Optimized Vector Selection for Multi-Axis Accelerometers in Implantable Medical Devices

Abstract

To provide an implantable medical system to adapt the pacing rate when increased activity of a patient is detected.SOLUTION: An implantable medical system comprises an implantable medical device 5 and a processor. The implantable medical device 5 has a multi-axis accelerometer 6 for measuring the acceleration of the implantable medical device 5 along a plurality of vectors V1, V2, V3. The processor acquires signals from the multi-axis accelerometer 6 as an automaticity or a triggered response, and automatically selects or proposes one of the vectors (V1, V2, V3) that has the maximum component in the direction of the gravitational vector, as a selected or proposed vector.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present disclosure relates to medical systems and corresponding methods. [Background technology]

[0002] Some implantable medical devices (IMDs) are equipped with accelerometers to detect patient movement / activity, for example to adapt the pacing rate of a pacemaker when an increase in the patient's activity is detected.

[0003] Multi-axis accelerometers enable motion detection through their ability to best measure motion by collecting data acquired along the axis (or axes) on the chip that best aligns with the motion vector of interest. In its simplest form, data collected from a single axis requires minimal system overhead (e.g., current budgeting, calculations, etc.) to report motion in a specified direction (or in the opposite direction, since the polarity of the motion along the axis is not important). Alternatively, if no single axis on the chip aligns well with the motion direction of interest, data collected from multiple axes can be computationally combined (e.g., by weighting, vector mathematics, etc.) to report data that best aligns a mathematically generated vector with the motion direction of interest.

[0004] Regardless of the approach, gravity imposes a dominant downward acceleration vector on the implant, which effectively generates an additive "DC offset" (DC - direct current, AC - alternating current) response to the signal transmission collected from any accelerometer axis aligned with the gravity vector. By examining each of the accelerometer chip's axes in a "no motion" state and assessing their baseline amplitudes, one can readily facilitate determining which axis or combination of axes aligns with this gravity vector. Such information is often sufficient to select which vector is preferred for product functional support.

[0005] Currently, the selection of accelerometer vectors within implantable medical devices (IMDs) is either established as a "hard-coded" configuration during product development and / or factory configuration, or requires follow-up interaction with a clinician, who must select a vector after performing a series of patient movements / exercises and analyzing the resulting data. The former process requires significant insight during product development to select vectors likely to be useful for a large proportion of the patient population. This approach thereby denies responses tailored to individual needs. Alternative follow-up approaches require a time-consuming process. In currently known devices, a single vector is selected for data collection, and then a movement / exercise routine is performed by the patient. To evaluate the impact on multiple axes, the routine must be repeated for each available axis on the chip. Each cycle of this iterative process can typically require 15 minutes or more of in-clinic follow-up time. Once all axes have been evaluated, it is then possible to select the optimal vector. Thus, for a three-axis accelerometer, such a process requires approximately 45 minutes (3 axes x 15 minutes). This duration poses a challenge to accessing optimized patient care, as not everyone can sustain prolonged physical activity over such a span and clinical resources are often limited.

[0006] Furthermore, sequential testing (i.e., one vector at a time) is not guaranteed to show identical results from one round to the next, and therefore results gathered from one vector may not be well suited for direct comparison with another. As such, steps are often skipped, default values ​​are chosen, and if the IMD orientation is such that the default is inappropriate, any dependent functions will not operate at their intended performance levels.

[0007] The orientation of an IMD within a patient is often unique. This situation is exacerbated for implantable cardiac monitors (ICMs) and leadless pacemaker systems compared to pocket-based implants, which are most often placed within the patient's anatomy with known lead port-up locations and consistently held in place by a through-device suturing process. The large number of implant sites compatible with ICMs and leadless pacemaker systems means that it is more challenging to determine which axis of a multi-axis accelerometer within the device best aligns with physical physiological references (e.g., head-to-toe vectors) that are critical to associated functional support. Summary of the Invention

[0008] With regard to the above drawbacks, the problem to be solved can be seen in the duration and complexity of the in-clinic procedure required to determine the "best" in-device accelerometer vector.

[0009] In particular, this disclosure details a scheme whereby the implant can run a routine to evaluate signal transmission for each of the vectors, enabling optimized selection of the accelerometer axis that best pairs with the feature sensing needs. This support can be enabled either as an automated (and potentially adaptive) routine for functional support during follow-up, or as support for ease in the clinical workflow during follow-up to select or encourage optimized vectors through the relay of critical metrics to the user via a GUI presentation.

