Medical device system for determining atrial fibrillation load

Abstract

Systems and methods are disclosed for determining and recording one or more atrial fibrillation key indicators for a patient, including determining an atrial fibrillation indication of the patient in a respective detection window of a day using received physiological information, recording first physiological information of the patient at a first sampling frequency for the determined atrial fibrillation indication of the patient until and not exceeding a first threshold of the medical device system for transmission to a remote device, and determining and recording one or more atrial fibrillation key indicators at a second sampling frequency lower than the first sampling frequency for the determined atrial fibrillation indication of the patient without concerning the first threshold.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 529,973, filed July 31, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This document generally relates to medical devices, and more specifically to systems and methods for determining atrial fibrillation load in patients. Background Technology

[0004] Ambulatory medical devices (AMDs), including implantable, subcutaneous, wearable, or other medical devices, can monitor, detect, or treat various conditions, including heart failure (HF) and atrial fibrillation (AF). AMDs may include sensors for sensing physiological information from a patient, and one or more circuits for using the sensed physiological information to detect one or more physiological events or to transmit the sensed physiological information or detected physiological events to one or more remote devices. Frequent patient monitoring can provide early detection of deteriorating patient conditions, including worsening heart failure or atrial fibrillation.

[0005] Cardiac arrhythmias are abnormal heart rhythms (e.g., fast, slow, irregular, etc.). Among other things, cardiac arrhythmias include bradycardia, tachycardia, premature beats, extra heartbeats or skipped beats, and atrial or ventricular fibrillation affecting one or more chambers of the heart. Atrial fibrillation (AF) is an abnormal heart rhythm characterized by rapid and irregular activity in the left or right atrium of the heart. Atrial fibrillation is commonly associated with reduced cardiac output, heart failure, dementia, and an increased risk of stroke. Risk factors for atrial fibrillation include, among others, hypertension, heart failure, valvular heart disease, chronic obstructive pulmonary disease (COPD), obesity, and sleep apnea.

[0006] Mobile medical devices (AMDs) (including implantable, subcutaneous, wearable, or one or more other medical devices) can monitor, detect, or treat a variety of conditions, including heart failure and atrial fibrillation. AMDs may include sensors for sensing physiological information from a patient, and one or more circuits for using the sensed physiological information to detect one or more physiological events or to transmit the sensed physiological information or detected physiological events to one or more remote devices. Frequent patient monitoring can provide early detection of deterioration in a patient's condition, including worsening heart failure or atrial fibrillation.

[0007] Accurate identification of patients or patient groups at increased risk of future adverse events can control the selection of modes or features or resource management for one or more mobile medical devices; control notifications or messages to various users associated with a specific patient or patient group within a connected system; organize or schedule physician or patient contacts or treatments; or prevent or reduce patient hospitalizations. Proper identification and safe management of the risk of patient deterioration can avoid unnecessary medical interventions, extend the lifespan of mobile medical devices, and reduce healthcare costs. Summary of the Invention

[0008] Systems and methods for determining and recording one or more key metrics for atrial fibrillation in a patient are disclosed. These include determining an atrial fibrillation indication for the patient within a corresponding detection window of a day using received physiological information; recording the patient's first physiological information at a first sampling frequency up to and not exceeding a first threshold of the medical device system for transmission to a remote device, based on the determined atrial fibrillation indication; and determining and recording one or more key metrics for the determined atrial fibrillation indication at a second sampling frequency lower than the first sampling frequency, regardless of the first threshold. In some examples, one or more key metrics may be used to determine the patient's atrial fibrillation load indication—such as comparing one or more key metrics with proportionate metrics used for a determined episode. In other examples, the one or more key metrics may be used to change, alter, or control a mode or operation of one or more components of the medical device system.

[0009] Examples of the subject (e.g., a medical device system) may include signal receiver circuitry configured to receive physiological information from a patient; and evaluation circuitry configured to: use the received physiological information to determine an atrial fibrillation indication for the patient within a corresponding detection window of a day; record first physiological information of the patient at a first sampling frequency for the determined atrial fibrillation indication up to and including a first threshold of the medical device system for transmission to a remote device; and determine and record one or more atrial fibrillation key indicators at a second sampling frequency lower than the first sampling frequency for the determined atrial fibrillation indication, regardless of the first threshold.

[0010] In the example, which may be combined with any one or more examples described herein, the evaluation circuit may be configured to determine and record one or more atrial fibrillation key indicators for a determined atrial fibrillation indication without limitation, optionally including determining and recording one or more atrial fibrillation key indicators for a determined atrial fibrillation indication up to and exceeding the first threshold.

[0011] In the example, the example may be combined with any one or more examples described herein, and the first threshold may include or represent a first data limit stored or transmitted by the evaluation circuit for a period of time between a determined atrial fibrillation indication, a time period, or a sequential transmission to the remote device.

[0012] In the examples, the examples may be combined with any one or more examples described herein, and the first threshold may include a daily threshold for the determined atrial fibrillation indication.

[0013] In the example, which may be combined with any one or more examples described herein, the evaluation circuit may be configured to stop recording the patient's first physiological information for the remainder of the day after the amount of first physiological information recorded for a day has reached or exceeded the first threshold.

[0014] In the example, the example can be combined with any one or more examples described herein, and the evaluation circuit can be configured to determine and record one or more key indicators of atrial fibrillation for each of the identified atrial fibrillation indications of the patient for transmission to the remote device.

[0015] In the example, the example can be combined with any one or more examples described herein, and the evaluation circuit can be configured to determine and record the one or more key indicators of atrial fibrillation for each detection window of the determined atrial fibrillation indication.

[0016] In the example, the example can be combined with any one or more examples described herein, and the evaluation circuit can be configured to determine and record the one or more atrial fibrillation key indicators for each detection window of the determined atrial fibrillation indication and at least one detection window before or after the determined atrial fibrillation indication.

[0017] In the examples, the examples can be combined with any one or more examples described herein, and each identified atrial fibrillation indication may include one or more detection windows.

[0018] In the example, the example can be combined with any one or more examples described herein, and the evaluation circuit can be configured to determine and record the one or more key indicators of atrial fibrillation for each detection window of a day, each detection window including detection windows with and without the determined atrial fibrillation indication.

[0019] In the examples, the examples may be combined with any one or more examples described herein, and the subject matter may optionally include implantable or mobile medical devices, the medical devices including the signal receiver circuitry and the evaluation circuitry.

[0020] In the examples, the examples can be combined with any one or more examples described herein, and the duration of the detection window can be between 30 seconds and 2 minutes.

[0021] In this example, the example can be combined with any one or more examples described herein, and the first physiological information of the patient at the first sampling frequency may include: ECG signals of the patient at a sampling frequency greater than 100 samples per second for a determined atrial fibrillation indication, up to and not exceeding the first threshold of the medical device system.

[0022] In the example, the example may be combined with any one or more examples described herein, and the one or more atrial fibrillation key indicators may include: one or more measures or values ​​representative of one or more detection windows with a determined indication having a second sampling frequency of less than 5 samples per detection window.

[0023] In the examples, the examples may be combined with any one or more examples described herein. For each of the one or more detection windows identified as atrial fibrillation indicators, the one or more atrial fibrillation key indicators may include one or more of the following measures or values: RR variability; timing interval between consecutive valid R waves; R wave morphology; P wave presence; and heart rate.

[0024] In the example, the example may be combined with any one or more of the examples described herein, wherein the measure or value of one or more of the RR variability, the timing interval between consecutive effective R waves, and the heart rate includes an indication that one or more of the RR variability, the timing interval between consecutive effective R waves, and the heart rate is higher or lower than a patient-specific or population threshold for one or more detection windows for each determined atrial fibrillation indication.

[0025] In the example, the example can be combined with any one or more examples described herein, and the evaluation circuit can be configured to use one or more recorded key indicators of atrial fibrillation to determine the patient's atrial fibrillation load indication.

[0026] In the examples, the examples can be combined with any one or more examples described herein, and the evaluation circuit can be configured to determine the patient's atrial fibrillation load indication by comparing one or more recorded key indicators with a proportionality indicator used for a determined episode.

[0027] An example of a subject (e.g., a method, such as operating a medical device system) may include receiving physiological information of a patient using signal receiver circuitry; and using evaluation circuitry to: determine an atrial fibrillation indication of the patient within a corresponding detection window of a day using the received physiological information; record first physiological information of the patient at a first sampling frequency for the determined atrial fibrillation indication up to and not exceeding a first threshold for transmission to the remote device; and determine and record one or more key atrial fibrillation indicators for the determined atrial fibrillation indication of the patient at a second sampling frequency lower than the first sampling frequency, regardless of the first threshold.

[0028] In the example, the example can be combined with any one or more examples described herein. Identifying and recording one or more atrial fibrillation key indicators for the identified atrial fibrillation indication of the patient, regardless of the first threshold, may optionally include identifying and recording one or more atrial fibrillation key indicators for the identified atrial fibrillation indication, regardless of the limitation, and may optionally include identifying and recording one or more atrial fibrillation key indicators for the identified atrial fibrillation indication up to and exceeding the first threshold.

[0029] In the examples, the examples can be combined with any one or more examples described herein, and the first threshold may optionally include a daily threshold for the determined atrial fibrillation indication.

