Optimized Vector Selection for a Multi-Axis Accelerometer in an Implantable Medical Device

Abstract

The present disclosure relates to a medical system (1) comprising at least an implantable medical device (5), and a multi-axis accelerometer (6) comprised by the implantable medical device (5) to measure the acceleration of the implantable medical device (5) along a plurality of vectors (V1, V2, V3), wherein the multi-axis accelerometer (6) is configured to provide for each vector (V1, V2, V3) a signal indicative of the acceleration of the implantable medical device (5) in the direction of the respective vector (V1, V2, V3). The medical system (1) is configured to evaluate the signals to automatically select or propose the vector among the plurality of vectors (V1, V2, V3) that comprises the best alignment with a predetermined vector (g).

Description

Technical Field

[0001] The present disclosure relates to a medical system and a corresponding method. Background Art

[0002] Some implantable medical devices (IMDs) include accelerometers to detect a patient's movement / activity, e.g., to adapt the pacing rate of a pacemaker when increased patient activity is detected.

[0003] A multi-axis accelerometer allows for the detection of movement, which has the ability to optimally measure such movement by collecting data obtained by the on-chip axis (or axes) that is best aligned with the motion vector of interest. In its simplest form, data collected from a single axis requires the least system overhead (e.g., current budget, computation, etc.) to report movement in a specified direction (or the opposite direction, since the polarity of movement along the axis is not important). Alternatively, in the absence of a single on-chip axis being well-aligned with the direction of movement of interest, data collected from many axes can be computationally combined (e.g., via weighting, vector mathematics, etc.) to report data that optimally aligns the mathematically generated vector with the direction of movement of interest.

[0004] Regardless of the scenario, gravity presents a dominant downward acceleration vector on the implant, which effectively produces an additional "DC offset" (DC - direct current, AC - alternating current) response to the signal collected from any accelerometer axis aligned with the gravity vector. Surveying each of the axes of the accelerometer chip under "no motion" conditions and evaluating their baseline magnitudes can easily facilitate determining which axis or combination of axes is aligned with this gravity vector. Such information is typically sufficient to select which vector is preferred for product feature support.

[0005] Currently, the selection of an accelerometer vector within an implantable medical device (IMD) is established as a "hard-coded" configuration during product development and / or as a factory configuration, or the IMD employs clinician follow-up interactions that require the selection of a vector after performing a series of patient movements / exercises and analysis of the resulting data. The former process requires sufficient insight during product development to pick a vector that is likely to serve many patient populations. The solution thus negates responsiveness to individual needs. In the alternative follow-up-based solution, a time-consuming process is required. In currently known devices, a single vector is selected for data collection, and then the patient performs a movement / exercise routine. To evaluate the effects on multiple axes, the routine must be repeated for each of the available on-chip axes. Each cycle in this iterative process can typically require no less than 15 minutes of in-clinic follow-up time. Once all axes have been evaluated, then the optimal vector can be selected. For a 3-axis accelerometer, such a process would thus require ~45 minutes (3 axes multiplied by 15 minutes). This duration poses a challenge to obtaining optimized patient care because not everyone can sustain prolonged physical activity within such a span, and clinical resources are typically limited.

[0006] In addition, sequential testing (i.e., one vector at a time) does not guarantee the same results being demonstrated from one round to the next, so the results collected from one vector may not be well-suited for direct comparison with another vector. As a result, the process is often skipped, default values are selected, and if the orientation of the IMD makes the default value inappropriate, any associated features do not operate at their intended performance levels.

[0007] The in-patient orientation of an IMD is typically unique. For implantable cardiac monitors (ICMs) and leadless pacemaker systems, this condition is more complex compared to pocket-based implants, which typically reside within the patient anatomy in a known, lead-port-up position and are regularly held in place via a trans-device suture procedure. The many implant sites compatible with ICMs and leadless pacemaker systems means that it is more challenging to determine which axis of the multi-axis accelerometer within the device best aligns with an overall physiological reference (e.g., a head-to-toe vector) that is crucial for accessory feature support.

[0008] Regarding the above drawbacks, the problem to be solved lies in shortening the duration and complexity of the in-clinic process required to determine the "optimal" accelerometer vector within the device. SUMMARY OF THE INVENTION

[0009] In particular, the present disclosure details a solution by which an implant can execute routines to evaluate signals regarding each of the vectors and allow for an optimized selection of the accelerometer axes that best pair with the feature sensing requirements. This support can either be in the form of an automated (and potentially adaptive) routine for feature support between follow-ups, or can support streamlining the clinical workflow during follow-ups to select or facilitate optimized vectors by relaying key metrics to the user via a GUI presentation.

