Premature ventricular contraction (PVC) detection

Abstract

Techniques for determining whether a ventricular depolarization is a premature ventricular contraction (PVC) depolarization can include processing circuitry of a medical system that identifies an interval from a maximum slope point to a minimum slope point of each of a plurality of ventricular depolarizations and, for each of the plurality of ventricular depolarizations as a current ventricular depolarization, determines that an interval from a maximum slope point to a minimum slope point of the current ventricular depolarization, a previous adjacent ventricular depolarization of the plurality of ventricular depolarizations, and a subsequent adjacent ventricular depolarization of the plurality of ventricular depolarizations satisfies one or more slope criteria. The processing circuitry determines, based on the interval from the maximum slope point to the minimum slope point that satisfies the one or more slope criteria, that the current ventricular depolarization is a PVC depolarization.

Description

Technical Field

[0001] This disclosure generally relates to medical device systems, and more specifically, to medical device systems configured to detect premature ventricular contractions (PVCs). Background Technology

[0002] Medical devices can be used to monitor a patient's physiological signals. For example, some medical devices are configured to sense electrocardiogram (EGM) signals, which indicate the heart's electrical activity via electrodes. Some medical devices can be configured to deliver treatment in conjunction with or independently of monitoring physiological signals.

[0003] PVCs are premature beats originating from the ventricles. PVCs are premature because they occur before the regular heartbeat originating from the sinoatrial node. During a PVC event, the ventricles discharge and contract prematurely before the normal discharge reaches the sinoatrial node. PVCs can occur in healthy individuals. As examples, PVCs can be caused by caffeine, smoking, alcohol consumption, stress, fatigue, pharmacological toxicity, electrolyte imbalance, hypoxia, and heart attack. Common symptoms associated with PVCs include palpitations, dizziness, fatigue, shortness of breath, chest pain, and lightheadedness. PVCs are generally considered benign but can lead to cardiomyopathy, ventricular arrhythmias, and heart failure.

[0004] Management strategies for PVC-induced cardiomyopathy include pharmacological therapy and catheter ablation, with catheter ablation playing an increasingly important role due to its potential to permanently suppress PVC. Ablation that suppresses PVC may lead to improvement in left ventricular systolic dysfunction (LVSD) and normalization of left ventricular ejection fraction (LVEF). PVC load, i.e., the quantification of PVC levels over a period of time, can be an independent predictor of PVC-induced cardiomyopathy. Currently, 24-hour Holter monitoring is the most commonly used method for determining PVC load. Summary of the Invention

[0005] Generally, this disclosure relates to techniques for detecting PVCs using a medical device to, for example, facilitate the determination of PVC load. More specifically, this disclosure relates to techniques for evaluating ventricular depolarization in the cardiac EGM to determine whether they are PVC depolarizations. The processing circuitry system can determine whether ventricular depolarization is PVC depolarization based on the satisfaction of one or more criteria, including criteria related to depolarization intervals (e.g., RR intervals) indicating the rate of depolarization or criteria related to the morphology of depolarization in the cardiac EGM.

[0006] For some medical devices, such as those utilizing external, subcutaneous, or other extravascular electrodes, the position and orientation of the electrodes used to sense the cardiac EGM relative to the heart and other tissues may vary between patients and within a given patient over time. Consequently, the morphology of depolarization may change and may introduce noise into the cardiac EGM. According to the technology disclosed herein, the criteria used by the processing circuitry system to determine whether a given depolarization is PVC improve the sensitivity and specificity of PVC detection under such conditions. This can facilitate more accurate determination of PVC load, cardiac health, and the risk of sudden cardiac death, and may lead to clinical interventions to suppress PVC, such as pharmaceuticals and PVC ablation.

[0007] In some instances, the processing circuitry can use noise criteria to avoid classifying noise depolarization in the cardiac EGM as PVC depolarization. In some instances, morphological criteria include one or more slope criteria, and the processing circuitry can consider whether the interval between the maximum and minimum slope points in the depolarization meets the slope criteria. As an alternative to or addition to slope criteria, morphological criteria for identifying PVC depolarization may include one or more correlation criteria, against which the processing circuitry can compare correlation values ​​between depolarizations. The processing circuitry can use cross-correlation techniques, difference techniques, or other techniques to determine the correlation values. In some instances, correlation criteria may include one or more thresholds that, during update cycles prior to the current depolarization under consideration, may be adjusted based on the maximum correlation between depolarizations (e.g., the maximum cross-correlation value or the minimum sum of differences).

[0008] In one example, the medical system includes multiple electrodes configured to sense a patient's electrocardiogram; and a processing circuitry system. The processing circuitry system is configured to identify multiple ventricular depolarizations within the electrocardiogram, and for each of the multiple ventricular depolarizations, to identify a maximum slope point, a minimum slope point, and an interval from the maximum slope point to the minimum slope point. The processing circuitry system is further configured to, for each of the multiple ventricular depolarizations that is the current ventricular depolarization, determine that the interval from the maximum slope point to the minimum slope point of the current ventricular depolarization, the previously adjacent ventricular depolarizations of the multiple ventricular depolarizations, and the subsequently adjacent ventricular depolarizations of the multiple ventricular depolarizations satisfies one or more slope criteria, and determine, based on the interval from the maximum slope point to the minimum slope point that satisfies one or more slope criteria, that the current ventricular depolarization is a premature ventricular contraction (PVC) depolarization.

[0009] In another example, a method includes sensing a patient's electrocardiogram using multiple electrodes and identifying multiple ventricular depolarizations within the electrocardiogram. The method further includes, for each of the multiple ventricular depolarizations, identifying a maximum slope point, a minimum slope point, and an interval from the maximum slope point to the minimum slope point. The method further includes, for each of the multiple ventricular depolarizations that is a current ventricular depolarization, determining that the interval from the maximum slope point to the minimum slope point of the current ventricular depolarization, the previously adjacent ventricular depolarizations of the multiple ventricular depolarizations, and the subsequently adjacent ventricular depolarizations of the multiple ventricular depolarizations satisfies one or more slope criteria, and determining that the current ventricular depolarization is a premature ventricular contraction (PVC) depolarization based on the interval from the maximum slope point to the minimum slope point that satisfies one or more slope criteria.