[0030] In the example, the example may be combined with any one or more examples described herein, and the subject matter may optionally include stopping the recording of the patient's first physiological information for the remainder of the day after the amount of first physiological information recorded for a day has reached or exceeded the first threshold.

[0031] In the example, the example can be combined with any one or more examples described herein. Identifying and recording the one or more atrial fibrillation key indicators may optionally include identifying and recording the one or more atrial fibrillation key indicators for each detection window of the day, each detection window optionally including detection windows with and without the identified atrial fibrillation indication.

[0032] In the example, the example can be combined with any one or more examples described herein. Identifying and recording the one or more atrial fibrillation key indicators may optionally include identifying and recording the one or more atrial fibrillation key indicators for each of the identified atrial fibrillation indicators of the patient, for transmission to the remote device.

[0033] In the examples, the examples may be combined with any one or more examples described herein, and each identified atrial fibrillation indication may optionally include one or more detection windows.

[0034] In the examples, the examples can be combined with any one or more examples described herein, and the duration of the detection window can optionally be between 30 seconds and 2 minutes.

[0035] In the example, the example may be combined with any one or more examples described herein, and the first physiological information of the patient at a first sampling frequency may optionally include: the patient's ECG signal at a sampling frequency greater than 100 samples per second for a determined atrial fibrillation indication, up to and not exceeding a first threshold of the medical device system.

[0036] In the example, the example may be combined with any one or more examples described herein, and the one or more key indicators of atrial fibrillation may optionally include: one or more measures or values ​​representative of one or more detection windows with a determined indication having a second sampling frequency of less than 5 samples per detection window.

[0037] In the examples, the examples can be combined with any one or more examples described herein. For each of the one or more detection windows identified as atrial fibrillation indicators, the one or more key indicators of atrial fibrillation may optionally include one or more of the following measures or values: RR variability; timing interval between consecutive valid R waves; R wave morphology; P wave presence; and heart rate.

[0038] In the examples, the examples may be combined with any one or more examples described herein, and the subject matter may optionally include using the comparison of the one or more recorded key indicators with a proportionality indicator used for a determined episode to determine the patient's atrial fibrillation load indication.

[0039] In the examples, the system or apparatus may optionally combine any part or combination of any one or more of the above examples, or may optionally combine any part or combination of any one or more of the above examples to include an "apparatus" for performing any part of any one or more functions or methods in the above examples, or include at least one "non-transitory machine-readable medium" containing instructions that, when executed by a machine, cause the machine to perform any part of any one or more functions or methods in the above examples.

[0040] This summary is intended to provide an overview of the subject matter of this patent application. It is not intended to provide a unique or exhaustive interpretation of this disclosure. The detailed description is included to provide further information regarding this patent application. Other aspects of this disclosure will be apparent to those skilled in the art upon reading and understanding the following detailed description and viewing the accompanying drawings, which form a part of it, and each of the drawings should not be construed as limiting. Attached Figure Description

[0041] In accompanying drawings that are not necessarily drawn to scale, the same numbers may describe similar parts in different views. The same numbers with different letter suffixes may represent different instances of similar parts. The accompanying drawings illustrate various embodiments discussed in this document by way of example and not by way of limitation.

[0042] Figure 1 An example graph of daily atrial fibrillation load is shown.

[0043] Figure 2 An example method is shown for determining atrial fibrillation indications and recording ECG information associated with such determined atrial fibrillation indications under existing hardware limitations.

[0044] Figure 3 An example method is shown for determining and recording one or more key indicators of atrial fibrillation or atrial fibrillation load over a period of time without substantially exceeding or affecting existing hardware limitations.

[0045] Figure 4 An example medical device system is shown.

[0046] Figure 5 An example patient management system is shown.

[0047] Figure 6 An example machine is shown on which any one or more of the techniques discussed in this article can be executed. Detailed Implementation

[0048] Implantable or mobile medical devices may include one or more electrodes located within, on, or near the heart, such as those coupled to leads and located in or near one or more chambers of the heart, or configured to receive cardiac electrical information therefrom. Implantable or mobile medical devices may also include or be configured to receive mechanical acceleration information from one or more accelerometer sensors to determine and monitor patient acceleration information, such as cardiac acceleration or vibrational information associated with blood flow or movement in the heart or the patient's vascular system (e.g., heart sounds, heart wall motion, etc.), patient physical activity or location information (e.g., patient posture, activity, gait, etc.), respiratory information (e.g., respiratory rate, volume, phase, breath sounds, etc.), impedance information, plethysmography information, chemical information, temperature information, or other physiological information of the patient.

[0049] Cardiac arrhythmia events, including potential arrhythmia events (such as atrial fibrillation events or potential events), can be detected using sensed or received cardiac electrical information, including, for example, detected atrial or ventricular events (such as heartbeats, R waves, P waves, etc.) or the intervals between events occurring within a detection window, typically between 30 seconds and 2 minutes, but longer or shorter in some examples, such as between 15 seconds and 5 minutes. For example, in some examples, a mobile medical device can use timing information between events, combined with one or more other detected events, to determine whether atrial fibrillation is present in each detection window, and can additionally determine, based on this determination, whether to store or transmit sensed or detected information, for example, to a remote device. In some examples, a mobile medical device can aggregate information from multiple sensors, using information from each sensor individually or in combination to detect various events, update the detection status based on this information, and transmit a message or alarm to one or more remote devices indicating that a detection has been performed, and that the information has been stored or transmitted, so that one or more additional processes or systems can use the stored or transmitted detection or information for one or more other reviews or processes.

[0050] Atrial fibrillation detection algorithms typically rely on cardiac electrical information features, such as the cardiac interval between consecutive R waves and individual stroke-by-stroke variability. Examples of atrial fibrillation detection algorithms (including various atrial fibrillation detection parameters and criteria) can be found, for example, in commonly assigned U.S. Patent Application No. 14 / 825,669, entitled "Atrial Fibrillation Detection Using Ventricular Rate Variability" (hereinafter referred to as "'669 application") by Krueger et al.; U.S. Patent Application No. 15 / 082,440, entitled "Atrial Fibrillation Detection" (hereinafter referred to as "'440 application") by Perschbacher et al.; U.S. Patent Application No. 15 / 341,565, entitled "Method and Apparatus for Enhancing Ventricular Based Atrial Fibrillation Detection Using Atrial Activity" (hereinafter referred to as "'565 application") by Krueger et al.; and U.S. Patent Application No. 15 / 341,565, entitled "Atrial Fibrillation Discrimination Using Heart Rate" by Perschbacher et al. The following is found in U.S. Patent Application No. 15 / 864,953, entitled "Clustering" (referred to herein as the "'953 application"), each of which is incorporated herein in its entirety, including its disclosures on atrial fibrillation detection and algorithms, including, for example: atrial fibrillation detection using pairs of ventricular information detected from the ventricles (including heart rate variability and heart rate variability characteristics), and determining valid heartbeats or intervals using various characteristics (including threshold heart rate, intervals, morphological criteria, etc.), as disclosed in '669 application; atrial fibrillation detection using the distribution of ventricular depolarization intervals, as disclosed in '440 application; atrial fibrillation detection using atrial activity fractions from an atrial detection window before ventricular polarization is detected, as disclosed in '565 application; and atrial fibrillation identification using clustered depolarization information, as disclosed in '953 application, etc.

[0051] Existing mobile medical devices (such as short-term or long-term insertable cardiac monitors (ICMs)) measure atrial fibrillation load over a period of time—for example, by determining an indication of the occurrence of one or both of atrial fibrillation and non-atrial fibrillation within various detection windows (such as every two-minute detection window throughout the day). Atrial fibrillation episodes and associated physiological information (such as electrocardiogram (ECG) information) are reported to clinicians. The number of atrial fibrillation episodes and the physiological information associated with being recorded, transmitted, and reviewed by clinicians are often only a subset of the total atrial fibrillation load reported to or available for review (e.g., stored without transmission, transmitted without review, etc.). In many cases, the reported load is greater than the reviewable load (e.g., no recording, storage, or transmission, etc.).

[0052] Certain mobile medical devices have limitations, such as hardware constraints (e.g., power, processing resources, circuitry, etc.), in terms of how many episodes can be recorded over a period of time (e.g., 5 detected episodes per day), how much physiological information can be recorded in a single episode (e.g., 6 minutes per episode at a specific sampling frequency), or how much physiological information can be transmitted over a period of time (e.g., 30 minutes per day at a specific sampling frequency). Recorded and transmitted episodes can be reviewed and judged (e.g., by a clinician using one or more additional procedures, or a combination thereof). However, incomplete physiological information recorded and transmitted by such limited mobile medical devices (e.g., ECG information with a portion of the identified atrial fibrillation episode and the identified atrial fibrillation episode length (e.g., the number of detection windows), but lacking representative information from each detection window of the identified atrial fibrillation episode unless such a detection window is identified as an atrial fibrillation episode) may lead to a higher number of false positives than actually occur. Furthermore, the device and algorithm can learn from the decisions, allowing false positives to be directly fed back to the mobile medical device. This saves processing, storage, and transmission resources, further reducing the likelihood that false positives will consume any limited resources or reduce operational resources, thus extending the lifespan or service life of the mobile medical device. In other examples, clinicians may only be interested in longer segments of atrial fibrillation, such as sustained segments exceeding a threshold time (e.g., 10 minutes), which may not be available with certain limited mobile medical devices.

