delivery device may be retracted from patient 14 (eg, including retracting the delivery device over the proximal end of IMD 16A, depending on whether IMD 16A may be secured prior to full deployment).

[0047] In many cases, the efficacy of IMD 16A may be affected by the quality of fixation of IMD 16A. For example, IMD 16A may include a plurality of fixation tines configured to press a distal electrode of IMD 16A upward against tissue at a target site of patient 14. If the fixation tines poorly secure the tissue, it may be difficult or impossible for IMD 16A to provide the functionality described herein using such distal electrodes. For example, if only one of the plurality of fixation tines is attached to the tissue, or if the fixation tines are attached to IMD 16A at an angle relative to the tissue, the contact of the distal electrode with the target site may be relatively poor (e.g., poor contact with right atrium 20). As a result of such poor contact (which itself is a result of poor fixation), the efficacy of IMD 16A may be reduced.

[0048] In some instances, a clinician may utilize a "pull test" to verify that the fixation elements of IMD 16A have properly engaged tissue at the target site. The pull test may include using, for example, a tether (e.g., Figure 5B and 5D In some instances, such as when the tether 162 of the IMD 16A is pulled firmly on the proximal end of the IMD 16A. Figure 5B and 5D , the pull test can be performed when the IMD 16A is substantially fully deployed out of the deployment chamber 52 and substantially unconstrained therein. The clinician can view the IMD 16A at the target site using fluoroscopy or the like to ensure that the fixation elements appear to have properly engaged the tissue of the target site. However, in some instances, the target site may be a relatively thin wall of tissue such that it may be difficult for the clinician to adequately see such engagement. For example, the walls of the right atrium 20 and / or the left atrium 24 may be relatively thin, making it difficult or impossible for the clinician to use the fixation elements to verify that the IMD 16A has been effectively attached to the tissue of the target site.

[0049] Various aspects of the present disclosure relate to verifying that one or both of the delivery device and IMD 16A are defining a favorable fixed configuration that may result in good contact between the distal electrodes, etc., of IMD 16A and the tissue of the target site. For example, the delivery device may be configured to provide an electrical signal to the fluid and / or tissue of patient 14 between a first electrode within the deployment chamber of the delivery device and a second electrode outside the deployment chamber. When the distal opening of the delivery device is not aligned with the target site (e.g., such that the face defining the distal opening is at an angle relative to the tissue of the target site), the path between the two electrodes (e.g., the path of least resistance that the electricity between the electrodes will take) may substantially contain the fluid of patient 14. Conversely, when the distal opening of the delivery device is aligned and properly pressed into the tissue of the target site, the path between the two electrodes may contain at least some tissue of patient 14 (e.g., the path of the electrical signal such as the path of the housing of the deployment chamber that leaves through the distal port). The path through the tissue of patient 14 may have a higher impedance than a path that substantially or completely contains the fluid of patient 14. Processing circuitry (such as processing circuitry of a delivery device or circuitry 28 of IMD 16A) can detect this relatively high impedance (e.g., an impedance that exceeds or otherwise meets a threshold) and may cause a user interface (e.g., a screen or light, etc.) to indicate to the clinician that the delivery device is properly oriented for deploying IMD 16A.

[0050] Additionally or alternatively, the processing circuitry (of the delivery device or of IMD 16A) may be configured to send an electrical signal between a distal electrode of IMD 16A and a second electrode proximal to the distal electrode of IMD 16A after IMD 16A is deployed. In this example, the processing circuitry may be configured to evaluate the impedance of the signal provided between the first electrode and the other electrode after IMD 16A has been deployed and secured to tissue. If the fixation element of IMD 16A (e.g., a fixation tine as described above) has pressed the first electrode against tissue at the target site, the impedance of the signal may include a substantially stable impedance value. In contrast, if the fixation device of IMD 16A does not engage tissue at the target site as expected, the processing circuitry of the delivery device may identify harmonics in the impedance value of the electrical signal across the electrodes, such as a bimodal feature or a relatively "noisy" slope. Processing circuitry of the delivery device may determine whether the signal is “stable” or contains harmonics, and may, as a result of this determination, cause a user interface (eg, screen or light, etc.) to indicate to the clinician whether the fixture of IMD 16A is well or poorly engaged, respectively.

[0051] Because the processing circuitry (of the delivery device and / or IMD 16A) verifies that the delivery device is properly oriented for deployment and / or verifies that IMD 16A has achieved proper fixation after deployment, the processing circuitry can improve the clinician's ability to arrange system 10A so that each IMD 16A (and the distal electrode of each IMD 16A therein) makes good contact with tissue at the intended target site. Because IMD 16A has good contact, system 10A can have the approved ability to treat and / or monitor patient 14 as described herein.

[0052] Figure 1A Further depicted is an external device 18, such as a (clinician or patient) programmer, that wirelessly communicates with IMD 16A. In some examples, external device 18 comprises a handheld computing device, a computer workstation, or a networked computing device. External device 18 may include a user interface that presents information to a user and receives input from the user. It should be noted that a user may also interact with external device 18 remotely through a networked computing device.

[0053] A user (e.g., a physician, technician, surgeon, electrophysiologist, other clinician, or patient) interacts with external device 18 to communicate with IMD 16A. For example, a user may interact with external device 18 to retrieve physiological or diagnostic information from IMD 16A. For example, a user may use external device 18 to retrieve information from IMD 16A regarding the heart rhythm of heart 12, heart rhythm trends over time, or episodes of arrhythmias. A user may also interact with external device 18 to program IMD 16A.

[0054] In some instances, the user may use external device 18 to retrieve information from IMD 16A regarding other sensed physiological parameters of patient 14 or to identify information derived from sensed physiological parameters, such as intracardiac or intravascular pressure, activity, posture, tissue oxygen level, blood oxygen level, respiration, tissue perfusion, heart sounds, electrocardiac graph (EGM), intracardiac impedance, thoracic impedance, etc. In some instances, the user may use external device 18 to retrieve information from IMD 16A regarding the performance or integrity of IMD 16A or the performance or integrity of corresponding components of system 10A, such as a power supply of IMD 16A. As another example, the user may interact with external device 18 to select values ​​for parameters of a therapy provided by IMD 16A, such as pacing and / or neural stimulation therapy.

[0055] Further, in some instances, external device 18 may include a user interface as described herein for indicating fixed and / or non-fixed configurations to a clinician. For example, a circuit system configured to deliver an electrical signal to tissue and / or fluid between two electrodes and to use the impedance of the signal therein to verify whether the delivery device and / or IMD 16A defines a fixed configuration may then provide this information to external device 18 (using telemetry as described herein). Further, a clinician may provide input or commands to the circuit system regarding verification or testing of a fixed configuration using external device 18. For example, a clinician may use an interface of external device 18 to cause the circuit system of IMD 16A and / or the delivery device to start verifying whether the delivery device defines a first fixed configuration, stop verifying whether the delivery device defines a first fixed configuration, start verifying whether IMD 16A defines a second fixed configuration, stop verifying whether IMD 16A defines a second fixed configuration, etc.

[0056] IMD 16A and external device 18 may communicate via wireless communication using any technology known in the art. Examples of communication technology may include low frequency or radio frequency (RF) telemetry. In some examples, external device 18 may include a programming head that may be placed proximate to the patient's body near the implant site of IMD 16A to improve the quality or safety of communication between IMD 16A and external device 18.

[0057] Figure 1B is a conceptual diagram showing another example therapy system 10B that can be used to monitor one or more physiological parameters of patient 14 and / or provide therapy to heart 12 of patient 14 using leads 30A, 30B, 30C (collectively referred to as "leads 30") implanted in patient 14 using delivery devices and methods described herein. Therapy system 10B includes an IMD 16B coupled to leads 30 and external device 18. As referred to herein, all IMDs 16B and leads 30 can generally be collectively referred to as IMDs. In one example, IMD 16B can be an implantable pacemaker that provides electrical signals to heart 12 through electrodes coupled to one or more of leads 30. IMD 16B can include an electrical stimulation generator and can be attached to the proximal end of medical lead 30. In other examples, in addition to or alternatively to pacing therapy, IMD 16B can deliver neural stimulation signals. In some examples, IMD 16B can also include cardioversion and / or defibrillation functions. In other examples, IMD 16B may exclusively or primarily provide monitoring functions.

[0058] Medical leads 30 extend into heart 12 of patient 14 to sense electrical activity of heart 12 and / or deliver electrical stimulation to heart 12. In some examples, Figure 1BEach medical lead 30 can be delivered to its corresponding target site using a delivery device according to the delivery techniques described herein. Figure 1B In the example shown, a right ventricular (RV) lead 30B extends through one or more veins (not shown), the superior vena cava (not shown), and the right atrium 20, and into the right ventricle 22. The RV lead 30B can be used to deliver RV pacing to the heart 12. A left ventricular (LV) lead 30A extends through one or more veins, the vena cava, the right atrium 20, and into the coronary sinus 32 to a region of the free wall of the left ventricle 26 adjacent to the heart 12. Alternatively, the LV lead 30A can be implanted "directly" in the left ventricle 26, such that the LV lead 30A extends, for example, through a hole in the ventricular septum or the atrial septum. The LV lead 30A can be used to deliver LV pacing to the heart 12. A right atrial (RA) lead 30C extends through one or more veins and the vena cava, and into the right atrium 20 of the heart 12. The RA lead 30C can be used to deliver RA pacing to the heart 12.

[0059] In some examples, system 10B may additionally or alternatively include one or more leads or lead segments that deploy one or more electrodes within the vena cava or other veins or within or near the aorta. Figure 1B ). Moreover, in another example, system 10B may additionally or alternatively include one or more additional intravenous or extravascular leads or lead segments that deploy one or more electrodes on the epicardium (e.g., near the epicardial fat pad or close to the vagus nerve). In other examples, system 10B may not include one of ventricular leads 30A and 30B.

[0060] One or more of the medical leads 30 may include one or more fixation elements (such as a set of fixation tines) to fix the distal end of the medical lead to the patient tissue or at a fixed position relative to the patient tissue (for example, wherein the fixation elements of one or more medical leads 30 are expanded against rather than through the patient tissue). Because other fixation devices (such as distal helical coils, etc.) can be used in some examples, each medical lead 30 is shown to include a fixation element (such as a tines) for the purpose of clarity only. As depicted, the fixation element may include a distal tine configured to extend distally from the lead 30 and self-bias when deployed (for example, deployed into a biased configuration from a deployment chamber of a delivery device as described herein). In other examples, the fixation element may include other types of tines (such as tines that are not self-biased (but biased or deformed or actuated by another component)), tines of other shapes (for example, spiral tines), tines configured to be manually controlled by a clinician, etc. The fixation element (such as a tine) can be constructed of substantially any biocompatible material.

[0061] As mentioned above, one or more medical leads 30 can be delivered and deployed to the corresponding target site using the delivery device described herein. The medical lead 30 can be deployed to the corresponding target site in or near the heart 12 in a subsequent procedure using one or more delivery devices herein. In such an example, the fixed element of the corresponding medical lead 30 can be navigated to the target site within the deployment chamber of the delivery device, so that the other parts of the corresponding medical lead 30 can be accommodated by the lumens of some of the deployment chambers and / or elongated members of the delivery device. When the distal end of the medical lead 30 is deployed to fix the corresponding medical lead 30 to the target site, the delivery device can be withdrawn over the corresponding medical lead 30 to retract the delivery device from the patient 14. In this way, after successfully deploying one of the medical leads 30, the clinician can retract the delivery device so that the delivery device moves proximally relative to the corresponding deployed medical lead 30 (e.g., so that the corresponding deployed and distally fixed medical lead 30 slides in one or more lumens defined by the deployment chamber and / or elongated member of the delivery device when the delivery device is retracted).

[0062] IMD 16B may sense electrical signals accompanying depolarization and repolarization of heart 12 via electrodes coupled to at least one of leads 30. In some examples, IMD 16B provides pacing pulses to heart 12 based on the electrical signals sensed within heart 12. The configuration of electrodes used by IMD 16B for sensing and pacing may be unipolar or bipolar.

[0063] IMD 16B may also provide neurostimulation therapy, defibrillation therapy, and / or cardioversion therapy via electrodes positioned on at least one of leads 30. For example, upon detection of ventricular fibrillation of ventricles 22 and 26, IMD 16B may deliver defibrillation therapy in the form of electrical pulses to heart 12. In some instances, IMD 16B may be programmed to deliver a progression of therapy (e.g., pulses with increasing energy levels) until the fibrillation of heart 12 ceases. As another example, IMD 16B may deliver cardioversion or anti-tachycardia pacing (ATP) in response to detection of a tachycardia (e.g., a tachycardia of ventricles 22 and 26).

[0064] As described above with respect to IMD 16A of FIG1 , external device 18 (e.g., a clinician or patient programmer) may be used to communicate with IMD 16B. In addition to the functionality described with respect to IMD 16A of FIG1 , a user may use external device 18 to retrieve information from IMD 16B regarding the performance and integrity of lead 30, and may interact with external device 18 to select parameters for any additional therapies provided by IMD 16B (e.g., cardioversion and / or defibrillation).

[0065] Leads 30 may be electrically coupled to signal generation circuitry and sensing circuitry (not shown) of IMD 16B via connector block 34. In some examples, the proximal end of lead 30 may include electrical contacts that are electrically coupled to corresponding electrical contacts within connector block 34 of IMD 16B. Figure 1B 14. Although not shown in the drawings, IMD 16B may include circuitry 28 similar to IMD 16A. Circuitry 28 may include the processing circuitry, signal generation circuitry, and sensing circuitry described above, as well as any other circuitry, power supplies, antennas, or other hardware or software necessary or helpful to configure IMD 16B to provide therapy and / or monitor a condition of patient 14. In some instances, the signal generation circuitry of IMD 16A may be used to deliver electrical signals between electrodes as described herein to verify a fixation configuration. In other instances, leads 30 may be coupled to another system to generate electrical signals and identify impedances of those signals to verify a fixation configuration as described herein.

[0066] Figure 1B The configuration of the system 10B shown in FIG. 1 is only one example. In other examples, as Figure 1B In place of or in addition to the venous lead 30 shown in , the system may include an extravascular lead, a subcutaneous lead, a substernal lead, an epicardial lead, and / or a patch electrode. Further, IMD 16B need not be implanted in patient 14. For each of these examples, any number of medical leads may include a set of fixed tines on the distal end of the medical lead that are navigated to their respective target sites using a delivery device according to the techniques described herein.

[0067] Additionally, in other examples, the system may include any suitable number of leads coupled to IMD 16B, and each of the leads may extend to any location within or proximate to heart 12. For example, other examples of the system may include a Figure 1B 2 and an additional lead positioned in or near left atrium 24. Other examples of the system may include a single lead extending from IMD 16B into right atrium 20 or right ventricle 22 or two leads extending into respective ones of right ventricle 22 and right atrium 20. In each of these examples, any number of medical leads may include a fixation mechanism on the distal end of the medical leads and may be delivered with a medical delivery device according to the techniques described herein.

[0068] Figure 2AAn example medical delivery device 50 for delivering an implantable medical device such as an IMD 16A is depicted. Although the delivery device 50 is depicted and discussed herein as deploying and verifying an IMD 16A and / or a fixed configuration for the IMD, it should be understood that in other instances, the delivery device 50 can be used to deploy and verify a fixed configuration for other IMDs or other IMD components (e.g., lead 30 of IMD 16B). The delivery device 50 can include a deployment chamber 52 configured to accommodate at least a portion of the IMD 16A and deploy the IMD 16A. In some instances, the deployment chamber 52 can be configured to accommodate substantially all of the IMD 16A prior to deploying the IMD 16A. The deployment chamber 52 can be connected to a distal portion of an elongated member 54 of the delivery device 50. The deployment chamber 52 and the elongated member 54 can be configured to navigate the intravascular system of a patient. For example, a clinician can navigate the deployment pod 52 and the elongated member 54 through the intravascular system until the deployment pod 52 is at a target site in the patient's body in order to deploy the IMD 16A from the deployment pod 52. The clinician can use the hub 56 of the delivery device 50 to manipulate the delivery device 50 and / or navigate the deployment pod 52 to the target site. The hub 56 of the delivery device 50 can be at a proximal portion 58 of the delivery device 50. In some examples, the hub 56 can be configured to remain external to the patient 14 while the deployment pod 52 is navigated to the target site, thereby enabling the clinician to use one or more mechanisms or ports (not depicted) of the hub 56 to navigate the intravenous system and deploy the IMD 16A. The deployment pod 52 can be positioned at or near the distal end of the delivery device 50, and the hub 56 can be positioned at or near the proximal end of the delivery device 50, with the elongated member 54 extending between the hub 56 and the deployment pod 52.