[0010] In another example, the medical system includes multiple electrodes configured to sense a patient's electrocardiogram; and a processing circuitry system. The processing circuitry system is configured to identify multiple ventricular depolarizations within the electrocardiogram. For each of the multiple ventricular depolarizations that is the current ventricular depolarization, the processing circuitry system is configured to determine a correlation value between one of the current ventricular depolarization, a previously adjacent ventricular depolarization, and a subsequently adjacent ventricular depolarization and each pair of the other of the previously adjacent ventricular depolarization, the current ventricular depolarization, and the subsequently adjacent ventricular depolarization. The processing circuitry system is further configured to determine that the correlation value satisfies one or more correlation criteria including one or more thresholds, and based on the correlation value satisfying the one or more correlation criteria, determine that the current ventricular depolarization is a premature ventricular contraction (PVC) depolarization. The processing circuitry system is further configured to, for the multiple correlation values ​​determined during an update cycle prior to the current depolarization, identify one of a plurality of correlation values ​​representing the largest correlation among the multiple correlation values, and adjust the one or more thresholds based on one of the identified multiple correlation values.

[0011] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the systems, apparatus, and methods described in detail in the following drawings and specification. Further details of one or more embodiments of this disclosure are set forth in the following drawings and specification. Other features, objectives, and advantages will become apparent from the description, drawings, and claims. Attached Figure Description

[0012] Figure 1 The patient demonstrated the environment of the example healthcare system.

[0013] Figure 2 It is a demonstration Figure 1 Functional block diagram of an example configuration of an implantable medical device (IMD) for a medical system.

[0014] Figure 3 It is shown Figure 1 and 2 A conceptual side view of the IMD instance configuration.

[0015] Figure 4 It is a demonstration Figure 1 A functional block diagram of an example configuration of an external device.

[0016] Figure 5 This is a block diagram illustrating an example system that includes an access point, a network, external computing devices such as servers, and one or more other computing devices that can interact with... Figure 1-4 The IMD is coupled to external devices.

[0017] Figure 6 The diagram illustrates cardiac EGM, including PVC depolarization, and an example technique for detecting PVC depolarization based on cardiac EGM.

[0018] Figure 7 This is a flowchart illustrating an example operation for detecting PVC depolarization.

[0019] Figure 8 This is a flowchart illustrating an example operation used to determine whether the interval and morphological criteria are met to determine whether the current ventricular depolarization is PVC depolarization.

[0020] Figure 9 This is a flowchart illustrating an example operation used to determine whether a current depolarization is a PVC depolarization by satisfying morphological criteria based on amplitude and slope.

[0021] Figure 10 This is a flowchart illustrating example operations for adjusting relevant thresholds used to determine whether ventricular depolarization is PVC depolarization.

[0022] Figure 11 This is a flowchart illustrating another example operation for adjusting the relevant thresholds used to determine whether ventricular depolarization is PVC depolarization.

[0023] Throughout the specification and drawings, the same reference numerals denote the same elements. Detailed Implementation

[0024] Various types of medical devices sense cardiac EGM. Some medical devices for sensing cardiac EGM are non-invasive, such as those using multiple electrodes placed in contact with external parts of the patient, such as at various locations on the patient's skin. As an example, electrodes used for monitoring cardiac EGM in these non-invasive procedures can be attached to the patient using adhesive, tape, belt, or vest, and electrically coupled to a monitoring device, such as an electrocardiograph, Holter monitor, or other electronic device. The electrodes are configured to sense electrical signals associated with the electrical activity of the patient's heart or other cardiac tissue, and these sensed electrical signals are provided to electronic devices for further processing and / or display of the electrical signals. Non-invasive devices and methods can be used on a temporary basis, such as to monitor the patient during a clinical visit, such as during a physician appointment, or, for example, within a predetermined time period, such as a day (24 hours), or a period of several days.

[0025] External devices that can be used for noninvasive sensing and monitoring of cardiac EGM include wearable devices such as patches, watches, or necklaces with electrodes configured to contact a patient's skin. An example of a wearable physiological monitor configured to sense cardiac EGM is the SEEQ, commercially available from Medtronic plc in Dublin, Ireland. TM Mobile cardiac telemetry systems. These external devices facilitate relatively long-term monitoring of patients during normal daily activities and can periodically transmit collected data to network services, such as Medtronic's Carelink. TM network.

[0026] Some implantable medical devices (IMDs) also sense and monitor cardiac EGM. Electrodes used by the IMD to sense cardiac EGM are typically integrated into the IMD's housing and / or coupled to the IMD via one or more thin leads. Examples of IMDs that monitor cardiac EGM include pacemakers and implantable cardioverter defibrillators that can be coupled to intravascular or extravascular leads, and pacemakers with a housing configured for implantation within the heart, which may be leadless. An example of a pacemaker configured for intracardiac implantation is the Micra. TM Transcatheter pacing systems are available from Medtronic. Some IMDs (Intravascular Doppler Devices) do not provide a therapy, such as implantable patient monitors that sense cardiac EGM. An example of such an IMD is the subcutaneously insertable Reveal LINQ. TM Insertable cardiac monitors (IMDs) are available from Medtronic. These IMDs facilitate relatively long-term monitoring of patients during normal daily activities and can periodically transmit collected data to network services such as Medtronic's Carelink. TM network.

[0027] Any medical device configured to sense cardiac EGM via implanted or external electrodes, including the examples identified herein, can implement the techniques of this disclosure for assessing ventricular depolarization in the cardiac EGM to determine whether it is PVC depolarization, which may help determine PVC load. The techniques involve assessing the cardiac EGM using criteria configured to provide the desired PVC detection sensitivity and specificity, despite noise and variations in depolarization morphology due to different electrode locations. The techniques of this disclosure for identifying PVC depolarization can facilitate the determination of PVC load, cardiac health, and risk of sudden cardiac death, and may lead to clinical interventions to suppress PVC, such as pharmaceuticals and PVC ablation.

[0028] Figure 1 An example medical system 2 incorporating one or more technologies according to this disclosure is illustrated in the environment of a patient 4. The example technologies can be used with an IMD 10, which can be used with an external device 12 and... Figure 1 At least one of the other devices not shown in the diagram communicates wirelessly. In some instances, the IMD 10 can be implanted outside the chest cavity of patient 4 (e.g., subcutaneously). Figure 1 (As shown in the pectoral muscle location). IMD 10 can be positioned near the sternum at or just below the patient's heart level, for example, at least partially within the heart contour. IMD 10 contains multiple electrodes ( Figure 1 (Not shown in the image), and is configured to sense cardiac EGM via multiple electrodes. In some instances, the IMD 10 employs LINQ. TM ICM or similar systems such as LINQ TM A version of the ICM or a modified form of another ICM.