[0053] Among other things, the inventors have recognized that key indicators of atrial fibrillation can be identified and recorded over a period of time (e.g., a day, a portion of a day, or a time period commensurate with a day or a portion of a day, etc.) and transmitted for review, such as by a clinician, one or more additional processes, or a combination thereof, to facilitate manual and automatic adjustment of atrial fibrillation load without substantially affecting existing hardware limitations. This allows information from each detection window having one or more atrial fibrillation indicators, or in some examples from each detection window over an entire day or one or more other time periods, to contribute to atrial fibrillation load determination, such as by a clinician or one or more other processes, in a reviewable manner, without affecting existing hardware limitations. Key indicators of atrial fibrillation may include, for example, information representing one or more detection windows (e.g., values, morphology, etc.), which requires less storage and transmission resources compared to recorded ECG information. In examples, key indicators of atrial fibrillation may include: physiological information recorded (detected in some examples) at a second resolution lower than ECG information recorded at a first resolution. In some examples, key metrics for atrial fibrillation can be identified and compared with commensurate metrics used for a categorized atrial fibrillation episode (e.g., physiological information with associated records, such as recorded ECG information). In these examples, a patient's atrial fibrillation load can be determined based on the comparison between the recorded key metrics and the commensurate metrics used for a categorized episode. For example, if the recorded key metrics are similar to the commensurate metrics used for a categorized episode, such as being within a threshold amount (e.g., percentage), the patient's atrial fibrillation load can be determined based on the determined load for the categorized episode. In other examples, a patient's atrial fibrillation load can be determined based on a measure of dissimilarity between the recorded key metrics and the commensurate metrics for a categorized episode. Information from one or more detection windows, or some information from each detection window, used for review and determination provides improvements in detecting false positive episodes and increases the confidence of determination, such as in comparison to categorized episodes that benefit from recorded ECG information.

[0054] In some examples, comparisons of recorded key patient metrics with proportionate metrics for one or more determined episodes may be presented to a clinician or automated algorithm for review to adjust atrial fibrillation load. In other examples, automated algorithms, such as those executed by one or more processors or circuits (such as evaluation circuitry), may be presented to a clinician for review, for example, based on recorded key patient metrics to determine the most similar or least similar determined episodes. Depending on the outcome of the comparison (e.g., within or outside a threshold of similarity), atrial fibrillation load may be increased (e.g., as a function of the comparison) or not increased.

[0055] Among other things, key metrics may include one or more of the following: detected RR variability (e.g., RR variability exceeding a first AF variability threshold); undetected RR variability (e.g., RR variability not exceeding a first AF variability threshold, or not exceeding one or more other thresholds); heart rate (e.g., average heart rate within a detection window, variability or variance of heart rate within a detection window, or one or more other heart rate metrics); RR variability measure; time interval between consecutive valid R waves or a measure of variance or heart rate variation within a time interval; R wave morphology measure (e.g., percentage of heartbeats within a detection window that corresponds to a patient-specific or group-specific normal sinus rhythm (NSR) template, or a threshold of the previous heartbeat); P wave measure in the percentage of heartbeats or heartbeats within a detection window, or an indication of the presence (or alternatively, absence) of one or more P waves; or one or more other measures used by an atrial fibrillation algorithm to determine a patient’s atrial fibrillation, such as those described or disclosed in one or more applications incorporated herein by reference. For example, key metrics may include continuous or grouped heartbeat measures with detected RR variability exceeding a threshold or individually not exceeding a threshold (e.g., very little or no detected RR variability), such as a moving average over a group of heartbeats throughout the day. In some examples, the atrial fibrillation load value may be accumulated over a day as a function of one or more key metrics, and when the atrial fibrillation load value exceeds a threshold, an atrial fibrillation alert may be determined and provided to the clinician or procedure. In some examples, the threshold may be determined as a patient-specific value, such as based on one or more determinations by the clinician or procedure relative to the patient or from prior information from the patient, or as a population value, based on one or more clinical determinations relative to one or more other patients.

[0056] In some examples, key metrics can be identified and recorded for time periods or detection windows that have one or more atrial fibrillation indications. In other examples, key metrics can be identified and recorded for each time period or detection window (such as a whole day) to allow comparison of identified atrial fibrillation time periods or detection windows with no atrial fibrillation indications.

[0057] In other examples, key indicators can be identified and recorded for each detection window of an atrial fibrillation episode, including detection windows where ECG information cannot be recorded due to hardware limitations (e.g., the aforementioned limited mobile medical devices). In such examples, a comparison of information from each detection window in the episode can be determined, directly contrasting with existing mobile medical devices that have hardware limitations (which restrict the recording or transmission of information about each detection window in the identified atrial fibrillation episode), not only in that each detection window in the identified atrial fibrillation episode is identified as part of the atrial fibrillation episode.

[0058] In other examples, information about one or more interventions or therapies can be recorded, and key indicators can be adjusted, flagged, or otherwise recorded, and comparisons with determined episodes can be adjusted based on the recorded interventions or therapies. For example, information about the use of beta-blockers that reduce the natural heart rate can be received and recorded. In response, the determination of atrial fibrillation load can be adjusted, such as by reducing the weight of heart rate-dependent measures of atrial fibrillation in one or more functions (or increasing other measures) to determine atrial fibrillation load. Other interventions or therapies include ablation, pacing therapy, antiarrhythmic drugs (e.g., Class I, II, III, IV, etc.). In other examples, the determination of the most similar or least similar determined episodes can be selected for comparison or presentation based on a specific recorded intervention or therapy.

[0059] Figure 1 Example Figure 100 shows a patient’s daily atrial fibrillation load 101 over a period of time (e.g., a day), including indications of atrial fibrillation load 102-105 detected throughout the time period, and the time period of detected atrial fibrillation episode 106 and recorded physiological information 107 (e.g., recorded ECG information) that occurred before hardware limitations (HW limitations) (e.g., one or more hardware limitations on episodes, detection windows, time periods, or physiological information that can be recorded or transmitted over a period of time (e.g., a day).

[0060] For example, a common sampling rate for ECG information is 250 to 1000 samples per second. Over a 6-minute duration (360 seconds) at a sampling rate of 500 samples per second, 180,000 samples might be required. At 2 bytes per sample, 360 kilobytes of storage might be needed to store 6 minutes of ECG signals. In some examples, hardware limitations may include storage limits that, once exceeded, restrict the information available for review to confirm subsequent events or determine atrial fibrillation load. In other examples, other sampling frequencies may be used, such as below 250 samples per second, such as above 100 samples per second, 200 samples per second, etc., or in some examples above 1000 samples per second.

[0061] Even after exceeding one or more hardware limitations, some mobile medical devices can continue to determine and aggregate atrial fibrillation load throughout the day. However, due to such hardware limitations, this determination beyond those limitations is often unverifiable.

[0062] Figure 2 An example prior art method 200 is illustrated for determining an atrial fibrillation indication and recording ECG information associated with such determined atrial fibrillation indication under existing hardware limitations. At step 201, physiological information from the patient, such as cardiac electrical information (e.g., heart rate or interval information occurring on consecutive or grouped effective heartbeats, RR variability, heart rate, etc.), may be received, for example, using a signal receiver circuit over one or more detection windows occurring over a period of time (e.g., one day). At step 202, an evaluation circuit may be used, for example, to determine one or more atrial fibrillation (AF) or atrial fibrillation load indications using the received physiological information. If one or more implantable or mobile medical devices, such as those detecting physiological information from the patient, do not exceed one or more hardware limitations within such a period of time (e.g., one day), then at step 203, the patient's ECG information associated with the detected atrial fibrillation or atrial fibrillation load indication can be recorded, stored, or transmitted by the implantable or mobile medical device, for example, using the evaluation circuit. However, if one or more hardware limitations are exceeded, additional physiological information (such as the patient's ECG information) is not recorded, resulting in an additional atrial fibrillation load determination that does not have the recorded information to verify or review such a determination.

[0063] Figure 3 An example method 300 is illustrated for identifying and recording one or more key indicators of atrial fibrillation or atrial fibrillation load over a period of time (e.g., a day, a portion of a day, or a time period commensurate with a day or a portion of a day, etc.) while substantially not exceeding or impacting existing hardware limitations. This allows information from each detection window to have one or more atrial fibrillation indications, or in some examples, allows each detection window of a full day or one or more other time periods to contribute to the determination of atrial fibrillation load in a reviewable manner, such as by a clinician or one or more other processes, while substantially not exceeding or impacting existing hardware limitations. Key indicators of atrial fibrillation or atrial fibrillation load are typically only a few bytes, tens of bytes, etc., much smaller than the recorded ECG information, which typically requires hundreds of kilobytes of storage and transmission.

