Implantable medical device with motion detector

Abstract

The present disclosure provides a medical system including an implantable medical device (IMD) configured to be positioned within a heart of a patient. The IMD is configured to receive an applied force from a tissue wall of a beating heart when a fixation element of the IMD is implanted in the tissue wall. The IMD includes a motion sensor configured to sense motion of the IMD generated by a force applied to the IMD by the tissue wall. The processing circuitry is configured to compare the sensed motion to representative cardiac activity. The processing circuitry is configured to evaluate engagement of the fixation element and the tissue wall based on the comparison. The processing circuit may be configured to evaluate the engagement when a clinician engages the fixation element with the tissue wall.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 374,175, filed on August 31, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to an implantable medical system, such as an implantable medical device. Background Art

[0003] Implantable medical devices are typically placed in a subcutaneous pocket and are coupled to one or more transvenous medical electrical leads carrying pacing and sensing electrodes positioned in the heart. Recently, intracardiac pacemakers that can be implanted in the ventricular chambers of a patient's heart to deliver ventricular pacing pulses without the use of electrical leads have been introduced. Such pacemakers or other implantable medical devices may also be able to detect the occurrence of arrhythmias such as fibrillation, tachycardia, and bradycardia in the patient's heart. An implantable cardiac defibrillator may deliver an electric shock to the patient's heart in response to detecting tachycardia or fibrillation to restore the patient's normal heartbeat. In some cases, a single implantable medical device is used as both an implantable pacemaker and an implantable cardiac defibrillator.

[0004] Implantable medical devices may include electrodes and / or other elements for physiological sensing and / or therapy delivery. Electrodes and / or other elements may be implanted at target locations that are selected to detect a patient's physiological condition and / or deliver one or more therapies. For example, electrodes and / or other elements may be delivered to target locations within the atria or ventricles to sense intrinsic cardiac signals and deliver pacing or anti-tachyarrhythmic shock therapy from a medical device coupled to leads. Summary of the invention

[0005] The present disclosure describes an implantable medical device (IMD) configured to be positioned within a patient's heart. The IMD is configured to receive an applied force from a tissue wall of a beating heart when a fixation element of the IMD is implanted in the tissue wall of the heart. The applied force can cause movement of the IMD. The IMD includes a motion sensor configured to sense the movement of the IMD, and includes a processing circuit configured to compare the sensed movement with representative cardiac activity. The processing circuit is configured to evaluate the engagement of the fixation element and the tissue wall based on the comparison. A medical system can assist a clinician in assessing whether the IMD is being and / or has been properly deployed in the heart. For example, when the visibility provided by fluoroscopy, ultrasound, and / or other imaging modalities is limited, the medical system can provide feedback to the clinician during implantation of the IMD.

[0006] In one example, a medical system includes: an implantable medical device configured to engage tissue within a patient's heart, wherein the implantable medical device includes: a housing; a fixation element configured to gradually embed into the tissue to couple the implantable medical device to the tissue, wherein the fixation element is configured to transfer force from the tissue to the housing as the fixation element gradually engages; and a motion sensor configured to provide a sensor signal indicating movement of the housing; and a processing circuit configured to compare the sensor signal with representative cardiac activity when the fixation element engages the tissue, and estimate engagement of the implantable medical device with the tissue based on the comparison. The representative cardiac activity can be based on, for example, sensed cardiac activity of the patient, expected cardiac activity based on historical cardiac activity of the patient or other patients, or another indicator indicating representative cardiac activity.

[0007] In one example, a method includes: using a fixation element to engage an implantable medical device to tissue within a patient's heart, wherein engaging the fixation element includes gradually engaging the fixation element to the tissue, and wherein the fixation element is configured to transfer force from the tissue to a housing of the implantable medical device as the fixation element gradually engages the tissue; using a processing circuit to compare a sensor signal with representative cardiac activity as the fixation element gradually engages the tissue, wherein the sensor signal is provided by a motion sensor, and wherein the sensor signal indicates movement of the housing; and based on the comparison, using the processing circuit to evaluate engagement of the implantable medical device with the tissue.

[0008] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a conceptual diagram illustrating an exemplary medical system including an implantable medical device.

[0010] Figure 2 is a schematic diagram of an implantable medical device and a tissue wall.

[0011] Figure 3 yes Figure 2 Schematic diagram of an implantable medical device in which a fixation element contacts a tissue wall.

[0012] Figure 4 yes Figure 2 and Figure 3 Schematic diagram of an implantable medical device in which a fixation element engages a tissue wall.

[0013] Figure 5 is a graphical example of representative cardiac activity.

[0014] Figure 6 is a graphical example of a motion signal provided by a motion sensor of an implanted medical device when the implanted medical device is displaced from a tissue wall.

[0015] Figure 7 is a graphical example of a motion signal provided by a motion sensor of an implanted medical device, showing perturbations caused by the motion of a tissue wall.

[0016] Figure 8 is a graphical example of a motion signal provided by a motion sensor of an implantable medical device, illustrating rotation of the device housing relative to a tissue wall.

[0017] Fig. 9 is an exemplary illustration of the relative orientation between an implantable medical device and a tissue wall.

[0018] Fig.10 is a functional block diagram illustrating an exemplary configuration of an exemplary medical system.

[0019] Fig.11 Exemplary techniques for assessing engagement of an implantable medical device with a tissue wall are shown. DETAILED DESCRIPTION

[0020] The present disclosure describes a medical system comprising an implantable medical device (IMD) configured to be positioned within a patient's heart, such as within an atrium, a ventricle, a coronary sinus, or other portion of the heart. The IMD comprises a fixation element configured to engage with tissue of the heart to substantially attach the IMD to a target location within the heart. The fixation element may be, for example, a spiral (one or more turns) or another structure and / or component configured to engage with tissue. The medical system is configured to assist a clinician in assessing whether the IMD is being and / or has been properly deployed in the heart. For example, when visibility provided by fluoroscopy, ultrasound, and / or other imaging modalities is limited, the medical system may provide feedback to the clinician during implantation of the IMD.

[0021] The IMD is configured such that forces applied to the fixation element from engaged tissue of the heart (e.g., due to a heartbeat) cause corresponding movement of the IMD along one or more geometric axes of the IMD. The IMD includes a motion sensor (e.g., an accelerometer) configured to sense movement of the IMD along the one or more geometric axes. The medical system is configured to compare the IMD movement with representative cardiac activity of the heart in order to assess coupling between the structural mechanism and the engaged tissue. In an example, the medical system is configured to compare the IMD movement with representative cardiac activity during implantation of the IMD within the heart. The medical system may be configured to provide an output during the implantation process so that a clinician can assess coupling between the IMD and cardiac tissue as the implantation process progresses.

[0022] IMD motion may refer to motion indicating movement of the IMD in geometric space along one or more principal axes. In an example, IMD motion indicates movement of the housing of the IMD. In an example, the motion indicating the IMD and / or the housing of the IMD may be movement of a proof mass and / or other component sensed by a motion sensor mechanically supported by the IMD (e.g., the IMD housing). In some examples, the motion indicating the movement of the IMD may be caused by movement of the IMD. For example, the motion indicating the movement of the IMD may be movement of a proof mass of an accelerometer, the accelerometer being configured such that movement of the IMD causes movement of the proof mass.

[0023] The medical system may be configured such that the clinician's actions cause the fixation element of the IMD to be gradually embedded into the cardiac tissue during implantation. For example, the fixation element may be a helix configured to be gradually embedded into the cardiac tissue when the helix contacts the cardiac tissue and the clinician (e.g., using a delivery member) applies torque to the IMD. The fixation element may be one or more tines configured to be gradually embedded when one or more of the tines contact the cardiac tissue, and the clinician causes proximal retraction of the delivery catheter and / or applies an axial force to the IMD. The medical system is configured to sense the movement of the IMD and associate the movement with representative cardiac activity during implantation, so that the clinician can assess when contact between the fixation element and the cardiac tissue occurs, assess the progression of coupling between the fixation element and the cardiac tissue as the clinician gradually embeds the fixation element, assess the quality of coupling between the fixation element and the cardiac tissue, assess the orientation of the IMD relative to the surface of the cardiac tissue, and / or assess other aspects of the IMD implantation.

[0024] The fixation element can be mechanically supported by the housing of the IMD such that forces applied to the fixation element by cardiac tissue (e.g., caused by the beating of the heart) cause movement of the IMD housing. The IMD housing can define one or more axes, such as a main axis extending through the distal and proximal portions of the IMD, a first radial axis perpendicular to the main axis, and a second radial axis perpendicular to the first radial axis and the perpendicular axis. The motion sensor can be configured to sense movement of the IMD along one or more of the main axis, the first radial axis, and / or the second radial axis (e.g., by sensing acceleration to sense movement). The processing circuit can receive one or more signals indicating IMD movement along one or more of the main axis, the first radial axis, and / or the second radial axis, and evaluate the deviation between the IMD movement and the movement that is expected to occur based on representative cardiac activity.

[0025] The motion sensor may be configured to sense, for example, an acceleration indicating an acceleration of the IMD housing caused by a force applied to the IMD housing (e.g., via a fixation element) when the heart beats and applies force to the fixation element. In an example, the motion sensor is configured to sense the acceleration of the proof mass. The processing circuit is configured to compare the sensed IMD motion with representative cardiac activity and provide an output indicating coupling between the fixation element and the cardiac tissue. The representative cardiac activity may be based on, for example, sensed cardiac activity of the patient, expected cardiac activity based on historical cardiac activity of the patient or other patients, or another indicator indicating representative cardiac activity. In an example, the medical system is configured to sense the frequency of the IMD motion along the main axis, the first radial axis, and / or the second radial axis (e.g., based on the frequency of the perturbation of the measured acceleration) to determine a frequency-based sensor parameter, and compare the frequency-based sensor parameter with one or more frequencies of the representative cardiac activity. In an example, the medical system is configured to sense the amplitude of the IMD movement along the main axis, the first radial axis, and / or the second radial axis (e.g., based on the amplitude of the perturbation of the measured acceleration) to determine the amplitude-based sensor parameters, and compare the amplitude-based sensor parameters to one or more amplitudes of representative cardiac activity. In an example, the medical system may be configured to determine the force on the IMD (e.g., based on the acceleration sensed by the motion sensor) and compare the determined force to the force that the representative cardiac activity is expected to exert on the IMD. The processing circuitry may be configured to compare the determined force to the representative cardiac activity and provide an output indicating the coupling between the fixation element and the cardiac tissue.

[0026] The medical system may include an output device configured to provide an indication to a clinician during implantation of the IMD. For example, the medical system may compare the IMD motion sensed along one or more of the main axis, the first radial axis, and / or the second radial axis with representative cardiac activity, and provide an indication that there is contact between the fixation element of the IMD and the cardiac tissue. Such an indication may allow the clinician to assess, for example, whether the IMD is still substantially free floating in the heart and / or intermittently in contact with the cardiac tissue before the clinician takes action to gradually embed the fixation element into the tissue. The medical system may compare the IMD motion with representative cardiac activity, and provide an indication of the pressure (e.g., force) applied by the fixation element to the cardiac tissue, for example, to allow the clinician to assess whether the existing pressure is too low or too high to implant the IMD into the cardiac tissue. In an example, when the clinician's action (e.g., rotating the IMD and / or withdrawing the delivery catheter) causes the fixation element to gradually embed into the cardiac tissue, the medical system may substantially monitor the IMD motion to provide an indication of the progress of the fixation element into the cardiac tissue when the clinician takes action. For example, when the fixation element is a helix, the medical system can evaluate the IMD motion to determine rotation of the IMD housing about the primary axis when the medical system compares the IMD motion to representative cardiac activity so as to determine the number of rotations of the IMD caused by the clinician as the helix is ​​gradually embedded in the tissue. In an example, the medical system is configured to evaluate and / or indicate the likely success of the implant based on, for example, the number of rotations, the comparison of the IMD motion to representative cardiac activity, and / or other parameters and / or indications.