[0029] External device 12 may be a computing device having a user-viewable display and an interface (i.e., a user input mechanism) for providing input to external device 12. In some instances, external device 12 may be a laptop computer, tablet computer, workstation, one or more servers, cellular phone, personal digital assistant, or another computing device that can run an application that enables the computing device to interact with IMD 10. External device 12 is configured to wirelessly communicate with IMD 10 and optionally with another computing device ( Figure 1 (Not shown in the image). For example, the external device 12 can communicate via near-field communication technology (e.g., inductive coupling, NFC, or other communication technologies that can operate at a range of less than 10-20 cm) and far-field communication technology (e.g., according to 802.11 or...). The RF telemetry of the specification set or other communication technologies that can operate at a range greater than that of near-field communication technologies can communicate.

[0030] External device 12 can be used to configure the operating parameters of IMD 10. External device 12 can be used to retrieve data from IMD 10. The retrieved data may include values ​​of physiological parameters measured by IMD 10, indications of arrhythmias or other disease episodes detected by IMD 10, and physiological signals recorded by IMD 10. For example, external device 12 can retrieve information related to PVC detection by IMD 10, such as PVC counts or other quantifications, for example, over a period of time since the external device last retrieved information. External device 12 can also retrieve cardiac EGM segments recorded by IMD 10, for example, when IMD 10 determines that an arrhythmia or other disease episode occurred during said segment, or in response to a request to record segments from patient 4 or another user. (See below for more details.) Figure 5 In more detail, one or more remote computing devices may interact with IMD 10 via a network in a manner similar to external device 12, for example, to program IMD 10 and / or retrieve data from IMD 10.

[0031] The processing circuitry of the medical system 2, such as the IMD 10, the external device 12, and / or one or more other computing devices, can be configured to perform the example techniques of this disclosure for determining whether a depolarization is a PVC depolarization. In some instances, the processing circuitry of the medical system 2 analyzes the cardiac EGM sensed by the IMD 10 to determine whether the current depolarization is a PVC depolarization based on whether the current depolarization and adjacent depolarizations (e.g., a comparison between these depolarizations) in the cardiac EGM meet multiple criteria. Criteria may include noise criteria, depolarization interval (e.g., RR interval) criteria, and / or morphological criteria, as described in more detail below. Although described in the context of instances where the IMD 10 sensing the cardiac EGM includes an insertable cardiac monitor, example systems comprising one or more implantable or external devices of any type configured to sense the cardiac EGM can be configured to implement the techniques of this disclosure.

[0032] Figure 2 This demonstrates one or more technologies as described herein. Figure 1 A functional block diagram of an example configuration of IMD 10 is provided. In the illustrated example, IMD 10 includes electrodes 16A and 16B (collectively referred to as “electrodes 16”), antenna 26, processing circuitry 50, sensing circuitry 52, communication circuitry 54, storage device 56, switching circuitry 58, and sensor 62. Although the illustrated example includes two electrodes 16, in some examples, IMDs including or coupled to more than two electrodes 16 may implement the techniques of this disclosure.

[0033] Processing circuitry system 50 may include fixed-function circuitry systems and / or programmable processing circuitry systems. Processing circuitry system 50 may include any one or more of the following: microprocessors, controllers, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or equivalent discrete or analog logic circuitry systems. In some instances, processing circuitry system 50 may include multiple components (e.g., any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs) and other discrete or integrated logic circuitry systems. The functionality attributed herein to processing circuitry system 50 may be embodied in software, firmware, hardware, or any combination thereof.

[0034] Sensing circuitry 52 can be selectively coupled to electrode 16 via switching circuitry 58, for example, to select electrode 16 for sensing cardiac EGM and its polarity, referred to as the sensing vector, as controlled by processing circuitry 50. Sensing circuitry 52 can sense signals from electrode 16, for example, to generate cardiac EGM, in order to monitor the electrical activity of the heart. As an example, sensing circuitry 52 can also monitor signals from sensor 62, which may include one or more accelerometers, pressure sensors, and / or optical sensors. In some instances, sensing circuitry 52 may include one or more filters and amplifiers for filtering and amplifying signals received from electrode 16 and / or sensor 62.

[0035] Sensing circuitry 52 and / or processing circuitry 50 may be configured to detect cardiac depolarization (e.g., atrial depolarization P waves or ventricular depolarization R waves) when the cardiac EGM amplitude crosses a sensing threshold. In some instances, sensing circuitry 52 may include rectifiers, filters, amplifiers, comparators, and / or analog-to-digital converters for cardiac depolarization detection. In some instances, sensing circuitry 52 may output an indication to processing circuitry 50 in response to sensing cardiac depolarization. In this manner, processing circuitry 50 may receive a detected cardiac depolarization indication corresponding to the occurrence of detected R and P waves in the respective chambers of the heart. Processing circuitry 50 may use the indications of the detected R and P waves to determine the depolarization interval, heart rate, and detect arrhythmias, such as tachyarrhythmias and cardiac arrest.

[0036] According to the technology of this disclosure, the sensing circuit 52 can also provide one or more digitized cardiac EGM signals to the processing circuit system 50 for analysis, for example, for heart rhythm differentiation, and / or for analysis to determine whether one or more PVC detection criteria are met. In some instances, the processing circuit system 50 can store the digitized cardiac EGM in a storage device 56. According to the technology of this disclosure, the processing circuit system 50 of the IMD 10 and / or the processing circuit system of another device retrieving data from the IMD 10 can analyze the cardiac EGM to determine whether one or more PVC detection criteria are met.

[0037] The communication circuitry 54 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device such as external device 12, another networked computing device, or another IMD or sensor. Under the control of the processing circuitry 50, the communication circuitry 54 can receive downlink telemetry from external device 12 or another device and send uplink telemetry to it via internal or external antennas, such as antenna 26. Additionally, the processing circuitry 50 can communicate with external devices (e.g., external device 12) and Medtronic. The network communicates with computer networks and networked computing devices. Antenna 26 and communication circuitry 54 can be configured to transmit and / or receive signals via inductive coupling, electromagnetic coupling, near field communication (NFC), radio frequency (RF) communication, Bluetooth, WiFi, or other proprietary or non-proprietary wireless communication schemes.