[0010] In particular, further objects can be found in one or more of the following objects: Extend the ability to support vector optimization to scenarios where patients are physically limited and face challenges in completing an "exercise" test (i.e., unable to walk or perform other required exercises for approximately 45 minutes); - Provide improved GUI reporting of IMD accelerometer responses to better inform clinicians about the trade-offs available when selecting the "best" in-device accelerometer vector; -Providing improved sensing of accelerometer-based inputs for relevant IMD function support, thereby providing an improved patient experience with IMD between follow-ups; and -Regular assessment of accelerometer vectors during follow-up provides a means to adapt choices if alternative options emerge as preferred.

[0011] A medical system as described in clause 1 and a method as described in clause 13 are provided.

[0012] In one aspect, a medical system is disclosed comprising at least an implantable medical device and a multi-axis accelerometer included in the implantable medical device for measuring acceleration of the implantable medical device along a plurality of vectors (also referred to herein as acceleration vectors or axes), wherein the multi-axis accelerometer is configured to provide, for each vector, a signal indicative of the acceleration of the implantable medical device in the direction of the vector under consideration.

[0013] The medical system (particularly the medical implant device) is configured to evaluate the signal and automatically select or suggest a vector from the plurality of vectors of the accelerometer that forms the best alignment with a predefined vector.

[0014] In particular, the selected or proposed vector is the one of the vectors that has the largest component in the direction of the predefined vector.

[0015] In particular, the plurality of vectors comprises or consists of three orthogonal or linearly independent vectors (eg, in the x, y, and z directions).

[0016] In particular, the system, and in particular the implantable medical device, is configured to measure the acceleration of the implantable medical device during movement of the device in the direction of a selected (or proposed) vector.

[0017] The implantable medical device may be configured to collect data when the patient is instructed to remain stationary in a particular body position (e.g., standing or sitting). The collected data may include at least, for each vector (V1, V2, V3), an accelerometer DC signal indicative of the acceleration of the implantable medical device in the direction of the respective vector (V1, V2, V3), where the selected or suggested vector may be the one associated with the signal having the largest amplitude among the signals.

[0018] According to one embodiment of the medical system, the medical system may consist solely of an implantable medical device that automatically selects the accelerometer vector, however, the system may also include additional devices that may interact with the implantable medical device (also referred to herein as an implant).

[0019] In other words, this disclosure details a scheme whereby the implant can run a routine to evaluate signal transmission for each of the vectors, enabling optimized selection of the accelerometer axis / vector that best pairs with the feature sensing needs. This support can be enabled either as an automated (and potentially adaptive) routine for functional support during follow-up, or as support for ease in the clinical workflow during follow-up to select or encourage optimized vectors through relaying critical metrics to the user via GUI presentation.

[0020] In one embodiment, the implantable medical device has the capability to acquire data from any one of multiple accelerometer axes / vectors automatically and / or as a triggered response.

[0021] Additionally, in one embodiment, the implant has the ability to determine the best accelerometer axis / vector for targeted functional support (particularly rate adaptation) based on data collected from multiple accelerometer axes / vectors.

[0022] Further, according to one embodiment, the implantable medical device is configured to collect data as the implantable medical device is moved along predefined vectors, the collected data including at least, for each vector, an accelerometer signal indicating the magnitude of acceleration of the implantable medical device in the direction of that vector, and the selected or suggested vector is the one associated with the signal having the largest amplitude among the signals.

[0023] Furthermore, according to one embodiment, the implantable medical device is one of an intracardiac pacing system (also called an implantable leadless pacemaker), an implantable cardiac monitor (also called a loop recorder), and an implantable pulse generator (IPG) for neural stimulation.

[0024] In particular, when the implantable medical device is an intracardiac pacing system, the latter is preferably configured to automatically select and / or adapt the accelerometer vector used for rate adaptation based on signals from the accelerometer.

[0025] Further, according to one embodiment, when the implantable medical device is an intracardiac pacing system, the implantable medical device is configured to generate and apply pacing pulses to the patient's heart at a rate, and the implantable medical device is configured to adapt the rate in response to a selected or proposed acceleration of the implantable medical device relative to the vector.

[0026] According to one embodiment, the predefined vector is the gravity vector, i.e. the direction of gravity.

[0027] Additionally, in one embodiment, the system or implantable medical device has the capability to collect data from each of multiple accelerometer axes / vectors in a sequentially scanned format.

[0028] Furthermore, in one embodiment, the medical system or 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, thereby obtaining the amplitude of each accelerometer signal for each vector. Furthermore, in one embodiment, the implantable medical device is configured to store the collected data in the medical implant device.