[0010] In particular, other objectives are visible in one or more of the following objectives:

[0011] - Extend the ability to support vector optimization in scenarios where the patient's body is restricted and there are challenges in completing 'exercise' tests (i.e., unable to walk or perform other required exercises for more than 45 minutes),

[0012] - Provide an improved GUI report of the IMD accelerometer response to better inform clinicians of the effective trade-offs when selecting the 'optimal' in-device accelerometer vector,

[0013] - Provide improved sensing of accelerometer-based input for related IMD feature support and thereby provide an improved patient experience with the IMD between follow-ups, and

[0014] - Provide means to periodically evaluate the accelerometer vector and adapt the selection between follow-ups if an alternative selection emerges as preferred.

[0015] A medical system according to claim 1 and a method according to claim 13 are provided.

[0016] In one aspect, a medical system is disclosed that includes at least an implantable medical device and a multi-axis accelerometer included by the implantable medical device for measuring the acceleration of the implantable medical device along a plurality of vectors (also referred to herein as acceleration vectors or axes), where in particular, the multi-axis accelerometer is configured to provide a signal for each vector that indicates the acceleration of the implantable medical device in the direction of the considered vector.

[0017] The medical system (particularly an implantable medical device) is configured to evaluate the signals to automatically select or propose a vector among the plurality of vectors of the accelerometer that includes the best alignment with a predetermined vector.

[0018] In particular, the selected or proposed vector is the vector among the plurality of vectors that has the largest component in the direction of the predetermined vector.

[0019] In particular, the plurality of vectors includes or consists of three orthogonal or linearly independent vectors (e.g., in the x, y, and z directions).

[0020] In particular, the system (especially an implantable medical device) is configured to measure the acceleration of the implantable medical device in the direction of a selected (or proposed) vector during device operation.

[0021] The implantable medical device may be configured to collect data when the patient's posture is prescribed to be stationary in a particular position (e.g., a standing position or a sitting position). The data collected may include at least the DC signal of the accelerometer for each vector (V1, V2, V3), which indicates the acceleration of the implantable medical device in the direction of the corresponding vector (V1, V2, V3), where the selected or proposed vector is the vector associated with the signal having the largest magnitude among the signals.

[0022] According to an embodiment of the medical system, the medical system may consist of an implantable medical device alone, and the implantable medical device automatically selects the accelerometer vector. However, the system may include additional devices that may interact with the implantable medical device (also referred to herein as the implant).

[0023] In other words, the present disclosure details a scheme by which the implant can execute routines to evaluate the signals for each of the vectors and allow for an optimized selection of the accelerometer axis / vector that best matches the feature sensing requirements. This support can be in the form of an automated (and potentially adaptive) routine for feature support between follow-ups, or can support simplifying the clinical workflow during follow-up to select or facilitate the optimized vector by relaying key metrics to the user via a GUI presentation.

[0024] In an embodiment, the implantable medical device includes the ability to obtain data from any one of a plurality of accelerometer axes / vectors in response to automaticity and / or triggering.

[0025] Additionally, in an embodiment, the implant includes the ability to determine the best accelerometer axis / vector for target feature support (especially rate adaptation) based on data collected from a number of accelerometer axes / vectors.

[0026] Furthermore, according to an embodiment, the implantable medical device is configured to collect data when the implantable medical device moves along a predetermined vector, where the data collected includes at least the signal of the accelerometer for each vector, which indicates the magnitude of the acceleration of the implantable medical device in the direction of the vector, and where the selected or proposed vector is the vector associated with the signal having the largest magnitude among the signals.

[0027] Additionally, according to an embodiment, the implantable medical device is one of the following: an intracardiac rhythm system (also known as an implantable leadless pacemaker); an implantable cardiac monitor (also known as a loop recorder); and an implantable pulse generator (IPG) for nerve stimulation.

[0028] In particular, in the case where the implantable medical device is an intracardiac rhythm system, the latter is preferably configured to automatically select and / or adapt the accelerometer vector for rate adaptation based on signals from the accelerometer.

[0029] Furthermore, according to an embodiment, in the case where the implantable medical device is an intracardiac rhythm system, the implantable medical device is configured to generate and apply pacing pulses to the patient's heart at a certain rate, wherein the implantable medical device is configured to adapt the rate depending on the acceleration of the implantable medical device with respect to the selected or proposed vector.

[0030] According to an embodiment, the predetermined vector is the gravity vector, i.e., the direction of gravity.

[0031] Furthermore, in an embodiment, the system or the implantable medical device includes the ability to collect data from each of a plurality of accelerometer axes / vectors in a sequential scan format.

[0032] Furthermore, in an embodiment, the medical system or the implantable medical device is configured to collect the data or signals from each of a plurality of accelerometer vectors in a sequential manner. In particular, the medical system / implantable medical device cycles through each vector one by one, and thereby obtains the amplitude of the corresponding signal of the accelerometer of each vector. Additionally, in an embodiment, the implantable medical device is configured to store the collected data in the medical implant device.

[0033] Furthermore, according to an embodiment, the system is configured to perform an activity test during which the patient exercises for a predetermined amount of time, wherein the implantable medical device is configured to sample the patient's heart rate and adapt the rate of the pacing pulses of the implantable medical device based on the acceleration of the implantable medical device with respect to the selected or proposed vector.