[0069] The elongated member 54 can be a flexible, elongated component that extends longitudinally along the delivery device 50. The elongated member 54 can extend along the longitudinal axis 60 of the delivery device 50 between the deployment chamber 52 and the hub 56 of the delivery device 50. The elongated member 54 can be substantially cylindrical, such that the elongated member 54 defines a substantially circular cross-sectional shape. In other examples, the elongated member 54 can define one or more other cross-sectional shapes, including defining multiple cross-sectional shapes along the longitudinal length of the elongated member 54.

[0070] The elongated member 54 may define a plurality of longitudinal lumens for various purposes. For example, as shown in FIG. Figure 2BAs depicted in the conceptual cross-sectional view of , the elongated member 54 can define a lumen 64 that occupies a majority of the cross-sectional width of the elongated member 54. The lumen 64 can be configured to accommodate a deployment mechanism 66 that can slide axially relative to the delivery device 50 (e.g., slide along the longitudinal axis 60 of the delivery device 50) within the lumen 64. In this manner, once the clinician has navigated the deployment pod 52 to the target site due to the actions performed using the deployment mechanism 66, the clinician can, for example, deploy the IMD 16A from the deployment pod 52. For example, returning to Figure 2A , deployment mechanism 66 can include a push element 68 at a distal end of deployment mechanism 66. In response to deployment mechanism 66 sliding distally within lumen 64, push element 68 can be configured to contact a proximal surface of IMD 16A and apply a distal force to the proximal surface. Additionally or alternatively, deployment mechanism 66 can include a tether or hook (e.g., similar to a tethered device) for holding, pushing, retracting, or otherwise moving IMD 16A relative to deployment compartment 52. Figure 5B and 5D tether 162).

[0071] Back to Figure 2B , lumen 64 may alternatively or additionally be configured to accommodate an inserted or implanted medical device (e.g., where the implanted medical device comprises Figure 1B The elongated member 62 may further define a guidewire lumen 70 configured to accommodate a guidewire that can slide axially (e.g., move along the longitudinal axis 60 of the delivery device 50) within the guidewire lumen 70 relative to the delivery device 50 (e.g., so that the deployment chamber 52 is navigated to the target site by sliding the delivery device 50 along the guidewire that was previously navigated to the target site). Alternatively or additionally, one or more deflection members 72 may be embedded in the elongated member 54. The deflection member 72 may be configured to deflect the elongated member 54 in one or more directions. For example, the deflection member 72 may include a guidewire that is pulled or pushed using a port or control member on the hub 56 to deflect the elongated member 54. The deflection member 72 may be configured to deflect the elongated member 54 in a predetermined manner that is configured to navigate the delivery device 50 to the target site. In other words, the deflection member 72, as longitudinally embedded within the elongated member 54, may be configured to deflect the elongated member 54 in a predetermined manner when the delivery device 50 is inserted into the patient 14 (e.g., to navigate through the particular tortuosity and predetermined length of the intravascular system).

[0072] Back to Figure 2AAs discussed above, delivery device 50 can be configured to be inserted into patient 14 to deliver IMD 16A. In some instances, delivery device 50 can be configured to be inserted into patient 14 using an introducer sheath (not depicted). Delivery device 50 can be made of one or more biocompatible materials. For example, delivery device 50 can include a polymeric material such as polyether block amide (PEBA), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), nylon, etc., and / or delivery device 50 can be made of a metallic material (such as titanium, nitinol, stainless steel, etc.).

[0073] In some instances, such as Figure 2A , the deployment pod 52 can house the IMD 16A within a recess 74 defined by an outer wall 76 of the deployment pod 52. The deployment pod 52 can define the recess 74 as a physical space sized to partially or fully contain the IMD 16A as the delivery device 50. The outer wall 76 can surround the axial length of the IMD 16A. In some examples, as depicted, the outer wall 76 can extend radially inward at the proximal end of the deployment pod 52 to prevent the IMD 16A from moving relative to the proximal side of the deployment pod 52. Although the deployment pod 52 is shown at the bottom for illustrative purposes, Figure 2A 16A), it should be understood that deployment pod 52 may define a substantially continuous housing that may or may not be transparent and that radially surrounds IMD 16A mostly or completely along the length of IMD 16A.

[0074] The deployment pod 52 may define a distal opening 78 through which the IMD 16A passes to the recess 74. The delivery device 50 may be configured to deploy the IMD 16A from the recess 74 through the distal opening 78. In some examples, a distal surface 80 of the deployment pod 52 may define the distal opening 78. The deployment pod 52 may define the recess 74 such that when the IMD 16A is received within the recess 74, one or more fixation elements 82 are proximate to the distal opening 78. In some examples, before and during navigation of the IMD 16A to the target site, the one or more fixation elements 82 may interface with the inner surface of the outer wall 76 of the deployment pod 52. In other words, when the IMD 16A is within the deployment pod 52, the distal ends of the fixation elements 82 may contact the inner surface of the outer wall 76, and further, the fixation elements 82 may press against the inner surface and / or the distal surface 80 to deploy the IMD 16A at the target site.

[0075] The delivery device 50 may include a plurality of electrodes and a set of circuit systems configured to verify when the deployment capsule 52 and / or IMD 16A defines one or more fixed configurations relative to tissue at a target site in the patient 14. For example, the delivery device 50 may include a first electrode 90, a second electrode 92, and a circuit system 94 for verifying whether the deployment capsule 52 and / or IMD 16A defines a fixed configuration. The circuit system 94 may be configured to cause the first electrode 90 and the second electrode 92 to deliver an electrical signal to the fluid and / or tissue along a path between the first electrode 90 and the second electrode 92. The circuit system 94 may then use the determined impedance of the electrical signal across this path to verify whether the deployment capsule 52 and / or IMD 16A is defining a fixed configuration relative to tissue at the target site. The depicted positioning and size of each of the first electrode 90, the second electrode 92, and the circuit system 94 are for illustrative purposes only, as each of these components may be in many locations and may have different sizes and shapes as described herein (e.g., in a plurality of locations such as in the embodiment of the present invention). Figure 2C and 2D as depicted in ).

[0076] The first electrode 90 can be positioned within the recess 74 of the deployment chamber 52. For example, the first electrode 90 can be secured to the inner surface of the outer wall 76 of the deployment chamber 52. Alternatively, the first electrode 90 can be secured to the distal tip 96 of the housing 98 of the IMD 16A. In such an example, the first electrode 90 can be a primary sensing / pacing / defibrillation electrode of the IMD 16A. Regardless of the positioning, the first electrode 90 can be configured to be exposed to the patient's fluid when the deployment chamber 52 is navigated to the target site in the patient. In other words, the conductive surface of the first electrode 90 can be configured to be directly electrically coupled to the patient's fluid (e.g., blood) when the deployment chamber 52 is navigated to the target site in the patient's body.

[0077] In some examples, second electrode 92 can be positioned outside of recess 74 of deployment chamber 52. For example, second electrode 92 can be secured to an outer surface of outer wall 76 of deployment chamber 52. In other examples, second electrode 92 can be secured to an outer surface of a distal portion of elongated member 54, or second electrode 92 can be secured to a transition between elongated member 54 and deployment chamber 52. Alternatively (or additionally as described below), second electrode 92 can be positioned within recess 74 of deployment chamber 52. For example, second electrode 92 can be secured to proximal portion 100 of IMD 16A. Similar to first electrode 90, second electrode 92 can be configured to be exposed to fluid of patient 14 when deployment chamber 52 is navigated to a target site within patient 14.

[0078] Both the first electrode 90 and the second electrode 92 can be electrically coupled to the circuit system 94. The delivery device 50 can include one or more conductors configured to electrically couple the first electrode 90 and the second electrode 92 to the circuit system 94. For example, referring back to Figure 2B , first and second conductors 102A, 102B (collectively, "conductors 102") may extend longitudinally through delivery device 50 embedded in a wall of elongated member 54. First conductor 102A may be coupled to first electrode 90 and second conductor 102B may be coupled to second electrode 92. In other examples (not shown), one or both of conductors 102 may be embedded within deployment mechanism 66 or may be configured to extend within a lumen of elongated member 54 (rather than being embedded therein). For example, one or both of conductors 102 may extend longitudinally within lumen 64 of elongated member 54. When conductors 102 extend longitudinally through delivery device 50, the conductors may be electrically insulated from each other. In other examples (e.g., where circuitry 28 of IMD 16A includes some or all of circuitry 94 described herein), conductors 102 may extend in whole or in part within IMD 16A to couple circuitry 94 to first electrode 90 and second electrode 92.

[0079] Back to Figure 2A , the depicted circuit system 94 can be positioned within the delivery device 50. For example, the circuit system 94 can be positioned within the hub 56 of the delivery device 50. In other examples, the circuit system 94 can be within a separate housing that can be coupled to the delivery device 50. For example, the circuit system 94 can be contained within a housing that can be coupled to the delivery device 50 (e.g., coupled to a port of the hub 56 in a manner such that the circuit system 94 of the housing is electrically coupled to the conductor 102 and therein to the first electrode 90 and the second electrode 92 of the delivery device 50). Alternatively, as Figure 1A , some of all of circuitry 94 may be included in circuitry 28 of IMD 16A. For example, first electrode 90 may be on distal tip 96 of IMD 16A, second electrode 92 may be secured to proximal portion 92 of IMD 16A, and circuitry 94 may be within a hermetically sealed housing of IMD 16A such that techniques for verifying that IMD 16A is secured to a target site are performed only by components of IMD 16A.

[0080] The circuit system 94 may include a circuit system configured to deliver an electrical signal to a fluid and / or tissue along a path between the first electrode 90 and the second electrode 92. For example, the circuit system 94 may be configured to couple the first electrode 90 to the positive electrode or supply terminal of the energy supply, and couple the second electrode 92 to the negative electrode or return terminal of the energy supply. In this way, when a conductive medium (such as tissue or fluid) is provided on the path between the first electrode 90 and the second electrode 92, the circuit system 92 can create a circuit. The path may include fluid and / or tissue at the target site of the patient 14. In some instances (for example, in the case where the circuit system 94 uses a power source (such as a battery) to generate an electrical signal), the circuit system 94 may be configured to maintain a substantially static voltage potential or a substantially static current across the first electrode 90 and the second electrode 92 (for the purpose of clarity, the voltage potential is mainly discussed herein). The static voltage or current can be provided in a sinusoidal or pulsed form. Since the first electrode 90 and the second electrode 92 deliver an electrical signal with a substantially static voltage potential or current, the value of the impedance of the signal can be reliably related to the change of the material of the path. In other words, the resistance of the path traveled by the signal can be calculated by measuring the current due to providing a known and / or constant voltage, and alternatively, the resistance of the path can be calculated by measuring the voltage due to providing a known and / or constant current. For example, the tissue of patient 14 can have a relatively higher resistance than the fluid of patient 14, so that when the electrical signal passes through the tissue rather than just through the fluid of patient 14, the impedance of the signal can increase.

[0081] Circuit system 94 can identify an impedance of the electrical signal. Internal signal 94 can determine when the impedance indicates that deployment chamber 52 and / or IMD 16A define one or more fixed configurations. For example, circuit system 94 can cause first electrode 90 within deployment chamber 52 and second electrode 92 fixed to the outer surface of deployment chamber 52 to deliver the electrical signal to the fluid between first electrode 90 and second electrode 92 of patient 14. When distal surface 80 of deployment chamber 52 defining distal opening 78 is not flush with tissue of patient 14 (e.g., so that fluid of patient 14 can flow into and out of recess 74 through distal opening 78), the electrical signal can follow a path that does not pass through any tissue of patient 14. Circuit system 94 can be configured to identify that the impedance of the electrical signal is below a predetermined threshold (e.g., a level indicating that the electrical signal has passed through tissue). Similarly, when distal surface 80 of deployment chamber 52 is flush with tissue of patient 14, the path of the electrical signal can pass through at least some tissue (e.g., due to fluid of patient 14 being trapped in deployment chamber 52). Because the path includes at least some tissue, the impedance of the electrical signal between the first electrode 90 inside the recess 74 and the second electrode 92 outside the recess 74 can increase. The circuit system 94 can identify that the impedance of the electrical signal has risen above an impedance threshold, thereby indicating that the distal surface 80 of the deployment capsule 52 is (substantially or substantially) flush with the target site and that the deployment capsule 52 is defining a first fixed configuration therein.

[0082] Because the deployment compartment 52 defines a first fixed configuration, the circuit system 94 may cause the user interface 104 to indicate the first fixed configuration (e.g., Figure 4B 152A) depicted in . The user interface 104 may include an interface configured to present information or data or feedback to a user (e.g., a clinician). For example, the user interface 104 may include a display screen, a speaker, or other device capable of providing auditory feedback or a tactile device. In the case where the user interface 104 is a display screen, the circuit system 94 may be configured to cause the user interface 104 to present the current impedance value to the clinician (e.g., by displaying text or images indicating a successful first fixation configuration and / or an unsuccessful first fixation configuration and / or one or more transitions therebetween). In some instances, the user interface 104 may be positioned at Figure 1A and Figure 1B on programmer 18 , such as where user interface 104 is a display of programmer 18 and circuit system 94 communicates with user interface 104 using telemetry techniques as described herein.

[0083] Alternatively or additionally, the user interface 104 can be positioned on a proximal portion of the delivery device 50. For example, the user interface 104 can be positioned on the hub 56 of the delivery device 50. As described herein, in the case where the circuit system 94 is positioned on a separate device, the user interface 104 can be positioned on the same device. In some examples, the user interface 104 can include a light, such as a light emitting diode (LED), etc. For example, in the case where the user interface 104 includes an LED, the circuit system 94 can be configured to cause the LED to display a first predetermined color (e.g., red) in response to identifying that the impedance of the electrical signal is below a threshold level (e.g., such that the deployment module 52 does not define the first fixed configuration) and then display a second predetermined color (e.g., green) in response to identifying that the impedance of the electrical signal rises above the threshold level (e.g., because the deployment module 52 defines the first fixed configuration relative to the target site), thereby flipping back and forth between the two in response to the changing impedance level.

[0084] Alternatively or additionally, circuit system 94 may be configured to verify when an electrical signal between first electrode 90 and second electrode 92 indicates that IMD 16A defines a second fixed configuration relative to tissue of a target site of patient 14. For example, first electrode 90 may be fixed to distal tip 96 of IMD 16A, and second electrode 92 may be fixed to an outer surface of outer wall 76 of deployment capsule 52. As discussed herein, first electrode 90 may be configured to be compressed into tissue at a target site of patient 14 after being deployed from deployment capsule 52. In some examples, the target site may be a target site at or within heart 12 of patient 14.

[0085] In some instances where the target site is at or within the heart 12 of the patient 14, the manner in which the IMD 16A is pressed into the heart 12 may affect the efficacy of the therapy and / or monitoring provided by the IMD 16A. For example, in the case where the IMD 16A is deployed from the deployment bay 52 such that only one of the fixation elements 82 becomes secured to the target site, the first electrode 90 may not be pressed into the tissue "square" such that one side of the first electrode 90 does not contact the tissue, or the first electrode 90 may be pressed into the tissue with a force less than a threshold such that signals between the tissue and the first electrode 90 cannot effectively pass. When the IMD 16A is deployed such that the first electrode 90 on the distal tip 90 of the IMD 16A is not pressed into the tissue as desired, it may be difficult or impossible for the IMD 16A to provide monitoring, pacing, or defibrillation techniques as desired. Circuitry 94 may be configured to verify when fixation element 82 presses first electrode 90 squarely (eg, straight such that a longitudinal axis of IMD 16A is at right angles to a surface of the target site) into tissue of the target site with at least a threshold force.

[0086] For example, circuit system 94 may analyze the "stability" or "clarity" of the impedance of the electrical signal transmitted between first electrode 90 and second electrode 92, where stability or clarity indicates a smooth and non-volatile set of slopes of the impedance waveform as discussed herein. In other words, as IMD 16A is deployed near or within heart 12, the impedance of the electrical signal transmitted between the path of tissue and fluid between first electrode 90 and second electrode 92 may reflect and / or incorporate the intrinsic waveforms of heart 12 (e.g., electrocardiogram waveforms, phase waveforms, pressure waveforms). The impedance of the electrical signal as detected by circuit system 94 may reflect these intrinsic waveforms with more "clarity" or with "noise" (e.g., noise that is a series of relatively non-smooth slopes between repeated peaks and valleys of the waveform and / or a double-peaked feature within the waveform), depending on the quality of deploying IMD 16A from deployment chamber 52. Further, circuit system 94 may be configured to isolate or highlight this noise or clarity. For example, the circuit system 94 can be configured to determine the first derivative of the impedance value so that any noise can be amplified and more easily identified therein. Additionally or alternatively, the circuit system 94 can be configured to perform a fast Fourier transform (FFT) algorithm on the impedance value to isolate specific frequency components of the signal, thereby analyzing the noise or clarity of these frequency components therein. Further, the circuit system 94 can be configured to identify the amount of hysteresis between the current and voltage across the electrodes 90, 92 to identify the phase of the impedance of the electrical signal, and to identify therein whether the phase waveform meets various noise thresholds as described herein.