[0029] Further, according to one embodiment, the system is configured to perform an activity test during which the patient performs exercise for a predefined amount of time, and the implantable medical device is configured to sample the patient's heart rate and adapt the rate of pacing pulses of the implantable medical device based on a selected or proposed acceleration of the implantable medical device with respect to the vector.

[0030] In particular, according to one embodiment, the implantable medical device has the capability to store data within the implant detailing the activity response of any accelerometer vector examined.

[0031] Furthermore, according to one embodiment, the medical system includes a monitoring device (e.g., a Holter device) configured to be placed outside the patient's body, and the implantable medical device is configured to transmit 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.

[0032] Thus, the medical system may have the option to eliminate implant storage for accelerometer vector or axis signaling and instead stream the indicated data to a patient-worn monitoring device. In particular, the monitoring device may be able to collect the accelerometer vector / axis data streamed at the implant for later programmer query.

[0033] According to a further embodiment, the medical system comprises a programmer (also referred to as a programming device) configured to receive collected data from an implantable medical device or a monitoring device, the programmer configured to evaluate the collected data and automatically select or suggest the vector that forms the best alignment with the predefined vector.

[0034] Thus, the medical system programmer may have the ability to interpret the data collected by the implant and / or monitoring / Holter device and calculate the best accelerometer vector selection for the intended function support (especially rate adaptation).

[0035] Furthermore, according to one embodiment, the medical system, and in particular the programmer, includes a graphical user interface (GUI) for configuring, initiating, and interpreting, among other things, motion and vector optimization tests.

[0036] In particular, the graphical user interface is configured to graphically display collected data or information derived from collected data, and / or display selected or suggested acceleration vectors, and / or display an image of the implantable medical device showing the selected or suggested acceleration vectors.

[0037] In particular, the medical system, and in particular the GUI, has the ability to orient an image of the implantable medical device according to the collected data and highlight which acceleration vector is best aligned with a predefined vector (e.g., the gravity vector). In particular, the GUI is configured to show the comparative alignment of acceleration vector response data to a predefined vector (e.g., the gravity vector), including promoting a single acceleration vector as the best choice.

[0038] Further, according to one embodiment, the graphical user interface comprises: receiving a user input to cause a programmer or system to automatically select the vector from the plurality of vectors that forms the best alignment with a predefined vector; - displaying information about available vector configurations to give the user insight into which ones align best with predefined vectors; - receiving user input to confirm the proposed vector as the selected vector (or receiving user input to select a different accelerometer vector); receiving user input to initiate an activity test, during which the patient performs exercise for a predefined amount of time and the implantable medical device records the patient's heart rate and / or raw activity signal output from an accelerometer, and rate adaptation of pacing pulses by the implantable medical device is based on acceleration of the implantable medical device with respect to the selected or proposed vector; - displaying (e.g., as one or more trend plots) the heart rate and / or raw activity signal output recorded during the activity test; - receiving input from a user to modify a therapy program setting of an implantable medical device; and - displaying a preview of an expected heart rate response to the modified therapy program settings.

[0039] Additionally, in one embodiment, the programmer has the ability to retain / display information regarding "before" and "after" exercise and vector optimization tests and simultaneously present such information to the user. Such support proves useful solely for cases in which multiple sequential vector optimization and / or exercise tests are performed. In such a situation, the "before" data represents the output from the last test performed, and the "after" data represents the output from the current test, which is now performed purely theoretically according to adjustments made to the sensor configuration in response to data evaluated in the last (i.e., "before") optimization test. A "preview" option / function can replace the need for any "after" data collection / management, as adjustments to sensor settings within the GUI can instead be used to predict what the response would have been given those changed sensor settings. This approach avoids the complications associated with requiring "before" and "after" exercise regimens to be matched in exertion, body movement, and duration as a means to best facilitate comparison of sensor configuration settings.

[0040] Additionally, according to one embodiment, the system has the ability to render plotted activity response data for any of the accelerometer axes / vectors along which the data was collected, whether acquired in a sequentially scanned "simultaneous" manner or collected one at a time in separate tests within a single implant / programmer follow-up session.

[0041] According to yet another aspect, a method is disclosed for automatically selecting or suggesting a vector from among several vectors of a multi-axis accelerometer of an implantable medical device, the accelerometer being configured to measure acceleration of the implantable medical device along the vector, the method comprising: - collecting data (e.g., by the implantable medical device) while the patient's body is oriented in alignment with a predefined vector (e.g., during a supervised follow-up procedure), wherein the data collected from each of the accelerometer vectors indicates a magnitude of static acceleration of the implantable medical device in the direction of the predefined vector; - automatically selecting or suggesting a vector from said number of vectors that is associated with the signal having the largest amplitude among the signals.