[0034] In particular, according to an embodiment, the implantable medical device includes the ability to store data within the implant that details the activity response of any surveyed accelerometer vector.

[0035] Furthermore, according to an embodiment, the medical system includes a monitoring device (e.g., a Holter device) that is configured to be placed outside the patient's body, wherein the implantable medical device is configured to transmit the collected data to the monitoring device. In particular, the monitoring device is a cardiac monitoring device for monitoring the patient's heart, and in particular, the monitoring device is configured to sample the patient's electrocardiogram.

[0036] Thus, the medical system can include the option to eliminate implant storage of accelerometer vector or axis signals and stream the data to a monitoring device worn by the patient. In particular, the monitoring device can be capable of collecting accelerometer vector / axis data streamed from the implant for subsequent programmer interrogation.

[0037] According to other embodiments, the medical system includes a programmer (also referred to as a programming device) configured to receive collected data from an implantable medical device or from a monitoring device, wherein the programmer is configured to evaluate the collected data to automatically select or propose a vector that includes the best alignment with the predetermined vector.

[0038] Thus, the programmer of the medical system can include the ability to interpret data collected by the implant and / or the monitoring / Holter device and calculate the best accelerometer vector selection for the intended feature support (especially rate adaptation).

[0039] Furthermore, according to an embodiment, the medical system (especially the programmer) includes a graphical user interface (GUI), particularly for configuring, initiating, interpreting exercise, and vector optimization testing.

[0040] In particular, the graphical user interface is configured to graphically display the collected data or information derived from the collected data, and / or display the selected or proposed acceleration vector, and / or display a picture of the implantable medical device that shows the selected or proposed acceleration vector.

[0041] In particular, the medical system (especially the GUI) includes the ability to orient the picture of the implantable medical device according to the collected data to highlight which acceleration vector is best aligned with a predetermined vector (such as the gravity vector). In particular, the GUI is configured to show the comparative alignment of the acceleration vector response data with a predetermined vector (such as the gravity vector), including proposing a single acceleration vector as the best choice.

[0042] Furthermore, according to an embodiment, the graphical user interface is configured to perform at least one of the following:

[0043] - Receive input from the user to cause the programmer or system to automatically select the vector that includes the best alignment with the predetermined vector from the plurality of vectors,

[0044] - Display information about the available vector configurations to guide the user's insight towards the vector that is best aligned with the predetermined vector,

[0045] - Receive input from the user to confirm the proposed vector as the selected vector (or receive input from the user to select another accelerometer vector),

[0046] - Receive input from a user to initiate an activity test, during which the patient exercises for a predetermined amount of time, and the implantable medical device records the patient's heart rate and / or the raw activity signal output from an accelerometer, wherein the rate adaptation of the pacing pulses of the implantable medical device is based on the acceleration of the implantable medical device with respect to a selected or proposed vector.

[0047] - Display the heart rate and / or the raw activity signal output recorded during the activity test (e.g., as one or more trend plot lines).

[0048] - Receive input from a user to change the therapy program settings of the implantable medical device, and

[0049] - Display a preview of the expected heart rate response to the changed therapy program settings.

[0050] In addition, in an embodiment, the programmer includes the ability to retain / display information "before" and "after" an exercise and vector optimization test and present such information to the user simultaneously. Such support will only be useful in cases where multiple sequential vector optimizations and / or exercise tests are performed. In such a context, the "before" data will represent the output from the last run test, and the "after" data will represent the output from the current test, which is theoretically performed in response to an adjustment made to the sensor configuration, which in turn is in response to the data evaluated in the last (i.e., "before") optimization test. The "preview" option / capability can replace the need for any "after" data collection / management capabilities, since the response that the changed sensor settings will experience can be determined using the adjustment of the sensor settings within the GUI. This scheme avoids the problems associated with "before" and "after" exercise rules that need to match in terms of movement, body motion, and duration as a means of best facilitating the comparison of sensor configuration settings.

[0051] In addition, according to an embodiment, the system includes the ability to present plotted activity response data on any accelerometer axis / vector for which data has been collected, whether the data is obtained in a "simultaneous" sequential scan method or collected individually in separate tests during a single implant / programmer follow-up session.

[0052] According to yet another aspect, a method is disclosed for automatically selecting or proposing a vector from among a plurality of vectors of a multi-axis accelerometer of an implantable medical device, wherein the accelerometer is configured to measure the acceleration of the implantable medical device along the vector. The method includes the following steps:

[0053] - Data (e.g., by an implantable medical device) is collected when the patient's body orientation is aligned with a predetermined vector (e.g., during a guided follow-up procedure), where the data collected from each of the vectors of the accelerometer indicates the magnitude of the static acceleration of the implantable medical device in the direction of the predetermined vector, and

[0054] - Automatically select or propose the vector among the plurality of vectors that is associated with the signal having the maximum magnitude among the signals.