[0087] When IMD 16A is deployed in a manner such that first electrode 90 on distal tip 96 of IMD 16A is pressed loosely or at an angle into tissue at a target site, the impedance of the electrical signal as identified by circuit system 94 may be relatively noisy. In contrast, where IMD 16A is deployed such that first electrode 90 on distal tip 96 is pressed at a right angle into tissue at a target site with at least a threshold force, the impedance waveform as identified by circuit system 94 is repeatable, predictable, and may maintain magnitude. In some instances, a clinician may determine that IMD 16A defines a second fixed configuration when circuit system 94 indicates that the impedance waveform maintains a relatively static and stable waveform even when IMD 16A is pulled during deployment (e.g., such that the impedance waveform does not acquire a bimodal feature or confines an excessively noisy slope to within a predetermined slope threshold).

[0088] Because circuit system 94 determines that the impedance indicates that IMD 16A defines the second fixed configuration, circuit system 94 may cause user interface 104 to indicate the implementation of the second fixed configuration. For example, where user interface 104 is an LED, circuit system 94 may be configured to cause the LED to display a predetermined color (e.g., blue) in response to identifying that the impedance waveform is stable and relatively static (e.g., because IMD 16A defines the second fixed configuration relative to the target site). Alternatively, where user interface 104 is a display screen (e.g., where external device 18 includes user interface 104), circuit system 94 may be configured to cause user interface 104 to present the impedance waveform and / or noise level and a "pass" or "fail" message to the clinician.

[0089] In some examples, the delivery device 50 may include one or more radiopaque elements that can indicate the location of the deployment pod 52 within the patient. For example, the deployment pod 52 may include a radiopaque element that enables a clinician monitoring the intravenous navigation of the delivery device 50 to determine when the deployment pod 52 has reached the target site. The clinician may use various fluoroscopic techniques to track the location of the deployment pod 52. The radiopaque element may be fixed to the elongated member 54 at a location proximate to the deployment pod 52, and / or the radiopaque element may be fixed to the deployment pod 52. The radiopaque element includes a band of radiopaque material embedded in the delivery device 50, a band running along the outer circumference of a portion of the delivery device 50, a doped portion of the delivery device 50 (e.g., relative to an adjacent portion), etc. In other examples, the clinician may use the material of the IMD 16A to track the location of the deployment pod 52. For example, the clinician may track the progression of an electrode on the distal tip 96 of the IMD 16A to track the location of the deployment pod 52.

[0090] As discussed above, delivery device 50 may include two or more electrodes. For example, as shown in the side view of delivery device 50 showing IMD 16A outside of deployment chamber 52, Figure 2CAs depicted in the conceptual diagram of FIG. 1 , the deployment chamber 52 may include a pair of first electrodes 90A and second electrodes 92A, while the IMD 16A includes a second pair of first electrodes 90B and second electrodes 92B. The first electrode 90A may include a conductive material secured to an inner surface of the outer wall 76 of the deployment chamber, and the second electrode 92A may include a conductive material secured to an outer surface of the outer wall 76 of the deployment chamber 52. The first electrode 90A may expose the conductive material only to the inner surface of the deployment chamber 52, while the second electrode 92A exposes the conductive material only to the outer surface of the deployment chamber 52. Additionally, the first electrode 90B may be secured to a distal tip 96 of the housing of the IMD 16A, while the second electrode 92B is secured to a proximal portion 100 of the IMD 16A. The two first electrodes 90A, 90B may be substantially similar to the first electrode 90, except for any differences described herein. Similarly, the two second electrodes 92A, 92B may be substantially similar to the second electrode 92 as described herein, except for any differences described herein.

[0091] The circuit system 94 can be configured to provide a first electrical signal between the first electrode 90A and the second electrode 92A of the deployment chamber to determine whether the deployment chamber 52 defines a first fixed configuration. Additionally, the circuit system 94 can be configured to provide a second electrical signal between the first electrode 90B and the second electrode 92B of the IMD 16A to determine whether the IMD 16A defines a second fixed configuration. In some instances, a different set of circuit systems 94 can provide and analyze the first electrical signal as well as the second electrical signal. For example, the first set of circuit systems 94 can reside in the hub 56 of the delivery device 50, and the circuit system 28 of the IMD 16A can include a second set of circuit systems 94. Alternatively, in some instances, a single set of circuit systems 94 can provide and analyze both the first electrical signal between the first electrode 90A and the second electrode 92A of the deployment chamber 52 and the second electrical signal between the first electrode 90B and the second electrode 92B of the IMD 16A.

[0092] Alternatively, in some examples, delivery device 50 may include a common electrode that sends a signal to two (or more) other electrodes to verify the fixed configuration. For example, as shown in the side view of delivery device 50 showing IMD 16A outside of deployment chamber 52 Figure 2DAs depicted in the conceptual diagram of , the deployment chamber 52 may include a pair of first electrodes 90A and second electrodes 92A, and the IMD 16A includes a second version of the first electrode 92A. The circuit system 94 of the delivery device 50 may be configured to provide a first electrical signal between the first electrode 90A and the second electrode 92A of the deployment chamber to determine whether the deployment chamber 52 defines a first fixed configuration, and to provide a second electrical signal between the first electrode 90B and the second electrode 92A of the IMD 16A to determine whether the IMD 16A defines a second fixed configuration. In other words, in some examples, a common electrode (here, the second electrode 92) may be configured to provide an electrical signal to two different paths between two different electrodes (here, the first electrode 90A and the first electrode 90B).

[0093] In some examples, delivery device 50 may be configured to verify both the first and second fixed configurations using first electrode 90B and second electrode 92B of IMD 16A. For example, as shown in FIG. 5A , a side view of delivery device 50 is shown with IMD 16A contained within deployment chamber 52. Figure 2E As depicted in the conceptual diagram of FIG. 1 , the deployment chamber 52 may include one or more holes 86A defined through the outer wall 76 of the deployment chamber 52, while the IMD 16A includes a first electrode 90B and a second electrode 92B. The one or more holes 86A of the deployment chamber 52 may extend radially through the outer wall 76. The one or more holes 86A may be configured to enable blood to flow through the holes 86A to enter the second electrode 92B. In some examples, when the IMD 16A is housed in the deployment chamber 52, the one or more holes 86A may be positioned along the deployment chamber 52 adjacent to the location where the second electrode 92B may be positioned. As depicted, the deployment chamber 52 may define multiple holes 86A at multiple radial and longitudinal locations. Further, in some examples, the IMD 16A may be configured to generally engage the inner surface of the outer wall 76 of the deployment chamber (e.g., such that the outer diameter of the IMD 16A is only nominally smaller than the inner diameter of the deployment chamber 52), making it difficult for fluid to flow within the deployment chamber 52 between the first electrode 90B and the second electrode 92B. Conversely, to allow fluid to flow between first electrode 90B and second electrode 92B, such fluid may flow from distal opening 74 and then through one of the one or more apertures 86A to define such a path. Circuitry 94 of delivery device 50 (e.g., which may be included within circuitry 28 of IMD 16A) may be configured to provide a first electrical signal between first electrode 90B and second electrode 92B to determine whether deployment capsule 52 defines a first fixed configuration, and to provide a second electrical signal between first electrode 90B and second electrode 92B of IMD 16A to determine whether IMD 16A defines a second fixed configuration.

[0094] In some examples, the delivery device 50 can define an aperture in a manner such that the aperture is sealed within the delivery device. Figure 2F and depicts a cross-sectional view through cutting plane 106 Figure 2G As depicted in the conceptual diagram of FIG, the deployment chamber 52 may include one or more ribs 108 extending inwardly from the outer wall 76 to engage the IMD 16A. The ribs 108 may be configured to be deformable to radially compress to secure the IMD 16A within the deployment chamber 52 prior to deployment. For example, the ribs 108 may be made of a relatively soft and compressible biocompatible material such as rubber, silicone, LDPE, thermoplastic elastomer, polyethylene (PE), etc. The ribs 108 may extend longitudinally along the length of the deployment chamber 52. The deployment chamber 52 may define multiple ribs 108 at different longitudinal and radial locations. In some instances, the deployment chamber 52 may include multiple ribs 108 radially arranged around the inner surface of the outer wall 76 of the deployment chamber 52. For example, as depicted, the deployment pod 52 may include four individual ribs 108 that are equally spaced about the longitudinal axis 60 of the delivery device 50 (e.g., such that each of the ribs 108 is 90° away from the circumferentially adjacent ribs 108) all at a shared longitudinal location within the deployment pod 52. In other examples, the deployment pod 52 may include more or fewer ribs 108 radially arranged about the longitudinal axis 60, such as three ribs 108 that are 120° away from each other or five ribs 108 that are each approximately 72° away from the circumferentially adjacent ribs 108. The ribs 108 may be adhesively bonded or otherwise fixedly attached to the inner surface of the outer wall 76 of the deployment pod 52.

[0095] In addition to any differences described herein, the delivery device 50 can include one or more apertures 86B that are substantially similar to aperture 86A. Figure 2F and 2G As depicted in , each of the holes 86B can be aligned with one of the ribs 108. The holes 86B can extend radially inward through the outer wall 76 and the ribs 108. Although Figure 2G Aperture 86B is depicted extending through only one of ribs 108 , but in other examples, aperture 86B may extend through more or all of ribs 108 .

[0096] As ribs 108 extend inwardly to engage IMD 16A, aperture 86B seals against second electrode 92B. As ribs 108 seal second electrode 92B within deployment pod 52 such that second electrode 92B is only exposed to the patient's fluids when inserted into the patient's body, circuit system 94 as discussed herein can identify a more pronounced impedance change caused by deployment pod 52 defining a first fixed configuration as described herein. As a result of the more pronounced impedance change, delivery device 50 can be relatively more likely to correctly determine when deployment pod 52 is defining or not defining a fixed configuration, thereby increasing the likelihood that IMD 16A will be deployed in an effective manner therein.

[0097] Further, in some examples, apertures 86A, 86B (collectively, “apertures 86”) can improve the manner in which deployment capsule 52 is withdrawn from patient 14. For example, as deployment capsule 52 is withdrawn from patient 14 (e.g., after deployment of IMD 16A), distal opening 74 can create a relative negative pressure within deployment capsule 52 that pulls some of the patient's fluid or tissue into deployment capsule 52. Once deployment capsule 52 is fully withdrawn from patient 14 (e.g., by an introducer sheath, etc.), this relative negative pressure can stabilize, thereby causing any fluid or tissue that has been drawn into deployment capsule 52 to leak out or drain from deployment capsule 52. As deployment capsule 52 is withdrawn from the patient, aperture 86 can improve the ability of pressure within deployment capsule 52 to normalize (e.g., to be relatively equal inside and outside of deployment capsule 52), thereby reducing or eliminating a vacuum effect that could pull fluid or tissue into deployment capsule 52. Reducing or eliminating this vacuum effect may reduce or eliminate the possibility of the deployment capsule 52 accumulating and then leaking and / or expelling fluid or tissue from the patient 14 as the deployment capsule 52 is withdrawn from the patient 14 .

[0098] In some examples, the delivery device 50 can be configured to verify when the deployment capsule 52 is pressed into the patient's tissue with a threshold amount of force. Figure 2H As depicted in the conceptual diagram of FIG. 1 , deployment capsule 52 may include a first electrode 90A within deployment capsule 52 and a second electrode 92C at a distal tip of deployment capsule 52. First electrode 90A may be secured to an interior surface of deployment capsule 52 and / or the first electrode may be secured to IMD 16A (e.g., such that first electrode 90B is used in conjunction with second electrode 92C).

[0099] In some examples, the second electrode 92C can be "masked" by a non-conductive material 88 near the distal tip of the deployment chamber 52. The non-conductive material 88 can be any material that does not conduct electricity well. For example, the non-conductive material 88 can include an adhesive applied to the outer surface of the second electrode 92C. The area of ​​the second electrode 92C that is masked by the non-conductive material 88 can include most or all of the distal surface 80 of the second electrode 92 that is adjacent to the deployment chamber 52 (e.g., within about 1 mm of the distal surface). Although the area masked by the non-conductive material 88 is depicted as masking an uneven portion of the second electrode 92C, in other examples, the distal edge second electrode 92C can be uniformly masked by the non-conductive material 88.

[0100] Because the non-conductive material 88 covers the second electrode 92C, the conductive surface of the second electrode 92C may not contact the tissue of the target site when the deployment capsule 52 initially contacts but does press into the tissue of the target site, the electrical signal may include the fluid between the first electrode 90A and the tissue of the target site and the fluid between the second electrode 92C and the tissue of the target site. If the clinician provides further distal force on the delivery device 50, the deployment capsule 52 may press into the tissue of the target site with sufficient force to deform the tissue upward around the outer wall 76 of the deployment capsule 52 and contact the conductive surface of the second electrode 92C that is not covered by the non-conductive material 88. Therefore, the electrical signal between the first electrode 90A and the second electrode 92C may include the fluid between the first electrode 90 and the tissue and then include the tissue between this fluid and the second electrode 92C (e.g., and does not include any fluid between the second electrode 92C and the tissue). Circuitry 94 of delivery device 50 may be configured to identify when the impedance of the electrical signal changes due to contact of the non-masked portion of second electrode 92C with tissue at the target site. In situations where it is advantageous for deployment capsule 52 to be pressed into the tissue with at least a threshold amount of force prior to deployment of IMD 16A, circuitry 94 may indicate when the impedance of the electrical signal rises above a threshold level indicative of this threshold amount of force such that deployment capsule 52 defines a first fixed configuration.

[0101] In some examples, circuitry 94 of delivery device 50 may be coupled to a proximal portion of a metallic conductive can (eg, a housing of IMD 16A) of IMD 16A to create a first electrode at a distal portion of IMD 16A. Fig.2Iis a conceptual diagram showing an example first electrode 90C of a metal can containing an IMD 16A and a second electrode 92D on the elongated member 54 of the delivery device 50. The second electrode 92D can be substantially similar to the second electrodes 92A, 92B, 92C, except for any differences described herein. The second electrode 92D can be fixed to the outer surface of the distal portion of the elongated member 54 and can be configured to be exposed to the fluid of the patient 14 when the deployment capsule 52 is navigated to the target site. Further, the delivery device 50 can include a clamp 110, which includes teeth 112. The clamp 110 can be configured to slide within the deployment mechanism 66 of the delivery device 50. Specifically, the clamp 110 can be configured to be longitudinally movable within the lumen of the deployment mechanism 66 so that the teeth 112 of the clamp 110 can be closed on the proximal hook 114 of the IMD 16A. The teeth 112 can be actuatable (e.g., openable or closable) under the control of the clinician. For example, as described above, the clinician can actuate the teeth 112 of the clamp 110 to open or close it from the control mechanism on or adjacent to the hub 56 for the deployment mechanism 66. Fig.2I 1. For purposes of clarity, proximal hook 114 is shown without engagement of clamp 110, but it should be understood that clamp 110 may engage proximal hook 114 until IMD 16A is verified (eg, by circuit system 94) to be securely secured to the target site as discussed herein.

[0102] In some examples, the clamp 110 and the teeth 112 can be electrically coupled to a power source. For example, the second electrode 92D can be electrically coupled to a first terminal of the power source, while the clamp and the teeth are electrically coupled to a second terminal of the same power source. Thus, when the teeth 112 are closed on the proximal hooks 114 of the metal can of the IMD 16A, the metal can can be electrically coupled to the second terminal of the power source, such that the metal can is the first electrode 90C.

[0103] In some examples, some or most of IMD 16A may include coating 116. Coating 116 may include an electrically insulating material. For example, some or most of IMD 16A may be coated with coating 116 including a chemical vapor deposition material such as poly-para-xylylene, specifically Parylene. A portion of coating 116 may be stripped near proximal hook 114 and distal tip 96. Because it should be understood that in other examples, more or less of IMD 16A may be covered by coating 116, the amount of IMD 16A covered by coating 116 is depicted for purposes only. In some examples, it may be advantageous to maximize the amount of IMD 16A covered by coating 16A to better electrically insulate IMD 16A and potentially improve the battery life of the power source of IMD 16A therein.

[0104] Teeth 112 of clamp 110 may engage proximal snap 114 of proximal end 100 to “light up” the metal can of IMD 16A (e.g., electrically couple the can to a power source beneath insulating coating 116). In this manner, the surface of the metal can near distal tip 96 of IMD 16A acts as first electrode 90C as described herein, such that circuit system 94 may analyze the impedance of a path between first electrode 90C outside distal opening 74 of deployment capsule 52 and second electrode 92D on the distal portion of elongated member 54.