[0064] For example, while the recorded ECG information may require storage at 500 samples per second, as described above, key indicators of the recorded atrial fibrillation load (such as representative information as described above and in this article) may only require one or a few samples per detection window, every few detection windows, or per episode (e.g., for each type of representative information). For one or two key indicators recorded within a 2-minute detection window, the recorded key indicators may require very few samples per detection window (e.g., less than 5, less than 10, etc. in some examples) (120 seconds in this example) instead of 500 samples per second (for the recorded ECG information), which is substantially much less information than the recorded ECG information (e.g., 30,000–60,000 times less), an addition that substantially does not exceed or impacts existing hardware limitations. In this scenario, even covering every 2-minute detection window throughout the day (regardless of whether there is a confirmed atrial fibrillation indication) would require very few 720 samples per day, which is less than the additional 2 seconds of ECG information recorded at 500 samples per second (e.g., compared to existing hardware limitations that allocate at least several minutes of such information). To account for such additional samples, additional samples could be provided for mobile medical devices within hardware limitations, or in some examples, existing limitations could be reduced proportionally to accommodate such additional samples (e.g., reducing the existing daily 6-minute ECG recording allocation by 1 second, 1.5 seconds, etc.).

[0065] At step 301, physiological information from the patient, such as cardiac electrical information (e.g., heart rate, RR variability, heart rate or interval information occurring on consecutive or grouped effective heartbeats), may be received, for example, using a signal receiver circuit over one or more detection windows occurring over a period of time (e.g., one day). At step 302, therapeutic information may be optionally received, for example, using a signal receiver circuit, such as one or more indications for interventions or therapies (e.g., electrotherapy (e.g., pacing) performed by one or more medical devices, or the application or use of one or more drugs or other therapies (e.g., beta-blockers, antiarrhythmic drugs, ablation, etc.)).

[0066] In some examples, at step 303, the following can be performed: Figure 2One or more steps of the prior art method 200 shown. For example, at step 304, one or more atrial fibrillation (AF) or atrial fibrillation load indications may be determined using received physiological information, such as by using an evaluation circuit. If one or more hardware limitations of one or more implantable or mobile medical devices or components thereof, such as detecting physiological information from the patient, are not exceeded within a period of time (e.g., a day), then at step 305, the patient's ECG information associated with the detected atrial fibrillation or atrial fibrillation load indication may be recorded, stored, or transmitted by the implantable or mobile medical device, such as by using the evaluation circuit or one or more other components of the implantable or mobile medical device.

[0067] At step 306, in conjunction with steps 303 and Figure 2 Compared to the prior art method 200 shown, regardless of whether certain prior art hardware limitations are exceeded, at step 307, for each detection window of an atrial fibrillation episode (including detection windows where ECG information cannot be recorded due to exceeding one or more hardware limitations), one or more key atrial fibrillation indicators can be determined and recorded, for example, using an evaluation circuit. In some examples, one or more key atrial fibrillation indicators can be determined and recorded for each detection window with an atrial fibrillation indication, such as those determined at step 304. In other examples, one or more key atrial fibrillation indicators can be determined and recorded after one or more hardware limitations have been exceeded, such as instead of recording ECG information at step 305. In some examples, one or more key atrial fibrillation indicators can be determined and recorded for groups of detection windows (e.g., a group of two or more detection windows, all detection windows corresponding to detected atrial fibrillation indications, etc.), or one or more key indicators can be determined for a recorded atrial fibrillation episode spanning one or more detection windows. In some examples, one or more key indicators can be identified and recorded for each detection window of the identified atrial fibrillation indicator and at least one detection window before, after, or continuing after the identified atrial fibrillation indicator to provide contextual information around the identified atrial fibrillation indicator, or to provide information on the differences between one or more key indicators before or after the detected indicator and one or more key indicators of the detected atrial fibrillation indicator, to help select judged episodes for comparison, to provide clinicians with additional information for review, to more accurately determine atrial fibrillation load indicators, etc.

[0068] At step 308, an evaluation circuit may be used, for example, to optionally determine one or more detection windows for proportionate indicators of the determined episode, for comparison with recorded key atrial fibrillation indicators of one or more detection windows, such as determining atrial fibrillation load for one or more detection windows based on previous determined episodes, thereby reducing the workload of clinicians, improving the sensitivity and specificity of determining a patient's atrial fibrillation load, and reducing the likelihood of false positive determinations of a patient's atrial fibrillation and atrial fibrillation load.

[0069] At step 309, for example, an evaluation circuit may be used to optionally determine one or more measures of atrial fibrillation load based on one or more recorded key indicators for the patient's atrial fibrillation. Compared to the prior art, in addition to the determination of atrial fibrillation at step 304, the recorded key indicators of atrial fibrillation determined at step 307 may be used, for example, as an additional filtering step, or to more accurately determine the measure of the patient's atrial fibrillation load (e.g., one or more values, etc.), or to determine the confidence level of such determination based on a function of the determined atrial fibrillation load and the output of the recorded key indicators compared with one or more previously determined episodes, thereby reducing false positives and allowing additional information to be displayed to clinicians or presented to one or more additional processes for determination, etc.

[0070] At step 310, the recorded atrial fibrillation key indicators may be stored, for example, using evaluation circuitry, and transmitted via the control of the evaluation circuitry or using one or more communication circuits to one or more additional processes or components, such as output circuitry (e.g., a display, a controller for the display, etc.). At step 311, an alert may optionally be provided, for example, if the recorded atrial fibrillation key indicators are available for review or transmission, if one or more detection windows for comparison have been identified for judgment, if one or more comparisons have been made with one or more previously judged episodes, if one or more recorded atrial fibrillation key indicators exceed a threshold, or if the difference between key indicators of the same or different detected atrial fibrillation episodes exceeds a threshold or expected value. In the example, the output of the recorded atrial fibrillation key indicators may be provided to a user interface for display to a user, or to another circuitry to control or adjust the process or function of an implantable or mobile medical device.

[0071] At step 312, one or more modes or functions of the assessment circuitry or implantable or mobile medical device may be optionally adjusted based on one or more of the recorded key atrial fibrillation indicators, the determined atrial fibrillation load, or one or more other measures, values, or indicators. For example, if one or more of the recorded key atrial fibrillation indicators or the determined atrial fibrillation load indicate that the expected end of life (EOL) is longer than the estimated remaining battery state of the determined implantable or mobile medical device, one or more modes or functions of the implantable or mobile medical device may be changed to increase the remaining battery state of the medical device. If the recorded key atrial fibrillation indicators or the determined atrial fibrillation load indicate that the expected patient EOL is shorter than the estimated remaining battery state of the determined implantable or mobile medical device, one or more modes or functions of the implantable or mobile medical device may be changed to improve data collection or sensing, or otherwise provide more patient benefit to reduce the remaining battery state of the medical device, but not shorter than the expected patient EOL, with additional tolerances in some examples. For example, one or more hardware limitations can be adjusted to, among other things, record more or less ECG information of the patient; increase the frequency of communication between the implantable or mobile medical device and external devices (such as remote devices, programmers, etc.), such as increasing the frequency of patient monitoring; switch to different or more power- or resource-intensive monitoring algorithms; and so on.

[0072] At step 313, one or more therapies may be selectively provided or adjusted based on the recorded key atrial fibrillation indicators, the determined atrial fibrillation load, or one or more other measures, values, or indicators, as described herein.

[0073] Figure 4 An example system 400 (e.g., a medical device system) is illustrated. In the example, one or more aspects of the example system 400 may be components of a medical device or communication coupled to a medical device, such as an implantable medical device (IMD), an insertable cardiac monitor, a mobile medical device (AMD), etc. The system 400 may be configured to monitor, detect, or treat various physiological conditions of the body, such as cardiac conditions associated with a reduced ability of the heart to adequately deliver blood to the body, including heart failure, arrhythmia, asynchrony, etc., or one or more other physiological conditions, and in some examples, may be configured to provide electrical stimulation or one or more other therapies or treatments to the patient.

[0074] System 400 may include a single or multiple medical devices implanted in or otherwise positioned on or around a patient to monitor the patient’s physiological information using information from one or more sensors, such as sensor 401. In the example, sensor 401 may include one or more of the following: a respiratory sensor configured to receive respiratory information (e.g., respiratory rate, respiratory volume (tidal volume), etc.); an acceleration sensor (e.g., accelerometer, microphone, etc.) configured to receive cardiac acceleration information (e.g., cardiac vibration information, pressure waveform information, heart sound information, endocardial acceleration information, acceleration information, activity information, posture information, etc.); an impedance sensor configured to receive impedance information (e.g., intrathoracic impedance sensor, transthoracic impedance sensor, chest impedance sensor, etc.); a cardiac sensor configured to receive electrocardiogram information; an activity sensor configured to receive information about body movement (e.g., activity, gait, etc.); a posture sensor configured to receive posture or position information; a pressure sensor configured to receive pressure information; a volumetric sensor (e.g., photoplethysmography sensor, etc.); a chemical sensor (e.g., electrolyte sensor, pH sensor, anion gap sensor, etc.); a temperature sensor; a skin elasticity sensor; or one or more other sensors configured to receive physiological information of a patient.

[0075] Example system 400 may include signal receiver circuitry 402 and evaluation circuitry 403. Signal receiver circuitry 402 may be configured to receive physiological information from sensor 401 about a patient (or patient group). Evaluation circuitry 403 may be configured to receive information from signal receiver circuitry 402 and use the received physiological information (such as that described herein) to determine one or more parameters (e.g., physiological parameters, stratification, etc.) or existing or changing patient conditions (e.g., indications of patient dehydration, respiratory status, cardiac status (e.g., heart failure, arrhythmia), sleep apnea, etc.). Among other things, physiological information may include cardiac electrical information, impedance information, respiratory information, heart sound information, activity information, posture information, temperature information, or one or more other types of physiological information.