[0038] In some instances, storage device 56 contains computer-readable instructions that, when executed by processing circuitry system 50, cause IMD 10 and processing circuitry system 50 to perform various functions pursuant to this document. Storage device 56 may contain any volatile, non-volatile, magnetic, optical, or electrical medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital medium. As an example, storage device 56 may store programmed values ​​of one or more operating parameters of IMD 10 and / or data collected by IMD 10 for transmission to another device using communication circuitry system 54. As an example, data stored by storage device 56 and transmitted by communication circuitry system 54 to one or more other devices may include PVC detection quantification and / or digitized cardiac EGM.

[0039] Figure 3 It is a demonstration Figure 1 and 2 A conceptual side view of an example configuration of IMD 10. Figure 3In the example shown, the IMD10 may comprise a leadless subcutaneous implantable monitoring device having a housing 15 and an insulating cover 76. Electrodes 16A and 16B may be formed or placed on the outer surface of the cover 76. (The above refers to...) Figure 2 The described circuit systems 50-62 can be formed or placed on the inner surface of the cover 76 or within the housing 15. In the illustrated example, the antenna 26 is formed or placed on the inner surface of the cover 76, but in some examples, it can be formed or placed on the outer surface. In some examples, one or more sensors 62 can be formed or placed on the outer surface of the cover 76. In some examples, the insulating cover 76 can be positioned over the open housing 15 such that the housing 15 and the cover 76 surround the antenna 26 and the circuit systems 50-62, and protect the antenna and circuit systems from fluids such as bodily fluids.

[0040] One or more of the antenna 26 or circuit systems 50-62 can be formed on the inside of the insulating cover 76, such as by using flip-chip technology. The insulating cover 76 can be flipped onto the housing 15. When flipped and placed onto the housing 15, the components of the IMD 10 formed on the inside of the insulating cover 76 can be positioned in the gap 78 defined by the housing 15. The electrode 16 can be electrically connected to the switching circuit system 58 through one or more through-holes (not shown) formed in the insulating cover 76. The insulating cover 76 can be formed of sapphire (i.e., corundum), glass, parylene, and / or any other suitable insulating material. The housing 15 can be formed of titanium or any other suitable material (e.g., a biocompatible material). The electrode 16 can be formed of stainless steel, titanium, platinum, iridium, or alloys thereof. Furthermore, the electrode 16 can be coated with a material such as titanium nitride or fractal titanium nitride, but other suitable materials and coatings for such electrodes can be used.

[0041] Figure 4 This is a block diagram illustrating an example configuration of the components of external device 12. Figure 4 In one example, the external device 12 includes a processing circuit system 80, a communication circuit system 82, a storage device 84, and a user interface 86.

[0042] The processing circuitry system 80 may include one or more processors configured to implement functions and / or processing instructions for execution within the external device 12. For example, the processing circuitry system 80 may be capable of processing instructions stored in the storage device 84. The processing circuitry system 80 may include, for example, a microprocessor, DSP, ASIC, FPGA, or equivalent discrete or integrated logic circuitry system, or a combination of any of the foregoing devices or circuitry systems. Therefore, the processing circuitry system 80 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions attributed herein to the processing circuitry system 80.

[0043] The communication circuitry 82 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device such as IMD 10. Under the control of the processing circuitry 80, the communication circuitry 82 can receive downlink telemetry from IMD 10 or another device, and send uplink telemetry to it. The communication circuitry 82 may be configured to transmit or receive signals via inductive coupling, electromagnetic coupling, near field communication (NFC), radio frequency (RF) communication, Bluetooth, WiFi, or other proprietary or non-proprietary wireless communication schemes. The communication circuitry 82 may also be configured to communicate with devices other than IMD 10 via any of a variety of wired and / or wireless communication and / or network protocols.

[0044] Storage device 84 can be configured to store information within external device 12 during operation. Storage device 84 may comprise a computer-readable storage medium or a computer-readable storage device. In some instances, storage device 84 comprises one or more of short-term or long-term memory. Storage device 84 may comprise, for example, RAM, DRAM, SRAM, magnetic disk, optical disk, flash memory, or various forms of EPROM or EEPROM. In some instances, storage device 84 is used to store data indicating instructions executed by processing circuitry system 80. Storage device 84 can be used by software or applications running on external device 12 to temporarily store information during program execution.

[0045] The data exchanged between the external device 12 and the IMD 10 may include operating parameters. The external device 12 may transmit data containing computer-readable instructions that, when implemented by the IMD 10, can control the IMD 10 to change one or more operating parameters and / or export collected data. For example, the processing circuitry 80 may transmit instructions to the IMD 10 requesting it to export collected data (e.g., PVC detection data and / or digitized cardiac EGM) to the external device 12. Furthermore, the external device 12 can receive the collected data from the IMD 10 and store it in the storage device 84. The processing circuitry 80 may implement any of the techniques described herein to analyze the cardiac EGM received from the IMD 10, for example, to determine whether ventricular depolarization is PVC depolarization.

[0046] Users such as clinicians or patients can interact with external devices 12 through user interface 86. User interface 86 includes a display (not shown), such as a liquid crystal display (LCD) or a light-emitting diode (LED) display or other type of screen, wherein the processing circuitry 80 can present information related to IMD 10, such as cardiac EGM, PVC detection indications, and quantifications of detected PVC, such as PVC load quantification. Additionally, user interface 86 may include an input mechanism to receive input from the user. The input mechanism may include, for example, buttons, a keypad (e.g., an alphanumeric keypad), a peripheral pointing device, or a touchscreen, or another input mechanism that allows the user to navigate the user interface presented by the processing circuitry 80 of external device 12 and provides input. In other instances, user interface 86 also includes an audio circuitry for providing auditory notifications, instructions, or other sounds to the user, receiving voice commands from the user, or both.