[0105] In some examples, as described herein, the second electrode may not be directly attached to the delivery device 50 but may instead be attached via a patch electrode, a subcutaneous electrode, or the like. For example, the delivery device 50 may not include the second electrode 92D, but rather the second electrode may include a patch electrode on the skin of the patient 14 or a subcutaneous electrode in a subcutaneous pocket of the patient 14. This second electrode may be a return electrode coupled to a power source. The circuit system 94 as described herein may calculate the impedance of the electrical signal between the first electrode 90C and this second electrode to verify whether the deployment module 52 defines a fixed configuration.

[0106] Figure 3 A schematic block diagram of circuitry 94 is shown that may be used with any of the devices described herein to verify that a deployment module and / or an IMD defines a first and / or second fixed configuration as described herein as identified by sending and analyzing electrical signals between a first electrode and a second electrode. Figure 3 For purposes of illustration, the circuit system 94 is depicted as a set of blocks, but it is understood that the circuit system 94 may include any number of current sources, regulators, oscillators, transistors, capacitors, etc. Further, by focusing on the delivery device 50 and the like for purposes of clarity below, Figure 2A The corresponding first electrode 90 and second electrode 92 are discussed in Figure 3 94, but it should be understood that in some examples, Figure 3 Circuitry 94 may additionally or alternatively be included within circuitry 28 of IMD 16A. Circuitry 94 includes processing circuitry 120, memory 122, signal generation circuitry 124, impedance detection circuitry 126, indication circuitry 128, and power supply 130.

[0107] Processing circuitry 120 may include any one or more microprocessors, controllers, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic circuitry, or any processing circuitry configured to perform the features attributed to processing circuitry 120. The functionality attributed to the circuitry described herein, including processing circuitry 120, signal generation circuitry 124, impedance detection circuitry 126, and indication circuitry 128, may be provided by hardware devices and embodied in software, firmware, hardware, or any combination thereof.

[0108] Memory 122 may include any volatile or non-volatile media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, etc. Memory 122 may store computer-readable instructions that, when executed by the circuit system of circuit system 94, cause circuit system 94 to perform various functions described herein. In some instances, memory 122 may be considered a non-transitory computer-readable storage medium containing instructions that cause one or more processors (e.g., processing circuit system 120) to implement one or more of the example techniques described in the present disclosure. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or propagated signal. However, the term "non-transitory" should not be interpreted to mean that memory 122 is non-removable. As an example, memory 122 may be removed from delivery device 50 and moved to another device. In some instances, a non-transitory storage medium may store data that may change over time (e.g., in RAM).

[0109] The processing circuit system 120 is configured to cause the signal generation circuit system 124 to generate an electrical signal and deliver the electrical signal to the tissue of the patient 14 along the path 132 between the first electrode 90 and the second electrode 92. The signal generation circuit system 124 includes an electrical signal generation circuit system such as a current source (e.g., a current mirror and some transistors coupled to the power supply 130), and is configured to generate the electrical signal and deliver the electrical signal in the form of a known and / or constant voltage potential or current across the first electrode 90 and the second electrode 92 (e.g., so that regardless of the waveform of the electrical signal, the signal generation circuit system 124 can compensate for impedance so that although the electrical signal can change over time in a predetermined manner as expected, the amplitude of the electrical signal can remain consistent). For example, the signal can contain 100 microamps and can be between 8 kilohertz and 100 kilohertz.

[0110] In some examples, the delivery device 50 may be configured such that the conductors as described herein are independently coupled to one or more electrodes. For example, the delivery device 50 may be configured to verify that the distal surface 80 defining the distal opening 78 of the deployment chamber 52 is defining a first fixed configuration in which the first electrode 90A is within the recess 74 and the second electrode 92A is fixed to the outer surface of the outer wall 76 of the deployment chamber 52. Additionally, the delivery device 50 may be configured to verify that the IMD 16A is defining a second fixed configuration in which the first electrode 90B is at the distal tip 96 of the IMD 16A and the alternative second electrode 92B is on the outer surface of the proximal portion 100 of the IMD 16A. In such examples, the processing circuit system 120 may control the signal generation circuit system 124 to generate and deliver different electrical signals through different combinations of conductors and / or electrodes (e.g., to the initial second electrode 92A positioned outside the recess 74 and the alternative second electrode 92 on the proximal portion 100 of the IMD 16A). In these examples, the processing circuitry 94 may include switching circuitry for switching delivery of electrical signals between different pairs of first and second electrodes 90 , 92 (eg, as switched under control of the processing circuitry 120 ).

[0111] Impedance detection circuitry 126 may be configured to identify and analyze the impedance of electrical signals sent across path 132 between first electrode 90 and second electrode 92. As described herein, the impedance may change depending on the positioning of deployment capsule 52 and IMD 16A relative to the tissue of the target site. For example, the impedance may increase when path 132 contains tissue rather than just fluid of patient 14, and the impedance may reflect the inherent waveform of heart 12 with more or less noise and / or stability depending on the degree to which first electrode 90 is seated against the tissue of the target site. Impedance detection circuitry 126 may be configured to isolate and identify this impedance.

[0112] The impedance detection circuit system 126 can identify the impedance level by including a sample and hold circuit system to sample the voltage drop across the resistor. Using this voltage drop, the impedance detection circuit system 126 can calculate the impedance. The impedance detection circuit system 126 can sample the voltage drop at a sampling rate high enough to reliably identify the impedance signal. For example, the impedance detection circuit system 126 can sample the voltage drop at a sampling rate of approximately 1000 Hz.

[0113] Once the impedance detection circuit system 126 determines the impedance, the processing circuit system 120 can determine whether these impedance characteristics indicate that the deployment chamber 52 and / or IMD 16A define a first or second fixed configuration relative to the tissue of the target site. Although the processing circuit system 120 is discussed herein as analyzing "raw" or otherwise unmanipulated impedance data, it should be understood that the processing circuit system 120 can perform one or more operations before determining whether the impedance data indicates a first or second fixed configuration. For example, before and / or in addition to performing the functions discussed herein, the processing circuit system 120 can identify one or more derivatives of the impedance data. As the derivatives can highlight any sudden changes in the impedance data over time, the use of identifying and analyzing the derivative data can improve the ability of the processing circuit system 120 to identify fixed configurations and / or non-fixed configurations.

[0114] For example, processing circuitry 120 may determine whether an electrical signal generated by signal generation circuitry 124 and delivered to path 132 between first electrode 90 and second electrode 92 results in an impedance above an impedance threshold 134 stored in memory 122. Impedance threshold 134 may comprise a static value, where a momentary spike is sufficient for impedance detection circuitry 126 to determine that deployment compartment 52 has defined a first fixed configuration. Additionally, impedance threshold 134 may comprise an average impedance magnitude over a period of time (e.g., over 1 or two seconds).

[0115] Additionally or alternatively, processing circuit system 120 can be configured to identify the amount by which the current leads or lags the voltage across path 132 in order to identify the phase of heart 12 based on the impedance. Processing circuit system 120 can identify whether the phase satisfies a phase threshold 133 as stored in memory 122. In some examples, processing circuit system 120 can be configured to determine whether the identified phase satisfies a plurality of phase thresholds 133 as related to whether deployment capsule 52 is generally contacting or pressing into tissue at a target site as discussed herein. Further, processing circuit system 120 can be configured to perform an FFT on the electrical signal across path 132 to identify various frequency components as reflected in the impedance.

[0116] In the event that the impedance detected by the impedance detection circuitry 126 is above the impedance threshold 134 and / or when the phase identified by the processing circuitry 120 is above the phase threshold 133, the processing circuitry 120 may cause the indication circuitry 128 to provide a first fixed configuration indication on the user interface 104. The indication circuitry 128 may include components that may provide an output that may be identified by a clinician as indicating a fixed or non-fixed configuration. For example, the indication circuitry 128 may include an LED (e.g., a user interface 104 positioned on the hub 56), a speaker, a tactile feedback device, a screen, etc. The processing circuitry 120 may cause the indication circuitry to provide a predetermined output (e.g., a green color on an LED or a positive ding on a speaker or a success message on a screen) in response to determining that the impedance indicates a fixed configuration. For another example, the indication circuitry 128 may include a telemetry circuitry, and the processing circuitry 120 may cause the indication circuitry 128 to be Figure 1A and Figure 1B The external device 18 provides a message to display the successful first fixed configuration on the display of the external device 18.

[0117] For another example, circuitry 94 may be used to determine whether IMD 16A defines a second fixed configuration. In such an example, processing circuitry 120 may cause signal generation circuitry 124 to provide a signal to path 132 between electrodes 90, 92 that is similar to or different from the signal used to determine whether deployment compartment 52 defines a first fixed configuration (and / or path 132 as described herein). Processing circuitry 120 may cause signal generation circuitry 124 to provide a second signal and / or cause impedance detection circuitry 126 to identify an impedance therein, which processing circuitry 120 uses to determine whether the second signal indicates that IMD 16A defines a second fixed configuration in response to obtaining input (e.g., from a clinician) that is particularly relevant to verifying the second fixed configuration. Alternatively, processing circuit system 120 may cause signal generation circuit system 124 to generate a second signal and then cause impedance detection circuit system 126 to determine an impedance that processing circuit system 120 uses to determine whether the impedance of the second signal automatically indicates the second fixed configuration (such that deployment compartment 52 defines the first fixed configuration) in response to impedance detection circuit system 126 identifying that the impedance of the first signal determined by processing circuit system 120 exceeds impedance threshold 134. In some examples, processing circuit system 120 may cause signal generation circuit system 124 to provide a continuous first signal and cause impedance detection circuit system 126 to continuously determine the real-time impedance level in response to processing circuit system 120 determining the real-time first fixed configuration or non-fixed configuration. When signal generation circuit system 124 begins to provide the second signal and processing circuit system 120 begins to determine whether the impedance of the second signal indicates the second fixed configuration (e.g., in the case where different groups of conductors and electrodes provide signals), processing circuit system 120 may cause signal generation circuit system 124 and impedance detection circuit system 126 to provide these continuous functions and assessments.

[0118] Processing circuit system 120 can determine whether the electrical signal generated by signal generation circuit system 124 and delivered to first electrode 90 and second electrode 92 indicates that IMD 16A defines a second fixed configuration by evaluating the amount of noise in the impedance waveform. In other words, processing circuit system 120 determines whether the impedance waveform of the second signal across path 132 contains and / or satisfies one or more noise indicators 135, or whether the impedance of the second signal is stable and smooth as described herein. Noise indicators 135 stored in memory 122 and used by processing circuit system 120 include slope threshold 136, bimodal feature 137, phase threshold 138, and FFT threshold 139.

[0119] Slope threshold 136 may include a set of threshold slopes that the impedance may include or be within and recognized by processing circuitry 120 as defining the second fixed configuration. For example, the slope may satisfy slope threshold 136 where the slope is substantially smooth (e.g., linear or nearly linear) between peaks and valleys of the impedance waveform such that the slope substantially avoids defining steps, level segments, sharp angles, etc. between peaks and valleys. Fig. 8A and 8B 1 and the discussion below depict and discuss slopes that may or may not satisfy slope threshold 136. Processing circuitry 120 may determine that the impedance waveform identified by impedance detection circuitry 126 satisfies slope threshold 136, thereby indicating therein that IMD 16A defines a second fixed configuration. In response to this determination, processing circuitry 120 may cause indicating circuitry 128 to indicate the second fixed configuration using user interface 104.

[0120] Further, the double peak signature 137 may include a minimum peak in an otherwise generally sinusoidal impedance waveform (e.g., Fig. 8A ). Processing circuitry 120 may determine that the impedance waveform containing double-peaked feature 137 indicates that IMD 16A defines a second fixed configuration. In response to this determination, processing circuitry 120 may cause indicating circuitry 128 to indicate the second fixed configuration using user interface 104.

[0121] Further, as discussed herein, processing circuit system 120 may identify the amount of noise in the signal by analyzing the relative hysteresis of the current and voltage across path 132. For example, processing circuit system 120 may identify and evaluate the phase of the impedance based on the relative hysteresis. Once identified, processing circuit system 120 may determine whether the phase is within phase threshold 138. If the waveform of the phase defines relatively static peaks and valleys across the waveform, processing circuit system 120 may determine that the phase is within phase threshold 138. For example, if each peak is substantially similar to adjacent peaks (e.g., within 0.2°) and each valley is substantially similar to adjacent valleys (e.g., within 0.2°), the phase may be within phase threshold 138. Further, processing circuit system 120 may identify whether the phase waveform contains a double-peaked feature 137 as discussed herein. If processing circuit system 120 determines that the phase waveform satisfies phase threshold 138 and fails to define double-peaked feature 137, the impedance detection circuit system may determine that the phase waveform indicates that IMD 16A defines a second fixed configuration. In response to this determination, processing circuitry 120 may cause indicating circuitry 128 to indicate the second fixed configuration using user interface 104 .

[0122] Additionally, as discussed herein, processing circuit system 120 may use FFT to identify components of impedance. Processing circuit system 120 may use FFT to isolate frequency components of the signal across path 132. For example, processing circuit system 120 may identify a fundamental frequency corresponding to the heartbeat of patient 14 and multiple harmonic frequencies of the signal. Once identified, processing circuit system 120 may identify whether the amplitude of any of the identified harmonics satisfies an FFT threshold 139 stored in memory 122. FFT threshold 139 may be related to the ratio of the amplitude of one or more harmonic frequencies to the amplitude of the fundamental frequency. For example, FFT threshold 139 may include a ratio between 1:5 and 1:3 (e.g., 1:4) between the first harmonic (e.g., the harmonic with the largest amplitude) and the fundamental frequency. Processing circuitry 120 may be configured to use this 1:4 FFT threshold 139 to identify that the determined FFT data indicates that IMD 16A defines a fixed configuration when the amplitude of the first harmonic is less than 25% of the amplitude of the fundamental frequency (e.g., due to successful fixation of fixation element 82 of IMD 16A to tissue at the target site). Similarly, processing circuitry 120 may use this FFT threshold 139 to identify that the FFT data indicates that IMD 16A defines a non-fixed configuration when the amplitude of the first harmonic is greater than 25% of the amplitude of the fundamental frequency.

[0123] For another example, FFT threshold 139 may include a ratio between 1:3 and 2:3 between the sum of the amplitudes of the first two, three, or four harmonics (e.g., the four harmonics with the four largest amplitudes) and the fundamental frequency. In some examples, FFT threshold 139 may include a ratio of 1:2 between the sum of the amplitudes of the first three harmonics and the fundamental frequency. Processing circuit system 120 may be configured to use this FFT threshold 139 to identify that the determined FFT data indicates that IMD 16A defines a fixed configuration when the sum of the amplitudes of the first three harmonics is less than 50% of the amplitude of the fundamental frequency. Similarly, when the sum of the amplitudes of the first three harmonics is greater than 50% of the amplitude of the fundamental frequency, processing circuit system 120 may use this FFT threshold 139 to identify that the FFT data indicates that IMD 16A defines a non-fixed configuration.

[0124] Although the FFT of the impedance signal is primarily discussed herein, in other instances, other Fourier transforms and / or other transformations of other components into the frequency domain may be used to determine whether the signal indicates a fixed or non-fixed configuration. For example, the processing circuit system 120 may be configured to analyze an electrogram from a lead inserted / implanted in the right ventricle 22 or a surface electrocardiogram from a surface patch or the pressure of the left ventricle 26 collected from a pressure sensor inserted / implanted in the left ventricle 26 using FFT techniques or other similar transformations. When converting these data signals into the frequency domain, the processing circuit system 120 may identify whether certain frequency components of these signals have a magnitude greater than a threshold (e.g., where the magnitude above the threshold is contained in the noise indicator 135 of the memory 122 of the circuit system 94), and may therefore determine that one or more components of the signal delivered or otherwise captured or identified by the delivery device 50 are defining a non-fixed configuration 150 due to the frequency components defining a magnitude greater than the threshold.

[0125] In some examples, circuit system 94 may be configured to determine and indicate a single instantaneous configuration arrangement of deployment pod 52 and IMD 16A relative to tissue at the target site. For example, processing circuit system 120 may cause signal generation circuit system 124 to generate a voltage potential across first electrode 90 and second electrode 92 for a time period sufficient for processing circuit system 120 to determine and analyze the impedance of the electrical signal delivered across path 132 in response to processing circuit system 120 causing signal generation circuit system 124 to cease the voltage potential (and causing indication circuit system 128 to provide an indication of the configuration to user interface 104). For example, processing circuit system 120 may cause signal generation circuit system 124 to provide a signal for between 1 second and 5 seconds (a duration that may provide an indicative average value). In such examples, a clinician may provide input to circuit system 94 (e.g., using user interface 104 and / or programmer 18, etc.) in response to the circuit system providing a single configuration analysis (e.g., deployment pod 52 defines a first fixed configuration, IMD 16A defines a second fixed configuration, no delivery device 50 is in any fixed configuration). In other words, in some examples, the circuit system 94 may be configured to provide a "snapshot" of the instantaneous and transient spatial alignment of the delivery device 50 with tissue at the target site.