[0076] In some examples, evaluation circuit 403 may aggregate information from multiple sensors or devices, use information from each sensor or device individually or in combination to detect various events, update the detection status for one or more patients based on the information, and transmit messages or alarms to one or more remote devices that one or more patients have been detected or that information has been stored or transmitted, so that one or more additional processes or systems can use the stored or transmitted detection or information for one or more other examinations or processes.

[0077] In some examples, such as to detect improvement or deterioration in a patient's condition, initial assessments are typically required to establish a baseline level or condition based on one or more sensors or physiological information. Subsequent detection of deviations from the baseline level or condition can be used to determine whether the patient's condition has improved or deteriorated. However, in other examples, the amount of variability or change in physiological information over different time periods (e.g., relative or absolute change) can be used to determine the risk of adverse medical events, or to predict or stratify the risk of a patient experiencing an adverse medical event (e.g., heart failure event) some time after a detected change, either in conjunction with or separately from any baseline level or condition.

[0078] Variations in different physiological information can be aggregated and weighted based on one or more patient-specific stratifiers, and in some examples compared to one or more thresholds, for example, to have clinical sensitivity and specificity for a specific condition (such as heart failure) across a target population, and for one or more specific time periods, such as daily values, short-term averages (e.g., daily values ​​aggregated over several days), long-term averages (e.g., daily values ​​aggregated over multiple short-term periods or more days, sometimes different from the number of days used for short-term averages (e.g., non-overlapping)).

[0079] System 400 may include output circuitry 404 configured to provide output to a user, or cause output to be provided to a user, such as via an output, display, or one or more other user interfaces, including scores, trends, alarms, or other indications. In other examples, output circuitry 404 may be configured to provide output to another circuit, machine, or process, such as treatment circuitry 405 (e.g., cardiac resynchronization therapy (CRT) circuitry, chemotherapy circuitry, stimulation circuitry, etc.), to control, adjust, or stop treatment by a medical device, drug delivery system, etc., or otherwise alter one or more processes or functions of one or more other aspects of the medical device system, such as one or more CRT parameters, drug delivery, dosing determination, or recommendations. In examples, treatment circuitry 405 may include one or more of stimulation control circuitry, cardiac stimulation circuitry, neural stimulation circuitry, dosing determination, or control circuitry. In other examples, treatment circuitry 405 may be controlled by evaluation circuitry 403 or one or more other circuitry. In some examples, the evaluation circuit 403 may include an output circuit 404 or may be configured to determine an output to be provided by the output circuit 404, which may provide a signal that causes the user interface to provide an output to the user based on the output determined by the evaluation circuit 403.

[0080] Technical challenges exist in medical devices and systems where, in low-power monitoring modes, mobile medical devices (e.g., including IMDs) powered by one or more rechargeable or non-rechargeable batteries must make certain trade-offs between: battery life, or, in the case of implantable medical devices with non-rechargeable batteries, during device replacement periods that typically include surgical procedures; and the sampling resolution, sampling period, or features or mode selection of the medical device or within the medical device for processing, storing, and transmitting sensed physiological information. Medical devices may include higher-power modes and lower-power modes. Physiological information (such as indications of potential adverse physiological events) can be used to transition from a low-power mode to a high-power mode. In some examples, a low-power mode may include a low-resource mode characterized by requiring less power, processing time, memory, or communication time or bandwidth (e.g., transmitting less data) than a corresponding high-power mode. A high-power mode may include a relatively high-resource mode characterized by requiring more power, processing time, memory, or communication time or bandwidth than a corresponding low-power mode. However, valuable information may be lost during the time when physiological information detected in low-power mode indicates a possible event and cannot be recorded in high-power mode.

[0081] Conversely, incorrect or inaccurate determination of high-power modes unnecessarily and inappropriately limits the lifespan of some mobile medical devices. For a variety of reasons, accurate detection and determination of physiological events, and avoiding unnecessary transitions from low-power to high-power modes, are beneficial for improving the utilization of medical device resources.

[0082] For example, a change in mode can enable higher resolution sampling, or an increase in sampling frequency, or the number or type of sensors used to sense physiological information elicited and including potential events. For instance, different physiological information may be sensed using non-overlapping time periods of the same sensor, or in some examples, at different sampling frequencies and power costs. In one example, non-overlapping time periods of the same, single-axis or multi-axis accelerometer may be used to detect heart sounds and patient activity at different sampling frequencies and power costs. In some examples, a transition to a high-power mode may include using an accelerometer to detect heart sounds throughout the entire high-power mode, or detecting heart sounds in a higher percentage of the high-power mode than in the corresponding low-power mode, and so on. In other examples, waveforms for medical events may be recorded, stored in long-term memory, and transmitted to a remote device for clinician review. In some examples, only notification that an event has been stored, or summary information about the event, may be transmitted. In response, the complete event may be requested for subsequent transmission and review. However, even when an event is stored but not transmitted, the medical device still provides resources for storing and processing the event.

[0083] Figure 5 An exemplary patient management system 500 and a portion of the environment in which the patient management system 500 may operate are illustrated. The patient management system 500 can perform a range of activities, including remote patient monitoring and disease condition diagnosis. These activities can be performed in proximity to the patient 501, such as in the patient's home or office; via a central server, such as in a hospital, clinic, or doctor's office; or via a remote workstation, such as a secure wireless mobile computing device.

[0084] The patient management system 500 may include one or more medical devices, an external system 505, and a communication link 511 providing communication between the one or more mobile medical devices and the external system 505. The one or more medical devices may include mobile medical devices (AMDs) (such as implantable medical devices (IMDs) 502), wearable medical devices 503, or one or more other implantable, leadless, subcutaneous, external, wearable, or medical devices configured to monitor, sense, or detect information from the patient 501, determine physiological information about the patient 501, or provide one or more therapies to treat various conditions of the patient 501, such as one or more cardiac or non-cardiac conditions (e.g., dehydration, sleep apnea, etc.).

[0085] In one example, implantable medical device 502 may include one or more cardiac rhythm management devices implanted in a patient's chest, having a lead system comprising one or more transvenous, subcutaneous, or non-invasive leads or catheters to position one or more electrodes or other sensors (e.g., heart sound sensors) within, on, or around the heart, or in one or more other locations in the chest, abdomen, or neck of patient 501. In another example, implantable medical device 502 may include, for example, a monitor subcutaneously implanted in the chest of patient 501. Implantable medical device 502 includes a housing containing a circuitry system and, in some examples, includes one or more sensors, such as temperature sensors.

[0086] Cardiac rhythm management devices, such as insertable cardiac monitors (ICMs), pacemakers, defibrillators, or cardiac resynchronizers, include implantable or subcutaneous devices having a sealed housing configured for implantation in a patient's chest. Cardiac rhythm management devices may include one or more leads to position one or more electrodes or other sensors at various locations within or near the heart, such as in one or more atria or ventricles of the heart, etc. Thus, cardiac rhythm management devices may include a subcutaneous aspect (albeit close to the patient's distal skin) and an aspect located near one or more organs of the patient (such as leads or electrodes). Separately from or in addition to the one or more electrodes or other sensors in the leads, cardiac rhythm management devices may include one or more electrodes or other sensors (e.g., pressure sensors, accelerometers, gyroscopes, microphones, etc.) powered by a power source within the cardiac rhythm management device. The one or more electrodes or other sensors in the leads, the cardiac rhythm management device, or combinations thereof, may be configured to detect physiological information from the patient or to provide the patient with one or more treatments or stimulations.

[0087] Implantable devices may additionally or separately include leadless pacemakers (LCPs), small (e.g., smaller than conventional implantable rhythm management devices, having a volume of about 1 cc in some examples, etc.) standalone devices comprising one or more sensors, circuitry, or electrodes configured to monitor physiological information from the heart (e.g., heart rate, etc.), detect physiological conditions associated with the heart (e.g., tachycardia), or provide one or more treatments or stimulations to the heart without the complications of conventional leaded or implantable rhythm management devices (e.g., required incisions and pockets, complications associated with lead placement, breakage, or migration, etc.). In some examples, leadless pacemakers may have more limited power and processing capabilities than conventional rhythm management devices; however, multiple leadless pacemakers may be implanted within or around the heart to detect physiological information from one or more chambers of the heart, or to provide one or more treatments or stimulations to one or more chambers of the heart. Multiple leadless pacemakers may communicate with each other or with one or more other implantable or external devices.

[0088] Implantable medical device 502 may include assessment circuitry configured to detect or determine specific physiological information of patient 501, or to determine one or more conditions, or to provide information or alerts to users such as patient 501 (e.g., a patient), clinicians, or one or more other caregivers or processes, as described herein. Implantable medical device 502 may alternatively or additionally be configured as a therapeutic device, configured to treat one or more medical conditions of patient 501. Therapies may be delivered to patient 501 via a lead system and associated electrodes or using one or more other delivery mechanisms. Therapies may include delivering one or more medications to patient 501, such as using implantable medical device 502 or one or more other mobile medical devices. In some examples, therapies may include a cardiac reflex (CRT) for correcting asynchrony in patients with heart failure and improving their cardiac function. In other examples, implantable medical device 502 may include a drug delivery system, such as a drug infusion pump, to deliver medication to a patient for managing arrhythmias or complications arising from arrhythmias, hypertension, hypotension, or one or more other physiological conditions. In other examples, the implantable medical device 502 may include one or more electrodes configured to stimulate the patient’s nervous system or to provide stimulation to the muscles of the patient’s airway, etc.