[0055] The method may further include modifying the routine for vector selection as described above to an adaptive format for use between follow-ups, where the device periodically samples information from the available accelerometer axes to develop a running history of (non-static, i.e., dynamic) accelerometer information (under non-fixed conditions), the accelerometer information indicating the magnitude of the signals regarding the different available axes, and (in turn) actively changing the "best" vector selection in a dynamic manner based on the collected history, or simply making such a history available as accessible statistics that can inform the user of a possible need to change the "best" vector to another selection.

[0056] According to other embodiments, the method includes the following additional steps: receiving the collected data from the implantable medical device or from a monitoring device with a programmer, and evaluating the collected data with the programmer to automatically select or propose the vector that is associated with the signal having the maximum magnitude among the signals. In an adaptive embodiment, the implantable medical device may be configured to manage the selection itself, where the preferred vector of the accelerometer is updated to the "best" condition between follow-ups.

[0057] According to other embodiments of the method, the system or programmer includes a graphical user interface (GUI).

[0058] According to other embodiments, the method further includes the following additional steps: graphically displaying the collected data or information derived from the collected data via the GUI, and / or graphically displaying the selected or proposed vector via the GUI, and / or graphically displaying a picture of the implantable medical device via the GUI, which shows the selected or proposed vector.

[0059] According to other embodiments, the method includes at least one of the following additional steps:

[0060] - Select, via a corresponding input into the GUI, the proposed vector that includes the best alignment with the predetermined vector,

[0061] - Confirm, via a corresponding input into the GUI, the proposed vector as the selected vector,

[0062] - Initiate an activity test via a corresponding input into the GUI. During the activity test, the patient performs an exercise for a predetermined amount of time, and the heart rate of the patient and / or the raw activity signal output from an accelerometer are recorded by an implantable medical device, and the rate of the pacing pulses of the implantable medical device is adapted based on the acceleration of the implantable medical device with respect to a selected or proposed vector.

[0063] - Display the heart rate and / or the raw activity signal output from the accelerometer recorded during the activity test (e.g., as one or more trend lines).

[0064] - Change the therapy program settings of the implantable medical device via a corresponding input into the GUI, and

[0065] - Display a preview of the expected heart rate for the changed therapy program settings via the GUI.

[0066] According to other aspects, an implantable medical device (IMD) is provided, such as an intravascular rhythm system (also known as a leadless pacemaker), an implantable cardiac monitor (also known as a loop recorder), or an implantable pulse generator (IPG) for nerve stimulation. The IMD may include an accelerometer. The accelerometer may be a multi-axis accelerometer configured to determine acceleration vectors in more than one axis (e.g., in three axes).

[0067] According to yet another aspect, a method is provided. The method may include determining a selected acceleration vector among a plurality of acceleration vectors (e.g., among three acceleration vectors), wherein the selected acceleration vector is aligned with the acceleration due to gravity. The alignment of the selected acceleration vector with the acceleration due to gravity may be based on a portion of the acceleration vector pointing in the direction of the acceleration due to gravity.

[0068] The method may be applied to an implantable medical device (IMD) having an accelerometer (e.g., a multi-axis accelerometer).

[0069] Features described with respect to the medical system may also be applied to the method, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Hereinafter, exemplary embodiments of the present invention and other features and advantages are described with reference to the accompanying drawings, wherein:

[0071] Figure 1 A schematic illustration of an embodiment of a medical system (e.g., an intravascular rhythm system) is shown,

[0072] Figure 2A and Figure 2B Two orientations of an intravascular pacemaker for vector selection are shown,

[0073] Figure 3Shows an interface for showing accelerometer response,

[0074] Figure 4 shows a graphical user interface (GUI), and

[0075] Figure 5 –11 show several views of another graphical user interface (GUI). Detailed Description

[0076] Figure 1 Shows a schematic illustration of a medical system 1, which at least includes an implantable medical device (also referred to as an implant) in the form of an intracardiac rhythm system 5 (also referred to herein as an intracardiac pacemaker). In particular, the intracardiac pacemaker 5 includes a housing 100 that surrounds an energy storage body 102 (such as a battery), an electronic module 103, and a communication unit 104. The housing 100 may include titanium or may be made of titanium.

[0077] At the distal end of the housing 100, a first electrode 106 (also referred to as a pacing electrode) is provided. In the proximal region of the housing 100, a second electrode 101 (also referred to as a sensing electrode) is arranged. The second electrode 101 may be formed as a ring electrode.

[0078] The pacemaker system 5 may be fixed to the heart tissue by a fixing element 105. The fixing element may be formed as a spike. It may include Nitinol or be made of Nitinol. In one embodiment, four spikes 105 made of Nitinol may be formed at the distal end of the housing 100.

[0079] The energy storage body 102 may be configured to supply electrical energy to the components of the intracardiac pacemaker system 10, particularly to the electronic module 103, the communication unit 104, and the first electrode 106.