[0126] In other examples, the circuit system 94 can be configured to determine and indicate configuration information that changes over time. For example, the processing circuit system 120 can cause the signal generation circuit system 124 to generate a continuous and substantially static voltage potential across the first electrode 90 and the second electrode 92, so that the impedance detection circuit system 126 identifies a continuous impedance, and the processing circuit system 120 uses the continuous impedance to provide a continuous analysis of the continuous impedance of the continuous electrical signal delivered across the path 132. Therefore, the processing circuit system 120 can control the indication circuit system 128 to cause the user interface 104 to provide a fixed configuration that changes over time in response to the impedance update from the impedance detection circuit system 126. In such examples, the clinician can provide an initial input to the circuit system 94 (e.g., using the user interface 104 and / or the external device 18, etc.) to start providing a continuous fixed configuration indication in response to the circuit system 94 can continue to provide an indication until the clinician instructs the circuit system 94 to stop providing a fixed configuration indication. For example, the clinician may, in response to the signal generation circuit system 124, deliver an electrical signal to the path 132 between the first electrode 90 and the second electrode 92, in response to the processing circuit system 120, initially determine that the impedance detected by the impedance detection circuit system 126 is below the impedance threshold 134, in response to the indication circuit system 128, cause the user interface 104 to indicate that the first fixation configuration has not been defined (e.g., by causing the LED to display a red light), in response to the clinician, cause the deployment chamber 52 to move against tissue at the target site, in response to the processing circuit system 120, determine that the impedance of the electrical signal across the path 132 identified ... The impedance has changed to above the impedance threshold 134, in response to the indication circuit system 128 causing the user interface 104 to indicate a first fixed configuration (e.g., a green light), in response to the clinician being able to unfold the IMD 16A, in response to the processing circuit system 120 being able to determine that the impedance waveform of the signal across the path 132 does not include a bimodal feature 137, in response to the indication circuit system 128 causing the user interface 104 to indicate a second fixed configuration (e.g., a blue light), in response to the clinician being able to provide an initial input to the circuit system 94 for providing an input for stopping delivery of an electrical signal to the path 132 between the first electrode 90 and the second electrode 92 to begin providing a fixed indication.

[0127] Power source 130 delivers operating power to the various components of circuit system 94. In some examples, power source 130 may represent a hard-wired power source of alternating current or direct current. In other examples, power source 130 may include a small rechargeable or non-rechargeable battery and power generation circuitry for generating operating power. In the case where power source 130 is rechargeable, recharging may be accomplished by proximal inductive interaction between an external charger and an inductive charging coil coupled to power source 130.

[0128] In some examples, as conceptually depicted, processing circuitry 120, memory 122, signal generation circuitry 124, impedance detection circuitry 126, indication circuitry 128, and power source 130 may all be directly physically coupled to each other and to electrodes 90, 92 through a physical medium (e.g., wires or vias or traces, etc.). Further, in some examples, each of processing circuitry 120, memory 122, signal generation circuitry 124, impedance detection circuitry 126, indication circuitry 128, and power source 130 may be housed within a single housing (e.g., a hermetically sealed housing of IMD 16A or within hub 56 of delivery device 50, etc.). In other examples, different elements of circuitry 94 may be housed in two or more housings and may communicate using various physical (e.g., wired) connections and wireless communication protocols.

[0129] For example, IMD 16A may include some signal generation circuitry 124, impedance detection circuitry 126, a power source 130 to power signal generation circuitry 124 and impedance detection circuitry 126, and some processing circuitry (e.g., processing circuitry similar to but less powerful than processing circuitry 120) configured to cause signal generation circuitry 124 to generate an electrical signal to a path 132 between electrodes 90, 92 and impedance detection circuitry 126 to detect the impedance of the signal across path 132. In this example, this processing circuitry 120 may be further configured to transmit impedance data detected by impedance detection circuitry 126 to another device including processing circuitry 120, memory 122, and indication circuitry 128 using telemetry circuitry (not depicted). For example, the IMD 16A may send impedance data to another device external to the IMD 16A (e.g., external device 18) that may include processing circuitry 120, memory 122, and indication circuitry 128 in response to the other device being able to analyze the impedance data and verify whether the deployment bay 52 and / or the IMD 16A define a first or second fixed configuration as described herein.

[0130] Figure 4A and 4B 1 is a conceptual diagram illustrating views taken along a longitudinal axis 60 of a delivery device 50 not defined and then defined in a first securement configuration relative to a target site 140 within a patient 14, respectively. Figure 4A and Figure 4BFor purposes of clarity, delivery device 50 is depicted without IMD 16A because the first fixation configuration is between deployment pod 52 and tissue of target site 140. As described herein, target site 140 may be in right atrium 20 of heart 12 of patient 14, although in other examples, delivery device 50 may be used to deliver implantable medical devices to other areas of patient 14. Target site 140 may include a tissue layer 142 that IMD 16A is configured to penetrate during deployment in order to secure IMD 16A to target site 140. In other words, in some examples, IMD 16A is configured to mechanically attach itself to tissue layer 142 of target site 140. IMD 16A may be configured to use fixation elements 82 (e.g., distal tines) that are configured to be attached to the target site 140 when IMD 16A is deployed (e.g., using Figure 2A and 2B Some other fixation device (e.g., a helical coil) extending distally from deployment bay 52 (e.g., a deployment mechanism 66 that pushes IMD 16A distally out of distal opening 78 of deployment bay 52) secures itself to tissue layer 142. Further, in some examples, target site 140 may include a muscle layer 144 that is beneath tissue 142 and distal to a reference of delivery device 50 (i.e., further away from delivery device 50 than tissue 142).

[0131] like Figure 4A As depicted in FIG. 1 , the clinician has navigated delivery capsule 52 of delivery device 50 to target site 140 such that IMD 16A ( FIG. 140 ) as at least partially contained within delivery capsule 52 is positioned within target site 140. Figure 4A Due to the distal force 146 applied to the delivery device 50, the deployment capsule 52 can be navigated close to the target site 140. The clinician can apply the distal force 146 by, for example, manually applying force to one or more proximal components of the delivery device 50. For example, the clinician can apply the distal force 146 to the hub 56 ( Figure 2A ) or otherwise applying distal force 146 using hub 56.

[0132] like Figure 4A As depicted in FIG. 1 , the deployment capsule 52 may contact tissue 142 at the target site 140 due to a distal force 156 (e.g., as applied by a clinician). The deployment capsule 52 may contact tissue 142 at an angle 148 relative to the longitudinal axis 60 of the delivery device 50. In other words, Figure 4AThe distal surface 80 of the deployment chamber 52 is depicted as defining a distal opening 78 that is at an angle 148 with respect to the target site 140 (e.g., rather than the two surfaces being flush or parallel to each other). Due to approaching the target site 140 at the angle 148, the deployment chamber 52 can define a path 132A (which can be substantially similar to the path 132) between the first electrode 90A and the second electrode 92A. Figure 4A , because deployment pod 52 contacts tissue 142 at angle 148, path 132A initially extends substantially only through fluid of patient 14 (e.g., not tissue 142). If delivery device 50 deploys IMD 16A when distal surface 80 defining distal opening 78 of deployment pod 52 is at angle 148 with respect to target site 140, tines or fixation elements 82 of IMD 16A may have difficulty securing to target site 140 as intended. For example, tines or fixation elements 82 of IMD 16A proximal to a side of deployment pod 52 that contacts tissue 142 may be secured to muscle 144, while tines or fixation elements opposite side 162 may not be successfully secured to any tissue 142 at target site 140.

[0133] The clinician may provide prompts to the circuit system 94 to send an electrical signal to the path 132A between the first electrode 90A and the second electrode 92A. Figure 4A The positioning of the first electrode 90A and the second electrode 92A depicted in FIG. 5 is for illustrative purposes only, as in other examples, both the first electrode 90A and the second electrode 92A may be at different locations and / or may be fixed to or otherwise be part of other components. For example, in some cases, as described herein, the first electrode 90A may be a distal electrode on the distal tip 96 of the IMD 16A. For another example, in some cases, the first and / or second electrodes 90A, 92A may not extend completely around the inner or outer surface of the deployment module 52, respectively, but may only occupy discrete circumferential portions of the inner or outer surface of the deployment module 52.

[0134] The clinician can provide a prompt to the circuit system 94 to test whether the expansion chamber 52 is defining a first fixation level relative to the tissue 142. The clinician can provide a prompt in response to detecting that the expansion chamber 52 has approached the tissue 142 of the target site 140. The clinician can detect that the expansion chamber 52 has approached the tissue 142 of the target site 140 by tracking one or more radiopaque elements (not depicted) fixed to or adjacent to the expansion chamber 52. In some instances, the first electrode 90A and / or the second electrode 92A can act as a radiopaque element. The clinician can use the external device 18 or use the user interface 104 on the hub 56 or use some other input mechanism to provide a prompt to start the test. In some instances, the clinician can provide a specific input to use the first electrode 90A in the expansion chamber 52 and the second electrode 92A outside the expansion chamber 52 to test whether the expansion chamber 52 defines a first fixation configuration relative to the tissue 142 of the target site 140 (for example, instead of testing whether the IMD 16A defines a second fixation configuration relative to the tissue 142 of the target site 140).

[0135] The processing circuit system 120 can receive input from the clinician and cause the signal generation circuit system 124 to generate a signal along the path 132A. The signal generation circuit system 124 can generate a relatively static voltage potential across the first and second electrodes 90A, 92A using the conductor 102 extending longitudinally through the delivery device 50. It should be understood that the signal generation circuit system 124 can generate a relatively static voltage potential across the first and second electrodes 90A, 92A using the conductor 102 extending longitudinally through the delivery device 50. Figure 4A (as well as Figure 4B ) is depicted for illustration purposes only. Processing circuit system 120 can detect that the impedance across path 132A detected by impedance detection circuit system 126 is below impedance threshold 134 due to path 132A being completely filled with fluid from patient 14. Therefore, processing circuit system 120 can detect that deployment capsule 52 is defining a non-fixed configuration 150A relative to tissue 142 of target site 140. Processing circuit system 120 can cause indication circuit system 128 to provide an indication that deployment capsule 52 is in non-fixed configuration 150A (e.g., using user interface 104).

[0136] In response to the clinician noticing the user interface 104 indicating the non-fixed configuration 150A (e.g., as displayed on the external device 18), the clinician can navigate or otherwise manipulate or deflect the deployment capsule 52 relative to the tissue 142 of the target site 140. For example, as in Figure 4BAs depicted in the conceptual view along the longitudinal axis 60 of the delivery device 50, the clinician can control the delivery device 50 (e.g., using one or more steering or movement or deflection mechanisms of the hub 56) to define a first fixed configuration 152A for the deployment chamber 52 relative to the tissue 142 of the target site 140. The first fixed configuration 152A can include a surface 80 defining the distal opening 78 of the deployment chamber 52 that is substantially and / or completely flush with the tissue 142 of the target site 140. In other words, the first fixed configuration 152A can include the longitudinal axis 60 of the delivery device 50 and in which the deployment chamber 52 is perpendicular to the surface defined by the tissue 142 of the target site 140 (substantially at right angles to the surface).

[0137] As discussed herein, the circuit system 94 can detect and verify when the deployment chamber 52 defines the first fixed configuration 152A relative to the tissue 142 of the target site 140. For example, as discussed herein, the processing circuit system 120 can cause the signal generation circuit system 124 to generate an electrical signal across the path 132A between the first electrode 90A and the second electrode 92A. Figure 4B , when the deployment chamber 52 defines the first fixed configuration 152A relative to the tissue 142 of the target site 140, the path 132A may include some of the tissue 142. The processing circuit system 120 may detect that the impedance detected by the impedance detection circuit system 126 has risen above the impedance threshold 134 (e.g., due to the path 132A including the tissue 142 of the patient 14). In response to the processing circuit system 120 detecting that the impedance of the path 132A has risen above the impedance threshold 134, the processing circuit system 120 may cause the indication circuit system 128 to provide an indication using the user interface 104 that the deployment chamber 52 is defining the first fixed configuration 152A.

[0138] In some examples, circuit system 94 can generate a continuous electrical signal on path 132A and can provide therein an indication as to whether deployment compartment 52 is defining first fixed configuration 152A. For example, in response to processing circuit system 120 determining that the impedance of path 132A is lower than 100% due to deployment compartment 52 defining non-fixed configuration 150A, Figure 4A 134, processing circuit system 120 may cause indication circuit system 128 to provide a continuous indication of non-fixed configuration 150A. Processing circuit system 120 may cause indication circuit system 128 to provide a continuous indication until processing circuit system 120 receives input from the clinician to stop providing the indication. If processing circuit system 120 detects that the impedance of path 132A detected by impedance detection circuit system 126 rises above impedance threshold 134 (e.g., as Figure 4B), processing circuit system 120 may cause indication circuit system 128 to provide different continuous indications indicating first fixation configuration 152A. In this manner, the clinician may receive a continuous indication of whether deployment pod 52 is stably defining first fixation configuration 152A (e.g., when deployment pod 52 defines first fixation configuration 152A for two second straight lines as indicated by user interface 104), and wherein the clinician may deploy IMD 16A in response to deployment pod 52 stably defining first fixation configuration 152A. By configuring circuit system 94 to determine and indicate a continuous and real-time (e.g., substantially instantaneous) fixation state of deployment pod 52, circuit system 94 may improve the ability of delivery device 50 to deploy IMD 16A in an effective fixed alignment as discussed herein.

[0139] In some examples, first fixation configuration 152A can include surface 80 defining distal opening 78 that contacts tissue 142, such that delivery device 50 is effectively arranged to deploy IMD 16A as long as surface 80 contacts tissue 142. In other words, in such examples, deployment capsule 52 defines first fixation configuration 152A as long as substantially all of distal surface 80 contacts tissue 142. In other examples, first fixation configuration 152A can include surface 80 defining distal opening 78 that presses against tissue 142 at a target site, such that delivery device 50 is effectively arranged to deploy IMD 16A as long as surface 80 presses into tissue 142. Distal surface 80 of deployment capsule 52 can press against tissue 142 due to distal force 146. Distal surface 80 can press into tissue 142 with sufficient force to momentarily deflect and / or deform tissue 142, but without penetrating or otherwise damaging tissue 142. Whether first fixation configuration 152A includes contacting tissue 142 or pressing into the tissue may be related to the manner in which fixation element 82 of IMD 16A is deployed from deployment bay 52 to become secured to tissue 142 at target site 140. For example, in some cases, fixation element 82 may be configured such that fixation element 82 may be relatively more likely to secure IMD 16A in a preferred manner when surface 80 initially contacts tissue 142. Alternatively, in other cases, fixation element 82 may be configured such that fixation element 82 may be relatively more likely to secure IMD 16A in a preferred manner when surface 80 is pressed against tissue 142. In either case, circuit system 94 may be configured to verify when distal surface 80 defines such a fixation configuration.

[0140] For example, the impedance of the electrical signal across path 132A may be relatively low due to distal surface 80 being flush with (rather than pressed against) tissue 142 of target site 140. The impedance may be relatively low due to slight deviations (e.g., non-flat features) in the surface of a small channel between defined surface 80 of tissue 142 and tissue 142 through which a small amount of fluid may pass (e.g., because surface 80 is not pressed against tissue 142 to deform tissue 142 and effectively eliminate the existence of such a channel therein). Thus, where fixation element 82 and IMD 16A are configured such that IMD 16A is more likely to be effectively fixed when distal surface 80 contacts tissue 142 (rather than pressed against the tissue), impedance threshold 134 stored in memory 122 and used by processing circuitry 120 may be relatively low. Similarly, where fixation element 82 and IMD 16A are configured such that IMD 16A is more likely to be effectively fixed when distal surface 80 is pressed against tissue 142 (rather than just flush with the tissue), impedance threshold 134 stored in memory 122 and used by processing circuit system 120 may be relatively high.