[0047] Figure 5 This is a block diagram illustrating an example system according to one or more techniques described herein. The example system includes an access point 90, a network 92, an external computing device such as a server 94, and one or more other computing devices 100A-100N (collectively, “Computing Device 100”), which can be coupled to IMD 10 and external device 12 via network 92. In this example, IMD 10 can communicate with external device 12 via a first wireless connection using communication circuitry 54, and with access point 90 via a second wireless connection. Figure 5 In this example, access point 90, external device 12, server 94 and computing device 100 are interconnected and can communicate with each other through network 92.

[0048] Access point 90 may include a device connected to network 92 via any of a variety of connections, such as dial-up, digital subscriber line (DSL), or cable modem connections. In other instances, access point 90 may be coupled to network 92 via different forms of connection, including wired or wireless connections. In some instances, access point 90 may be a user device that can be co-located with the patient, such as a tablet or smartphone. IMD 10 may be configured to transmit data, such as PVC detection information, PVC quantification, and / or cardiac EGM, to access point 90. Access point 90 can then transmit the retrieved data to server 94 via network 92.

[0049] In some cases, server 94 can be configured to provide a secure storage site for data already collected from IMD 10 and / or external device 12. In some cases, server 94 can compile the data into web pages or other documents via computing device 100 for viewing by trained professionals (such as clinicians). Figure 5 One or more aspects of the system shown can be similar to those of Medtronic. The network provides general network technologies and functions for implementation.

[0050] In some instances, one or more computing devices in computing device 100 may be tablets or other smart devices located with the clinician, through which the clinician can be programmed to receive alerts and / or query IMD 10. For example, the clinician can access data collected by IMD 10, such as when patient 4 is between clinician visits, via computing device 100 to check the status of the patient's medical condition. In some instances, the clinician may input instructions for medical interventions for patient 4 into an application executed by computing device 100, such as based on the status of the patient's condition determined by IMD 10, external device 12, server 94, or any combination thereof, or based on other patient data known to the clinician. Device 100 can then transmit the instructions for the medical intervention to another computing device in computing device 100 located with patient 4 or patient 4's caregiver. Such instructions for medical interventions may include instructions for changing medication dosages, timing or selection, scheduling visits with the clinician, or seeking medical attention. In another instance, computing device 100 can generate alerts to patient 4 based on the status of patient 4's medical condition, enabling patient 4 to proactively seek medical attention before receiving instructions for medical intervention. In this way, patient 4 can be authorized to take action as needed to address his or her medical condition, which can help improve patient 4's clinical outcomes.

[0051] In the Figure 5 In the example shown, server 94 includes, for example, a storage device 96 and a processing circuitry 98 for storing data retrieved from IMD 10. Although Figure 5 Not shown, computing device 100 may similarly include storage devices and processing circuitry. Processing circuitry 98 may include one or more processors configured to implement functions and / or processing instructions for execution within server 94. For example, processing circuitry 98 may be able to process instructions stored in memory 96. Processing circuitry 98 may include, for example, a microprocessor, DSP, ASIC, FPGA, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Therefore, processing circuitry 98 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions attributed herein to processing circuitry 98. The processing circuitry 98 of server 94 and / or the processing circuitry of computing device 100 may implement any of the techniques described herein to analyze cardiac EGM received from IMD 10, for example, to determine whether ventricular depolarization is PVC.

[0052] Storage device 96 may comprise a computer-readable storage medium or a computer-readable storage device. In some instances, storage device 96 comprises one or more of short-term or long-term memory. Storage device 96 may comprise, for example, RAM, DRAM, SRAM, magnetic disk, optical disk, flash memory, or various forms of EPROM or EEPROM. In some instances, storage device 96 is used to store data indicating instructions to be executed by processing circuitry system 98.

[0053] Figure 6 This diagram illustrates a cardiac EGM 120 including PVC depolarization and an example technique for detecting PVC depolarization based on the cardiac EGM 120. The techniques disclosed herein use different features such as inter-depolarization (e.g., RR) intervals and morphological features to distinguish PVC depolarization from normal ventricular depolarization. The IMD 10 senses the cardiac EGM 120 and uses, as described above... Figure 2 The described techniques for detecting ventricular depolarization (e.g., R-wave) are used to detect the timing of ventricular depolarizations 122A, 122B, 122C, and 122D (collectively referred to as "ventricular depolarization 122").

[0054] In some instances, the IMD 10 uses two or more, e.g., primary and secondary sensing channels, to sense ventricular depolarization 122. The different sensing channels may have different hardware, different firmware settings, and / or different software settings for processing the cardiac EGM 120 to detect ventricular depolarization 122. For example, the primary sensing channel may implement a relatively short blanking period, such as an automatically adjusted threshold of 150 milliseconds (ms), which has a relatively high depolarization detection amplitude. For the primary sensing channel, some instances may implement the technique described in U.S. Patent No. 7,027,858 to Cao et al.

[0055] However, because the ventricular depolarization waveform of PVC depolarization, such as the QRS complex, is typically wider and has a relatively lower frequency content than normal depolarization, the primary sensing channel may be in sensing PVC depolarization. The secondary sensing channel may include a relatively long blanking period, such as a fixed threshold of 520 ms, which may help detect PVC depolarization that might not have been detected by the primary sensing channel. The processing circuitry 50 and / or the sensing circuitry 52 may determine the fixed threshold for the secondary sensing channel to detect depolarization in a given cardiac cycle based on the amplitude of one or more previous ventricular depolarizations.

[0056] The characteristics that distinguish PVC depolarization from normal ventricular depolarization include: a shorter interval between PVC depolarization and the previous adjacent (temporally) depolarization; a longer interval between PVC depolarization and the subsequent adjacent depolarization; and different depolarization and repolarization waveforms between PVC depolarization and normal ventricular depolarization. To determine whether the current ventricular depolarization 122C is a PVC depolarization, the processing circuitry system 50 of IMD 10 or other processing circuitry systems of System 2 can consider the interval and morphological information of the current ventricular depolarization 122C, the previous (temporally) adjacent depolarization 122B, and the subsequent (temporally) adjacent depolarization 122D. The processing circuitry system can determine whether each ventricular depolarization 122 is a PVC depolarization in this way by iteratively performing the next depolarization, for example, depolarization 122C becomes the previous adjacent depolarization, depolarization 122D becomes the current depolarization, and the next (temporally) depolarization after depolarization 122D becomes the subsequent adjacent depolarization. Although the techniques used to determine whether ventricular depolarization is PVC depolarization are primarily described in this paper (e.g., regarding...), Figure 6 –10) is performed by the processing circuitry system 50 of IMD 10, but such technology may be performed wholly or partially by the processing circuitry system of any one or more devices of System 2 (such as the processing circuitry system 80 of external device 12, the processing circuitry system 98 of server 94, or the processing circuitry system of one or more computing devices 100).