[0042] The method may further include modifying the above-outlined routine for vector selection into a compatible format for use during follow-up, where the device periodically samples information from available accelerometer axes to build a running history of (non-static, i.e., dynamic) accelerometer information (while ambulatory) indicating the relative magnitude of signal transmission on the separate available axes, and (in turn) actively modifying the "best" vector selection in a dynamic manner based on the collected history, or simply making such history available as an accessible statistic that can alert the user to the possibility that the "best" vector should be modified to another option.

[0043] According to a further embodiment, the method includes the further step of receiving the collected data from the implanted medical device or monitoring device at a programmer, evaluating the collected data at said programmer, and automatically selecting or suggesting the vector associated with the signal having the largest amplitude among the signals. The medical implant device may be configured to manage the selection itself in compatible embodiments, where the preferred vector of the accelerometer is updated to the "best" state during follow-up.

[0044] According to a further embodiment of the method, the system or programmer includes a graphical user interface (GUI).

[0045] According to further embodiments, the method includes the further step of graphically displaying the collected data or information derived from the collected data via a GUI, and / or graphically displaying the selected or proposed vector via a GUI, and / or graphically displaying an image of the implantable medical device showing the selected or proposed vector via a GUI.

[0046] According to a further embodiment, the method comprises: - selecting, through a corresponding input in the GUI, the proposed vector that forms the best alignment with the predefined vector; - confirming the proposed vector as the selected vector through a corresponding input in the GUI; - initiating, through a corresponding input into the GUI, an activity test during which the patient performs exercise for a predefined amount of time, recording, by the implantable medical device, the patient's heart rate and / or raw activity signals output from the accelerometer, and adapting the rate of pacing pulses of the implantable medical device based on the acceleration of the implantable medical device with respect to the selected or proposed vector; - displaying (e.g., as one or more trend plots) raw activity signal outputs from the heart rate and / or accelerometer recorded during the activity test; - changing a therapy program setting of the implantable medical device through a corresponding input into the GUI; - displaying a preview of the expected heart rate for the changed therapy program settings via the GUI.

[0047] According to a further aspect, an implantable medical device (IMD), such as an intracardiac pacing system (also called a leadless pacemaker), an implantable cardiac monitor (also called a loop recorder), or an implantable pulse generator (IPG) for neural stimulation, is provided. The IMD may include an accelerometer. The accelerometer may be a multi-axis accelerometer configured to determine an acceleration vector in two or more axes, for example, three axes.

[0048] According to yet another aspect, a method is provided. The method may include determining a selected acceleration vector from among several acceleration vectors (e.g., from among three acceleration vectors), where the selected acceleration vector may be aligned with the acceleration of gravity. The alignment of the selected acceleration vector with the acceleration of gravity may be based on a portion of the acceleration vector that is oriented in the direction of the acceleration of gravity.

[0049] The method can be applied to implantable medical devices (IMDs) that have accelerometers, for example multi-axis accelerometers.

[0050] Features described with respect to medical systems can also be applied to methods, and vice versa.

[0051] In the following, exemplary embodiments of the invention as well as further features and advantages are described with reference to the figures. [Brief explanation of the drawings]

[0052] [Figure 1] 1 is a schematic diagram of one embodiment of a medical system (e.g., an intracardiac pacing system). [Figure 2A] FIG. 1 illustrates two orientations of an intracardiac pacemaker for vector selection. [Figure 2B] FIG. 1 illustrates two orientations of an intracardiac pacemaker for vector selection. [Figure 3] FIG. 10 illustrates an interface for showing accelerometer response. [Figure 4] Figure 1 shows the graphical user interface (GUI). [Figure 5] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 6A] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 6B] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 7] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 8] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 9] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 10] Some illustrations of different graphical user interfaces (GUIs) are shown. [Figure 11] Some illustrations of different graphical user interfaces (GUIs) are shown. DETAILED DESCRIPTION OF THE INVENTION

[0053] 1 shows a schematic diagram of a medical system 1 including at least an implantable medical device (also referred to herein as an implant) in the form of an intracardiac pacing system 5 (also referred to herein as an intracardiac pacemaker). In particular, the intracardiac pacemaker 5 includes a housing 100 that encloses an energy storage device 102 (e.g., a battery), an electronic module 103, and a communication unit 104. The housing 100 may include or be made of titanium.

[0054] A first electrode 106 (also called a pacing electrode) is disposed at the distal end of the housing 100. A second electrode 101 (also called a sensing electrode) is disposed in the proximal region of the housing 100. The second electrode 101 may be formed as a ring electrode.