[0141] Further, as discussed herein, circuitry 94 may be configured to detect and verify when and / or whether IMD 16A defines a second fixed configuration relative to tissue 142 of target site 140 when IMD 16A is deployed. For example, Figures 5A-5D A conceptual illustration of IMD 16A being deployed from deployment capsule 52 at target site 140 is depicted. Figures 5A-5D For purposes of illustration, outer wall 76 of deployment pod 52 is depicted as transparent to depict IMD 16A, but it should be understood that in some instances, outer wall 76 of deployment pod 52 may not be transparent. Circuit system 94 may generate electrical signals along path 132B between first electrode 90B and second electrode 92B (which may be substantially similar to path 132 and path 132A, except for any differences described herein) to be sent through tissue 142 and fluid of patient 14. As depicted, first electrode 90B may be secured to distal tip 96 of IMD 16A, while second electrode 92B comprises a band that runs around at least a portion of an outer perimeter of IMD 16A. First electrode 90B may be substantially similar to first electrode 90 and first electrode 90A, and second electrode 92B may be substantially similar to second electrode 92 and second electrode 92B.

[0142] Figures 5A-5D Fixation elements 82A, 82B (collectively, "fixation elements 82") are depicted deployed from deployment pod 52 to secure IMD 16A to tissue 142. Figures 5A-5DAs depicted in FIG. 8 , the fixing element 82 may include sharp teeth. The fixing element 82 includes a plurality of teeth. Figures 5A-5D The IMD 16A may include two tines that are mirror images of the mid-span electrode 90B, but may include more or fewer fixation elements 82 in other examples. For example, the IMD 16A may include three, four, or more tine fixation elements 82 arranged in a circular arrangement around the first electrode 90B on the distal tip 96 of the IMD 16A, or the IMD 16A may include a single helical coil that wraps around the electrode 90B as the helical coil extends distally from the distal tip 96 of the IMD 16A. The fixation element 82 including the tines may include a distal end that is configured to extend into the tissue 142 and then curl proximally out of the tissue 142 back toward the IMD 16A. However, in other examples, the fixation element 82 may include tines that operate differently, or the fixation element 82 may include a distal helical coil, etc. The fixation element 82 may be configured to secure the IMD 16A to the tissue 142 such that the first electrode 90B contacts the tissue 142. Further, fixation element 82 may be configured to provide forward pressure on electrode 90B such that electrode 90B is pressed into tissue 142 to ensure proper electrode-tissue contact.

[0143] like Figure 5A As depicted in FIG. 1 , the deployment compartment 52 may be at an angle (e.g., similar to Figure 4A The deployment chamber 52 may be configured to contact the tissue 140 at an angle 148 of the angle 148 such that the surface 80 of the deployment chamber 52 is not flush with the tissue 142. Because the surface 80 is not flush with the tissue 142, the deployment chamber 52 may define a non-fixed configuration 150A relative to the tissue 140. In some instances, because the clinician has not tested whether the deployment chamber 52 defines the first fixed configuration 152A (e.g., because the delivery device 50 is not configured to test whether the deployment chamber 52 defines the first fixed configuration 152A), the deployment chamber 52 may define the non-fixed configuration 150A. Alternatively, the deployment chamber 52 may have a previously defined first fixed configuration 152A as determined by the circuit system 94 and indicated to the clinician using the user interface 104, after which the deployment chamber 52 and / or the tissue 142 may move relative to each other when the IMD 16A is deployed.

[0144] like Figure 5A, the fixation elements 82 may extend distally beyond the distal opening 78. The fixation elements 82 may extend distally beyond the distal opening 78 due to the pushing element 68 pushing the IMD 16A distally within the deployment chamber 52. In the case where the deployment chamber 52 defines a non-fixed configuration 150A, some of the fixation elements 82 may not fully engage the tissue 142 when the fixation elements 82 extend distally from the deployment chamber 52. For example, as depicted, the fixation elements 82A may extend into the tissue 142 while the fixation elements 82B do not contact / engage the tissue 142. In some cases, as discussed above, the fixation elements 82A proximate to the tissue 142 may pierce the muscle 144 of the target site 140 when the IMD 16A is deployed (e.g., as shown in FIG. 1 ). Figure 4A and 4B ), although not shown for clarity. Figure 5A and 5B Such piercing is depicted in Figure 5B , fixation elements 82 may draw electrode 90B into contact with tissue 142. With some or all of fixation elements 82 engaging tissue 142, the clinician may partially proximally retract deployment capsule 52 and delivery device 50 to test fixation of IMD 16A.

[0145] For example, as discussed herein, the clinician may attempt a pull test in which the clinician pulls on the proximal end of IMD 16A to verify that IMD 16A is securely attached to tissue 142. The clinician may perform the pull test using a longitudinal member that engages the proximal end of IMD 16A. For example, IMD 16A may include a proximal hook 114 that extends proximally from IMD 16A and may engage with tether 162 of delivery device 50. Figures 5A-5D As depicted in FIG. 1 , the tether 162 can be configured to engage the aperture of the proximal hook 114. The tether 162 can be configured to move within the delivery device 50. For example, the tether 162 can be configured to be able to move within the delivery device 50 during the deployment mechanism (e.g., Figure 2A and Figure 2B The IMD 16A slides within the deployment mechanism 66 of the delivery device 50 and can be operated from the hub 56 of the delivery device 50. The clinician can pull the IMD 16A by pulling the tether 162 engaged with the hook 114.

[0146] However, the tissue 142 of the target site 140 may be so thin that the clinician may not be able to visually identify whether the fixation element 82 is secured to the tissue 142. For example, where the target site 140 is in the right atrium 20, the thickness of the tissue 142 may be between 2 and 3 millimeters (mm), such that the fixation element 82 may extend only 1 or 2 mm into the tissue 142 as the fixation element 82 attempts to avoid the muscle 144 behind the tissue 142. Thus, depending on the angle of the IMD 16A to the tissue 142 of the target site 140, it may be difficult or impossible to see whether the fixation element 82 has engaged any of the tissue 142 when deployed.

[0147] Thus, as discussed herein, a clinician may use circuitry 94 to verify that IMD 16A defines a second fixed configuration relative to tissue 142. Circuitry 94 may generate an electrical signal to path 132B (which may be substantially similar to path 132 and path 132A, except for any differences described herein) between first electrode 90B and second electrode 92B. In some examples, circuitry (e.g., Figure 1A The circuit system 28) may include some or all of the circuit system 94.

[0148] The circuit system 94 may include a processing circuit system 120 that causes the signal generating circuit system 124 to generate an electrical signal. As discussed herein, the electrical signal may be transmitted by generating a voltage potential across the first electrode 90B and the second electrode 92B. The processing circuit system 120 may analyze the impedance of the electrical signal detected by the impedance detection circuit system 126 on the path 132B between the first and second electrodes 90B, 92B. For example, in the case where the tissue 142 is tissue 142 of the heart 12, the impedance detected by the impedance detection circuit system 126 may include and / or reflect one or more intrinsic waveforms of the heart 12. The processing circuit system 120 may detect whether these one or more impedance waveforms of the electrical signal affected by the heart 12 are stable, or whether the impedance waveform has a noise amount greater than a threshold value (e.g., as stored in a memory cell). Figure 3 The waveform reflected in the impedance may be stable due to the degree to which the first electrode 90A engages the tissue 142 of the heart 12 (due to the fixation elements 82 engaging the tissue 142). For example, when a threshold amount of fixation elements 82 (e.g., at least two circumferentially adjacent fixation elements 82 of four fixation elements 82 surrounding the first electrode 90A in a circular arrangement or at least 75% of the helical screws of a single distal screw extending from a corresponding IMD) engage the tissue 142, the electrode 90A may be sufficiently engaged with the tissue 142 of the heart 12.

[0149] In some examples, processing circuitry 120 may detect that the impedance waveform of the electrical signal includes a double-peaked signature 137 and indicates therein that IMD 16A defines a non-fixed configuration 150B relative to tissue 142. In some examples, processing circuitry 120 may detect that the impedance waveform includes a double-peaked signature 137 when the clinician performs a pull test. For example, the pull test may exacerbate or make apparent any errors or deficiencies in the fixation of IMD 16A to tissue 142. By testing path 132B between electrodes 90B, 92B while the clinician is pulling proximal hook 114 using tether 162, the clinician may improve the ability of circuitry 94 to determine whether IMD 16A is deployed such that IMD 16A defines a second fixed configuration relative to tissue 142.

[0150] In response to processing circuitry 120 detecting that the impedance waveform includes double-peaked feature 137, processing circuitry 120 may cause indication circuitry 128 to provide an indication of second non-fixed configuration 150B on user interface 104. The clinician may view this indication of non-fixed configuration 150B of IMD 16A relative to tissue 142 and decide therein to fully retract IMD 16A back into deployment bay 52 to redeploy IMD 16A. Delivery device 50 may include any of a plurality of retraction mechanisms to retract IMD 16A into deployment bay 52 after deployment of fixation element 82 from deployment bay 52 that is partially attached to tissue 142. For example, the clinician may pull tether 162 to remotely pull IMD 16A back into deployment bay 52. ​​Pulling IMD 16A back into deployment bay 52 may release IMD 16A from patient tissue 142 and return IMD 16A to the deployment bay 52. Figure 2A For example, pulling IMD 16A back into deployment bay 52 may return fixation element 82 from a deployed position (a position in which the distal end of fixation element 82 extends proximally rearwardly toward IMD 16A) to a deployable position (a position in which the distal end of fixation element 82 extends distally from IMD 16A). From this position, the clinician may reposition IMD 16A as desired and redeploy IMD 16A.

[0151] For example, Figure 5C, the deployment chamber 52 can be repositioned relative to the tissue 142. The deployment chamber 52 can be positioned in the first fixed configuration 152A. For example, the clinician can use the electrodes of the delivery device 50 and the circuit system 94 to verify that the distal surface 80 defining the distal opening 78 of the deployment chamber 52 is flush with the tissue 142. Before the processing circuit system 120 causes the indication circuit system 128 to provide an indication of the first fixed configuration 152A to the user interface 104, the circuit system 94 can verify whether the impedance of the electrical signal provided across the path (e.g., path 132A) exceeds the impedance threshold 134.

[0152] Once deployment pod 52 defines first securement configuration 152A relative to tissue 142, IMD 16A can be pushed distally (eg, using pusher element 68) such that securement element 82 is positioned as shown in FIG. Figure 5C 14A and 16A may be extended distally out of deployment chamber 52 and engage tissue 142 as depicted in FIG. Once fixation element 82 is extended distally out of deployment chamber 52 to engage tissue 142, fixation element 82 may be configured to push IMD 16A distally to secure the IMD to tissue 142. In other examples, fixation element 82 may have to be manually secured to tissue 142.

[0153] In response to fixation element 82 deploying IMD 16A from deployment bay 52, delivery device 50 may verify that IMD 16A is in the second fixed configuration relative to tissue 142. For example, as described above, circuit system 94 may generate an electrical signal across path 132B and identify whether the impedance waveform is stable (e.g., stable via a pull test) or whether the impedance waveform includes a double-peaked feature 137. Figure 5D 142, the impedance waveform may be relatively stable and may have little or no noise indicator 135, such that the internal processing 94 may recognize that the IMD 16A defines the second fixation configuration 152B relative to the tissue 142. In some examples, as described herein, the clinician may perform one or more pull tests while the circuit system 94 provides electrical signals to the electrodes 90B, 92B and while the circuit system 94 verifies that the IMD 16A defines the second fixation configuration 152B. For example, the clinician may initially wait a few seconds (e.g., approximately 5 seconds) before starting the pull test, and then the clinician may maintain pressure on the tether 162 for a few seconds (e.g., approximately 5 seconds) to improve the ability of the circuit system 94 to collect a sufficient baseline for comparison. In response to the IMD 16A defining the second fixation configuration 152, the processing circuit system 120 of the circuit system 94 may provide an indication of a successful second fixation configuration 152B to the clinician using the user interface 104.

[0154] like Figure 5D, once IMD 16A is secured to patient tissue 142 in second securement configuration 152B, the clinician can release IMD 16A from tether 162. For example, the clinician can cut tether 162 at a port in hub 56 of delivery device 50 and remove tether 162 from delivery device 50 by pulling on one of the severed ends of tether 162. Figure 5D Once IMD 16A is released from tether 162 , the clinician may remove delivery device 50 , thereby securing IMD 16A to patient tissue 142 , as shown in FIG.

[0155] Figure 6 is a graph of example impedance data 114 that may be identified by processing circuitry 120 as indicating first fixed configuration 152A. It should be appreciated that Figure 6 The impedance data 114 provided in FIG. 1 is provided for illustrative purposes only, as other systems may vary the impedance values ​​and similar systems may generate different impedance values ​​depending on the medical condition of the patient 14. As depicted, the impedance data 114 may cover testing within multiple stages. For example, the first stage 162 includes a fluid that substantially only contains the patient 14 (e.g., Figure 4A ). Further, the second level 164 includes the impedance data 114 of the electrical signal across the path 132 when the distal opening 80 of the deployment chamber 52 is flush with the tissue 142 but not pressed against the tissue. Finally, the third level 166 includes the impedance data 114 of the electrical signal across the path 132 when the distal opening 80 of the deployment chamber 52 is flush with the tissue 142 of the target site 140 and pressed against the tissue. As will be appreciated by those of ordinary skill in the art, Figure 6 The oscillations in the signal indicated in (and Figure 7-9B ) represents the movement and activity of the heart 12 acquired by the electrodes 90, 92 during the cardiac cycle.

[0156] As depicted, the magnitude of the impedance data 114 may increase as the deployment capsule 52 contacts the tissue 142 of the target site 140 and then presses upward against the tissue. For example, the impedance data 114 may initially remain relatively stable at about 350Ω during the first stage 162, after which the impedance data 114 may fluctuate between about 400Ω and 370Ω during the second stage 164, after which the impedance data 114 may fluctuate between about 405Ω and 440Ω in the third stage 166. In this example, the circuit system 94 may use an impedance threshold 134 of about 370Ω, where the first fixed configuration 152A includes only flush contact with the tissue 142 of the target site 140, or the circuit system 94 may use an impedance threshold 134 of about 400Ω, where the first fixed configuration 152A includes pressing into the tissue 142. Alternatively, circuitry 94 may include impedance threshold 134 for impedance data 114 whose value increases between 100% and 150% above impedance data 114 of first stage 162. Other examples are possible.

[0157] Figure 7 is a graph of example phase data 168 that may be identified by impedance detection circuitry 126 and determined by processing circuitry 120 to be indicative of first fixed configuration 152A. For example, as discussed herein, phase data 168 may be identified by monitoring the angle by which voltage leads or lags current. It should be appreciated that Figure 7 The phase data 168 provided in FIG. 1 is provided for illustrative purposes only, as other systems may capture slightly different phase values ​​and similar systems may capture different phase values ​​depending on the medical condition of the patient 14. As depicted, the phase data 168 may cover testing within multiple stages, similar to the phase data discussed above. Figure 6 142). A graph of the invention (e.g., wherein the first level 162 includes phase data 168 when the path 132 contains substantially only fluid, the second level 164 includes phase data 168 when the distal opening 80 is flush with the tissue 142, and the third level 166 includes phase data 168 when the distal opening of the deployment chamber 52 is pressed against the tissue 142).

[0158] As depicted, the magnitude of the phase data 168 may increase as the deployment capsule 52 contacts the tissue 142 of the target site 140 and then presses upward against the tissue. For example, the phase data 168 may initially fluctuate between 11° and 11.5° during the first stage 162, after which the range of the phase data 168 during the second stage 164 may increase and float between approximately 11° and 12°, after which the phase data 168 may fluctuate between approximately 12° and 13° in the third stage 166. In this example, the circuit system 94 may use a phase threshold 133 of approximately 11.6°, where the first fixed configuration 152A includes only flush contact with the tissue 142 of the target site 140, or the circuit system 94 may use a phase threshold 133 of approximately 12.5°, where the first fixed configuration 152A includes pressing into the tissue 142. Alternatively, circuitry 94 may include a phase threshold 133 that is a percentage increase (eg, a 5% to 20% increase in the average value of phase data 168 of first stage 162). Other examples are possible.

[0159] Fig. 8A is a graph of example impedance data 170A that may be identified by the impedance detection circuitry 126 and determined by the processing circuitry 120 to be indicative of the second non-fixed configuration 150B. It should be appreciated that Fig. 8A The impedance data 170A provided in 170A is provided for illustrative purposes only, as other systems may vary the impedance value and similar systems may generate different impedance values ​​depending on the medical condition of the patient 14. As depicted, the impedance data 170A may cover testing within multiple stages. For example, the first stage 172A includes impedance data 170A of the electrical signal across the path 132 before the pull test (e.g., using the tether 162), while the second stage 174A includes impedance data 170A of the electrical signal across the path 132 during the pull test (e.g., using the tether 162).