[0027] In an example, a medical system is configured to evaluate the alignment of an IMD relative to a tissue wall (e.g., a septum) of the heart during and / or after implantation. For example, a processing circuit may compare IMD motion sensed between a main axis, a first radial axis, and / or a second radial axis to indicate a substantial perpendicularity of the IMD to the tissue wall. The processing circuit may evaluate perpendicularity based on IMD motion sensed along the axis individually, in comparison to one another, and / or in comparison to representative cardiac activity. In some examples, the processing circuit is configured to detect and / or evaluate pivoting of the main axis relative to the tissue wall (e.g., "fluttering" of the IMD) when the heart beats and forces are applied to the IMD, so that a clinician can evaluate and / or change orientation. Detection and / or evaluation of pivoting of the main axis may also provide an indication that the IMD has prematurely moved distally to a delivery cup or other structure configured to provide stability to the IMD during implantation.

[0028] The IMD is configured to pass through the patient's vasculature to position the IMD near a target area, such as an area within a cavity of the heart. For example, the IMD can be configured to allow a clinician to navigate the IMD through a vein of the heart (e.g., the innominate vein, the inferior vena cava (IVC), the superior vena cava (SVC), or another venous access) to a target location within the right ventricle (RV), the right atrium (RA), or another area of ​​the heart. In an example, the IMD is configured to be positioned with a lumen of a delivery catheter that is configured to pass the IMD through the vasculature. For example, the delivery catheter may include a delivery container (e.g., delivery container 111 ( Figures 2 to 4 )), the delivery container is configured to substantially retain the IMD as the delivery catheter traverses the vasculature.

[0029] Figure 1 1 is a conceptual diagram illustrating a portion of an example medical system 100 configured to deliver therapy (e.g., pacing) to a patient's heart 102. Medical system 100 includes an IMD 104 that includes a device housing 106 and a fixation element 108 extending from device housing 106. IMD 104 (e.g., device housing 106) can define a proximal portion 105 of IMD 104 ("IMD proximal portion 105") and a distal portion 107 of IMD 104 that is substantially opposite to IMD proximal portion 105 ("IMD distal portion 107"). In an example, medical system 100 includes a delivery member 110 that is configured to position IMD 104 proximate a target site 112 within heart 102.

[0030] For example, Figure 1 1 , target site 112 is an area in the ventricular wall of the right ventricle (RV) of heart 102. Target site 112 may include tissue wall 113, wherein surface tissue 115 at least partially defines an anatomical volume of heart 102 (e.g., RA and / or RV). In other examples, delivery member 110 and / or IMD 104 may be configured to be positioned proximate to a target site at another portion of heart 102. For example, delivery member 110 and / or IMD 104 implantable medical lead may be configured to be positioned proximate to a target site in the right atrium (RA), left atrium (not shown), left ventricle (not shown) of heart 102, or positioned within or around coronary sinus 114. Delivery member 110 and IMD 104 may be configured to extend through the patient's vasculature (e.g., inferior vena cava (IVC)) to position IMD 104 within heart 102. In an example, delivery member 110 can include a cup-shaped section (not shown) defining a lumen configured to engage IMD 104 .

[0031] Fixation element 108 is configured to fix IMD 104 to tissue of heart 102. In an example, device housing 106 mechanically supports fixation element 108. Fixation element 108 is configured to penetrate cardiac tissue (e.g., tissue wall 113 and / or surface tissue 115) at or near a target site, such as target site 112. For example, fixation element 108 may be configured to penetrate cardiac tissue of the septal wall in the RV, RA, LV, and / or LA of heart 102, or to penetrate cardiac tissue in another region of heart 102. Fixation element 108 may be configured to substantially maintain IMD 104 at or near the target site when fixation element 108 penetrates tissue at or near the target site.

[0032] The fixation mechanism 108 can be configured to allow a clinician to engage the fixation element 108 with tissue within the heart 102, such that the clinician can secure the IMD 104 after it is delivered to the target site 112. For example, the fixation element 108 can be configured to gradually embed into the tissue wall 113 as the fixation element 108 contacts the surface tissue 115 and the clinician's action causes the fixation element 108 to engage the tissue of the tissue wall 113. For example, the fixation element 108 can be configured to define an embedment depth between a distal end 116 of the fixation element 108 ("fixation element distal end 116") and the surface tissue 115 as the clinician engages the fixation element 108 with the tissue wall 113. The fixation element 108 can be configured to increase the embedment depth as the clinician manipulates one or more components of the medical system 100, such that the fixation element 108 gradually embeds into the tissue wall 113 during implantation of the IMD 104 in the heart 102. For example, when the clinician rotates the IMD 104 about the device axis LD, applies an axial force on the IMD 104 (e.g., substantially parallel to the device axis LD), moves one or more components of the medical system 100 relative to the IMD 104 (e.g., proximal retraction of the catheter 132), and / or manipulates the medical system 100 in another manner, the fixation element 108 can be configured to gradually embed to increase the embedment depth. The fixation element 108 can be, for example, a helix (one or more turns) or another structure and / or component configured to gradually embed within the tissue wall 113. The device axis LD can be an axis defined by a portion of the IMD 104 (such as the device housing 106) and / or another portion of the IMD 104. In an example, the device axis LD extends through the IMD proximal portion 105 and / or the IMD distal portion 107.

[0033] The medical system 100 is configured to sense movement of the IMD 104 and compare the movement of the IMD 104 with representative cardiac activity of the heart 102 before, during, and / or after the implantation process. The IMD 104 is configured such that forces applied to the fixation element 108 from the engaged tissue of the heart 102 (e.g., due to a heartbeat) cause corresponding movement of the IMD 104 along one or more geometric axes of the IMD, such as a principal axis substantially parallel to a device axis LD defined by the IMD 104 (e.g., the device housing 106), one or more axes substantially perpendicular to the principal axis, and / or another geometric axis. The IMD 104 includes a motion sensor 118 configured to sense movement of the IMD 104 and / or movement indicating movement of the IMD 104 along one or more geometric axes. The motion sensor 118 may be, for example, an accelerometer, a gyroscope, a magnetometer, an inertial measurement unit (IMU), and / or another motion sensor. In some examples, the motion sensor 118 is an accelerometer.

[0034] The medical system 100 is configured to compare the IMD motion to representative cardiac activity of the heart in order to assess coupling between the fixation element 108 and the engaged tissue within the tissue wall 113. For example, the medical system 100 may include a processing circuit 120 configured to receive one or more signals from the motion sensor 118 indicating motion of the IMD 104 (e.g., via a communication link 122). The processing circuit 120 may use the one or more signals to compare the motion of the IMD 104 to representative cardiac activity of the heart 102. The processing circuit 120 may be configured to provide an output to an output device 124 based on the comparison (e.g., via a communication link 126) so that a clinician can assess coupling between the IMD 104 and tissue within the tissue wall 113 as the implantation procedure progresses.

[0035] The motion sensor 118 may be configured to sense acceleration of at least a portion of the motion sensor 118 (e.g., a proof mass) and / or acceleration of the device housing 106 caused by forces applied to the device housing 106 via the fixation element 108, for example, when the heart 102 beats and applies forces to the fixation element 108. The motion sensor 118 may sense acceleration (e.g., of the proof mass) using electrical, piezoelectric, piezoresistive, capacitive, quantum tunneling, convection, motors, and / or other components. The processing circuit 120 is configured to compare the sensed IMD motion with representative cardiac activity of the heart 102 and provide an output indicating coupling between the fixation element 108 and the tissue wall 113 based on the comparison. The representative cardiac activity may be based on, for example, the sensed cardiac activity of the heart 102, expected cardiac activity based on historical cardiac activity of the patient or other patients, or another indicator indicating representative cardiac activity.

[0036] In some examples, the medical system 100 includes a medical device 125 configured to generate one or more signals indicating electrical activity and / or mechanical activity of the heart 102. The electrical activity and / or mechanical activity may be, for example, an electrical signal indicating muscle movement of the patient's heart. For example, the medical device 125 may be configured to sense ECG and / or EGM signals generated by the heart 102. The medical device 125 may be configured to provide (e.g., via a communication link 127) a signal indicating electrical activity and / or mechanical activity of the heart 102 to the processing circuit 120. The processing circuit 120 may be configured to determine representative cardiac activity using the signal provided by the medical device 125. In some examples, as an alternative or in addition to the medical device 125, the processing circuit 120 is configured to receive representative cardiac activity from an external device 129 (e.g., via a communication link 131). The external device 129 may include a database or other data structure configured to provide representative cardiac activity based on, for example, historical cardiac activity of the heart 102 and / or historical cardiac activity of one or more subject hearts in other patients.

[0037] The medical system 100 may be configured to sense the motion of the IMD 102 (e.g., using the motion sensor 118) and to correlate the motion with representative cardiac activity (e.g., using the processing circuit 120) so that a clinician can assess contact between the fixation element 108 and the tissue wall 113. For example, the medical system 100 may compare the motion of the IMD 104 with the representative cardiac activity to provide an indication of the pressure (e.g., force) applied by the fixation element 108 on the tissue wall 113 (e.g., the surface tissue 115 of the tissue wall 113). The indication of pressure may allow the clinician to assess whether the existing pressure is too low or too high to, for example, begin to gradually embed the fixation element 108 into the tissue wall 113 (e.g., by rotating the IMD 104, applying an axial force on the IMD 104, withdrawing the delivery catheter 132 proximally, and / or taking another action).

[0038] As the clinician gradually embeds the fixation element 108 into the tissue wall 113, the medical system 100 can (e.g., using the processing circuit 120) generally monitor the movement of the IMD 102 to, for example, provide an indication of the final mechanical coupling between the fixation element 108 and the tissue wall 113. In some examples, the fixation element 108 is configured (e.g., as a helix) such that rotation of the IMD 104 about the IMD axis LD causes the fixation element 108 to engage and / or disengage with tissue within the target site 112. For example, the fixation element 108 can be configured such that rotation of the IMD 104 about the IMD axis LD along a first rotational direction W1 causes the fixation element 108 to engage (or, alternatively, disengage from combinations of these) tissue within the target site 112. The fixation element 108 can be configured such that rotation of the IMD 104 about the IMD axis LD along a second rotational direction W2 that is substantially opposite to the first rotational direction W1 causes the fixation element 108 to disengage from (or, alternatively, engage with) tissue within the target site 112.