[0057] In some instances, the processing circuitry 50 determines a separate depolarization interval 124A-124C (collectively referred to as "depolarization interval 124") for each depolarization 122, such as an RR interval. For example, the processing circuitry 50 may determine the depolarization interval 124A of a previously adjacent depolarization 122B as the interval between the detection time of ventricular depolarization 122A and the detection time of ventricular depolarization 122B. Similarly, the processing circuitry 50 may determine the depolarization interval 124B of the current depolarization 122C as the interval between the detection time of ventricular depolarization 122B and the detection time of ventricular depolarization 122C, and determine the depolarization interval 124C of the subsequent adjacent depolarization 122D as the interval between the detection time of ventricular depolarization 122C and the detection time of ventricular depolarization 122D.

[0058] The processing circuitry 50 can also identify individual segments of the digitized version of the cardiac EGM 120 for each ventricular depolarization 122B-122D within each window 126A-126C (collectively, “Window 126”). Each window 126 may include a predetermined number of samples of the cardiac EGM 120, such as sixteen samples sampled at 64 Hz. The location of the window 126, and therefore which samples of the cardiac EGM 120 are within a given window 126, can be set relative to the time point at which the processing circuitry 50 detects the corresponding ventricular depolarization 122 or another reference marker of the cardiac EGM 120. In some instances, each of the windows 126 includes sixteen samples of the cardiac EGM 120 starting four samples prior to the detection point of the corresponding depolarization 122.

[0059] To determine whether the current ventricular depolarization 122C is a PVC depolarization, the processing circuitry 50 can determine whether ventricular depolarizations 122B-122D meet one or more morphological criteria based on segments within the corresponding window 126. For each of depolarizations 122B-122D, as an example, the processing circuitry 50 can determine one or more of the maximum amplitude, minimum amplitude, maximum slope, and minimum slope within the corresponding window 126A-126C. The processing circuitry 50 can determine the time interval between the maximum and minimum slope points for each depolarization 122B-122D, such as the number of samples, also referred to herein as the slope interval. The processing circuitry 50 can use any known technique to determine the slope of the cardiac EGM 120, such as by determining the derivative or differential signal of the cardiac EGM 120.

[0060] Morphological criteria may include criteria relating to the degree of correlation between various possible pairs of depolarizations 122B-122D. The processing circuitry 50 can determine the correlation value of a pair of depolarizations by performing correlation operations on segments of the cardiac EGM 120 within the respective windows 126 of the depolarizations. Example correlation operations include any known cross-correlation, wavelet-based comparison, feature set comparison, or difference and techniques.

[0061] An example formula for calculating cross-correlation is:

[0062]

[0063] Here, x and y are two segments of the cardiac EGM 120 to be compared, and different values ​​of L are different lags used to calculate the cross-correlation. The equation represents shifting one segment by one lag (L), multiplying it pointwise with the other segment, and summing the multiplication results pointwise. The same process is followed for different lags. In some instances, the lag is + / - four samples. The maximum value of C(L) will appear at the lag where the two segments x and y best match each other. In such instances, the processing circuitry 50 can determine the maximum value of C(L) as the correlation value for a given comparison between the two ventricular depolarizations 122.

[0064] To conserve processing and power resources of IMD 10, processing circuitry 50 can implement difference and sum techniques to determine correlation values ​​representing the degree of correlation between various pairs of depolarizations 122B-122D. Processing circuitry 50 can determine pointwise differences between segments of cardiac EGM 120 for two depolarizations 122 at various hysteresis (e.g., + / - 4 samples), and the hysteresis with the lowest difference sum will have the highest correlation between depolarizations 122. An example formula for calculating the difference sum is:

[0065]

[0066] Here, x and y are two segments of cardiac EGM 120 to be compared, and different values ​​of L represent different lags in calculating the difference sum. The lowest difference sum value D(L), compared to C(L), will appear at the lag where the two segments x and y best match each other. In other words, the lag with the greatest correlation between segments x and y will have the lowest difference sum value D(L).

[0067] In some instances, to determine whether the current ventricular depolarization 122C is a PVC depolarization, the processing circuitry 50 determines the correlation value between the current ventricular depolarization 122C and each of the previously adjacent ventricular depolarization 122B and the subsequently adjacent depolarization 122D. Figure 6In the example shown, the current ventricular depolarization 122C is a PVC depolarization, and both adjacent ventricular depolarizations 122B and 122D are normal ventricular depolarizations. Because ventricular depolarization 122C has a different morphology from adjacent ventricular depolarizations 122B and 122D, the processing circuitry 50 expects the correlation values ​​determined for these two comparisons to indicate a relatively low degree of correlation, e.g., a relatively high sum of differences. The processing circuitry 50 can also determine the correlation value between adjacent ventricular depolarizations 122B and 122D. Since both ventricular depolarizations 122B and 122D are expected to be normal ventricular depolarizations with similar morphologies, the correlation value between them is expected to indicate a relatively high degree of correlation, e.g., a relatively low sum of differences. The processing circuitry 50 can apply any combination of one or more morphological criteria described herein.

[0068] To determine whether the current ventricular depolarization 122C is PVC depolarization, the processing circuit system 50 can also evaluate the corresponding depolarization intervals 124A-124C of ventricular depolarizations 122B-122D. Since the current ventricular depolarization 122C is PVC depolarization, the depolarization interval 124B is expected to be shorter than the depolarization interval 124A, and the depolarization interval 124C is expected to be longer than the depolarization interval 124A, due to the compensatory pause after PVC depolarization. The processing circuit system 50 can also evaluate the maximum and minimum amplitudes and slope intervals of ventricular depolarizations 122B-122D to determine whether depolarization 122C is PVC depolarization. Since depolarization 122C is a PVC depolarization and is expected to have a wide QRS complex waveform, the interval (e.g., number of samples) between the maximum and minimum slopes of depolarization 122C is expected to be greater than the interval of normal depolarizations (e.g., adjacent depolarizations 122B and 122D).