[0160] As depicted, impedance data 170A defining IMD 16A of non-fixed configuration 150B may generally curve upward and downward between primary peak 176A and primary valley 178A. During first stage 172A, impedance data 170A may define a relatively noisy slope between primary peak 176A and primary valley 178A. For example, impedance data 170A defines a slope having bumps or steps, a slope that changes the direction of the curve, a substantially horizontal slope, etc. between primary peak 176A and primary valley 178A. Processing circuit system 120 may be configured to detect these relatively complex slopes that exceed slope threshold 136 stored in memory 122. Thus, processing circuit system 120 may be configured to detect that first stage 172A of impedance data 170A indicates second non-fixed configuration 150B.

[0161] Additionally or alternatively, processing circuit system 120 may analyze second level 174A. In some instances, second level data 174A may indicate second non-fixed configuration 150B with greater clarity and repeatability than first level data 172A (e.g., because the pull test highlights potential defects in the manner in which IMD 16A is fixed to tissue 142), thereby improving the ability of processing circuit system 120 to detect second non-fixed configuration 150B. For example, processing circuit system 120 may detect a double-peaked signature 180A incorporated into impedance data 170A during second level 174A of the pull test. Double-peaked signature 180A, as depicted and used herein, includes a more pronounced deviation in slope between peaks 176A and valleys 178A than impedance data 170A of first level 172A. For example, each of double-peaked signatures 180A may define a secondary peak 182 and a secondary valley 184 between defining primary peak 176A and primary valley 178A. For example, as depicted, during the second stage 174A, the impedance data 170A defines a secondary peak 182 of about 225Ω and a secondary valley 184 of about 215Ω in addition to a primary peak 176A of about 240Ω and a primary valley 178A of about 220Ω. The processing circuitry 120 may be configured to detect these secondary peaks 182 and secondary valleys 184 as a dual-peaked feature 180A. As thus detected, the processing circuitry 120 may be configured to detect that the impedance data 170A indicates the second non-fixed configuration 150B.

[0162] Figure 8B is a graph of example impedance data 170B that may be identified by impedance detection circuitry 126 and determined by processing circuitry 120 to be indicative of second fixed configuration 152B. It should be appreciated that Figure 8B The impedance data 170B provided in FIG. 1 is provided for illustrative purposes only, as other systems may vary the impedance value and similar systems may generate different impedance values ​​depending on the medical condition of the patient 14. As depicted, the impedance data 170B may cover testing within multiple stages. For example, the first stage 172B includes impedance data 170B of the electrical signal across the path 132 before the pull test (e.g., using the tether 162), while the second stage 174B includes impedance data 170B of the electrical signal across the path 132 during the pull test (e.g., using the tether 162).

[0163] As depicted, impedance data 170B of IMD 16A defining second fixed configuration 152B may generally curve upward and downward between primary peak 176B and primary valley 178B. However, the slope between primary peak 176B and primary valley 178B is relatively smooth compared to impedance data 170A detected by impedance detection circuitry 126 when IMD 16A defines second non-fixed configuration 150B. For example, the slope defined by impedance data 170B substantially avoids defining a bump or step, a change in direction, a substantially horizontal section, etc. between primary peak 176B and primary valley 178B. Processing circuitry 120 may be configured to detect these relatively smooth slopes within or otherwise satisfying slope thresholds 136 stored in memory 122. Thus, processing circuitry 120 may be configured to detect that first level 172B of impedance data 170B indicates second fixed configuration 152B.

[0164] Additionally or alternatively, the processing circuit system 120 may analyze the second stage 174B. The impedance data of the second stage collected during the pull test may indicate the possible second non-fixed configuration 150B with more clarity and repeatability than the impedance data collected when the pull test is not performed. Therefore, when the processing circuit system 120 analyzes the impedance data 170B of the second stage 174B, the processing circuit system 120 may classify the impedance data 170B as indicating the second fixed configuration 152B with a higher confidence (e.g., a higher confidence score). For example, the processing circuit system 120 may analyze the impedance data 170B of the second stage 174B and identify that the slope between the primary peak 176B and the primary valley 178B is substantially smooth. In some instances, the processing circuit system 120 may be configured to ignore (e.g., not consider) the transition data 182 at the initial period of the second stage 174B, where the impedance data 170B subsequently defines a slope within the slope threshold 136. Because the slope of the impedance data 170B is within the slope threshold 136 during the first stage 172A and the second stage 172B, the processing circuitry 120 may identify the impedance data 170B as indicating the second fixed configuration 152B.

[0165] Additionally or alternatively, the processing circuitry 120 may analyze the phase of the set of impedance data 170A, 170B to determine whether the set of impedance data 170A, 170B indicates the second non-fixed configuration 150B or the second fixed configuration 152B. Fig. 9A and 9B is a graph of example groups of phase data 190A, 190B that may be identified by processing circuitry 120 as indicating second non-fixed configuration 150B and second fixed configuration 152B, respectively. For example, as discussed herein, each group of phase data 190A, 190B may be identified by Fig. 8A and8B The impedance data 170A, 170B of the corresponding group are identified by identifying the hysteresis between the voltage and the current. It should be understood that Fig. 9A The phase data provided in 190A and Fig. 9B The phase data 190A and the phase data 190B provided in both are provided for illustration purposes only, as other systems may capture slightly different phase values ​​and similar systems may capture different phase values ​​depending on the medical condition of the patient 14. As depicted, both the phase data 190A and the phase data 190B may cover testing within multiple stages, similar to the above-discussed Fig. 8A and 8B ) (eg, where phase data for the first stages 172A and 172B is collected prior to a pull test and phase data for the second stages 174A and 174B is collected during a pull test).

[0166] As depicted, phase data 190A during first stage 172A may fluctuate widely between generally high values ​​(e.g., approximately 10°) and generally low values ​​(e.g., approximately 9.3°). Outside of these approximate upper and lower thresholds, phase data 190A may substantially avoid defining a repeating pattern. In other words, phase data 190A may avoid defining relatively consistent maximum values ​​(e.g., the same phase value as other peaks within first stage 172A, ±0.1°) or relatively consistent minimum values ​​(e.g., the same phase value as other valleys within first stage 172A, ±0.1°) within first stage 172A. Because the slope defined by phase data 190A fails to define relatively consistent maximum and minimum values, processing circuitry 120 may determine that phase data 190A is outside of phase threshold 138. Therefore, processing circuitry 120 may determine that phase data 190A indicates that IMD 16A defines a non-fixed configuration 150B.

[0167] Additionally or alternatively, processing circuit system 120 may analyze impedance data 190A of second stage 174A. In some instances, second stage data 174A may indicate second non-fixed configuration 150B with greater clarity and repeatability than first stage data 172A (e.g., because the pull test highlights potential defects in the way IMD 16A is fixed to tissue 142), thereby improving the ability of processing circuit system 120 to detect second non-fixed configuration 150B. For example, processing circuit system 120 may detect a double-peaked signature 180B incorporated into phase data 190A during second stage 174A of the pull test. Double-peaked signature 180B may be substantially similar to double-peaked signature 180A of impedance data 170A. For example, each of double-peaked signatures 180B may define secondary peaks and secondary valleys between defining primary peaks and primary valleys. Processing circuit system 120 may be configured to detect these secondary peaks and secondary valleys as double-peaked signatures 180B. As thus detected, the processing circuitry 120 may be configured to detect that the phase data 170A is indicative of the second non-stationary configuration 150B.

[0168] As discussed herein, processing circuitry 120 may also analyze the phase data and determine that the phase data indicates that IMD 16A defines second fixed configuration 152B. Fig. 9B , phase data 190B of IMD 16A defining second fixed configuration 152B may generally bend upward and downward between primary peak 192 and primary valley 194. As depicted, both the phase value of primary peak 192 and the phase value of primary valley 194 may be substantially consistent (e.g., ±0.1°). Further, the slope between primary peak 192 and primary valley 194 is relatively smooth (e.g., such that the slope defined by phase data 170B substantially avoids defining a bump, step, change in direction, substantially horizontal segment, etc. between primary peak 192 and primary valley 194). Processing circuitry 120 may be configured to detect these substantially consistent maximum and minimum values ​​(and or these relatively smooth slopes) that are within or otherwise satisfy phase threshold 138 stored in memory 122. Thus, processing circuitry 120 may be configured to detect that first level 172B of phase data 190B indicates second fixed configuration 152B.

[0169] Additionally or alternatively, processing circuit system 120 may analyze phase data 190B of second stage 174B. Phase data of the second stage collected during the pull test may indicate possible second non-fixed configuration 150B with more repeatability than phase data collected when the pull test is not performed. Therefore, when processing circuit system 120 analyzes phase data 190B of second stage 174B, processing circuit system 120 may classify phase data 190B as indicating second fixed configuration 152B with a higher confidence (e.g., a higher confidence score). For example, processing circuit system 120 may analyze phase data 190B of second stage 174B and identify that the slope between primary peak 192 and primary valley 194 is substantially smooth, such that phase data 190B of second stage 174B does not define double-peaked feature 180B. In some examples, processing circuitry 120 may be configured to ignore (e.g., disregard) transition data 196 of phase data 190B at an initial period of second stage 174B, where phase data 190B subsequently defines a slope within phase threshold 138 without bimodal feature 180B. Because the slope of phase data 190B is within phase threshold 138 during first stage 172A and second stage 172B without defining bimodal feature 180B, processing circuitry 120 may identify phase data 190B as indicating second fixed configuration 152B.

[0170] As discussed, in some examples, processing circuitry 120 may perform an FFT technique on impedance data 170 to identify FFT data 200A, 200B (collectively, “FFT data 200”). For example, Fig. 10A is a graph of example FFT data 200A generated by processing circuit system 120 by performing an FFT technique on impedance data 170A (although it should be understood that in other examples, processing circuit system 120 may perform FFT techniques on other sets of impedance data). Processing circuit system 120 may identify FFT data 200A as indicating second non-fixed configuration 150B as described below. It should be understood that Fig. 10A14. The FFT data 200A provided in FIG. 14 is provided for illustrative purposes only, as other systems may vary the impedance values ​​and similar systems may generate different impedance values ​​depending on the medical condition of patient 14. As depicted, during second stage 174, processing circuitry 120 may only perform the FFT technique to identify FFT data 200A of impedance data 170. In other words, processing circuitry 120 may be configured to identify FFT data 200 that occurs when a clinician is performing a pull test. In other examples, processing circuitry 120 may identify more or less FFT data 200. For example, processing circuitry 120 may additionally identify FFT data 200 during first stage 172 after IMD 16A is deployed but before a pull test.

[0171] Processing circuitry 120 may identify a fundamental frequency 202A and a plurality of harmonic frequencies 204A, 204B, 204C (collectively, “harmonic frequencies 204”) comprising FFT data 200A. As discussed above, fundamental frequency 202A may correspond to a heartbeat of patient 14. Processing circuitry 120 may determine that a ratio between one or more harmonic frequencies 204 and fundamental frequency 202A does not satisfy FFT threshold 139. For example, FFT threshold 139 may include a 1:4 ratio between fundamental frequency 202A and a first harmonic (e.g., a harmonic frequency having the largest amplitude, which processing circuitry 120 may identify as harmonic frequency 204A). Fig. 10A , processing circuitry 120 may identify that the amplitude of first harmonic frequency 204A is greater than 25% of the amplitude of fundamental frequency 202A, wherein the amplitude of first harmonic frequency 204A is approximately 50% of the amplitude of fundamental frequency 202A. In response to determining that the amplitude of first harmonic frequency 204A exceeds 25% of the amplitude of fundamental frequency 202A, processing circuitry 120 may cause indication circuitry 128 to indicate second non-fixed configuration 150B on user interface 104 as described herein.

[0172] Additionally or alternatively, FFT threshold 139 may include a ratio between the amplitude of fundamental frequency 202A and the sum of the amplitudes of plurality of harmonic frequencies 204, and processing circuitry 120 may identify whether the ratio satisfies FFT threshold 139. For example, FFT threshold 139 may include a 3:5 ratio between the amplitude of fundamental frequency 202A and the sum of the amplitudes of first three harmonic frequencies 204A, 204B, 204C. Processing circuitry 120 may identify whether the sum of the amplitudes of first three harmonic frequencies 204A, 204B, 204C satisfies FFT threshold 139. Fig. 10AIn response to determining that the sum of the amplitudes of the first three harmonic frequencies 204A, 204B, 204C is greater than 60% of the amplitude of the fundamental frequency 202A, the processing circuitry 120 may cause the indication circuitry 128 to indicate the second non-fixed configuration 150B on the user interface 104 as described herein.

[0173] Additionally, processing circuitry 120 may perform an FFT technique on impedance data 170 to determine that IMD 16A indicates second fixed configuration 152B. Fig. 10B 2 is a graph of example FFT data 200B generated by processing circuitry 120 by performing an FFT technique on impedance data 170B (although it should be understood that, as discussed above, in other examples, processing circuitry 120 may perform the FFT technique on other sets of impedance data). As depicted, while processing circuitry 120 may perform the FFT technique on other portions of impedance data 170, in other examples, processing circuitry 120 may perform the FFT technique only during second stage 174B to identify FFT data 200B for impedance data 170B (e.g., such as during first stage 172 after deploying IMD 16A but before pull testing).

[0174] Processing circuitry 120 may identify fundamental frequency 202B and a plurality of harmonic frequencies 206A, 206B, 206C (collectively, “harmonic frequencies 206”) of FFT data 200B. As discussed above, fundamental frequency 202B may correspond to a heartbeat of patient 14. Processing circuitry 120 may determine that a ratio between one or more harmonic frequencies 206 and fundamental frequency 202B satisfies FFT threshold 139. For example, FFT threshold 139 may include a 1:4 ratio between fundamental frequency 202B and a first harmonic (e.g., a harmonic frequency with the largest amplitude, which processing circuitry 120 may identify as harmonic frequency 206B). Fig. 10B , processing circuitry 120 may identify that the amplitude of first harmonic frequency 206B is less than 25% of the amplitude of fundamental frequency 202B, wherein the amplitude of first harmonic frequency 206B is about 20% of the amplitude of fundamental frequency 202B. In response to determining that the amplitude of first harmonic frequency 206B is less than 25% of the amplitude of fundamental frequency 202B, processing circuitry 120 may cause indication circuitry 128 to indicate second fixed configuration 152B on user interface 104 as described herein.

[0175] Additionally or alternatively, FFT threshold 139 may include a ratio between the amplitude of fundamental frequency 202B and the sum of the amplitudes of plurality of harmonic frequencies 206, and processing circuitry 120 may identify whether the ratio satisfies FFT threshold 139. For example, FFT threshold 139 may include a 1:2 ratio between the amplitude of fundamental frequency 202B and the sum of the amplitudes of first three harmonic frequencies 206A, 206B, 206C. Processing circuitry 120 may identify whether the sum of the amplitudes of first three harmonic frequencies 206A, 206B, 206C satisfies FFT threshold 139. Fig. 10B A is less than 50% of the amplitude of fundamental frequency 202B. In response to determining that the sum of the amplitudes of first three harmonic frequencies 206A, 206B, 206C is less than 50% of the amplitude of fundamental frequency 202B, processing circuitry 120 may cause indication circuitry 128 to indicate second fixed configuration 152B on user interface 104 as described herein.

[0176] Fig.11 A flow chart depicting a method of delivering a medical device to a target site in a patient using a delivery device as described herein. Figure 3 The circuit system 94 and Figure 2A The IMD 16A and the delivery device 50 are Fig.11 is discussed, but it should be understood that in other instances, Fig.11 The method can be accomplished using other delivery devices and circuit systems described herein to deliver an implantable medical device. Processing circuit system 120 can receive a request to test fixation (220). This request can be received from a clinician accessing user interface 104. In some examples, processing circuit system 120 can receive this request using telemetry technology.

[0177] The processing circuit system 120 may cause the signal generation circuit system 124 to deliver an electrical signal to the path 132 between the first electrode 90 and the second electrode 92 (222). The path 132 may include tissue and fluid of the patient 14. The signal generation circuit system 124 may deliver this electrical signal by providing a known (e.g., sinusoidal or pulsed) voltage potential across the electrodes 90, 92. The impedance detection circuit system 126 may detect the impedance level, and the processing circuit system 120 may identify the phase of the signal across the electrodes 90, 92 on the impedance (224). Identifying the phase across the path 132 may include identifying the amount by which the voltage lags or leads the current across the path 132. The processing circuit system 120 may verify whether this impedance meets (e.g., exceeds) an impedance threshold 134 as stored in the memory 122 (226). In the event that processing circuit system 120 determines that the impedance does not meet (e.g., is below) impedance threshold value 134, processing circuit system 120 may cause indication circuit system 128 to provide an indication of first non-fixed configuration 150A on user interface 104 (228). For example, in the event that user interface 104 is an LED, indication circuit system 128 may cause this LED to provide a red color. For another example, in the event that user interface 104 is a screen of external device 18, indication circuit system 128 may cause the screen of user interface 104 of external device 18 to display a failure message. In some examples, processing circuit system 120 may cause signal generation circuit system 124, impedance detection circuit system 126, and indication circuit system 128 to continue this logic loop until, for example, processing circuit system 120 receives a message (from a clinician) to stop testing the first fixed configuration.