[0039] The delivery member 110 can be configured to couple with the IMD 104 (e.g., the IMD proximal portion 105) such that torque on the delivery member 110 causes torque on the IMD 104, thereby rotating the IMD 104 about the device axis LD. In an example, the delivery member 110 includes a distal portion 128 ("delivery member distal portion 128") and a proximal portion 130 ("delivery member proximal portion 130"), the distal portion being configured to be inside the patient's body when the IMD 104 resides within the heart 102, and the proximal portion being configured to be outside the patient's body when the IMD 104 resides within the heart 102. The delivery member 110 can be configured such that when a clinician applies torque on the delivery member proximal portion 130, the delivery member distal portion 128 transmits some portion of the torque to the IMD 104 (e.g., the IMD proximal portion 105) to rotate the IMD 104 about the device axis LD. The processing circuit 120 may be configured to detect the rotation of the IMD 104 about the device axis LD when the processing circuit 120 compares the motion of the IMD 104 to the representative cardiac activity, such that the processing circuit 120 may substantially track the number of rotations of the IMD 104 that occurred as the fixation element 108 was progressively embedded within the tissue wall 113. The processing circuit 120 may provide an output (e.g., via the output device 124) such that a clinician may be informed of the number of rotations applied to the IMD 104 as the fixation element 108 was progressively embedded. In an example, the processing circuit 120 may be configured to assess that the fixation element may not be progressively embedded as the IMD 104 is rotated about the device axis LD based on, for example, the comparison of the motion of the IMD 104 to the representative cardiac activity.

[0040] In some examples, fixation element 108 includes one or more tines (not shown) configured to gradually embed into tissue wall 113 when one or more of the tines contact tissue wall 113 and the clinician retracts delivery catheter 132 proximally and / or applies an axial force to IMD 104 (e.g., using delivery member 110). Delivery catheter 132 can define a lumen 134 (delivery catheter lumen 134) and an opening 136 to delivery catheter lumen 134 ("delivery catheter opening 136"). Delivery catheter lumen 134 and delivery catheter opening 136 can be configured such that at least some portion of IMD 104 and / or delivery member 110 can pass therethrough. In an example, delivery catheter 132 includes a distal portion 138 ("delivery catheter distal portion 138") configured to be within the patient's body when IMD 104 resides within heart 102, and a proximal portion 140 ("delivery catheter proximal portion 140") configured to be outside the patient's body when IMD 104 resides within heart 102. Delivery catheter 132 can be configured such that movement of delivery catheter proximal portion 140 (e.g., caused by a clinician) causes movement of delivery catheter distal portion 138 and / or delivery catheter opening 136 relative to IMD 104. One or more tines that may be included in fixation element 108 can be configured to gradually engage tissue wall 113 when delivery catheter opening 136 is moved (e.g., moved proximally) relative to IMD 104 (e.g., when one or more tines are extended distally beyond delivery catheter opening 136) to increase the embedment depth of fixation element 108. The processing circuit 120 may be configured to compare the movement of the IMD 104 with representative cardiac activity as the one or more tines are embedded and provide an output to the output device 124 so that the clinician can be informed of the engagement of the one or more tines with the tissue wall 113 as the fixation element 108 is embedded.

[0041] Medical system 100 may be configured to evaluate the alignment of IMD 104 relative to tissue wall 113 during and / or after implantation of IMD 104 within heart 102. For example, processing circuit 120 may be configured to compare IMD motion sensed along the main axis, the first radial axis, and / or the second radial axis of motion sensor 118 when tissue wall 113 applies force to IMD 102. Processing circuit 120 may use the IMD motion sensed along the main axis, the first radial axis, and / or the second radial axis to evaluate the orientation of IMD 104 relative to tissue wall 113. For example, processing circuit 120 may be configured to indicate a substantial perpendicularity of IMD 104 to tissue wall 113 and / or other relative orientations of IMD 104 to tissue wall 113. In some examples, processing circuit 120 is configured to detect and / or assess pivoting of the main axis relative to tissue wall 113 (e.g., detect and / or assess "flutter" of IMD 104) as heart 102 beats and applies forces to IMD 104. Medical system 100 may provide (e.g., using output device 124) an indication of pivoting of the main axis so that a clinician may assess and / or change the relative orientation of IMD 104 and tissue wall 113. Detection and / or assessment of pivoting of the main axis may also provide an indication that IMD 104 has prematurely moved into a delivery cup or other structure of a delivery catheter 132 that is configured to provide stability to IMD 104 during implantation (e.g., configured to prevent flutter).

[0042] The IMD 104 may include a therapy delivery circuit 142 configured to deliver therapy (e.g., pacing) to the heart 102 and / or sense signals from the heart. In an example, the device housing 106 is configured to mechanically support the therapy delivery circuit 142. The therapy delivery circuit 142 may be configured to deliver therapy to the heart 102 and / or sense signals from the heart using one or more electrodes configured to electrically communicate with tissue of the heart 102. In an example, the therapy delivery circuit 142 is configured to deliver therapy to the heart 102 and / or sense signals from the heart using a first electrode 144 mechanically supported by the fixation element 108. In some examples, the therapy delivery circuit 142 is configured to deliver therapy to the heart 102 and / or sense signals from the heart using a second electrode 146 mechanically supported by the device housing 106 or another portion of the IMD 104 (e.g., a lead extending from the device housing 106). In some examples, the device housing 106 defines a return electrode 148 electrically connected to the therapy delivery circuit 142. Therapy delivery circuit 142 may be configured to deliver therapy to heart 102 and / or sense signals from the heart using one or more of first electrode 144, second electrode 146, return electrode 148, and / or another electrode of IMD 104. In an example, processing circuit 120 is configured to communicate with therapy delivery circuit 142 via, for example, communication link 122. Processing circuit 120 and / or therapy delivery circuit 142 may be located within and / or mechanically supported by device housing 106, medical device 125, external device 129, output device 124, and / or located Figure 1 Another device or group of devices not shown.

[0043] Thus, the medical system 100 is configured to sense movement of the IMD 104 before, during, and / or after implantation and correlate the movement with representative cardiac activity, such that a clinician can assess when contact occurs between the fixation element 108 and the tissue wall 113, assess the progression of coupling between the fixation element 108 and the tissue wall 113 as the clinician gradually embeds the fixation element 108 into the tissue wall 113, assess the quality of the coupling between the fixation element 108 and the tissue wall 113, assess the relative orientation of the IMD 104 and the tissue wall 113, and / or assess other aspects of an IMD implant.

[0044] Figure 2 An IMD 104 including a fixation element 108 and a motion sensor 118 is schematically illustrated, wherein the fixation element 108 is displaced from surface tissue 115 of a tissue wall 113 . Figure 3 IMD 104 is shown contacting tissue wall 113 such that fixation element 108 defines an embedment depth D1 between fixation element distal end 116 and surface tissue 115 . Figure 4 IMD 104 is shown embedded in tissue wall 113 such that fixation element 108 defines an embedment depth D2 between fixation element distal end 116 and surface tissue 115, wherein embedment depth D2 is greater than embedment depth D1. Figures 2 to 4 IMD 104 is shown positioned within a delivery receptacle 111 defined by and / or mechanically supported by delivery member 110. Delivery receptacle 111 can be configured to substantially restrict movement of device housing 106 in linear directions other than those directions substantially parallel to device axis LD.

[0045] The fixation element 108 is configured to gradually embed (e.g., transition from a defined embedment depth D1 to a defined embedment depth D2) when the fixation element 108 contacts the surface tissue 115 and the medical system 100 moves the fixation element 108 relative to the surface tissue 115. For example, the fixation element 108 may be configured to gradually embed into the tissue wall 113 when the fixation element 108 contacts the surface tissue 115 and the delivery member 110 applies a torque on the IMD 104 such that the device housing 106 rotates relative to the surface tissue 115 about the device axis LD. The fixation element 108 may be configured to gradually embed into the tissue wall 113 when the fixation element 108 contacts the surface tissue 115 and the delivery member 110 applies an axial force on the IMD 104 such that the device housing 106 translates proximally (e.g., in a proximal direction P) toward the surface tissue 115. In an example, the medical system 100 is configured so that the clinician can move the fixation element 108 relative to the surface tissue 115 so that the clinician can control the engagement of the fixation element 108 with the tissue wall 113. For example, the medical system 100 can be configured so that the clinician can cause relative movement between the fixation element 108 and the surface tissue 115 so that the fixation element 108 moves from Figure 2 The relative orientation depicted in FIG. 1 (where the fixation element 108 is displaced distally from the surface tissue 115) is transformed to Figure 3 The medical system 100 can be configured such that a clinician can cause relative movement between the fixation element 108 and the surface tissue 115 such that the fixation element 108 moves from the surface tissue 115 to the relative orientation depicted in FIG. Figure 3 The relative orientation depicted in the figure is transformed into Figure 4 , wherein fixation element 108 contacts tissue wall 113 and defines an embedding depth D2.

[0046] When the fixation element 108 is configured to gradually embed into the tissue wall 113, this may mean that the fixation element 108 is configured to increase the embedment depth within the tissue wall 113 due to the relative movement between the fixation element 108 and the surface tissue 115. In an example, the embedment depth is the distance from the distal end 116 of the fixation element and the surface tissue 115. The fixation element 108 may be configured to gradually embed into the tissue wall 113 so that the clinician can control (e.g., increase or decrease) the embedment depth by controlling the relative movement between the fixation element 108 and the surface tissue 115. For example, the fixation element 108 may be configured (e.g., as a helix) so that the clinician can control the embedment depth by controlling the rotation of the device housing 106 around the device axis LD. The fixation element 108 may be configured so that the clinician can control the embedment depth by controlling the axial force applied to the device housing 106.

[0047] The fixation element 108 can be supported (e.g., mechanically supported) by the device housing 106 such that when a force is applied to the fixation element 108, the fixation element 108 transmits the force to the device housing 106. For example, when the fixation element 108 gradually embeds and / or contacts the tissue wall 113 of the heart 102 ( Figure 1 ), the beating of the heart 102 can cause movement of the tissue wall 113 and exert force F1 and / or force F2 on the fixation element 108 (e.g., due to acceleration and contraction of the tissue wall 113). The fixation element 108 can transmit at least some portion of the force F1 and / or force F2 to the device housing 106, thereby causing movement of the device housing 106. The resulting movement of the device housing 106 caused by the engagement between the fixation element 108 and the tissue wall 113 can be related to the movement of the tissue wall 113 that occurs during a heartbeat. Therefore, (e.g., when the clinician causes the fixation element 108 to gradually embed) the engagement of the fixation element 108 with the tissue wall 113 can be evaluated by comparing the movement of the device housing 106 with representative cardiac activity indicative of movement of the tissue wall 113 during a heartbeat.

[0048] The medical system 100 is configured to sense movement of the device housing 106 (e.g., using the motion sensor 118) and compare the movement to representative cardiac activity (e.g., using the processing circuit 120) to assist a clinician in evaluating engagement between the fixation element 108 and the tissue wall 113 before, during, and / or after implanting the fixation element 108 within the tissue wall 113. For example, the motion sensor 118 may be configured to sense movement of the device housing 106 along the main axis P, the first radial axis R1, and / or the second radial axis R2. Movement of the device housing 106 along one or more of the main axis P, the first radial axis R1, and the second radial axis R2 may indicate engagement of the fixation element 108 with the tissue wall 113, and / or indicate a substantial lack of engagement between the fixation element 108 and the tissue wall 113.