[0080] The electronic module 103 may be configured to perform the functions of a pacemaker, including sensing cardiac events and providing pacing pulses. The electronic module 103 may include a processor and a memory. In addition, the pacemaker 10 preferably includes a multi-axis accelerometer 6, which is configured to measure the acceleration of the implantable medical device / pacemaker 10 along, for example, three linearly independent vectors / axes of the accelerometer 6.

[0081] The communication unit 104 may be configured to communicate with an external device (such as a programmer) 110. The communication unit 104 may include a coil for RF communication (RF - radio frequency).

[0082] Figure 2A Shows an exemplary illustration of the "optimal" vector (here, vector 2) for rate adaptation support in an intracardiac pacemaker system (IPS) 5, where the intracardiac pacemaker system (IPS) 5 includes a multi-axis accelerometer 6. Figure 2AThe figure on the left shows the orientation of the IPS 5 within the patient as evaluated by the IPS 5 itself, while Figure 2A the graph line on the right shows the comparative alignment of the vectors V1, V2, V3 with a predefined vector, which in this case is preferably formed by the gravity vector g (i.e., the direction of the acceleration due to gravity). The alignment of the vectors V1, V2, V3 with the gravity vector g can be measured as a percentage, for example, as a percentage of the absolute value of the respective vectors V1, V2, V3 with respect to 'g'.

[0083] In Figure 2B the left shows another orientation of the IPS 5. In Figure 2B the right shows the alignment of the acceleration vectors V1, V2, V3 with the acceleration due to gravity g. Here, the vector V1 is the rate-adapted "optimal" vector.

[0084] The IPS 5 can include Figure 1 some or all of the components of the IPS 5 shown.

[0085] One embodiment involves support within an IMD (e.g., within the IPS) that includes rapid sequential scanning through each axis of a multi-axis accelerometer and collecting data from each axis of the multi-axis accelerometer. Ideally, such an ability can be paired with automated algorithms and triggered responses. In other words, in cases where adaptation of the vector selection between follow-ups is valuable, the implant 5 can periodically evaluate all three vectors V1, V2, V3 to ensure that the selected setting is "optimal", or if the patient exceeds a rate threshold (or otherwise), such a condition can initiate a vector selection check based on the dominant patient needs. The triggered response will allow in-clinic follow-up evaluations, where the clinician forces the implant to acquire such information to allow exercise and vector optimization testing.

[0086] The orientation of the IPS 5 highly depends on the patient's anatomy, the quality and robustness of the device implantation site, and the skills of the implanting physician. There are few means to prescriptively enforce the alignment between the accelerometer axes V1, V2, V3 within any single device and the patient's gross anatomy. In such embodiments, the key use of the accelerometer 6 within the implant focuses on supporting rate adaptation. To optimally allow such support with minimal system overhead, selecting a single axis aligned with the patient's head-to-toe axis is theoretically optimal. Perhaps coincidentally, this axis is also the axis aligned with the gravity vector g. Whether performed as an automatic or triggered response, collecting data for all three of the axes / vectors V1, V2, V3 within the device accelerometer when the patient is sitting or standing, rather than during movement, provides a means to determine which of the vectors V1, V2, V3 within many systems best aligns with the patient's head-to-toe orientation g. Such a process can facilitate the automated determination of the g vector direction and facilitate / set the vector (V1, V2, or V3), without requiring any user input. In other words, the implant 5 or the system 1 itself can easily set and adapt the accelerometer axis selection that is optimally suited for rate adaptation. Possible embodiments can even perform this process invisibly to the user and reject another vector that the clinician might select that could serve rate adaptation in a less robust manner.

[0087] In other words, the axes V1, V2, V3 having responses that best align with 'g' can be determined and reported to the user. Figure 2A and Figure 2B One such display of this type is shown herein. Here, a visual representation of the implant 5 with an attached multi-axis overlay (left side of the figure) and / or data graph (right side of the figure) can be used to highlight the vector (e.g., Figure 2A V2 in Figure 2B and V1 in

[0088] To support in-clinic exercise testing, implant 5 will ideally collect information on all axes / vectors V1, V2, V3 of the accelerometer for a maximum duration of no greater than 30 minutes. The corresponding information can correspond to the signals of accelerometer 6 for the respective vectors V1, V2, V3, which indicate the acceleration of the accelerometer in the respective directions V1, V2, V3. Preferably, such information can be obtained repeatedly, for example, in a scheme of a frequency type of once per minute or half minute, where instead of turning all axes simultaneously, each activation will be of one axis or vector V1, V2, V3 to obtain an input, cycling through all axes / vectors V1, V2, V3 until the complete set is evaluated. Data collected from this operation can facilitate the generation of graphs such as Figure 2A and Figure 2B as seen. In a follow-up scenario, the calculation of these tests of several tens of minutes' duration can optimally be performed in programmer 110 to avoid overburdening implant resources.