[0178] Conversely, in response to the processing circuitry 120 determining that the impedance satisfies (e.g., exceeds) the impedance threshold 134, the impedance detection circuitry 128 may additionally determine whether the phase (as identified at 224) satisfies (e.g., exceeds) the phase threshold 133 (230). In the event that the processing circuitry 120 determines that the phase does not satisfy (e.g., is below) the phase threshold 133, the processing circuitry 120 may cause the indication circuitry 128 to provide an indication of the first non-fixed configuration 150A on the user interface 104 (228). Alternatively, when the processing circuitry 120 determines that the impedance satisfies the impedance threshold 134 and the phase satisfies the phase threshold 133, the processing circuitry 120 may cause the indication circuitry 128 to indicate a successful first fixed configuration 152A (232). The successful first fixed configuration 152 may be associated with the distal opening 78 of the deployment bay 52 of the deployed IMD 16A of the delivery device 50 being flush with the surface of the tissue 142 and / or pressed into the tissue 142 at the target site 140. In some instances, the indication circuit system 128 may continue to provide an indication of the first fixed configuration 152A as long as the processing circuit system 120 continues to detect that the impedance of the electrical signal across the path 132 exceeds the impedance threshold 134 (that is, step 232 may naturally loop back to step 222 unless affirmative input is received from the clinician to override this loop).

[0179] In some instances, the circuit system 94 may further test whether the IMD 16A defines a second fixed configuration. In such instances, the processing circuit system 120 may cause the signal generation circuit system 124 to deliver an electrical signal to the path 132 between the first electrode 90 and the second electrode 92 on the distal tip 96 of the IMD 16A (234). The impedance detection circuit system 126 may identify the impedance of this signal that the processing circuit system 120 may use to identify the phase of the signal (236). For example, the processing circuit system 120 may determine the phase of the heart 12 by identifying the amount by which the voltage of the signal across the path 132 leads or lags the current. The processing circuit system 120 may determine whether the impedance is noisy (238). If the impedance fails to meet the slope threshold 136 or if the impedance includes a bimodal feature 137 as stored in the memory 122, the processing circuit system 120 may determine that the impedance of the signal is noisy. If the impedance waveform fails to satisfy slope threshold 136 and / or includes bimodal feature 137, processing circuitry 120 may cause indication circuitry 128 to provide a message of second non-fixed configuration 150B to user interface 104 (240). In some examples, processing circuitry 120 may cause signal generation circuitry 124 to deliver an electrical signal to path 132 to test the first fixed configuration in response to determining that the impedance indicates second non-fixed configuration 150B (222).

[0180] In the event that the impedance waveform is stable such that the impedance waveform satisfies slope threshold 136 and does not define bimodal signature 137, processing circuitry 120 may determine whether the phase (as identified in 236) satisfies phase threshold 138 (242). Processing circuitry 120 may determine that the phase does not satisfy phase threshold 138 because the peaks and valleys of the phase are inconsistent and / or because the phase includes bimodal signature 137. Because the phase of the electrical signal does not reach phase threshold 138, processing circuitry 120 may cause indication circuitry 128 to provide a message of second non-fixed configuration 150B to user interface 104 (240). Similar to the above, in some examples, processing circuitry 120 may cause signal generation circuitry 124 to deliver an electrical signal to path 132 to test the first fixed configuration (222) in response to determining that the impedance indicates second non-fixed configuration 150B (e.g., to organize the reorientation of deployment pod 52 to re-deploy IMD 16A).

[0181] If processing circuit system 120 determines that the phase of the electrical signal satisfies phase threshold 138 and / or does not define bimodal feature 137, processing circuit system 120 may cause indication circuit system 128 to provide an indication of second fixation configuration 152B (244). Second fixation configuration 152B may include IMD 16A being fixed to tissue 142 according to a predetermined manner. For example, second fixation configuration 152B may include distal electrode 90 of IMD 16A being firmly and uniformly pressed into tissue 142 with at least a threshold amount of force. In some examples, processing circuit system 120 may be configured to determine whether IMD 16A defines second fixation configuration 152B on a long-term basis. For example, as Fig.11 , processing circuitry 120 may cause signal generation circuitry 124 to continue to send electrical signals across path 132 so that processing circuitry 120 may continuously identify whether IMD 16A is continuously defining second fixed configuration 152B. Processing circuitry 120 may be configured to thereby verify whether IMD 16A is defining second fixed configuration 152B on a regular schedule (e.g., once an hour, once a day, once a week, etc.). Processing circuitry 120 may be configured to cause indication circuitry 128 to send (e.g., to external device 18) a message indicating whether IMD 16A is still defining second fixed configuration 152B or whether IMD 16A has shifted (e.g., IMD 16A has begun to define second non-fixed configuration 150B).

[0182] Fig.12 A flow chart depicting a method of delivering a medical device to a target site in a patient using a delivery device as described herein. Figure 2A-7 The delivery device 50 and Figure 1A IMD 16A Fig.12is discussed, but it should be understood that in other instances, Fig.12 The method can be accomplished using other delivery devices described herein to deliver any insertable or implantable medical device. The clinician can deliver the delivery device 50 to the target site 140 in the patient 14 (250). For example, the clinician can navigate the deployment chamber 52 of the delivery device 50 to the right atrium 20 of the heart 12 of the patient 14 (e.g., Figure 1A ). After inserting the delivery device 50 into the introducer sheath inserted into the patient 14, the clinician can navigate the delivery device 50 to the target site 140. The clinician can navigate the delivery device 50 to the target site 140 using one or more deflection members 102, which are deflected using the steering or deflection mechanism of the hub 56. Once the clinician has navigated the deployment capsule 52 to the target site 140, the clinician can press the deployment capsule 52 against the target site 140. The clinician can use the radiopaque elements of the delivery device 50 (e.g., such as electrodes 90, 92) to navigate the deployment capsule 52 to the target site 140 using fluoroscopic techniques.

[0183] Once the clinician has positioned the deployment pod 52 at the target site 140, the clinician can provide an input for generating a first signal across a path between the first electrode 90 within the recess 74 of the deployment pod 52 and the second electrode 90 outside the recess 74 of the deployment pod 52 (252). The clinician can check to see if the circuit system 94 indicates that the deployment pod 52 defines a first fixed configuration 152A (254). The clinician can use the user interface 104 to determine whether the circuit system 94 indicates that the deployment pod 52 defines the first fixed configuration 152A. In the event that the user interface 104 does not indicate the first fixed configuration 152A (e.g., instead indicates the first non-fixed configuration 150A), the clinician can reposition the deployment pod 52 at the target site 140 (256).

[0184] Once the clinician views (as indicated by the user interface 104) that the circuit system 94 indicates that the deployment chamber 52 defines the first fixation configuration 152A, the clinician may deploy the IMD 16A at the target site 140 (258). Deploying the IMD 16A may include using the deployment mechanism 66 to push the IMD 16A distally relative to the deployment chamber 52 until the fixation device 82 engages the tissue 142. Once the IMD 16A is deployed, the clinician provides an input to the circuit system 94 to provide an input for generating a second signal to the path 132 between the first electrode 90 on the distal tip 96 of the IMD 16A and the second electrode 92 proximate the distal tip 96 (260). The clinician may provide the input for generating the second signal in the same manner as the clinician provided the input for the first signal. After providing the input, the clinician may perform a pull test on the IMD 16A (262). For example, the clinician may pull on tether 262 of delivery device 50 and verify the securement of IMD 16A therein after providing input to circuitry 94 for generating the second signal.

[0185] The clinician may determine whether the IMD 16A defines the second fixed configuration 152B (264). For example, the clinician may use the user interface 104 to view whether the circuit system 94 indicates that the IMD 16A defines the second fixed configuration 152B. In the event that the circuit system 94 indicates that the IMD 16B does not define the second fixed configuration 152B (e.g., but instead defines the second non-fixed configuration 150B), the clinician may retract the IMD 16A into the deployment compartment 52 (266). For example, the clinician may use the tether 162 engaged with the proximal hook 114 of the IMD 16A to retract the IMD 16A into the deployment compartment 52. In some examples, in response to retracting the IMD 16A, the clinician may consider repositioning the deployment compartment 52 in the first fixed configuration 152A (252) by providing an input for again generating the first signal.

[0186] In other examples, the clinician may recognize that user interface 104 indicates that IMD 16A defines second fixation configuration 152B. In the event that the clinician recognizes that circuitry 94 indicates that IMD 16A defines second fixation configuration 152B, the clinician may release IMD 16A (e.g., by cutting tether 162) (268). Once IMD 16A is deployed and fully released, the clinician may retract delivery device 50 out of patient 14 (270). The clinician may withdraw delivery device 50 from the introducer sheath through which delivery device 50 was inserted.

[0187] The present disclosure is generally directed to medical delivery devices that use impedance between electrodes to verify when a deployment chamber containing an implantable device and / or the device itself defines various fixation configurations that indicate that the implantable device is aligned to be fixed to or is currently properly fixed to a target site in the heart. However, one or more aspects of the present disclosure may also be applicable to delivering other insertable or implantable medical devices to other areas of a patient. For one example, as discussed herein, various aspects of the present disclosure may be applicable to delivering a lead containing a distal fixation element to a target site in a patient's body. Further, various aspects of the present disclosure may be applicable to delivering a lead to a patient's spinal cord or another organ. A person of ordinary skill in the art will also understand other applications of various aspects of the present disclosure.

[0188] Embodiment 1: In an example, a system for delivering an implantable medical device to tissue of a patient includes: a signal generating circuit system, the signal generating circuit system being configured to deliver an electrical signal to a path between a first electrode and a second electrode through at least one of the fluid or the tissue of the patient; and a processing circuit system, the processing circuit system being configured to: determine an impedance of the path based on the signal; determine whether the impedance of the path indicates to the tissue of the patient at least one of a first fixation configuration in which a distal portion of the implantable medical device delivery system is substantially flush with tissue of a target site or a second fixation configuration in which one or more fixation elements of the implantable medical device meet a fixation threshold; and provide an indication of when the impedance of the path indicates at least one of the first fixation configuration or the second fixation configuration.

[0189] Embodiment 2: The system of Embodiment 1, wherein the processing circuitry is configured to determine that the impedance of the path is indicative of the first fixed configuration when the impedance exceeds a threshold impedance.

[0190] Embodiment 3: The system of Embodiment 1 or 2, wherein the processing circuitry is configured to determine that the impedance of the path indicates the first fixed configuration by identifying that a phase waveform is above a threshold.

[0191] Embodiment 4: The system of any one of Embodiments 1 to 3, wherein the processing circuitry is configured to determine whether the impedance is indicative of at least one of the first or second fixed configurations by determining at least a first derivative magnitude of the impedance.

[0192] Embodiment 5: A system according to any one of Embodiments 1 to 4, wherein the processing circuit system is configured to determine whether the impedance of the path indicates a second fixed configuration by being configured to: determine the amount of noise in the waveform of the impedance; and determine whether the amount of noise satisfies a noise threshold.

[0193] Embodiment 6: The system of any one of Embodiments 1 to 5, wherein the noise includes a bimodal signature, and the processing circuitry is configured to determine that the waveform of the impedance is indicative of the second fixed configuration based on identification of the bimodal signature.

[0194] Embodiment 7: The system of any one of Embodiments 1 to 6, wherein the processing circuitry is configured to determine the amount of the noise by at least identifying a frequency component of the signal.

[0195] Embodiment 8: The system of any one of claims 1 to 7, wherein the system is integrated into the implantable medical device delivery system.

[0196] Embodiment 9: The system of any one of Embodiments 1 to 8, wherein the system is integrated into the implantable medical device.

[0197] Embodiment 10: An implantable medical device (IMD), comprising: a shell, the shell being configured to be fixed to a target site in a patient's body by one or more fixing elements extending distally from a distal tip of the shell; a first electrode, the first electrode being fixed to the distal tip of the shell; a second electrode, the second electrode being fixed to an outer surface of a proximal portion of the shell; a signal generating circuit system, the signal generating circuit system being configured to deliver an electrical signal to a path between the first electrode and the second electrode through at least one of the fluid or tissue of the patient; and a processing circuit system, the processing circuit system being configured to: determine an impedance of the path based on the signal; and generate an output, the output indicating via a user interface when the impedance of the path indicates that the IMD is in a fixed configuration relative to the target site of the patient.

[0198] Embodiment 11: An IMD according to Embodiment 10, wherein: the fixed configuration includes a threshold number of the fixed elements of the IMD fixed to the tissue at the target site; the processing circuit system is configured to determine the amount of noise in the waveform of the impedance, and determine whether the waveform indicates that the IMD is in the fixed configuration based on the amount of noise.

[0199] Embodiment 12: The IMD of Embodiment 10 or Embodiment 11, wherein the noise includes a bimodal characteristic, and the processing circuitry is configured to determine that the waveform of the impedance is indicative of the fixed configuration when the waveform does not define the bimodal characteristic.

[0200] Embodiment 13: The IMD of any one of Embodiments 10 to 12, wherein the processing circuitry is configured to determine the amount of the noise by at least one of: identifying frequency components above a threshold; or decomposing an impedance signal by frequency components.

[0201] Embodiment 14: The IMD of any one of Embodiments 10 to 13, wherein the IMD is a leadless pacemaker.

[0202] Embodiment 15: The IMD of any one of Embodiments 10 to 14, wherein the one or more fixation elements comprise one or more fixation tines.

[0203] Embodiment 16: The IMD of any one of Embodiments 10 to 15, further comprising telemetry circuitry, wherein the processing circuitry generates the output via the telemetry circuitry.

[0204] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. An implantable medical device delivery system, comprising: an elongated member configured to navigate an intravascular system of a patient; a deployment chamber connected to the distal portion of the elongated member and configured to accommodate at least a portion of an implantable medical device (IMD), the deployment chamber defining a distal opening configured for deploying the IMD out of the deployment chamber at a target site in a patient; a signal generating circuit system configured to deliver an electrical signal through at least one of a fluid or tissue of the patient to a path between a first electrode and a second electrode, the first electrode being positioned within the deployment capsule; as well as processing circuitry configured to: determining an impedance of the path between the first electrode and the second electrode located inside the deployment chamber based on the signal; and An output is generated that indicates, via a user interface, when the impedance of the pathway indicates that at least one of the IMD or the distal opening is in a fixed configuration relative to the target site of the patient.

2. The implantable medical device delivery system of claim 1, wherein the fixation configuration comprises a first fixation configuration in which the distal opening of the deployment compartment is substantially flush with tissue of the target site.

3. The implantable medical device delivery system of claim 2, wherein in the first fixed configuration, the deployment module is pressed against the tissue with a threshold amount of force.

4. The implantable medical device delivery system of claim 2 or 3, further comprising the IMD, wherein the first and second electrodes are first and second electrodes of the IMD.

5. The implantable medical device delivery system of claim 4, wherein the deployment chamber defines one or more apertures extending radially inwardly through the deployment chamber to expose the second electrode to the patient's fluid.

6. The implantable medical device delivery system of claim 5, further comprising one or more ribs extending radially inward from an inner surface of the deployment chamber to engage a shell of the IMD, wherein the one or more holes extend radially inward through the one or more ribs.

7. The implantable medical device delivery system of any one of claims 2 to 3, wherein the first electrode is fixed to an inner surface of the deployment chamber.

8. The implantable medical device delivery system according to any one of claims 2 to 3, wherein the second electrode is fixed to an outer surface of the deployment module or an outer surface of the elongated member.

9. An implantable medical device delivery system according to any one of claims 1 to 3, further comprising the IMD, wherein the first and second electrodes are the first and second electrodes of the IMD and the IMD includes one or more fixation elements, and wherein the fixation configuration includes a second fixation configuration, wherein a threshold amount of the one or more fixation elements of the IMD are fixed to the tissue at the target site.

10. An implantable medical device delivery system according to any one of claims 1 to 3, wherein the user interface comprises a display of an external device, the system further comprising a telemetry circuit system, wherein the processing circuit system is configured to use the telemetry circuit system to cause the display of the external device to indicate when the impedance of the path indicates that at least one of the IMD or the distal opening is in the fixed configuration relative to the target site of the patient.

11. The implantable medical device delivery system of any one of claims 1 to 3, wherein the user interface is positioned adjacent a proximal portion of the elongated member and is electrically coupled to the processing circuitry.

12. The implantable medical device delivery system of any one of claims 1 to 3, wherein the target site is a wall of an atrium of the patient.

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