[0049] The motion sensor 118 may be configured to provide one or more signals indicating movement of the device housing along (e.g., substantially parallel to) the main axis P, the first radial axis R1, and the second radial axis R2. The main axis P, the first radial axis R1, and the second radial axis R2 are configured relative to each other such that a vector sum of a first vector parallel to the main axis P, a second vector parallel to the first radial axis R1, and a third vector parallel to the second radial axis R2 describes a vector having a direction in three-dimensional space. In an example, the first radial axis R1 is substantially perpendicular to the main axis P. In an example, the second radial axis R2 is substantially perpendicular to the main axis P and the first radial axis R2. In some examples, the main axis P is substantially parallel to the device axis LD. The motion sensor 118 may provide one or more signals indicating movement of the device housing 106 to the processing circuit 120. For example, the motion sensor 118 may provide one or more of: a main signal indicating movement of the device housing 106 along the main axis P, a first radial signal indicating movement of the device housing 106 along the first radial axis R1, and / or a second radial signal indicating movement of the device housing 106 along the second radial axis R2.

[0050] The processing circuit 120 may be configured to compare one or more of the main signal, the first radial signal, and / or the second radial signal to representative cardiac activity to assess engagement of the fixation element 108 with the tissue wall 113. The processing circuit 120 may be configured to process the main signal, the first radial signal, and / or the second radial signal to substantially isolate portions of the respective signals that may indicate cardiac activity of the heart 102 (e.g., acceleration and contraction of the tissue wall 113 during a heartbeat of the heart 102). For example, the processing circuit 120 may be configured to evaluate one or more frequencies of the main signal, the first radial signal, and / or the second radial signal to determine one or more frequency-based sensor parameters, and compare the main signal, the first radial signal, and / or the second radial signal to the representative cardiac activity using the frequency-based sensor parameters. The frequency-based sensor parameters may be, for example, portions of the main signal, the first radial signal, and / or the second radial signal that exhibit frequencies that may be expected to be present due to motion caused by the tissue wall during representative cardiac activity, such as portions that exhibit frequencies in a frequency window between a lower frequency threshold and an upper frequency threshold (including the lower frequency threshold). The lower frequency threshold may be, for example, greater than or equal to about 1 Hertz (Hz), 5 Hz, 10 Hz, or another frequency. The upper frequency threshold may be, for example, less than or equal to about 20 Hz, 40 Hz, 100 Hz, 250 Hz, or another frequency.

[0051] In an example, instead of or in addition to evaluating one or more frequencies, the processing circuit 120 may be configured to evaluate one or more amplitudes to evaluate engagement of the fixation element 108 with the tissue wall 113. For example, the processing circuit 120 may be configured to evaluate one or more amplitudes of the main signal, the first radial signal, and / or the second radial signal to determine one or more amplitude-based sensor parameters, and compare the main signal, the first radial signal, and / or the second radial signal to representative cardiac activity using the amplitude-based sensor parameters. The amplitude-based sensor parameters may be, for example, a portion of the main signal, the first radial signal, and / or the second radial signal that exhibits an amplitude, amplitude variation, peak-to-peak amplitude, peak amplitude, and / or other fluctuations of the main signal, the first radial signal, and / or the second radial signal that may be expected to exist due to movement caused by the tissue wall during representative cardiac activity.

[0052] The processing circuit 120 may be configured to compare the main signal, the first radial signal, and / or the second radial signal to the representative cardiac activity and / or to compare one of the main signal, the first radial signal, and / or the second radial signal to the other of the main signal, the first radial signal, and / or the second radial signal using any signal matching method that is intended to enable comparison of the first signal to a template of the second signal and / or an expected signal (e.g., a template representing at least a portion of the representative cardiac activity). In an example, the processing circuit 120 is configured to compare the main signal, the first radial signal, and / or the second radial signal to the representative cardiac activity using a matching method that includes techniques such as Fourier transform (FT) comparison (e.g., FFT comparison), cross-correlation, correlation coefficient, variation standard deviation, template matching, and / or one or more other waveform similarity analyses.

[0053] The medical system 100 may be configured to provide (e.g., via an output device 124) an indication of whether the fixation element 108 appears to be displaced from the surface tissue 115 or appears to be in contact with the surface tissue 115. Such an indication may allow a clinician to assess, for example, whether the IMD 104 is substantially free-floating in the heart and / or intermittently in contact with the heart tissue before the clinician takes action to gradually embed the fixation element 108 into the tissue wall 113. The medical system 100 may be further configured to assess and / or provide an indication that the fixation element 108 is only partially fixed. For example, the processing circuit 120 may be configured to compare one or more of the main signal, the first radial signal, and / or the second radial signal with representative cardiac activity (e.g., using frequency-based sensor parameters and / or amplitude-based sensor parameters). The processing circuit 120 may assess that the fixation element 108 is only partially fixed based on, for example, correlation, similarity, and / or other comparisons of one or more of the main signal, the first radial signal, and / or the second radial signal with representative cardiac activity. For example, the processing circuit 120 can be configured to use one or more of the main signal, the first radial signal, and / or the second radial signal and the representative cardiac activity to determine a matching coefficient and / or other similarity parameters. The processing circuit 120 can be configured to compare the matching coefficient and / or other similarity parameters to a threshold value to assess whether the fixation element 108 is only partially fixed to the tissue wall 113.

[0054] For example, processing circuitry 120 may compare one or more frequencies of the primary signal, the first radial signal, and / or the second radial signal to representative cardiac activity and assess that fixation element 108 is likely not in contact with tissue wall 113 (e.g., as shown in FIG. Figure 2). The processing circuit 120 can assess the lack of contact based on an amount of reduction and / or a substantial lack of frequency in the main signal, the first radial signal, and / or the second radial signal, which amount of reduction and / or the substantial lack of frequency may be expected as a result of motion caused by representative cardiac activity. The processing circuit 120 can communicate with an output device 124 to cause the output device 124 to provide an indication representing the assessed lack of contact so that the clinician can be informed of the relative orientation of the fixation element 108 to the tissue wall 113. The clinician can then translate the IMD 104 and the fixation element 108 distally toward the tissue wall 113 so that contact between the fixation element 108 and the surface tissue 115 is indicated before attempting to gradually embed the fixation element 108 into the tissue wall 113. The processing circuit 120 may then compare one or more frequencies of the main signal, the first radial signal, and / or the second radial signal to representative cardiac activity and assess that the fixation element 108 is likely in contact with the tissue wall 113 (e.g., as shown in FIG. 1 ) based on, for example, frequencies in the main signal, the first radial signal, and / or the second radial signal that are expected to be present due to motion that may be caused by representative cardiac activity. Figure 3 and Figure 4 as depicted in ).

[0055] As an example, Figure 5 1 shows exemplary representative cardiac activity 151 indicating electrical and / or mechanical activity of a heart, such as heart 102. In an example, representative cardiac activity 151 is based on one or more signals generated by heart 102 and sensed by medical device 125, and / or generated by one or more other patients and sensed from external device 129 ( Figure 1 ) received by the processing circuit 120. The one or more signals may indicate, for example, ECG and / or EGM signals expected from and / or generated by the heart 102, accelerations generated and / or expected to occur during the cardiac cycle of the patient (e.g., heart 102) and / or the heart of other patients, movements generated and / or expected to occur during the cardiac cycle of the heart of the patient and / or the other patients, and / or other signals generated by the heart of the patient and / or the other patients. The processing circuit 120 may be configured to substantially correlate the representative cardiac activity 151 with actual and / or expected movement of the tissue wall 113 (e.g., during a heartbeat of the heart 102). Thus, the processing circuit 120 may compare the representative cardiac activity 151 with the movement of the IMD 104 sensed by the motion sensor 118 in order to assess engagement of the fixation element 108 with the tissue wall 113 (e.g., to assess whether the tissue wall 113 is applying force F1 and / or force F2 ( Figure 2 ) is transmitted to IMD 104).

[0056] Figures 6 to 8 An exemplary motion signal 152 generated by motion sensor 118 is shown. Figure 6 The motion signal 152 (e.g., as indicated by the movement of the fixation element 108) is displaced from the surface tissue 115 and / or the tissue wall 113. Figure 3 as depicted in ). Figure 7 and Figure 8 A motion signal 152 is provided indicating when the fixation element 108 is engaged with the tissue wall 113. The motion signal 152 may include one or more of a main signal 154, a first radial signal 156, and / or a second radial signal 158. The main signal 154 may indicate movement of the device housing 106 along (e.g., substantially parallel to) the main axis P. The first radial signal 156 may indicate movement of the device housing 106 along the first radial axis R1. The second radial signal 158 may indicate movement of the device housing 106 along the second radial axis R1. In an example, the main signal 154, the first radial signal 156, and / or the second radial signal 158 indicate movement of a point P1 defined by the device housing 106.

[0057] Processing circuit 120 may compare one or more frequencies of main signal 154, first radial signal 156, and / or second radial signal 158 to representative cardiac activity 151 to assess whether fixation element 108 is likely to be in contact with tissue wall 113. For example, when motion sensor 118 provides Figure 6 When the motion signal 152 is received, the processing circuit 120 may define a window 160 ( Figure 6 ), the main signal 154 exhibits one or more frequencies over the window. The processing circuit 120 may compare the portion of the main signal 154 within the window 160 with one or more windows defined for the representative cardiac activity 151, such as the representative window 162. The processing circuit 120 may determine a degree of waveform similarity between the portion of the main signal 154 within the window 160 and the portion of the representative cardiac activity 151 within the representative window 162. The processing circuit 120 may assess contact or lack of contact between the fixation element 108 and the tissue wall 113 based on the degree of waveform similarity. For example, the processing circuit 120 may assess that the fixation element 108 is not in contact with the tissue wall 113 (e.g., based on a lack of similarity between the waveforms in the window 160 and the representative window 162). Figure 3 ). The processing circuit 120 can communicate with the output device 124 to cause the output device 124 to provide an indication representing the lack of assessed contact so that the clinician can be informed of the relative orientation of the fixation element 108 and the tissue wall 113.

[0058] Conversely, when the motion sensor 118 provides Figure 7 When the motion signal 152 is received, the processing circuit 120 may define a window 164 ( Figure 7), the main signal 154 exhibits one or more frequencies in the window. The processing circuit 120 can compare the portion of the main signal 154 within the window 164 with the portion of the representative heart activity 151 within the representative window 162, and determine the degree of similarity between the waveforms in the window 164 and the representative window 162. The processing circuit 120 can be configured to assess whether the fixation element 108 is likely in contact with the tissue wall 113 (e.g., based on the degree of similarity between the waveforms in the window 164 and the representative window 162). Figure 4 and Figure 5 ). The processing circuit 120 can communicate with the output device 124 to cause the output device 124 to provide an indication representing contact so that the clinician can understand the relative orientation of the fixation element 108 and the tissue wall 113.