[0089] A variant embodiment that will significantly reduce implant data storage overhead can place a temporary monitoring device (e.g., a Holter device) 114 on the patient's body (nominal above the heart) to collect data on the signals observed on each of the axes V1, V2, V3 of accelerometer 6 (see Figure 1 ). After the implant receives a test initiation command from programmer 110, such data will be relayed via a trans-body network communication strategy to monitoring device (e.g., a Holter device) 114. Monitoring device (e.g., a Holter device) 114 can then relay the information to programmer wand 113 at the end of the execution of the test. This scheme will mean that implant 5 will simply stream accelerometer data to the monitoring (e.g., Holter) device 114 during the test without storing such information in its on-board memory.

[0090] For the inter-follow-up process, it will be required to use a shorter data collection time (i.e., much less than a survey of several tens of minutes) based on the implant to determine which vectors V1, V2, V3 optimally support the rate adaptation feature. This inter-follow-up scheme will adapt / update the main vector for rate adaptation over time or report it as statistical data (without updating the programmed vectors) to inform changes at subsequent follow-ups. Such adaptation and / or tracking will be particularly useful for patients with progressive diseases, in which the cardiac geometry changes over time and / or conditions, where the implant becomes increasingly encapsulated (and potentially less mobile in a given direction).

[0091] Similar to the exercise testing allowed in traditional pocket-based pacemakers, data obtained during exercise testing at follow-up can be collected and plotted (at the end of the test interrogation), as Figure 3As shown. The response can be represented as a rate or an activity count, and in one GUI embodiment (GUI - Graphical User Interface), the clinician can switch between two options. In particular, GUI 112 can be implemented in programmer 110, which can be connected to wand 113, which is configured to receive or transmit data (see Figure 1 ).

[0092] In the illustration shown, one vector V1, V2, V3 is displayed at a time, depending on which is selected in the interface (see dropdown menu) 112 to view. The "before" plot is intended to represent the baseline response of implant axes V1, V2, or V3 after completion of the first exercise test. If a change is made to the test parameters, a "preview" curve is generated to predict how the behavior of implant 5 on axis V1, V2, or V3 being viewed will change based on the edited parameters. Such feedback can help the user adjust the response of device 5 and see how it might change the response before running the second parameter adjustment exercise and vector optimization test. After applying the new parameter settings and running the test again, programmer 110 will retain the last collected data as "before", and then overwrite the new test data as "after". In this way, "before", predicted (i.e., "preview") data, and "after" data can be displayed to optimally inform the clinician of the targeted system response. As previously mentioned, use / support can preferably exclude support for both "before" and "after" data displays. Thus, only data from the most recent run can be available for display and interaction - including the "preview" capability, which will predict what response will occur with a changed accelerometer configuration setting.

[0093] A variant embodiment of the exercise and vector optimization test would be to survey only a single, clinician-selectable axis out of the multiple axes available within the implant. Doing so reduces the implant data storage requirements to 1 / 3 of what is required for a scenario that acquires and stores data for all three axes. The same interface as shown in Figure 2A , Figure 2B and Figure 3 can be used for this scenario, although the available data will not represent a complete set until each of the three axes can be selected. In such an instance, Figure 2A and Figure 2B the plots on the left may not be available until a complete set of tests has been run. Instead, a standard leadless pacemaker can be shown, which includes updated axes to reflect the clinician's vector selection.

[0094] Some of the elements associated with GUI support for this feature are shown in box format in Figure 4 , where the details shown in Figure 3 represent a detailed embodiment of "plotted rate sensor response data", andFigure 2A and Figure 2B represents a detailed embodiment of "Implant Orientation Map / Feedback". In the GUI interface 112 supported by this exercise and vector optimization test, IEGM (IEGM - Intracardiac Electrogram) provides real-time feedback when the system communicates with the implant. The page also provides means for changing / driving test operations via the "Test Execution Parameter Entry / Setting" field. The test is initiated with the "Test 'Start' button", and the results collected from the test execution are supported by bringing the IMD back into communication with the programmer and using the "Implant 'Query' button" (which can be automated in one embodiment and thus may not necessarily require such a button).

[0095] Figure 5 -11 show several views of the GUI 112, which are further described below in conjunction with the steps a user might sequentially take to determine the "best" vector among vectors V1, V2, V3.

[0096] The user accesses the test page ( Figure 5 shown in), which is pre-populated with parameters obtained by initially querying the device (i.e., the settings in the implant at the start of communication). Within this page, the user can initiate the optimal vector selection and (optionally, subsequently) collect active response data by pressing the "Start Test" button.