[0069] Figure 7 This is a flowchart illustrating an example operation for detecting PVC depolarization. Although Figure 7 The example operation is described as being performed by the processing circuitry system 50 of the IMD 10 and regarding Figure 6 The cardiac EGM 120 is used to perform this operation, but in other instances, some or all of the example operations may be performed by the processing circuitry of another device and with respect to any cardiac EGM.

[0070] according to Figure 7In one instance, the processing circuitry 50 obtains segments (130) of the cardiac EGM 120 within depolarization intervals 124A-124C and windows 126A-126C for a previous adjacent ventricular depolarization 122B, the current ventricular depolarization 122C, and the subsequent adjacent ventricular depolarization 122D. Although described in the context of using two adjacent depolarizations 122B and 122D to determine whether depolarization 122C is a PVC depolarization, the techniques of this disclosure can be used in instances with a single adjacent depolarization or additional depolarizations that are temporally close to the current depolarization.

[0071] The processing circuitry 50 further determines whether one or more noise criteria (132) are met. A noise criterion may be met based on the presence of one or more characteristics of noise in segments of the cardiac EGM 120 within depolarization intervals 124A–124C and windows 126A–126C. For example, if any of the depolarization intervals 124A–124C is less than or equal to a short interval threshold, such as 300 ms, one noise criterion may be met. If any of the depolarization intervals 124A–124C is greater than or equal to a long interval threshold, such as 2000 ms, another noise criterion may be met. If the amplitude of any of the depolarizations 122B–122D, for example, the absolute difference between the maximum and minimum amplitudes of the depolarizations, is less than or equal to a threshold, such as 25 millivolts (mV), another noise criterion may be met. Another noise criterion can be met based on the identification of the threshold number of sign changes in the first derivative of any segment of the cardiac EGM 120 within windows 126A-126C, where such sign changes occur at the sample when the absolute amplitude of the second derivative of the segment is greater than or equal to the threshold.

[0072] In some instances, the processing circuitry 50 may determine whether the noise criterion (132 is satisfied) is met based on any of these criteria being met for any of the ventricular depolarizations 122B-122D. In some instances, the processing circuitry 50 may determine whether the noise criterion (132 is satisfied) is met based on certain combinations of these criteria. Based on the determination that the noise criterion (132 is satisfied), the processing circuitry 50 may proceed to the next depolarization 122 to determine whether the depolarization currently being used is a PVC depolarization (134). In some instances, based on the determination that the noise criterion (132 is satisfied), the processing circuitry 50 may advance a predetermined number of depolarizations to avoid using a noisy ventricular depolarization 122 as the current or adjacent depolarization.

[0073] Based on the determination that the noise criterion (No) is not met (132), the processing circuit system 50 determines whether the depolarization intervals 124A-124C meet one or more depolarization interval criteria (136). In some instances, the depolarization interval criteria are met based on the depolarization intervals 124A-124C meeting a corresponding threshold. Meeting such a corresponding threshold indicates that the corresponding lengths of the depolarization intervals 124A-124C conform to the expected lengths when ventricular depolarization 122C is PVC depolarization; for example, interval 124B is relatively short and interval 124C is relatively long. The following is about... Figure 8 Describe the standard for depolarization intervals.

[0074] Based on the determination that the depolarization interval criterion (No) is not met (136), the processing circuitry 50 can determine whether it is time to update one or more thresholds for morphological criteria (138) and ultimately proceed to the next ventricular depolarization 122 without indicating that the current ventricular depolarization 122C is a PVC depolarization (134). Based on the determination that the depolarization interval criterion (Yes) is met (136), the processing circuitry 50 can determine whether one or more morphological criteria are met (140). The processing circuitry 50 can determine whether ventricular depolarizations 122B–122D meet morphological criteria based on, for example, the maximum amplitude, minimum amplitude, and / or slope interval of depolarizations and correlation values ​​between depolarizations (e.g., cross-correlation and / or difference sum values). The following is about Figure 8 Describe the example form standard.

[0075] Based on the determination that one or more morphological criteria (140) are met, the processing circuit system 50 can determine that the current ventricular depolarization 122C is PVC depolarization (142). In this way, Figure 7 The example operation requires both the depolarization interval and morphological criteria to be met in order to determine whether the current ventricular depolarization is PVC depolarization, which can facilitate the required specificity of PVC detection. Other instances of the technology according to this disclosure may require meeting fewer, additional, or different criteria.

[0076] Regardless of whether the one or more morphological criteria are met (140 yes) or not met (140 no), the processing circuitry 50 can determine whether it is time to update one or more thresholds used for the morphological criteria (138). For example, the processing circuitry 50 can update the thresholds by comparing the correlation values ​​of ventricular depolarization 122B–122D with the thresholds based on the correlation values ​​determined for previously depolarized morphology. In some instances, the processing circuitry 50 periodically updates the thresholds based on the correlation values ​​determined during an update cycle; for example, every N heartbeats, the processing circuitry 50 updates the thresholds to be used for the subsequent N heartbeats based on the correlation values ​​determined during N heartbeats. N is an integer number of heartbeats, such as twelve. The processing circuitry 50 updates the correlation thresholds based on determining that it is time to update the correlation thresholds (138 yes) (144). Figure 10 and 11 A further detailed description of example techniques for determining whether it is time to update the threshold (138) and for updating the threshold (144) is provided. Regardless of whether the threshold is updated (144) or not (No 138), the processing circuitry system 50 can proceed to the next depolarization (134) and again obtain fragments of cardiac EGM 120 within the depolarization interval 124 and window 126 for the new previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization to determine whether the current ventricular depolarization is in PVC depolarization (130).

[0077] As described above, the processing circuitry system (such as the processing circuitry system 50 of IMD 10) may include any combination of hardware, firmware, and software configured to implement one or more of the techniques described herein. In some instances, implementation of certain aspects of the techniques in hardware can improve the computational and power performance of the implementing device (e.g., IMD 10). As an example, the processing circuitry system may include hardware configured to calculate differential sums or other correlation values, maximum and minimum R-wave amplitudes, maximum and minimum slopes, slope intervals, and differential signals for identifying noise characteristics, and firmware for other functions described herein.