[0059] In an example, such as when representative cardiac activity 151 indicates a signal sensed by medical device 125, windows 160, 164 and representative window 162 may be substantially simultaneous signals (e.g., may be substantially synchronized in time). In some examples, such as when representative cardiac activity 151 is provided by external device 129, windows 160, 164 may be substantially asynchronous with representative window 162. In some examples, processing circuit 120 is configured to detect representative window 162 using a template matching algorithm configured to search for one or more representative windows that substantially match the signals represented by windows 160, 164 in intervals (e.g., consecutive intervals) of representative cardiac activity 151. Furthermore, although windows 162 and 164 are in the same period of time, the representative window 162 may be substantially synchronous with each other. Figure 6 to Figure 7 164, the processing circuit 120 may be configured to define one or more windows that include portions of the first radial signal R1 and / or the second radial signal R2, and to evaluate the likelihood of contact between the fixation element 108 and the tissue wall 113 by comparing the one or more windows to the representative window 164, in substantially the same manner as described for window 162.

[0060] In some examples, the medical system 100 (e.g., the processing circuit 120) is configured to assess that the fixation element 108 is likely in contact with and / or becoming embedded in the tissue wall 113 by comparing a fluctuation pattern present in one of the main signal 154, the first radial signal 156, or the second radial signal 158 with a fluctuation pattern present in another of the main signal 154, the first radial signal 156, or the second radial signal 158. The processing circuit 120 may be configured to assess that the fixation element 108 is likely embedded in the tissue wall 113 based on similarities in the fluctuation patterns detected in the main signal 154, the first radial signal 156, and / or the second radial signal 158. The processing circuit 120 may communicate with the output device 124 so that the output device 124 provides an indication to the clinician that the fixation element 108 is likely embedded in the tissue wall 113 based on the fluctuation patterns detected in the main signal 154, the first radial signal 156, and / or the second radial signal 158.

[0061] For example, refer to Figure 7 , the processing circuit 120 may detect a fluctuation pattern FP in the main signal 154, wherein the pattern FP includes fluctuations detected at times T1, T2, T3, T4, T5, T6, T7, and T8. Fluctuations may be defined, for example, by a rate of change of the main signal 154, such as a rate of change that causes the main signal 154 to move upward and then the main signal 154 to move downward. Similarly, the processing circuit 120 may detect a fluctuation pattern F1 in the first radial signal 156, wherein the first pattern F1 includes fluctuations in the first radial signal 156 detected at times T1, T2, T3, T4, T5, T6, T7, and T8. Likewise, the processing circuit 120 may detect a fluctuation pattern 2 in the second radial signal 158, wherein the second pattern F2 includes fluctuations in the second radial signal 158 detected at times T1, T2, T3, T4, T5, T6, T7, and T8. The processing circuit 120 may compare the pattern FP, the pattern F1, and / or the pattern F2 to assess that the fixation element 108 is likely embedded in the tissue wall 113 based on, for example, similar temporal distributions of perturbations within the pattern FP, the pattern F1, and / or the pattern F2. The processing circuit 120 may be configured to assess that the fixation element 108 is likely embedded in the tissue wall 113 based on similarities in the fluctuation patterns detected in the main signal 154, the first radial signal 156, and / or the second radial signal 158. The processing circuit 120 may communicate with the output device 124 to cause the output device 124 to provide an indication representing the assessment that the fixation element 108 is embedded in the tissue wall 113.

[0062] In an example, the medical system 100 is configured to assess that the IMD 104 is experiencing movement relative to the tissue wall 113 and provide an indication of the relative movement (e.g., via the output device 124). For example, when a clinician uses the delivery member 110 to induce relative movement between the IMD 104 and the tissue wall 113 (e.g., to cause the IMD 104 to rotate relative to the tissue wall 113), the medical system 100 (e.g., the processing circuit 120) can evaluate the main signal 154, the first radial signal 156, and / or the second radial signal 158 to identify the movement. The processing circuit 120 can substantially correlate the sensed relative movement with an assessment of whether the fixation element 108 is likely to be embedded in the tissue wall 113, so that when the clinician induces movement of the IMD 104, the clinician can be informed whether the fixation element 108 is embedded in the tissue wall 113.

[0063] The processing circuit 120 may be configured to use one or more of the main signal 154, the first radial signal 156, and / or the second radial signal 158 to evaluate movement of the fixation element 108 and / or the device housing 106 relative to the tissue wall 113 and / or the surface tissue 115. For example, the processing circuit 120 may be configured to evaluate the main signal 154, the first radial signal 156, and / or the second radial signal 158 to indicate rotation of the fixation element 108 and / or the device housing 106 about the device axis LD (e.g., caused by a clinician during implantation), or another relative movement of the fixation element 108 and / or the device housing 106 relative to the surface tissue 115 and / or the tissue wall 113. The processing circuit 120 may be configured to process the main signal 154, the first radial signal 156, and / or the second radial signal 158 to substantially isolate portions of the respective signals that may indicate relative movement.

[0064] For example, the processing circuit 120 may be configured to evaluate one or more lower frequencies of the main signal 154, the first radial signal 156, and / or the second radial signal 158 to determine one or more lower frequency-based sensor parameters, and evaluate the lower frequency-based sensor parameters to provide an indication of relative movement of the fixation element 108 and / or the device housing 106 relative to the surface tissue 115 and / or the tissue wall 113. The lower frequency-based sensor parameter may be, for example, a portion of the main signal 154, the first radial signal 156, and / or the second radial signal 158 that exhibits frequencies outside of frequencies that may be expected to be present during representative cardiac activity due to movement caused by the tissue wall, such as a portion that exhibits frequencies below a lower frequency limit. The lower frequency limit may be, for example, less than or equal to approximately 1 Hertz (Hz), 5 Hz, 10 Hz, 50 Hz, or another frequency.

[0065] The processing circuit 120 may evaluate the main signal 154, the first radial signal 156, and / or the second radial signal 158 to provide an indication that the fixation element 108 and / or the device housing 106 has or is rotating about the device axis LD relative to the surface tissue 115 and / or the tissue wall 113. The processing circuit 120 may evaluate the rotation based on a perturbation (e.g., a cycle) of the main signal 154, the first radial signal 156, and / or the second radial signal 158. For example, the processing circuit 120 may be configured to detect a perturbation of the main signal 154, the first radial signal 156, and / or the second radial signal 158 based on an expected effect of a gravity vector (e.g., a non-zero gravity vector) acting on the motion sensor 118. The processing circuit 120 may be configured to evaluate that the fixation element 108 and / or the device housing 106 has or is rotating about the device axis LD based on the expected effect of the gravity vector. In an example, the processing circuit 120 is configured to detect perturbations in the amplitude of the main signal 154, the first radial signal 156, and / or the second radial signal 158, and compare the amplitude perturbations to amplitude perturbations that are expected to be present when the motion sensor 118 undergoes rotation under the influence of the gravity vector. The processing circuit 120 can communicate with the output device 124 so that the output device 124 provides an indication representing the estimated rotation of the fixation element 108 and / or the device housing 106, so that the clinician can be informed of the movement of the fixation element 108 and / or the device housing 106 relative to the surface tissue 115 and / or the tissue wall 113.

[0066] As an example, Figure 6 A motion signal 152 is shown that exhibits perturbations due to rotation of the IMD 104 about the device axis LD (eg, due to torque transmitted to the IMD 104 via the delivery member 110). As discussed, Figure 6 Motion signal 152 is shown when IMD 104 is displaced from tissue wall 113 (e.g., Figure 2 ). The processing circuit 120 is configured to detect perturbations of the main signal 154, the first radial signal 156, and / or the second radial signal 158, such as perturbations P1 of the first radial signal 156 and / or perturbations P2 of the second radial signal 158. The processing circuit 120 may be configured to identify perturbations based on cycles of the main signal 154, the first radial signal 156, and / or the second radial signal 158 across a substantial mean, such as cycles of the first radial signal 156 across a mean MR1 and / or cycles of the second radial signal 158 across a mean MR2. In an example, the processing circuit 120 is configured to determine the mean MR1 and / or the mean MR2 based on the first radial signal 156 and / or the second radial signal 158. The processing circuit 120 may be configured to assess that the motion sensor 118 (and the device housing 106) may be rotating about the device axis LD based on the detection of perturbations P1 and / or perturbations P2. Although Figure 6The substantial absence of perturbations in primary signal 154 due to the constraint of delivery container 111 on IMD 104 is shown, but processing circuitry may be configured to assess rotation of motion sensor 118 (and device housing 106) about an axis defined by IMD 104 by detecting perturbations of primary signal 154 in substantially the same manner as described for first radial signal 156 and / or second radial signal 158. Processing circuitry 120 may be configured to assess that fixation element 108 may not be progressively embedded within tissue wall 113 based on a substantial lack of IMD movement corresponding to representative cardiac activity (e.g., a corresponding lack of IMD movement and / or IMD movement below a threshold).

[0067] In a similar manner, processing circuit 120 may be configured to evaluate rotation of motion sensor 118 (and device housing 106) about an axis defined by IMD 104 when fixation element 108 is embedded within tissue wall 113. For example, Figure 7 Indicates that when IMD 104 engages tissue wall 113 (e.g., Figure 3 and Figure 4 1 (depicted in FIG. 1 ) exhibits a perturbation in motion signal 152 due to rotation of IMD 104 about device axis LD. Processing circuit 120 may be configured to detect perturbations of main signal 154, first radial signal 156, and / or second radial signal 158 in a manner substantially similar to that described for detection of perturbations P1 and / or perturbations P2. For example, processing circuit 120 may be configured to identify perturbation P3 based on cycles of first radial signal 156 across mean MR3. Processing circuit 120 may be configured to identify perturbation P4 based on cycles of second radial signal 158 across mean MR4. Processing circuit 120 may be configured to assess that motion sensor 118 (and device housing 106) may be rotating about device axis LD based on detection of perturbations P3 and / or perturbations P4.

[0068] The processing circuit 120 may be configured to assess that the fixation element 108 is becoming embedded within the tissue wall 113 by assessing the substantially simultaneous occurrence of contact between the fixation element 108 and the tissue wall 113 and movement (e.g., rotation) of the fixation element 108 and / or the device housing 106 relative to the tissue wall 113 and / or the surface tissue 115. For example, as discussed, the processing circuit 120 may utilize the main signal 154, the first radial signal 156, and / or the second radial signal 158 to assess that the fixation element 108 may be embedded in the tissue wall 113. The processing circuit 120 may utilize the main signal 154, the first radial signal 156, and / or the second radial signal 158 to assess that the fixation element 108 and / or the device housing 106 may be experiencing movement relative to the tissue wall 113 and / or the surface tissue 115. The processing circuit 120 may be configured to assess that the apparent embedding of the fixation element 108 and the apparent movement of the fixation element 108 and / or the device housing 106 are substantially simultaneous events (e.g., occur substantially simultaneously). Processing circuit 120 may be configured to indicate, based on the detected substantially simultaneous events, that fixation element 108 is becoming embedded within tissue wall 113. Processing circuit 120 may provide an indication to output device 124 that substantially simultaneous events were detected, such that a clinician is aware that movement of IMD 104 (e.g., caused by the clinician) may cause fixation element 108 to become embedded within tissue wall 113.