[0055] The pacemaker system 5 may be secured to the cardiac tissue by fixation elements 105. The fixation elements may be formed as tines, which may include or be made of nitinol. In one embodiment, four tines 105 made of nitinol may be formed at the distal end of the housing 100.

[0056] The energy storage 102 may be configured to provide electrical energy to the components of the intracardiac pacemaker system 10 , in particular the electronic module 103 , the communication unit 104 , and the first electrode 106 .

[0057] Electronic module 103 may be configured to perform pacemaker functions, including sensing cardiac events and providing pacing pulses. Electronic module 103 may include a processor and memory. Additionally, pacemaker 10 preferably includes a multi-axis accelerometer 6 configured to measure acceleration of implantable medical device / pacemaker 10, e.g., along three linearly independent vectors / axes of accelerometer 6.

[0058] The communication unit 104 may be configured for communication with an external device (e.g., a programmer) 110. The communication unit 104 may comprise a coil for RF communication (RF - radio frequency).

[0059] FIG. 2A shows an exemplary depiction of a “best” vector (here, vector 2) for rate-adaptive support in an intracardiac pacemaker system (IPS) 5 equipped with a multi-axis accelerometer 6. The graphic on the left side of FIG. 2A shows the orientation of the IPS 5 within the patient as assessed by the IPS 5 itself, while the plot on the right side of FIG. 2A shows the comparative alignment of vectors V1, V2, and V3 with a predefined vector, which in this case is preferably formed by the gravity vector g (i.e., the direction of gravitational acceleration). The alignment of vectors V1, V2, and V3 with gravity vector g may be measured, for example, as a percentage of the absolute value of the respective vector V1, V2, and V3 relative to “g.”

[0060] Another orientation of IPS5 is shown on the left side of Figure 2B. The alignment of acceleration vectors V1, V2, and V3 with the gravitational acceleration g is shown on the right side of Figure 2B, where vector V1 is the "best" vector for rate adaptation.

[0061] The IPS 5 may include some or all of the components of the IPS 5 shown in FIG.

[0062] One embodiment involves including support within the IMD (e.g., within the IPS) for rapidly sequentially scanning each axis of the multi-axis accelerometer to collect data from each axis of the multi-axis accelerometer. Ideally, such capability could be paired with an automated algorithm and also with triggered responses. In other words, if adapting vector selection between follow-ups is beneficial, the implant 5 could periodically evaluate all three vectors V1, V2, and V3 to ensure the selected settings are "best," or if the patient exceeds a rate threshold (or otherwise), such a condition could initiate a vector selection check based on the patient's general needs. Triggered responses enable in-clinic follow-up evaluations where the clinician forces the implant to obtain such information to enable motion and vector optimization testing.

[0063] The orientation of the IPS 5 is highly dependent on the patient's anatomy, the characteristics and robustness of the device implant site, and the skill of the implanting physician. There are few means to normatively enforce alignment between any single in-device accelerometer axis V1, V2, V3 and the patient's overall anatomy. In such embodiments, the primary use of the in-implant accelerometer 6 centers on supporting rate adaptation. To optimally enable such support with minimal system overhead, it is purely theoretically best to choose a single axis aligned with the patient's head-to-toe axis. Perhaps coincidentally, this axis is also aligned with the gravity vector g. Whether done automatically or as a triggered response, collecting data on all three in-device accelerometer axes / vectors V1, V2, V3 while the patient is sitting or standing but otherwise motionless provides a means to determine which of the many in-system vectors V1, V2, V3 is best aligned with the patient's head-to-toe orientation g. Such a procedure can facilitate automated determination of the g-vector direction and encourage / set that vector (V1, V2, or V3) without necessarily requiring any user input. In other words, the implant 5 or system 1 itself can easily set and adapt the accelerometer axis selection best suited for rate adaptation. Furthermore, possible embodiments can make this process invisible to the user, denying the clinician any means to choose an alternative vector that might serve the rate adaptation in a less robust manner.

[0064] In other words, the axes V1, V2, V3 with the best aligned responses to "g" can be determined and reported to the user. One such display of this type is shown in FIGS. 2A and 2B. Here, a visual representation of the implant 5 with accompanying multi-axis overlays (left side of the figure) and / or data graphics (right side of the figure) can be used to highlight the vector (e.g., V2 in FIG. 2A and V1 in FIG. 2B) that best aligns with the patient's head-to-toe orientation, i.e., the gravity vector g. Selection of such a best-aligned vector, whether automated by the implant 5 or selected by the clinician, then best facilitates vector selection that is well-tuned to support the rate-matching needs of the product. The "best" axis may be color-coded in the plots and graphics to encourage or report that selection.