[0097] After pressing the "Start Test" button, the GUI 112 instructs the user to sit or stand for 30 seconds ( Figure 6A ). During this 30 - second duration ( Figure 6B ) after pressing the "Start Recording" button, the implant 5 collects DC measurements (DC - Direct Current) from each of the three axes / vectors V1, V2, V3 in the implant 5. Assuming that offset correction has been managed for each axis (i.e., trimmed) V1, V2, V3 in the IC (IC - Integrated Circuit) design, the implant returns the DC magnitudes of each of the three vectors V1, V2, V3. The programmer 110 takes the maximum of the magnitudes of the three vectors V1, V2, V3 and reports it to the user via the GUI 112 as the preferred vector.

[0098] The programmer 110 reports the recommended vector on the right and changes the vector value within the treatment program settings on the main page ( Figure 7 ). If the recommended vector is different from the vector originally queried by the programmer 110, it will be shown in color (e.g., blue) within the treatment program settings. The user can either not change the recommended vector selection at this time and run the active test, or change the vector settings and then run the active test. Running the test is facilitated by the user pressing the "Continue" option, which opens the active test interface ( Figure 8)。Any vector V1, V2, V3 selected within the treatment program will be the vector for the active test to collect data. The user can even skip the active test and simply accept the recommended vector and program his device 5 with it.

[0099] The active test interface provides all the relevant information required to instruct the patient to perform the active test ( Figure 8 ). After pressing the "Start Activity" button, the user removes the wand 113 (for communication between the programmer 110 and the implant 5) and moves around to perform the exercise. The implant 5 collects the patient's rate / activity data for more than, for example, 20 minutes.

[0100] After the exercise has been performed, the user returns to the programmer 110 and places the wand 113 back on top of the implant 5. By pressing the "Query" button ( Figure 9 ), the system 1 collects the rate data that has been collected during the (up to) 20-minute exercise duration.

[0101] The collected information is plotted on the test page, i.e., in response to pressing the "Query" button ( Figure 10 ). Two curves C1, C2 are shown as part of the query display – the preview curve C2 and the original curve C1. Initially, the two curves C1, C2 are superimposed on each other and both reflect the response associated with the parameter settings within the treatment program section of the page.

[0102] The user adjusts one of the treatment program settings to be different from that used during the active test, for example, adjusts "Auto" to "Low", and the GUI 112 responds to this change by changing the preview curve C2 ( Figure 11 ) to match the revised settings in the treatment program. In Figure 3 , three curves are shown. In the current embodiment, only the preview curve C2 and the original curve C1 are shown. At any time, if the user likes the settings present within the GUI 112 (i.e., which may also have been present in Figure 10 ), he / she can send them to the permanent program configuration page by pressing the "Copy to Program" button. The user can then further adjust the treatment and reprogram the device (if necessary).

[0103] If a large-amplitude signal of a certain short duration is detected, the selected vector can also be used for fall detection, for example, if the patient has epilepsy and falls, or a pain event causes him to fall, or arrhythmia causes him to lose consciousness.

[0104] Below, a list of other features used in the present invention alone or in combination with each other is provided:

[0105] - A multi-axis accelerometer within the IMD,

[0106] - The ability of the implant to acquire data from any of multiple accelerometer axes as an automatic and / or triggered response,

[0107] -The ability to collect data in a sequential scan format from each of multiple accelerometer axes,

[0108] - the ability of the implant to determine the “best” accelerometer axis for targeted feature support (especially rate adaptation) based on data collected from many accelerometer axes,

[0109] - the ability to automatically select and adapt the axis for rate adaptation based on the aforementioned points,

[0110] - the ability to store data within the implant detailing the activity response of any surveyed accelerometer vector,

[0111] - the option to eliminate implant storage for accelerometer axis signals and instead stream said data to a Holter device worn by the patient,

[0112] - A patient-worn Holter device capable of collecting implant-streamed accelerometer axis data for subsequent programmer interrogation,

[0113] - Programmer GUI for configuring, launching, interpreting exercises and vector optimization tests,

[0114] - Programmer capability to interpret data collected by the implant and / or Holter device and calculate the "optimal" accelerometer vector selection for intended feature support (especially rate adaptation),

[0115] - the ability of the programmer to retain information about "before" and "after" exercises and vector optimization tests and to present such information to the user simultaneously,

[0116] - The ability to render plotted activity response data about any accelerometer axis for which data has been collected, whether acquired in a "simultaneous" sequential scanning approach or collected one by one in separate tests within a single implant / programmer follow-up "session",

[0117] - the ability to present data graphs showing comparative alignment of vector response data to the 'g' gravity vector, including making a single vector the 'best' choice, and

[0118] - The ability to orient a picture of the device to highlight which vector best aligns with 'g' based on the information gathered in the previous points.

[0119] In addition, other embodiments of the present disclosure may have one or more of the following advantages:

[0120] -Accelerometer-based feature support to best fit individual patient needs,

[0121] - Facilitate the ability to adapt to disease state progression and / or package between follow-ups, and

[0122] - Significantly reduce the total clinical time required to select the "optimal" accelerometer axis to support a given, relevant feature.