[0069] In some examples, processing circuit 120 may be configured to evaluate (e.g., count) the number of rotations of IMD 104 about device axis LD when fixation element 108 is assessed to be embedded within tissue wall 113. Processing circuit 120 may assess the rotation based on a perturbation exhibited by one or more of primary signal 154, first radial signal 156, and / or second radial signal 158. In an example, processing circuit 120 is configured to assess the number of rotations based on the number of complete cycles of one or more perturbations exhibited by primary signal 154, first radial signal 156, and / or second radial signal 158. For example, the processing circuit 120 may be configured to assess that the IMD 104 has completed a full rotation about the device axis LD when a motion signal (e.g., one of the main signal 154, the first radial signal 156, and / or the second radial signal 158) indicating motion on an axis of motion (e.g., one of the main axis P, the first radial axis R1, and / or the second radial axis R1) exhibits a waveform indicating that the axis has swept through an angle of 360 degrees relative to the direction of a reference vector (e.g., the gravity vector). In an example, the processing circuit 120 is configured to assess that the IMD 104 has completed a full rotation about the device axis LD based on identifying that the waveform has substantially completed a waveform cycle over a waveform period.

[0070] For example, Figure 8 1 shows a motion signal 152 that may be expected to exist when the IMD 104 is substantially rotated about the device axis LD. The processing circuit 120 may be configured to identify a first rotation of the IMD 104 about the device axis LD based on identifying that the first radial signal 156 has completed the first waveform period WC1 over the waveform period WP1. The processing circuit 120 may be configured to use the first radial signal 156 to identify subsequent rotations of the IMD 104 about the device axis LD. For example, the processing circuit 120 may be configured to identify a second rotation of the IMD 104 about the device axis LD based on identifying the completion of the second waveform period WC2 over the waveform period WP2, identify a third rotation of the IMD 104 about the device axis LD based on identifying the completion of the third waveform period WC3 over the waveform period WP3, and so on. In an example, the processing circuit 120 may be configured to identify the waveform period based on the behavior (e.g., amplitude) of the first radial signal 156 relative to the mean MR1. For example, the processing circuit 120 may be configured to identify a waveform period of the first radial signal 156 based on a basic cycle of the amplitude of the first radial signal 156 around the mean MR1 and substantially between the first threshold UR1 and the second threshold LR1. The processing circuit 120 may be configured to provide an indication to the output device 124 indicating the number of rotations completed by the IMD 104 around the device axis LD. In an example, the processing circuit 120 is configured to evaluate the number of rotations completed by the IMD 104 around the device axis LD when the fixation element 108 is engaged with the tissue wall 113. The processing circuit 120 may be configured to communicate with the output device 124 so that the output device 124 provides an indication reflecting the number of times the fixation element 108 is engaged with the tissue wall 113, so that the clinician can be informed of the number of rotations of engagement experienced by the IMD 104.

[0071] Medical system 100 may be configured to assess the pressure (e.g., force) applied by fixation element 108 on surface tissue 115, for example, to allow a clinician to assess whether the existing pressure is too low or too high before implanting IMD 104 within tissue wall 113. Medical system 100 (e.g., processing circuit 120) may be configured to compare the motion of IMD 104 to representative cardiac activity 151 to assess the pressure. For example, with respect to Figure 7, processing circuit 120 may compare the portion of main signal 154 within window 164 with the portion of representative cardiac activity 151 within representative window 162 to determine the pressure between fixation element 108 and surface tissue 115. Processing circuit 120 may determine the degree of waveform similarity between window 164 and representative window 162, and assess the pressure based on the degree of waveform similarity. Processing circuit 120 may communicate with output device 124 to cause output device 124 to provide an indication representing the pressure so that, for example, a clinician may be aware of the pressure between fixation element 108 and surface tissue 115 before implanting IMD 104 within tissue wall 113.

[0072] The medical system 100 may be configured to evaluate the alignment of the IMD 104 relative to the tissue wall 113 during and / or after implantation. In an example, the processing circuit 120 is configured to compare the main signal 154, the first radial signal 156, and / or the second radial signal 158 to evaluate the alignment of the IMD 104. For example, the processing circuit 120 may be configured to evaluate the alignment of the IMD 104 by evaluating the pivoting of one or more main axis P, first radial axis R1, and / or second radial axis R2 relative to the surface tissue 115 (e.g., evaluating the "flutter" of the IMD 104) when the heart 102 beats and applies forces to the IMD 104. The processing circuit 120 may cause the output device 124 to provide an indication representing the alignment so that the clinician can evaluate and / or change the alignment between the IMD 104 and the surface tissue 115. Detecting and / or evaluating pivoting of the primary axis P, the first radial axis R1, and / or the second radial axis R2 may also provide an indication that the IMD 104 has prematurely moved distally into the delivery receptacle 111 or other structure configured to provide stability to the IMD 104 during implantation.

[0073] For example, Fig. 9 IMD 104 is schematically shown with fixation element 108 implanted within tissue wall 113. Fig. 9In the example of , the motion sensor 118 is supported so that the main axis P is substantially parallel to the device axis LD, but this is not required. The processing circuit can be configured to compare the main signal 154, the first radial signal 156, and / or the second radial signal 158 to evaluate the pivoting of one or more main axis P, the first radial axis R1, and / or the second radial axis R2 relative to the surface tissue 115. For example, the processing circuit 120 can use the first radial signal 156 to detect the movement of the IMD 104 substantially along the first axis R1. The processing circuit 120 can determine that the beating of the heart 102 and the forces F1 and F2 applied to the IMD 104 cause a relatively large degree of movement (e.g., cyclic, periodic motion) of the IMD 104 in the direction of the first radial axis R1. For example, when tissue wall 113 applies force F1 and force F2 as heart 102 beats, movement along first radial axis R1 can indicate that device axis LD is pivoting between a position indicated by LD' and a position indicated by LD". Similarly, processing circuit 120 can use second radial signal 158 to assess that application of force F1 and force F2 to IMD 104 is causing a relatively greater degree of movement of IMD 104 in the direction of second radial axis R2. When heart 102 applies force F1 and force F2 to IMD 104, processing circuit 120 can cause output device 124 to provide an indication of pivoting of principal axis P so that, for example, a clinician can assess and / or change the alignment between IMD 104 and surface tissue 115.

[0074] Fig.10 is a diagram illustrating one or more examples and / or techniques described herein. Figures 1 to 4 and Fig. 9 14. The medical system 100 includes electrodes 177, which include a first electrode 144, a second electrode 146, a return electrode 148, and / or other electrodes 178 within the medical system 100. The medical system 100 may include an antenna 180, a therapy delivery circuit 142, an operating circuit 166, a sensing circuit 184, a processing circuit 120, a communication circuit 186, a memory 188, a switching circuit 190, a sensor 192 (including a motion sensor 118), and / or a power source 133. In some examples, the memory 188 includes computer-readable instructions that, when executed by the operating circuit 166, cause the operating circuit 166 to perform various functions attributed to the operating circuit 166 herein. Memory 188 may include any volatile memory, nonvolatile memory, magnetic memory, optical memory, or dielectric memory, such as random access memory (RAM), ferroelectric RAM (FRAM), read-only memory (ROM), nonvolatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital media.

[0075] The operational circuitry 166 (e.g., the processing circuitry 120, the therapy delivery circuitry 142, the sensing circuitry 184, and / or the switching circuitry 190) may include fixed function circuitry and / or programmable operational circuitry. The operational circuitry 166 may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some examples, the operational circuitry 166 may include multiple components (such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs) and other discrete or integrated logic circuitry. The functionality attributed herein to the operational circuitry 166 may be embodied as software, firmware, hardware, or any combination thereof. The processing circuitry 120, the therapy delivery circuitry 142, the sensing circuitry 184, and / or the switching circuitry 190 may have the properties of the operational circuitry 166 and / or perform any of the functionality of the operational circuitry.

[0076] The sensing circuit 184 and the communication circuit 186 may be selectively coupled to the electrode 177 via a switching circuit 190 as controlled by the operating circuit 166. The sensing circuit 184 may monitor signals from the electrode 177 to monitor the electrical activity of the heart 102 (e.g., to generate an ECG / EGM), deliver pacing signals to the heart 102, and / or perform other functions related to one or more physiological signals of the patient. The sensing circuit 184 may also monitor signals from sensors 192, which include the motion sensor 118 and may include an impedance sensor, an accelerometer, a gyroscope, a PPG sensor, a tissue oxygen sensor, a blood pressure monitor, a respiratory rate sensor, a respiratory force sensor, a respiratory pattern sensor, a temperature sensor, or other such sensors configured to monitor one or more physiological signals of the patient. In some examples, the sensing circuit 184 may include one or more filters and amplifiers for filtering and amplifying signals received from one or more of the electrodes 177 and / or the sensors 192.

[0077] The communications circuitry 186 may include any suitable hardware, firmware, software, or any combination thereof, for communicating with another device, such as a patient input / output device and / or a clinician input / output device. The communications circuitry 186 may be configured to communicate using communications links 122, 126, 127, 131, and / or other links. Under control of the operational circuitry 166, the communications circuitry 186 may receive downlink telemetry from another device and send uplink telemetry to another device (e.g., via antenna 180). In addition, the operational circuitry 166 may be coupled to a networked computing device and computer network, such as the Medtronic 1200, developed by Medtronic, plc of Dublin, Ireland. Network) communications.

[0078] A clinician or other user may retrieve data from the operational circuitry 166 using a clinician input / output device, a patient input / output device, and / or another local or networked computing device configured to communicate with the operational circuitry 166 via the communications circuitry 186. A clinician may also program parameters of the operational circuitry 166 using a clinician input / output device, a patient input / output device, and / or another local or networked computing device.

[0079] The power supply 133 is configured to deliver operating power to the components of the medical system 100. The power supply 133 may include one or more batteries and a power generation circuit for generating operating power. In some examples, one or more batteries may include a rechargeable battery to allow extended operation. In some examples, recharging is achieved by proximal inductive interaction between an external charger and an inductive charging coil within the medical system 100 (e.g., within the device housing 106). The power supply 133 may include any one or more of a variety of different battery types, such as nickel-cadmium batteries and lithium-ion batteries. Non-rechargeable batteries may be selected to last for several years, while rechargeable batteries may be inductively charged from an external device, for example, on a daily or weekly basis. In some examples, the power supply 133 may include both rechargeable batteries and non-rechargeable batteries.

[0080] In an example, processing circuitry 120 and / or therapy delivery circuitry 142 are located within device housing 106 of IMD 104. In other examples, processing circuitry 120 and / or therapy delivery circuitry 142 are located within another device or group of devices external to IMD 104 (e.g., located within a Figure 1 Thus, techniques and capabilities attributed herein to processing circuitry 120 and / or therapy delivery circuitry 142 may be attributed to IMD 104 and Figure 1 Any combination of other devices not shown in the figure. Therefore, the medical system 100 ( Figure 1) can represent a system in which the various parts are configured to be implanted in a patient and / or configured to be external to the patient, and can include any fixed or mobile computer system (e.g., a controller, microcontroller, personal computer, microcomputer, tablet computer, etc.), and can be generally described as including substantially all or part of the processing circuit 120 and / or the therapy delivery circuit 142.

[0081] Fig.11 1. Techniques for implanting an IMD 104 within a heart 102 are shown in FIG. Although the techniques are primarily described with reference to the IMD 104 of the medical system 100, in other examples, the techniques may be applied to other medical devices.