[0065] To support in-clinic exercise testing, the implant 5 ideally collects information about all accelerometer axes / vectors V1, V2, and V3 for a maximum duration of 30 minutes or less. Each piece of information may correspond to the accelerometer 6 signal for each vector V1, V2, and V3, indicating the accelerometer's acceleration in each direction V1, V2, and V3. Preferably, such information is acquired repeatedly, for example, in a frequency-type approach of once per minute or once per 30 seconds. In this approach, rather than turning on all axes simultaneously, one axis or vector V1, V2, and V3 at a time may be activated to acquire input, cycling through all axes / vectors V1, V2, and V3 until the complete set has been evaluated. The data collected by this work can facilitate the generation of graphics such as those shown in FIGS. 2A and 2B through relative comparison of the generated data for each axis V1, V2, and V3. In follow-up scenarios, calculations based on these tests of nominal duration of 10 seconds may best be performed by the programmer 110 to avoid taxing the implant's resources.

[0066] An alternative embodiment that significantly reduces the implant's data storage overhead would be one in which a temporary monitoring device (e.g., a Holter device) 114 could be placed on the patient's body (nominally over the heart) to collect data related to signal transmission observed for each of the V1, V2, and V3 axes of the accelerometer 6 (see FIG. 1 ). Such data would be relayed to the monitoring device (e.g., Holter device) 114 via a through-body networked communication strategy after the implant receives a test start command from the programmer 110. The monitoring device (e.g., Holter device) 114 can then relay the information to the programmer wand 113 at the end of test execution. This approach means that the implant 5 simply streams accelerometer data to the monitoring (e.g., Holter) device 114 during the test but does not store such information in its on-board memory.

[0067] For inter-follow-up procedures, this work requires an implant-based determination of which vectors V1, V2, V3 best support the rate adaptation function using shorter data collection periods (i.e., substantially less than 10-second minutes). This inter-follow-up approach can adapt / update the primary vector used for rate adaptation over time, or can be reported as a statistic (without updating the programmed vector) to notify changes at subsequent follow-ups. Such adaptation and / or tracking may prove particularly useful for patients with progressive disease where the shape of the heart changes over time and / or conditions where the implant becomes increasingly encapsulated (and may be less prone to movement in a given direction).

[0068] Similar to the exercise testing available with older pocket-based pacemakers, data acquired during follow-up exercise testing can be collected and plotted (at the end of the test query) as shown in Figure 3. Responses may be expressed as rates or activity counts, and in one GUI embodiment (GUI - Graphical User Interface), the clinician can toggle between the two options. In particular, the GUI 112 can be implemented in a programmer 110 (see Figure 1), which can be connected to a wand 113 configured to receive or transmit data.

[0069] In the depicted depiction, one vector V1, V2, or V3 is displayed at a time, depending on which is selected for viewing within the interface (see drop-down menu) 112. The “Before” plot is meant to represent the baseline response of the implant axis V1, V2, or V3 after the completion of the first kinematic test. If changes are made to the test parameters, a “Preview” curve is generated to predict the behavior of the implant 5 on the viewed axis V1, V2, or V3 in light of the edited parameter changes. Such feedback can help the user adjust the response of the device 5 to see how it may change the response before running a second, parameter-adjusted kinematic and vector optimization test. After applying new parameter settings and running the test again, the programmer 110 retains the last collected data as “Before” and then overlays the new test data as “After.” In this way, “Before,” predicted (i.e., “Preview”), and “After” data can be presented to best inform the clinician of the target system response. As mentioned above, the use / support may prefer to exclude support for displaying both "before" and "after" data, so that only data from the most recent run is made available for display and interaction, including a "preview" feature that predicts what the response would have been given changed accelerometer configuration settings.

[0070] An alternative embodiment of the motion and vector optimization test is to investigate only a single clinician-selectable axis of the multiple axes available within the implant. By doing so, the implant's data storage needs are reduced to one-third of that required for a strategy that acquires and stores data for all three axes. The same interface shown in FIGS. 2A, 2B, and 3 can be used with this approach, but the available data does not represent a complete set until each of the three axes can be selected. In such an example, the left diagrams in FIGS. 2A and 2B may not be available until the full suite of tests is performed. In their place, a standard leadless pacemaker could be shown, including axes that update to reflect the clinician-selected vector.