[0089] Wearable medical device 503 may include one or more wearable or external medical sensors or devices (e.g., automated external defibrillator (AED), Holter monitor, patch-based device, smartwatch, smart accessory, wrist or finger-worn medical device, such as finger-based photoplethysmography sensor, etc.).

[0090] External system 505 may include dedicated hardware / software systems, such as a programmer, a remote server-based patient management system, or alternatively, a software-defined system primarily running on a standard personal computer. External system 505 may manage patient 501 via implantable medical device 502 or one or more other mobile medical devices connected to external system 505 via communication link 511. In other examples, implantable medical device 502 may be connected to wearable medical device 503 via communication link 511, or wearable device 503 may be connected to external system 505. This may include, for example, programming implantable medical device 502 to perform one or more of the following: acquiring physiological data, performing at least one self-diagnostic test (such as for device operating status), analyzing physiological data, or optionally delivering or adjusting therapy for patient 501. Furthermore, external system 505 may send or receive information to or from implantable medical device 502 or wearable medical device 503 via communication link 511. Examples of information may include: real-time or stored physiological data from patient 501; diagnostic data, such as detection of patient hydration status, hospitalization, and response to therapies delivered to patient 501; or device operational status (e.g., battery status, lead impedance, etc.) of implantable medical device 502 or wearable medical device 503. Communication link 511 may be an inductive telemetry link, a capacitive telemetry link, or a radio frequency (RF) telemetry link, or wireless telemetry based on standards such as “Strong” Bluetooth or IEEE 602.11 Wireless Fidelity “Wi-Fi” interface standards. Other configurations and combinations of patient data source interfaces are also possible.

[0091] External system 505 may include external device 506 located near one or more mobile medical devices, and remote device 508 located relatively far from one or more mobile medical devices, communicating with external device 506 via communication network 507. Examples of external device 506 may include a medical device programmer. Remote device 508 may be configured to evaluate collected patient or patient information and provide alarm notifications, among other possible functions. In an example, remote device 508 may include a centralized server acting as a central hub for storing and analyzing data collected from multiple different sources. The combination of information from multiple sources may be used to make determinations and update individual patient statuses, or to adjust one or more alarms or determinations for one or more other patients. The server may be configured as a single, multiple, or distributed computing and processing system. Remote device 508 may receive data from multiple patients. This data may be collected by one or more mobile medical devices and other data acquisition sensors or devices associated with patient 501. The server may include storage devices to store data in a patient database. The server may include alarm analyzer circuitry to evaluate the collected data to determine whether specific alarm conditions are met. The fulfillment of alarm conditions can trigger the generation of alarm notifications, for example, through one or more human-perceptible user interfaces. In some examples, alarm conditions may alternatively or additionally be evaluated by one or more mobile medical devices, such as implantable medical devices. By way of example, alarm notifications may include web page updates, telephone or pager calls, emails, SMS, text or "instant" messages, as well as messages to patients and direct notifications to emergency services and clinicians simultaneously. Other alarm notifications are also possible. The server may include alarm priority sorting circuitry configured to prioritize alarm notifications. For example, alarms for detected medical events may be prioritized using a similarity metric between physiological data associated with a detected medical event and physiological data associated with historical alarms.

[0092] Remote device 508 may additionally include one or more locally configured clients or remote clients securely connected to the server via communication network 507. Examples of clients may include personal desktop computers, laptops, mobile devices, or other computing devices. System users, such as clinicians or other qualified medical professionals, can use the clients to securely access stored patient data assembled in a database on the server, and select and prioritize patients and alerts for healthcare provisioning. In addition to generating alert notifications, remote device 508, including the server and interconnected clients, can also implement follow-up protocols by sending follow-up requests to one or more mobile medical devices, or by sending messages or other communications as compliance notifications to patients 501 (e.g., patients), clinicians, or authorized third parties.

[0093] Communication network 507 can provide wired or wireless interconnection. In this example, communication network 507 may be based on the Transmission Control Protocol / Internet Protocol (TCP / IP) network communication specification, although other types or combinations of networking implementations are also possible. Similarly, other network topologies and arrangements are also possible.

[0094] One or more of external devices 506 or remote devices 508 may output detected medical events to system users, such as patients or clinicians, or to a process including, for example, an instance of a computer program executable in a microprocessor. In examples, this process may include automatically generating recommendations for antiarrhythmic therapies, or recommendations for further diagnostic tests or treatments. In examples, external devices 506 or remote devices 508 may include corresponding display units for displaying physiological or functional signals, or alarms, alerts, emergency calls, or other forms of warning to signal the detection of an arrhythmia. In some examples, external system 505 may include an external data processor configured to analyze physiological or functional signals received by one or more mobile medical devices and confirm or reject the detection of an arrhythmia. Computationally intensive algorithms, such as machine learning algorithms, may be implemented in the external data processor to retrospectively process data to detect arrhythmias.

[0095] One or more portions of a mobile medical device or external system 505 may be implemented using hardware, software, firmware, or a combination thereof. One or more portions of a mobile medical device or external system 505 may be implemented using dedicated circuitry, which may be constructed or configured to perform one or more functions, or may be implemented using general-purpose circuitry, which may be programmed or otherwise configured to perform one or more functions. Such general-purpose circuitry may include a microprocessor or a portion thereof, a microcontroller or a portion thereof, or programmable logic circuitry, memory circuitry, network interfaces, and various components for interconnecting these components. For example, a "comparator" may, among other things, include an electronic circuit comparator that may be constructed to perform a specific function of comparing two signals, or the comparator may be implemented as part of a general-purpose circuitry that may be driven by code instructing a portion of the general-purpose circuitry to perform a comparison between two signals. A "sensor" may include electronic circuitry configured to receive information and provide an electronic output representing such received information.

[0096] Therapeutic device 510 can be configured to send or receive information from one or more of a mobile medical device or an external system 505 using a communication link 511. In the example, one or more mobile medical devices, an external device 506, or a remote device 508 can be configured to control one or more parameters of the therapeutic device 510. External system 505 can allow programming of one or more mobile medical devices and can receive information acquired by one or more mobile medical devices regarding one or more signals, such as those received via communication link 511. External system 505 may include a local external implantable medical device programmer. External system 505 may include a remote patient management system that can, for example, monitor patient status or adjust one or more therapies from a remote location.

[0097] In some examples, event storage can be triggered by received physiological information, or in response to one or more detected events or determined parameters reaching or exceeding a threshold (e.g., a static threshold, a dynamic threshold, or one or more other thresholds based on patient or population information). Information sensed or recorded in high-power mode can be transferred from short-term storage (such as in a loop recorder) to long-term or non-volatile memory, or in some examples, to prepare for communication to external devices separate from the medical device. In examples, cardiac electrical or cardiac mechanical information elicited (and in some examples included) a detected atrial fibrillation event can be stored, such as to increase the specificity of the detection. In examples, multiple loop recorder windows (e.g., 2-minute windows) can be stored sequentially. In systems without early detection, a loop recorder with a longer time period would be required to record this information, which would incur considerable additional costs (e.g., power, processing resources, component costs, storage capacity, etc.). Compared to longer loop recorder windows, using such early detection eliciting a single event to store multiple windows can provide a complete event assessment with savings in power consumption and cost. In addition, early detection can trigger additional parameter calculations or storage at different resolutions or sampling frequencies without excessively consuming limited system resources.

[0098] In some examples, one or more alarms may be provided, such as to a patient, doctor, or one or more other caregivers (e.g., using a patient smartwatch, cellular or smartphone, computer, etc.), in response to a transition to a high-power mode, in response to a detected event or condition, or after updating information or transmitting information from a primary device to a remote device. In other examples, the medical device itself may provide audible or tactile alarms to alert the patient to a detected condition. For example, an alarm may be issued to the patient in response to a detected condition, allowing them to perform corrective actions, such as sitting down.

[0099] In some examples, therapy can be provided in response to a detected condition. For example, pacing therapy can be provided, activated, or adjusted, such as to interrupt or reduce the effect of a detected atrial fibrillation event. In other examples, the delivery of one or more medications (e.g., vasoconstrictors, vasopressors, etc.) can be triggered, provided, or adjusted (e.g., using a drug pump) in response to a detected condition, either alone or in combination with pacing therapy (such as the pacing therapy described above), such as to increase arterial pressure, maintain cardiac output, and interrupt or reduce the effect of a detected atrial fibrillation event.