Claims

1. A medical system (1), comprising at least - an implantable medical device (5), and - A multi-axis accelerometer (6), which is included by the implantable medical device (5) to measure the acceleration of the implantable medical device (5) along a plurality of vectors (V1, V2, V3), wherein, The multi-axis accelerometer (6) is configured to provide a signal indicating the acceleration of the implantable medical device (5) in the direction of each vector (V1, V2, V3) for each vector (V1, V2, V3), wherein the medical system (1) is configured to evaluate the acceleration signal to automatically select or propose a vector among the plurality of vectors (V1, V2, V3) that includes the best alignment with a predetermined vector (g), wherein the medical system (1) is configured to sequentially scan the plurality of vectors (V1, V2, V3) and evaluate and select or propose the vectors periodically or in response to a trigger.

2. The medical system according to claim 1, wherein, The implantable medical device (5) is configured to collect data when the implantable medical device (5) is in motion, wherein the collected data includes at least the AC signal of the accelerometer (6) for each vector (V1, V2, V3), and the AC signal of the accelerometer (6) indicates the acceleration of the implantable medical device (5) in the direction of the corresponding vector (V1, V2, V3), wherein the selected or proposed vector is a vector associated with the DC signal having the maximum amplitude among the acceleration signals or a vector associated with the AC signal having the maximum amplitude among the acceleration signals.

3. The medical system according to claim 1 or 2, wherein, The implantable medical device is one of the following: an intracardiac pacemaker; an implantable cardiac monitor; an implantable pulse generator (IPG) for nerve stimulation.

4. The medical system according to claim 1 or 2, wherein, The implantable medical device (5) is an intracardiac pacemaker, wherein the implantable medical device (5) is configured to generate and apply pacing pulses to the patient's heart at a rate, and wherein the implantable medical device (5) is configured to adapt the rate depending on the acceleration of the implantable medical device (5) with respect to the selected or proposed vector.

5. The medical system according to claim 1 or 2, wherein The predetermined vector (g) is the gravity vector.

6. The medical system according to claim 2, wherein, The medical system (1) or the implantable medical device (5) is configured to collect data from each of the plurality of vectors (V1, V2, V3) in a sequential manner.

7. The medical system according to claim 2 or 6, wherein, The implantable medical device (5) is configured to store the collected data in the implantable medical device (5).

8. The medical system according to claim 2 or 6, wherein, The medical system (1) includes a monitoring device (114), and the monitoring device (114) is configured to be placed outside the patient's body, wherein the implantable medical device (5) is configured to transmit the collected data to the monitoring device (114).

9. The medical system according to claim 8, wherein, The medical system (1) includes a programmer (110), and the programmer (110) is configured to receive the collected data from the implantable medical device (5) or from the monitoring device (114), wherein the programmer (110) is configured to evaluate the collected data to automatically select or propose a vector that includes the best alignment with the predetermined vector (g).

10. The medical system according to claim 9, wherein, The medical system (1) or the programmer (110) includes a graphical user interface (112).

11. The medical system according to claim 10, wherein, The graphical user interface (112) is configured to graphically display the collected data or information derived from the collected data, and / or display the selected or proposed vectors, and / or display a picture of the implantable medical device (5), the picture showing the selected or proposed vectors.

12. The medical system according to claim 10 or 11, wherein, The graphical user interface (112) is configured to perform at least one of the following: - Receive an input from the user to cause the programmer (110) to automatically select a vector including the best alignment with the predetermined vector (g), - Display information about available vector configurations to direct the user's insight to the vector that best aligns with the predetermined vector, - Receive an input from the user to confirm the proposed vector as the selected vector, - Receive an input from the user to initiate an activity test, during which the patient performs an exercise for a predetermined amount of time, and the implantable medical device (5) records the patient's heart rate and / or the raw activity signal output from the accelerometer, wherein the rate adaptation of the pacing pulses of the implantable medical device (5) is based on the acceleration of the implantable medical device (5) with respect to the selected or proposed vector, - Display the heart rate and / or the raw activity signal output recorded during the activity test, - Receive an input from the user to change the treatment program settings of the implantable medical device (5), and - Display a preview of the expected heart rate response of the changed treatment program settings.

13. A method for automatically selecting or presenting a vector among a plurality of vectors of a multi-axis accelerometer (6) of an implantable medical device (5), wherein, The accelerometer (6) is configured to measure the acceleration of the implantable medical device (5) along the vectors (V1, V2, V3), and wherein the method includes the following steps: - Collect data by sequentially scanning the plurality of vectors (V1, V2, V3) when the patient's body orientation is aligned with the predetermined vector (g), wherein the data collected from each of the vectors (V1, V2, V3) of the accelerometer indicates the intensity of the static acceleration of the implantable medical device (5) in the direction of the predetermined vector, and - Automatically select or propose the vector among the plurality of vectors (V1, V2, V3) associated with the signal having the largest amplitude among the signals, wherein the step of automatically selecting or proposing the vector is performed periodically or in response to a trigger.

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