[0071] Some elements associated with GUI support for this functionality are shown in block format in FIG. 4, where the details shown in FIG. 3 correspond to a detailed embodiment of "Plotted Rate Sensor Response Data" and FIGS. 2A and 2B correspond to a detailed embodiment of "Implant Orientation Diagram / Feedback." Within this GUI interface 112 for motion and vector optimization test support, the IEGM (intracardiac electrogram) provides real-time feedback while the system is communicating with the implant. The page also provides a means to change / drive the operation of the test via an "Enter / Set Test Execution Parameters" field. Tests are initiated with a "Test 'Start' button," and results gathered from test execution are supported by returning the IMD to communication with the programmer and using a "Query Implant' button" (in one embodiment, this may be automated, thus not enforcing the need for such a button).

[0072] Several views of GUI 112 are shown in Figures 5-11 and are further described below, along with steps a user may take to determine the "best" vector among vectors V1, V2, and V3.

[0073] The user accesses a test page (shown in FIG. 5) pre-filled with parameters from the initial query of the device (i.e., settings in the implant at the start of communication). Within the page, the user can begin optimal vector selection and (optionally subsequently) collect activity response data by pressing the "Start Test" button.

[0074] After pressing the "Start Test" button, the GUI 112 instructs the user to sit or stand for 30 seconds (FIG. 6A). During this 30-second duration (FIG. 6B) following the pressing of the "Start Recording" button, the implant 5 collects DC measurements (DC—direct current) from each of the three axes / vectors V1, V2, and V3 of the implant 5. Assuming offset correction has been properly performed in the IC design (IC—integrated circuit) for each axis (i.e., trim) V1, V2, and V3, the implant returns a DC amplitude for each of the three vectors V1, V2, and V3. The programmer 110 takes the maximum amplitude of the three vectors V1, V2, and V3 and reports it to the user via the GUI 112 as the preferred vector.

[0075] The programmer 110 reports the recommended vector on the right-hand side and modifies the vector value in the treatment program settings on the main page (FIG. 7). If the recommended vector is different from the one originally queried by the programmer 110, the recommended vector is indicated by a color (e.g., blue) in the treatment program settings. The user can at this point leave the recommended vector selection unchanged and run an activity test, or change the vector settings and then run an activity test. Test execution is prompted by the user pressing the "Proceed" option, which opens the activity test interface (FIG. 8). Whichever vector V1, V2, V3 is selected in the treatment program is the one the activity test will use to collect data. The user may choose not to even run an activity test, and instead simply accept the recommended vector and program the device 5 with it.

[0076] The activity test interface provides all the relevant information needed to instruct the patient to perform an activity test (FIG. 8). After pressing the "Start Activity" button, the user removes the wand 113 (used for communication between the programmer 110 and the implant 5) and moves around performing the indicated exercise. The implant 5 collects approximately, e.g., 20 minutes' worth of patient rate / activity data.

[0077] After performing the exercise, the user returns to the programmer 110 and places the wand 113 back over the implant 5. By pressing the "Query" button (FIG. 9), the system 1 collects rate data that has been collected over the (maximum) 20 minute duration of the exercise.

[0078] The collected information is plotted on the test page, i.e., in response to pressing the "Query" button (FIG. 10). Two curves C1, C2 appear as part of the queried display: preview curve C2 and original curve C1. Initially, the two curves C1, C2 are superimposed, and both reflect responses related to parameter settings within the treatment program portion of the page.

[0079] If the user adjusts one of the therapy program settings to something other than that used during the activity test, e.g., from "Auto" to "Low," the GUI 112 responds to this change (FIG. 11) by modifying the preview curve C2 to match the revised settings in the therapy program. Three curves are shown in FIG. 3. In this embodiment, only the preview curve C2 and the original curve C1 are shown. At any time, if the user prefers the settings present in the GUI 112 (i.e., as could have been done in FIG. 10), he / she can send them to the permanent program configuration page by pressing the "Copy to Program" button. The user can then further fine-tune the therapy and reprogram the device as needed.

[0080] The selected vector may also be used for fall detection when a specific short duration, large amplitude signal transmission is detected, for example, when a patient experiences a seizure and fall, or a painful event that causes the patient to fall, or an arrhythmia that may cause the patient to lose consciousness.