[0100] In some examples, a patient's physiological information can be sensed, such as through one or more sensors located within, on, or near the patient, such as a cardiac sensor, a heart sound sensor, or one or more other sensors described herein. For example, a cardiac sensor can be used to sense a patient's cardiac electrical information. In other examples, a heart sound sensor can be used to sense a patient's cardiac acceleration information. The cardiac sensor and the heart sound sensor can be components of one or more (e.g., the same or different) medical devices (e.g., implantable medical devices, mobile medical devices, etc.). Timing indicators between different features (e.g., first cardiac features and second cardiac features, etc.) can be determined, such as through processing circuitry of the cardiac sensor or one or more other medical devices or medical device components. In some examples, the timing indicators may include the interval or indicator (e.g., duration of cardiac cycle or interval, QRS width, etc.) between the first and second cardiac features of a patient's first cardiac interval or between the first and second cardiac features of corresponding consecutive first and second cardiac intervals of the patient. In the examples, the first and second cardiac features include equivalent detected features in consecutive first and second cardiac intervals, such as consecutive R waves (e.g., RR intervals, etc.) or one or more other features of the cardiac electrical signal.

[0101] Heart sounds are repetitive mechanical signals associated with the vibrations of the heart or the acceleration of blood flow through the heart, or other cardiac movements during each cardiac cycle or interval, and can be distinguished and classified according to the activity associated with such vibrations, accelerations, movements, pressure waves, or blood flow. Heart sounds comprise four main characteristics: the first through fourth heart sounds (S1 through S4). The first heart sound (S1) is the vibrational sound produced by the heart during systole or at the onset of ventricular contraction, during the closure of the atrioventricular (AV) valves, mitral and tricuspid valves, and during the opening of the aortic valve. The second heart sound (S2) is the vibrational sound produced by the heart during diastole or at the onset of ventricular diastole, during the closure of the aortic and pulmonary valves. The third and fourth heart sounds (S3, S4) are associated with the filling pressure of the left ventricle during diastole. A sudden cessation of early diastolic filling results in the third heart sound (S3). Vibrations caused by atrial kicking result in the fourth heart sound (S4). The closure of valves in the heart and changes in blood flow and pressure cause acceleration, vibration, or motion of the heart wall, which can be detected using an accelerometer or microphone, thus providing an output referred to in this paper as cardiac acceleration information.

[0102] In the examples, the value of a portion of the heart sound signal, or a corresponding heart sound signal for a cardiac septum, can be detected as an amplitude relative to one or more cardiac electrical features or as one or more energy values ​​relative to a window of the heart sound signal, typically determined relative to one or more cardiac electrical features. For example, the value and timing of the S1 signal can be detected using the amplitude or energy of a heart sound signal occurring at or near the R wave of the cardiac septum. A portion of the S4 signal can be determined, such as by processing circuitry of a heart sound sensor or one or more other medical devices or medical device components. In some examples, the S4 signal portion may include a filtered signal from the S4 window of the cardiac septum. In the examples, the S4 interval can be defined as a set time period within the cardiac septum relative to one or more other cardiac electrical or mechanical features, such as forward from one or more features of the R wave, T wave, or heart sound waveform (such as the first, second, or third heart sound (S1, S2, S3)), or backward from the subsequent R wave or the detected S1 of a subsequent cardiac septum. In some examples, the length of the S4 window may depend on heart rate or one or more other factors. In the example, the timing indicator of the cardiac electrical information can be the timing indicator of the first cardiac interval, and the S4 signal portion can be the S4 signal portion of the same first cardiac interval.

[0103] In the example, heart sound parameters may include information about multiple identical heart sound parameters or different combinations of heart sound parameters within one or more cardiac cycles or a specified time period (e.g., 1 minute, 1 hour, 1 day, 1 week, etc.) or related information. For example, heart sound parameters may include composite S1 parameters representing multiple S1 parameters, for example, within a certain time period (e.g., several cardiac cycles, a representative time period, etc.).

[0104] In examples, heart sound parameters may include an ensemble average of a specific heart sound on a heart sound waveform, such as those disclosed in commonly assigned U.S. Patent No. 7,115,096, entitled "THIRD HEART SOUND ACTIVITY INDEX FOR HEART FAILURE MONITORING," by Siejko et al., or in commonly assigned U.S. Patent No. 7,853,327, entitled "HEART SOUND TRACKING SYSTEM AND METHOD," each of which is incorporated herein by reference in its entirety, including their disclosures of performing an ensemble average of an acoustic signal and determining a specific heart sound on a heart sound waveform. In other examples, a signal receiver circuit may receive at least one heart sound parameter or composite parameter, such as from a heart sound sensor or heart sound sensor circuitry.

[0105] In the example, a patient's cardiac electrical information can be received from a cardiac sensor (e.g., one or more electrodes) or cardiac sensor circuitry (e.g., including one or more amplifier or filter circuits), such as a signal receiver circuitry using a medical device. In the example, the received cardiac electrical information may include a timing indicator between the patient's first and second cardiac characteristics.

[0106] In the examples, the patient's cardiac acceleration information can be received from a heart sound sensor (e.g., an accelerometer, etc.) or heart sound sensor circuitry (e.g., including one or more amplifier or filter circuits, etc.), such as the same or different signal receiver circuitry using a medical device. In the examples, the received cardiac acceleration information may include an S4 signal portion occurring between the patient's first and second cardiac characteristics. In some examples, additional physiological information, such as heart rate information, patient activity information, or patient posture information, can be received from one or more other sensors or sensor circuitry.

[0107] In some examples, the high-power mode may be the opposite of the low-power mode and may include one or more of the following: enabling one or more additional sensors, switching from a low-power sensor or sensor group to a higher-power sensor or sensor group, triggering additional sensing from one or more additional sensors or medical devices, increasing the sensing frequency or sensing or storage resolution, increasing the amount of data to be collected, communicated (e.g., from a first medical device to a second medical device), or stored, triggering the storage of currently available information from the loop recorder in long-term storage or increasing the storage capacity or time period of the loop recorder, or otherwise altering the device behavior to capture additional or higher-resolution physiological information or perform more processing, etc.

[0108] Additionally or alternatively, event storage can be triggered. Information sensed or recorded in high-power mode can be transferred from short-term storage (such as in a loop recorder) to long-term or non-volatile memory, or in some examples, to prepare for communication to an external device separate from the medical device. In examples, cardiac electrical or cardiac mechanical information that elicits (and in some examples includes) the detected atrial fibrillation event can be stored, such as to increase the specificity of the detection. In examples, multiple loop recorder windows (e.g., 2-minute windows) can be stored sequentially. In systems without early detection, a loop recorder with a longer time period would be required to record this information, which would incur considerable additional costs (e.g., power, processing resources, component costs, etc.).

[0109] Figure 6 A block diagram of an example machine 600 is shown, on which any one or more of the techniques (e.g., methods) discussed herein can be executed. Parts of this description can be applied to the computational framework of one or more medical devices described herein, such as implantable medical devices, external programmers, etc. Furthermore, as described herein with respect to medical device components, systems, or machines, this may require regulatory compliance that is not possible with general-purpose computers, components, or machines.

[0110] As described herein, examples may include logic or multiple components or mechanisms in machine 600, or those that can be operated by them. A circuit system (e.g., a processing circuit system, an evaluation circuit, etc.) is a collection of circuits implemented in the tangible entity of machine 600, which includes hardware (e.g., simple circuits, gates, logic, etc.). The components of a circuit system can be flexible over time. A circuit system includes components that can perform specific operations individually or in combination during operation. In the examples, the hardware of the circuit system may be designed immutably to perform specific operations (e.g., hardwired). In the examples, the hardware of the circuit system may include physically connected components (e.g., execution units, transistors, simple circuits, etc.) including physically modified machine-readable media (e.g., magnetic, electric, movable placement of immutable aggregated particles, etc.) to encode instructions for specific operations. When the physical components are connected, the basic electrical characteristics of the hardware components change, for example, from an insulator to a conductor, and vice versa. Instructions enable embedded hardware (e.g., an execution unit or loading mechanism) to create components of the circuit system in the hardware via variable connections to perform portions of specific operations during operation. Therefore, in this example, during device operation, the machine-readable medium element is part of the circuit system or communicatively coupled to other components of the circuit system. In this example, any physical component can be used in more than one component of more than one circuit system. For example, during operation, an execution unit can be used in a first circuit of a first circuit system at one point in time and reused by a second circuit of the first circuit system, or reused by a third circuit of the second circuit system at a different time. The following are additional examples of these components of machine 600.

[0111] In alternative embodiments, machine 600 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, machine 600 may operate as a server machine, a client machine, or both in a server-client network environment. In the example, machine 600 may act as a peer-to-peer (P2P) (or other distributed) network environment. Machine 600 may be a personal computer (PC), tablet PC, set-top box (STB), personal digital assistant (PDA), mobile phone, network device, network router, switch, or bridge, or any machine capable of executing instructions (sequentially or otherwise) specifying the actions to be taken by that machine. Furthermore, while only a single machine is shown, the term "machine" should also be considered to include any collection of machines that independently or jointly execute one or more sets of instructions to implement any one or more of the methods discussed herein, such as cloud computing, Software as a Service (SaaS), and other computer cluster configurations.