[0082] The technique includes engaging an IMD 104 to a tissue wall 113 of a heart 102 via a fixation element 108 (1002). The IMD 104 can be moved relative to the tissue wall 113 to engage the fixation element 108 with the tissue wall. In an example, the device housing 106 and the fixation element 108 are rotated relative to the tissue wall 113 about a device axis LD of the IMD 104 to engage the fixation element 108 with the tissue wall 113. In an example, the delivery member 110 applies a torque to the IMD 104 to rotate the device housing 106 and the fixation element 108 relative to the tissue wall 113 about the device axis LD of the IMD 104.

[0083] In an example, fixation element 108 gradually engages tissue wall 113 as IMD 104 moves relative to tissue wall 113. As fixation element 108 gradually embeds, fixation element 108 can increase the embedment depth defined between fixation element distal end 116 and surface tissue 115. In an example, fixation element 108 receives a force (e.g., force F1 and / or force F2) applied by tissue wall 113 during beating of heart 1102. Fixation element 108 can transfer the force from tissue wall 113 to device housing 106.

[0084] The technique includes comparing sensor signals such as the main signal 154, the first radial signal 156, and / or the second radial signal 158 with the representative cardiac activity 151 using the processing circuit 120 (1004). The motion sensor 118 can sense the movement of the device housing 106 on the main axis P, the first radial axis R1, and / or the second radial axis R2, and provide the main signal 154, the first radial signal 156, and / or the second radial signal 158 to the processing circuit 120. In an example, the processing circuit 120 evaluates one or more frequencies of the main signal 154, the first radial signal 156, and / or the second radial signal 158 to determine one or more frequency-based sensor parameters. The processing circuit 120 can compare the main signal 154, the first radial signal 156, and / or the second radial signal 158 with the representative cardiac activity 151 using the frequency-based sensor parameters. In an example, the frequency-based sensor parameter is a portion of the main signal 154, the first radial signal 156, and / or the second radial signal 158 that exhibits a frequency expected to be present due to the movement caused by the tissue wall 113 during the representative cardiac activity 151, such as a portion of a frequency in a frequency window between and including a lower frequency threshold and an upper frequency threshold. The lower frequency threshold may be, for example, greater than or equal to about 1 Hertz (Hz), 5 Hz, 10 Hz, or another frequency. The upper frequency threshold may be, for example, less than or equal to about 20 Hz, 40 Hz, 100 Hz, 250 Hz, or another frequency. In an example, as an alternative or in addition to evaluating one or more frequency-based parameters, the processing circuit 120 evaluates one or more amplitudes of the main signal 154, the first radial signal 156, and / or the second radial signal 158 to determine one or more amplitude-based sensor parameters. The processing circuit 120 may compare the main signal 154, the first radial signal 156, and / or the second radial signal 158 to the representative cardiac activity 151 using the amplitude-based sensor parameters. In an example, an amplitude-based sensor parameter can be, for example, a portion of a main signal, a first radial signal, and / or a second radial signal that exhibits an amplitude, amplitude variation, peak-to-peak amplitude, peak amplitude, and / or other fluctuations of the main signal, the first radial signal, and / or the second radial signal that may be expected to exist due to movement caused by tissue walls during representative cardiac activity.

[0085] The processing circuit 120 compares the main signal 154, the first radial signal 156, and / or the second radial signal 158 to the representative cardiac activity 151 using a signal matching method that is intended to achieve a comparison of the first signal with a template of the second signal and / or the expected signal (e.g., a template representing at least a portion of the representative cardiac activity 151). The processing circuit 120 can compare the main signal 154, the first radial signal 156, and / or the second radial signal 158 to the representative cardiac activity 151 using the matching method, which includes techniques such as Fourier transform (FT) comparison (e.g., FFT comparison), cross-correlation, correlation coefficient, variation standard deviation, template matching, and / or one or more other waveform similarity analysis.

[0086] In an example, processing circuit 120 determines that fixation element 108 may not be in contact with surface tissue 115 and / or tissue wall 113 based on a comparison of main signal 154, first radial signal 156, and / or second radial signal 158 to representative cardiac motion 151. In some examples, processing circuit 120 determines that fixation element 108 may not be in contact with surface tissue 115 and / or tissue wall 113 based on a comparison of main signal 154, first radial signal 156, and / or second radial signal 158 to representative cardiac motion 151. In some examples, processing circuit 120 uses main signal 154, first radial signal 156, and / or second radial signal 158 to assess movement of IMD 104 relative to tissue wall 113 and / or surface tissue 115. For example, processing circuit 120 may use main signal 154, first radial signal 156, and / or second radial signal 158 to assess that IMD 104 has rotated or is rotating about device axis LD. Processing circuit 120 may communicate with output device 124 such that output device 124 provides output indicating possible contact or non-contact of fixation element 108 with surface tissue 115 and / or tissue wall 113 and / or output indicating movement of IMD 104 relative to surface tissue 115 and / or tissue wall 113 .

[0087] The technique includes evaluating engagement of the fixation element 108 with the tissue wall 113 using the processing circuit 120 (1006). The processing circuit 120 may evaluate engagement of the fixation element 108 with the tissue wall 113 based on a comparison of the main signal 154, the first radial signal 156, and / or the second radial signal 158 with the representative cardiac activity 151. In an example, the processing circuit 120 evaluates engagement of the fixation element 108 with the tissue wall 113 based on a comparison of one or more frequencies (e.g., frequencies within a window 160 or a window 164) of the main signal 154, the first radial signal 156, and / or the second radial signal 158 with one or more frequencies (e.g., frequencies within a window 162) of the representative cardiac activity 151. The processing circuit 120 may evaluate engagement of the fixation element 108 with the tissue wall 113 based on a comparison of a perturbation of one of the main signal 154, the first radial signal 156, or the second radial signal 158 with a perturbation of the other of the main signal 154, the first radial signal 156, or the second radial signal 158. The processing circuit 120 may communicate with the output device 124 to cause the output device 124 to provide an output indicative of possible engagement of the fixation element 108 with the surface tissue 115 and / or the tissue wall 113 .

[0088] The processing circuit 120 can assess that the fixation element 108 is gradually embedding into the tissue wall 113 by assessing the substantially simultaneous occurrence of contact between the fixation element 108 and the tissue wall 113 and movement (e.g., rotation) of the fixation element 108 and / or the device housing 106 relative to the tissue wall 113 and / or the surface tissue 115. The processing circuit 120 can be configured to indicate that the fixation element 108 is gradually embedding into the tissue wall 113 based on the detected substantially simultaneous events. The processing circuit 120 can communicate with the output device 124 to cause the output device to provide an indication indicating that the substantially simultaneous events were detected, so that, for example, a clinician is informed that the movement of the IMD 104 may cause the fixation element 108 to gradually embed into the tissue wall 113. In an example, when the fixation element 108 is assessed to be embedded in the tissue wall 113, the processing circuit 120 can assess (e.g., count) the number of rotations of the IMD 104 about the device axis LD. Processing circuitry 120 may communicate with output device 124 to cause output device 124 to provide an indication reflecting the number of times fixation element 108 has completed engagement with tissue wall 113 so that, for example, a clinician may be informed of the number of rotations of engagement that IMD 104 has undergone.

[0089] In an example, the processing circuit 120 evaluates the pressure (e.g., force) applied by the fixation element 108 on the surface tissue 115 to, for example, allow a clinician to evaluate whether the existing pressure is too low or too high. The processing circuit 120 can compare the movement of the IMD 104 to the representative heart activity 151 to evaluate the pressure. When the heart 102 beats and applies force to the IMD 104, the processing circuit can evaluate the alignment of the IMD 104 relative to the tissue wall 113 by evaluating the pivoting of one or more main axes P, the first radial axis R1, and / or the second radial axis R2 relative to the surface tissue 115. The processing circuit 120 can communicate with the output device 124 so that the output device 124 provides an indication representing the pressure and / or alignment so that, for example, the clinician can be informed of the pressure between the fixation element 108 and the surface tissue 115 and / or the alignment of the IMD 104 relative to the tissue wall 113.

[0090] Various examples of the disclosure have been described. Any combination of the described systems, operations, or functions is contemplated. These and other examples are within the scope of the following claims.

[0091] Embodiment 1. A medical system, comprising: an implantable medical device, the implantable medical device being configured to engage tissue within a patient's heart, wherein the implantable medical device comprises: a shell; a fixing element, the fixing element being configured to gradually embed into the tissue to couple the implantable medical device to the tissue, wherein the fixing element is configured to transfer force from the tissue to the shell as the fixing element gradually engages; and a motion sensor, the motion sensor being configured to provide a sensor signal indicating movement of the shell; and a processing circuit, the processing circuit being configured to: compare the sensor signal with representative cardiac activity when the fixing element engages the tissue, and evaluate the engagement of the implantable medical device with the tissue based on the comparison.

[0092] Example 2. A medical system according to Example 1, wherein the processing circuit is configured to provide an output indicating an assessed engagement of the implantable medical device with the tissue as the fixation element gradually engages with the tissue, and the medical system also includes an output device configured to display the output.

[0093] Example 3. A medical system according to Example 1 or Example 2, wherein the fixation element is configured to transmit the force to the shell when cardiac activity of the heart causes the heart to apply the force to the fixation element.

[0094] Example 4. A medical system according to any one of Examples 1 to 3, wherein the representative cardiac activity is based on a signal indicating at least one of muscle movement of the heart of the patient or expected muscle movement, wherein the expected muscle movement is based on muscle movement exhibited by one or more subject hearts other than the patient's heart.

[0095] Embodiment 5. The medical system according to any one of embodiments 1 to 4 further comprises a delivery member configured to gradually embed the fixation element into the tissue when the delivery member is coupled to the implantable medical device.

[0096] Example 6. A medical system according to Example 5, wherein the delivery member includes a distal portion configured to be positioned within the heart and a proximal portion configured to be positioned outside the patient's body, wherein the proximal portion is configured to cause movement of the distal portion when the proximal portion moves relative to the patient, and wherein the distal portion is configured to cause the fixation element to gradually embed into the tissue when the distal portion is coupled to the implantable medical device and the proximal portion causes the movement of the proximal portion relative to the patient.

[0097] Embodiment 7. The medical system of any one of Embodiments 1 to 6, wherein the motion sensor is configured to sense acceleration of the shell, wherein the acceleration is indicative of the movement of the shell.

[0098] Example 8. A medical system according to any one of Examples 1 to 7, wherein the fixation element is configured to limit an embedding depth of the implantable medical device engaged to the tissue, wherein the embedding depth is the distance from the surface of the tissue to the distal end of the fixation element, and wherein the fixation element is configured to increase the embedding depth as the fixation element gradually engages the tissue.

[0099] Example 9. The medical system of Example 8, wherein the processing circuit is configured to evaluate whether the fixation element defines the embedment depth based on the sensor signal and the representative cardiac activity.

[0100] Embodiment 10. The medical system of any one of Embodiments 1 to 9, wherein the fixation element comprises a helix configured to gradually embed into the tissue when the housing is rotated about a device axis defined by the housing.

[0101] Embodiment 11. The medical system of Embodiment 10, wherein the processing circuit is configured to use the sensor signal to detect rotation of the housing about the device axis.