[0081] Below is provided a list of further features that may be used in the present invention alone or in any combination with one another. -Multi-axis accelerometer in IMD, - the ability of the implant to acquire data from any one of multiple accelerometer axes automatically and / or as a triggered response; - the ability to collect data from each of multiple accelerometer axes in a sequentially scanned format; - the ability of the implant to determine the "best" accelerometer axis for targeted functional support (especially rate adaptation) based on data collected from multiple accelerometer axes; - the ability to automatically select and adapt the axis used for rate adaptation based on the preceding clauses; - the ability to store data within the implant detailing the activity response of any accelerometer vector investigated; - the option to eliminate implant storage for accelerometer axis signaling and instead stream the displayed data to a patient-worn Holter device; a patient-worn Holter device capable of collecting implant-streamed accelerometer axial data for later programmer interrogation; -Programmer GUI for configuring, starting and interpreting motion and vector optimization tests, - The programmer's ability to interpret data collected by the implant and / or Holter device and calculate the "best" accelerometer vector selection for the intended functional support (especially rate adaptation); - the ability for the programmer to maintain "before" and "after" information for motion and vector optimization tests and simultaneously present such information to the user; - The ability to render plotted activity response data for any of the accelerometer axes for which the data was collected, whether acquired in a sequentially scanned "simultaneous" manner or collected one at a time in separate trials within a single implant / programmer follow-up "session"; - the ability to present data graphics showing the comparative alignment of vector response data to the "g" gravity vector, including the promotion of a single vector as the "best" choice; and -Ability to orient the device's image according to the information gathered in the previous paragraph to highlight which vector is best aligned with "g".

[0082] Additionally, further embodiments of the present disclosure may have one or more of the following advantages. - Accelerometer-based functional support is best aligned with individual patient needs, - Facilitate the ability to adapt to the progression of the disease state and / or encapsulation during follow-up; and - A significant reduction in the total clinical time required to select the "best" accelerometer axis to support a given relevant function.

Claims

1. 1. An implantable medical system, comprising: an implantable medical device (5) comprising a multi-axis accelerometer (6) for measuring acceleration of the implantable medical device (5) along a plurality of vectors (V1, V2, V3), the multi-axis accelerometer (6) being configured to provide, for each vector (V1, V2, V3), a signal indicative of the magnitude of the acceleration of the implantable medical device (5) in the direction of each of the vectors (V1, V2, V3); a processor configured to automatically or in response to a trigger, for each of the vectors (V1, V2, V3), obtain from the multi-axis accelerometer a signal indicative of the magnitude of the acceleration of the implantable medical device (5) in the direction of each of the vectors (V1, V2, V3), and to automatically select or propose as a selected or proposed vector one of the vectors (V1, V2, V3) having a largest component in the direction of a gravity vector, the signals being obtained from each vector of the multi-axis accelerometer in a sequential manner; An implantable medical system comprising:

2. 2. The medical system of claim 1, wherein the implantable medical device is one of an intracardiac pacemaker (5), an implantable cardiac monitor, and an implantable pulse generator (IPG) for neural stimulation.

3. 2. The medical system of claim 1, wherein the implantable medical device is an intracardiac pacemaker, the implantable medical device is configured to generate and apply pacing pulses to the patient's heart at one rate, and the implantable medical device is configured to adjust the rate depending on an acceleration of the implantable medical device relative to the selected or proposed vector.

4. 4. The medical system according to claim 1 or 3, wherein the implantable medical device (5) is configured to store the acquired signals in the implantable medical device (5).

5. 2. The medical system of claim 1, wherein the medical system (1) comprises a monitoring device (114) configured to be placed outside the patient's body, and the implantable medical device (5) is configured to transmit the acquired signal to the monitoring device (114).

6. 2. The medical system of claim 1, wherein the medical system comprises a programmer, the programmer having the processor for evaluating the acquired signals to automatically select or suggest the selected or suggested vector.

7. 6. The medical system of claim 5, wherein the medical system comprises a programmer configured to receive the acquired signals from the monitoring device, the programmer configured to evaluate the acquired signals and automatically select or suggest the selected or suggested vector.

8. 8. The medical system according to claim 6 or 7, wherein the medical system (1) or the programmer (110) comprises a graphical user interface (112).

9. The medical system of claim 8, wherein the graphical user interface (112) is configured to graphically display the selected or proposed vector.

10. 1. A method of operating a processor of a medical system for automatically selecting or suggesting a selected or suggested vector from among a plurality of vectors of a multi-axis accelerometer (6) of an implantable medical device (5), the accelerometer (6) being configured to measure acceleration of the implantable medical device (5) along the plurality of vectors (V1, V2, V3), the multi-axis accelerometer (6) being configured to provide, for each vector (V1, V2, V3), a signal indicative of the magnitude of the acceleration of the implantable medical device (5) in the direction of a respective one of the vectors (V1, V2, V3), the method comprising: - acquiring in a sequential manner from the multi-axis accelerometer, automatically or in response to a trigger, the signals indicative of the magnitude of the acceleration of the implantable medical device (5) in the direction of each of the vectors (V1, V2, V3); - automatically selecting or proposing as a selected or proposed vector one of said plurality of vectors (V1, V2, V3) having a maximum component in the direction of the gravity vector.

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