[0112] Machine 600 (e.g., a computer system) may include a hardware processor 602 (e.g., a central processing unit (CPU), graphics processing unit (GPU), hardware processor core, or any combination thereof), main memory 604, static memory 606 (e.g., memory or storage device for firmware, microcode, basic input / output (BIOS), unified extensible firmware interface (UEFI), etc.), and mass storage 608 (e.g., hard disk drive, tape drive, flash storage, or other block device), some or all of which may communicate with each other via interconnect 630 (e.g., a bus). Machine 600 may also include a display unit 610, an input device 612 (e.g., a keyboard), and a user interface (UI) navigation device 614 (e.g., a mouse). In the example, display unit 610, input device 612, and UI navigation device 614 may be a touchscreen display. Machine 600 may additionally include a signal generation device 618 (e.g., a speaker), a network interface device 620, and one or more sensors 616, such as a global positioning system (GPS) sensor, a compass, an accelerometer, or one or more other sensors. Machine 600 may include output controller 628, such as serial (e.g., Universal Serial Bus (USB), parallel or other wired or wireless (e.g., infrared (IR), near field communication (NFC) etc.) connections, to communicate or control one or more peripheral devices (e.g., printers, card readers, etc.).

[0113] The registers of the hardware processor 602, main memory 604, static memory 606, or mass storage 608 may be or include a machine-readable medium 622, on which one or more sets of data structures or instructions 624 (e.g., software) embody or are utilized by any one or more of the technologies or functions described herein. During execution of the instructions 624 by the machine 600, the instructions 624 may also reside wholly or at least partially within any register of the hardware processor 602, main memory 604, static memory 606, or mass storage 608. In the example, one or any combination of the hardware processor 602, main memory 604, static memory 606, or mass storage 608 may constitute the machine-readable medium 622. Although the machine-readable medium 622 is shown as a single medium, the term "machine-readable medium" can include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) configured to store one or more instructions 624.

[0114] The term "machine-readable medium" can include any medium capable of storing, encoding, or carrying instructions executable by machine 600 and causing machine 600 to perform any one or more of the techniques disclosed herein, or any medium capable of storing, encoding, or carrying data structures used by or associated with those instructions. Examples of non-limiting machine-readable media can include solid-state memory, optical media, magnetic media, and signals (e.g., radio frequency signals, other photon-based signals, sound signals, etc.). In examples, non-transitory machine-readable media includes machine-readable media having a plurality of particles with invariant (e.g., rest) masses, and thus being a component of matter. Therefore, a non-transitory machine-readable medium is a machine-readable medium that does not include transiently propagating signals. Specific examples of non-transitory machine-readable media can include: non-volatile memory, such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices; disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0115] Commands 624 can be further sent or received via network interface device 620 and communication network 626 using a transmission medium, utilizing any of a variety of transport protocols (e.g., Frame Relay, Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Hypertext Transfer Protocol (HTTP), etc.). Example communication networks may include local area networks (LANs), wide area networks (WANs), packet data networks (e.g., the Internet), mobile phone networks (e.g., cellular networks), conventional telephone (POTS) networks, and wireless data networks (e.g., the IEEE 802.11 family of standards known as Wi-Fi®, the IEEE 802.16 family of standards known as WiMax®), the IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, and so on. In the example, network interface device 620 may include one or more physical jacks (e.g., Ethernet, coaxial, or telephone jacks) or one or more antennas for connection to communication network 626. In the example, network interface device 620 may include multiple antennas to perform wireless communication using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) technologies. The term "transmission medium" should be understood to include any intangible medium capable of storing, encoding, or carrying instructions executable by machine 600, and includes digital or analog communication signals or other intangible media to facilitate communication of such software. The transmission medium is a machine-readable medium.

[0116] Various embodiments are illustrated in the accompanying drawings above. One or more features from one or more of these embodiments can be combined to form other embodiments. The method examples described herein may be at least partially implemented by a machine or computer. Some examples may include a computer-readable or machine-readable medium encoded with instructions operable to configure an electronic device or system to perform the methods described in the examples above. Implementations of this method may include code, such as microcode, assembly language code, high-level language code, or the like. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, the code may be tangibly stored on one or more volatile or non-volatile computer-readable media during execution or at other times.

[0117] The detailed description above is intended to be illustrative and not restrictive. Therefore, the scope of this disclosure should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A medical device system comprising: means for receiving physiological information of a patient; means for determining an indication of atrial fibrillation of the patient in a respective detection window of a day using the received physiological information; means for recording first physiological information of the patient at a first sampling frequency for the determined indication of atrial fibrillation of the patient until and no more than a first threshold of the medical device system for transmission to a remote device; and means for determining and recording one or more atrial fibrillation key indicators at a second sampling frequency lower than the first sampling frequency for the determined indication of atrial fibrillation of the patient irrespective of the first threshold. The means for receiving physiological information of the patient comprises a signal receiver circuit configured to receive physiological information of a patient, 2. The medical device system of claim 1, wherein, wherein the means for determining an indication of atrial fibrillation of the patient, the means for recording first physiological information of the patient at the first sampling frequency, and the means for determining and recording one or more atrial fibrillation key indicators at the second sampling frequency for the determined indication of atrial fibrillation of the patient comprise an evaluation circuit configured to: determine an indication of atrial fibrillation of the patient in a respective detection window of a day using the received physiological information; record first physiological information of the patient at the first sampling frequency for the determined indication of atrial fibrillation of the patient until and no more than the first threshold of the medical device system for transmission to the remote device; and determine and record one or more atrial fibrillation key indicators at the second sampling frequency lower than the first sampling frequency for the determined indication of atrial fibrillation of the patient irrespective of the first threshold. Determining and recording the one or more atrial fibrillation key indicators for the determined indication of atrial fibrillation of the patient irrespective of the first threshold comprises determining and recording one or more atrial fibrillation key indicators for the determined indication of atrial fibrillation irrespective of a limit, including determining and recording one or more atrial fibrillation key indicators for the determined indication of atrial fibrillation until and beyond the first threshold.

3. The medical device system of claim 2, wherein, The first threshold represents a first data limit for storage or transmission by the evaluation circuit for the determined indication of atrial fibrillation, a time period, or a period of sequential transmissions to the remote device.

4. The medical device system of claim 2, wherein, 5. The medical device system of claim 2, wherein the first threshold comprises a daily threshold for the determined indication of atrial fibrillation, wherein the evaluation circuit is configured to stop recording first physiological information of the patient for a remaining portion of the day after an amount of the recorded first physiological information for the day has reached or exceeded the first threshold.

6. The medical device system of claim 2, wherein the evaluation circuit is configured to determine and record the one or more atrial fibrillation key indicators for one or more detection windows in each of the determined indications of atrial fibrillation of the patient for transmission to the remote device, each determined indication of atrial fibrillation comprises one or more detection windows. wherein ​ 7. The medical device system of claim 2, wherein the evaluation circuit is configured to determine and record, for each detection window of a determined atrial fibrillation indication, the one or more atrial fibrillation key indicators, wherein each determined atrial fibrillation indication comprising one or more detection windows.

8. The medical device system of claim 2, wherein the evaluation circuit is configured to determine and record, for each detection window of a determined atrial fibrillation indication and at least one detection window preceding or following the determined atrial fibrillation indication, the one or more atrial fibrillation key indicators, wherein each determined atrial fibrillation indication comprising one or more detection windows.

9. The medical device system of claim 2, wherein the evaluation circuit is configured to determine and record, for each detection window of the day, the one or more atrial fibrillation key indicators, the each detection window comprising detection windows with and without a determined atrial fibrillation indication.

10. The medical device system of claim 2, comprising an implantable or ambulatory medical device comprising the signal receiver circuit and the evaluation circuit, wherein the duration of the detection window being between 30 seconds and 2 minutes, wherein the first physiological information of the patient at the first sampling frequency comprises an ECG signal of the patient at a sampling frequency greater than 100 samples per second for a determined atrial fibrillation indication up to and no more than the first threshold of the medical device system, wherein the one or more atrial fibrillation key indicators comprise one or more measures or values representing one or more detection windows of the determined indication at the second sampling frequency having less than 5 samples per detection window.

11. The medical device system of claim 2, wherein each determined atrial fibrillation indication comprises one or more detection windows, wherein the one or more atrial fibrillation key indicators comprising, for the one or more detection windows of each determined atrial fibrillation indication, one or more of the following measures or values: R-R variability; a timing interval between consecutive valid R-waves; R-wave morphology; P-wave presence; and heart rate.

12. The medical device system of claim 11, wherein, the measure or value of one or more of the R-R variability, the timing interval between consecutive valid R-waves, and the heart rate comprising an indication that one or more of the R-R variability, the timing interval between consecutive valid R-waves, and the heart rate is above or below a patient-specific or population threshold for the one or more detection windows of each determined atrial fibrillation indication.

13. The medical device system of claim 2, wherein the evaluation circuit is configured to determine an atrial fibrillation burden indication for the patient using one or more recorded atrial fibrillation key indicators.

14. The medical device system of claim 13, wherein the evaluation circuit is configured to determine the atrial fibrillation burden indication for the patient using a comparison of one or more recorded key indicators to commensurate indicators for adjudicated episodes.

15. A method comprising: receiving, using a signal receiver circuit, physiological information of a patient; and determining, using an evaluation circuit: ​ determining, using the received physiological information, an indication of atrial fibrillation of the patient in a respective detection window of a day; recording, for the determined indication of atrial fibrillation of the patient, first physiological information of the patient at a first sampling frequency until and no more than a first threshold for transmission to the remote device; and determining and recording, irrespective of the first threshold, one or more atrial fibrillation key indicators for the determined indication of atrial fibrillation of the patient at a second sampling frequency lower than the first sampling frequency.

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