[0102] Example 12. A medical system according to Example 10 or Example 11, wherein the processing circuit is configured to determine the number of rotations of the shell around the device axis when the helix uses the detected rotation of the shell and the assessment of the engagement of the implantable medical device with the tissue to limit the embedment depth according to claim 6.

[0103] Embodiment 13. A medical system according to any one of Embodiments 1 to 9, wherein the fixation element comprises one or more tines supported by the IMD housing, wherein the one or more tines are configured to gradually embed into the tissue.

[0104] Embodiment 14. A medical system according to any one of Embodiments 1 to 10, wherein the processing circuit is configured to compare the sensor signal with the representative cardiac activity by at least one of: comparing one or more frequencies of the sensor signal with one or more frequencies of the representative cardiac activity, or comparing one or more amplitudes of the sensor signal with one or more amplitudes of the representative cardiac activity.

[0105] Example 15. A medical system according to any one of Examples 1 to 14, wherein the shell defines a main axis of a coordinate system, a first radial axis of the coordinate system, and a second radial axis of the coordinate system, wherein the motion sensor is configured to sense the movement of the shell along one or more of the main axis, the first radial axis, or the second radial axis, and wherein the sensor signal includes one or more of a main signal indicating movement of the shell along the main axis, a first radial signal indicating movement of the shell along the first radial axis, or a second radial signal indicating movement of the shell along the second radial axis.

[0106] Embodiment 16. The medical system of Embodiment 15, wherein the housing comprises a distal portion and a proximal portion, wherein the distal portion supports the fixation element, and wherein the main axis intersects the distal portion and the proximal portion.

[0107] Example 17. The medical system of Example 16 or Example 17, wherein the main axis is substantially parallel to the axis of the device according to claim 10.

[0108] Embodiment 18. A medical system according to any one of Embodiments 15 to 17, wherein the first radial axis is substantially perpendicular to the main axis, and wherein the second radial axis is substantially perpendicular to the main axis and substantially perpendicular to the first radial axis.

[0109] Example 19. A medical system according to any one of Examples 15 to 18, wherein the processing circuit is configured to use two or more of the main signal, the first radial signal, or the second radial signal to determine the orientation of the main axis relative to the surface of the heart.

[0110] Example 20. A medical system according to any one of Examples 15 to 19, wherein the processing is configured to use one or more of the main signal, the first radial signal, or the second radial signal to determine the pivoting of the axis of the device according to claim 10 relative to the heart surface of the heart.

[0111] Embodiment 21. A medical system according to any one of Embodiments 1 to 22, the medical system further comprising an output device, wherein the processing circuit is configured such that the output device provides an output indicative of the assessment of the engagement of the implantable medical device with the tissue.

[0112] Embodiment 22. The medical system of any one of Embodiments 1 to 22, wherein the processing circuit is configured to determine a pressure between the fixation element and a surface of the tissue based on the comparison.

[0113] Embodiment 23. A medical system according to any one of embodiments 1 to 22, wherein the processing circuit is configured to compare frequency-based sensor parameters and frequency-based activity parameters, wherein the frequency-based sensor parameters are based on one or more frequencies of the sensor signal, and wherein the frequency-based activity signal is based on one or more frequencies of the representative cardiac activity.

[0114] Embodiment 24. A method, comprising: using a fixation element to engage an implantable medical device to tissue within a patient's heart, wherein engaging the fixation element comprises gradually embedding the fixation element into the tissue, and wherein the fixation element is configured to transfer force from the tissue to a shell of the implantable medical device as the fixation element gradually embeds into the tissue; using a processing circuit to compare a sensor signal with representative cardiac activity as the fixation element gradually engages the tissue, wherein the sensor signal is provided by a motion sensor, and wherein the sensor signal indicates movement of the shell; and based on the comparison, using a processing circuit to evaluate the engagement of the implantable medical device with the tissue.

[0115] Embodiment 25. The method of Embodiment 24 further comprises providing an output to an output device using the processing circuit, wherein the output indicates the assessed engagement of the implantable medical device with the tissue as the fixation element becomes embedded within the tissue.

[0116] Example 26. The method according to Example 24 or Example 25, further comprising using the fixation element to transmit the force to the shell when cardiac activity of the heart causes the heart to apply the force to the fixation element.

[0117] Example 27. The method according to any one of Examples 24 to 26 further includes basing the representative cardiac activity on a signal indicating at least one of muscle movement of the heart of the patient or expected muscle movement, wherein the expected muscle movement is based on muscle movement exhibited by one or more subject hearts other than the heart of the patient.

[0118] Embodiment 28. The method of any one of embodiments 24 to 27, further comprising gradually embedding the fixation element into the tissue using a delivery member coupled to the implantable medical device.

[0119] Example 29. A method according to Example 28, wherein gradually embedding the fixation element into the tissue includes coupling a distal portion of the delivery member to the implantable medical device and moving the distal portion by moving the proximal portion of the delivery device relative to the patient, wherein the distal portion is configured to be positioned within the heart and the proximal portion is configured to be positioned outside the patient's body.

[0120] Embodiment 30. The method according to any one of embodiments 24 to 29 further includes increasing the embedment depth as the fixation element is gradually embedded in the tissue, wherein the embedment depth is the distance from the surface of the tissue to the distal end of the fixation element.

[0121] Embodiment 31. The method according to embodiments 24 to 30 further comprising using the processing circuit to evaluate whether the fixation element defines an embedding depth according to claim 29 based on the sensor signal and the representative cardiac activity.

[0122] Embodiment 32. A method according to any one of embodiments 24 to 31, wherein gradually embedding the fixation element into the tissue includes rotating the shell around a device axis defined by the implantable medical device to gradually embed the helix into the tissue.

[0123] Embodiment 33. The method of embodiment 32 further comprises using the processing circuit to detect rotation of the housing about the device axis using the sensor signal.

[0124] Example 34. The method according to Example 32 or Example 33 further includes using the processing circuit to determine the number of rotations of the shell around the device axis when the helix uses the detected rotation of the shell and the assessment of the engagement of the implantable medical device with the tissue to limit the embedment depth according to claim 30.

[0125] Example 35. The method according to any one of Examples 24 to 34 further includes using the motion sensor to sense the movement of the shell along one or more of the main axis of the coordinate system, the first radial axis of the coordinate system, or the second radial axis of the coordinate system, and wherein the sensor signal includes one or more of a main signal indicating the movement of the shell along the main axis, a first radial signal indicating the movement of the shell along the first radial axis, or a second radial signal indicating the movement of the shell along the second radial axis.

[0126] Example 36. The method according to Example 35 also includes using the processing circuit to determine the orientation of the main axis relative to the surface of the heart using two or more of the main signal, the first radial signal, or the second radial signal.

[0127] Example 37. The method according to Example 35 or Example 36 also includes using the processing circuit to determine the pivot of the main axis relative to the heart surface of the heart using two or more of the main signal, the first radial signal or the second radial signal.

[0128] Embodiment 38. The method of any one of Embodiments 24 to 37, wherein gradually engaging the fixation element to the tissue comprises engaging one or more tines to the tissue.

[0129] Example 39. A method according to any one of Examples 24 to 38, wherein comparing the sensor signal with the representative cardiac activity includes using the processing circuit to compare one or more frequencies of the sensor signal with one or more frequencies of the representative cardiac activity.

Claims

1. A medical system comprising: An implantable medical device configured to engage tissue within a patient's heart, wherein the implantable medical device comprises: case; a fixation element configured to gradually embed into the tissue to couple the implantable medical device to the tissue, wherein the fixation element is configured to transfer a force from the tissue to the housing when the fixation element is gradually engaged, and a motion sensor configured to provide a sensor signal indicative of motion of the housing; and A processing circuit, the processing circuit being configured to: comparing the sensor signal to representative cardiac activity when the fixation element engages the tissue, and The engagement of the implantable medical device with the tissue is assessed based on the comparison.

2. A medical system according to claim 1, wherein the processing circuit is configured to provide an output indicating the assessed engagement of the implantable medical device with the tissue as the fixation element gradually engages the tissue, and the medical system also includes an output device configured to display the output.

3. A medical system according to claim 1 or claim 2, wherein the fixation element is configured to transmit the force to the shell when cardiac activity of the heart causes the heart to apply the force to the fixation element.

4. A medical system according to any one of claims 1 to 3, wherein the representative cardiac activity is based on a signal indicating at least one of muscle movement of the heart of the patient or expected muscle movement, wherein the expected muscle movement is based on muscle movement exhibited by one or more subject hearts other than the heart of the patient.

5. The medical system of any one of claims 1 to 4, further comprising a delivery member configured to gradually embed the fixation element into the tissue when the delivery member is coupled to the implantable medical device.

6. The medical system according to claim 5, wherein the delivery member comprises a distal portion configured to be positioned within the heart and a proximal portion configured to be positioned outside the patient's body, wherein the proximal portion is configured to cause movement of the distal portion when the proximal portion moves relative to the patient, and Wherein the distal portion is configured to gradually embed the fixation element into the tissue when the distal portion is coupled to the implantable medical device and the proximal portion causes the movement of the proximal portion relative to the patient.

7. The medical system of any one of claims 1 to 6, wherein the motion sensor is configured to sense acceleration of the housing, wherein the acceleration is indicative of the motion of the housing.

8. The medical system according to any one of claims 1 to 7, wherein the fixation element is configured to define an embedding depth of the implantable medical device to the tissue, wherein the embedding depth is the distance from the surface of the tissue to the distal end of the fixation element, and Wherein the fixation element is configured to increase the embedment depth as the fixation element gradually engages the tissue.

9. The medical system of claim 8, wherein the processing circuit is configured to assess whether the fixation element defines the embedment depth based on the sensor signal and the representative cardiac activity.

10. The medical system of any one of claims 1 to 9, wherein the fixation element comprises a helical wire configured to gradually embed into the tissue when the housing is rotated about a device axis defined by the housing.

11. The medical system of claim 10, wherein the processing circuit is configured to use the sensor signal to detect the rotation of the housing about the device axis.

12. A medical system according to claim 10 or claim 11, wherein the processing circuit is configured to determine the number of rotations of the shell around the device axis when the helix uses the detected rotation of the shell and the assessment of the engagement of the implantable medical device with the tissue to limit the embedment depth according to claim 6.

13. A medical system according to any one of claims 1 to 10, wherein the processing circuit is configured to compare the sensor signal with the representative cardiac activity by at least one of: comparing one or more frequencies of the sensor signal with one or more frequencies of the representative cardiac activity, or comparing one or more amplitudes of the sensor signal with one or more amplitudes of the representative cardiac activity.

14. The medical system according to any one of claims 1 to 13, wherein the housing defines a major axis of the coordinate system, a first radial axis of the coordinate system and a second radial axis of the coordinate system, wherein the motion sensor is configured to sense the movement of the housing along one or more of the main axis, the first radial axis, or the second radial axis, and Wherein the sensor signal comprises one or more of a main signal indicating movement of the housing along the main axis, a first radial signal indicating movement of the housing along the first radial axis, or a second radial signal indicating movement of the housing along the second radial axis.

15. A medical system according to claim 14, wherein the processing is configured to use one or more of the main signal, the first radial signal, or the second radial signal to determine a pivoting of the device axis according to claim 10 relative to a cardiac surface of the heart.

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