[0078] Figure 8 This is a flowchart illustrating an example operation used to determine whether the interval and morphological criteria are met to determine whether the current ventricular depolarization is PVC depolarization. Figure 8 Example operations can be Figure 7 The example implementations of elements 136 and 140 are shown as based on not satisfying Figure 7 The noise standard (132) is used as a starting point. In other instances, Figure 8 The example operation can be performed as part of another method for identifying PVCs.

[0079] Figure 8Example operations include various paths, each including corresponding, different combinations of interval and morphological criteria. Based on satisfying said combinations, the processing circuitry 50 can identify the current ventricular depolarization 122C as PVC depolarization (142). The combination of interval and morphological criteria can be configured to provide the desired level of sensitivity and specificity for PVC detection.

[0080] according to Figure 8 In this instance, the processing circuit system 50 determines whether the first depolarization interval criterion (150) is met. If the first depolarization interval criterion is not met (No in 150), the processing circuit system 50 determines whether the second depolarization interval criterion (152) is met. If the second depolarization interval criterion is not met (No in 152), the processing circuit system 50 determines whether the third depolarization interval criterion (154) is met. If the third depolarization interval criterion is not met (No in 154), the processing circuit system 50 does not identify the current ventricular depolarization 122C as PVC depolarization and can continue to determine whether it is time to update the relevant threshold. Figure 7 (of 138).

[0081] In some instances, the first depolarization interval criterion is that the depolarization interval 124B is less than (depolarization interval 124A – j) and less than (depolarization interval 124C – j), where j is a predetermined offset, such as 10 ms. In some instances, the second depolarization interval criterion is that the ratio of depolarization interval 124B to depolarization interval 124A and the ratio of depolarization interval 124B to depolarization interval 124C are both less than a predetermined ratio threshold, such as 1.25, and the depolarization interval 124B is less than the first predetermined depolarization interval threshold, such as 800 ms. In some instances, the third depolarization interval criterion is that the depolarization interval 124B is less than the second predetermined depolarization interval threshold, such as 430 ms, and both the depolarization intervals 124A and 124C are greater than the third predetermined depolarization interval threshold, such as 500 ms.

[0082] Based on the determination that the first interval criterion (150) is met, the processing circuit system 50 determines whether the amplitude and / or slope criterion (156), which serves as an example of a morphological criterion, is met. The processing circuit system 50 can then base its determination on the above regarding... Figure 6 The description of ventricular depolarization 122B–122D determines whether the amplitude and / or slope criteria of ventricular depolarization 122C are met, based on the maximum amplitude, minimum amplitude, maximum slope, minimum slope, and slope interval. Figure 9 Further description. Based on determining that the amplitude and / or slope criteria (156 is met), the processing circuit system 50 can determine that the current ventricular depolarization 122C is PVC depolarization ( Figure 7(142).

[0083] Based on the determination that the amplitude and / or slope criteria (156) are not met, the processing circuit system 50 can determine whether a first correlation criterion (158) is met. To determine whether the correlation criteria are met, the processing circuit system 50 can determine the correlation value between each paired ventricular depolarization 122B–122D. The correlation value is as described above regarding… Figure 6 In the example of the difference and sum value determined by the processing circuit system 50, the processing circuit system 50 can determine the correlation value (D) between ventricular depolarization 122B and ventricular depolarization 122C. n-1,n The correlation value between ventricular depolarization 122C and ventricular depolarization 122D (D) n,n+1 ) and the correlation value between ventricular depolarization 122B and ventricular depolarization 122D (D n-1,n+1 ).

[0084] In some instances, the primary relevant criterion is:

[0085] {D n-1,n+1 <(240+aThr) and (D) n-1,n –D n-1,n+1 )>(100+aThr) and (D n,n+1 –D n-1,n+1 )>(100+aThr)} or {D n-1,n+1 <(285+aThr) and (D) n-1,n –D n-1,n+1 )>(165+aThr) and

[0086] (D n,n+1 –D n-1,n+1 Equation 3: (165 + aThr)

[0087] The variable aThr is an adaptive threshold, for example, as about Figure 10 and 11 Further details will be discussed. The various constant values ​​for summing with aThr in Equations 3–5 are examples and may differ in some instances, and may be programmable in some instances.

[0088] Based on meeting the first relevant criterion (158 is), the processing circuit system 50 can determine that the current ventricular depolarization 122C is PVC depolarization. Figure 7 (142). Based on the non-compliance of the first relevant criterion (No in 158), the processing circuit system 50 can determine whether the second interval criterion (152) is met. Based on the satisfaction of the second interval criterion (Yes in 152), the processing circuit system 50 can determine whether the second relevant criterion (160) is met. In some instances, the second relevant criterion is:

[0089] {D n-1,n+1 <(60+aThr) and (D) n-1,n )>(180+aThr) and (D n,n+1 )>(180+aThr)} or {D n-1,n+1 <(130+aThr) and (D) n-1,n )>(250+aThr) and (D n,n+1 Equation 4: )>(250+aThr)}

[0090] Based on meeting the second relevant criterion (160 is), the processing circuit system 50 can determine that the current ventricular depolarization 122C is PVC depolarization. Figure 7 (142). Based on the failure to meet the second relevant criterion (No in 160), the processing circuit system 50 can determine whether the third interval criterion (154) is met. Based on the satisfaction of the third interval criterion (Yes in 154), the processing circuit system 50 can determine whether the third relevant criterion (162) is met. In some instances, the third relevant criterion is:

[0091] D n-1,n+1 <(245+aThr) and (D) n-1,n –D n-1,n+1 )>(35+aThr) and (D n,n+1 –D n-1,n+1 Equation 5 > (35 + aThr)

[0092] Based on meeting the third relevant criterion (162 is), the processing circuit system 50 can determine that the current ventricular depolarization 122C is PVC depolarization ( Figure 7 (142). Based on the failure to meet the third relevant criterion (No in 162), the processing circuit system 50 does not identify the current ventricular depolarization 122C as PVC depolarization, and can continue to determine whether it is time to update the relevant threshold ( Figure 7 (of 138). Although Figure 8 Example operations include identifying the current ventricular depolarization as PVC depolarization if one or more criteria are met (142), and continuing to determine whether it is time to update the relevant threshold if the criteria are not met (138). However, it should be understood that the processing circuitry can also determine whether it is time to update the relevant threshold (138) after identifying the current ventricular depolarization as PVC depolarization (142), such as... Figure 7 As shown.

[0093] In addition, although Figure 8 It is described in the context of instances of the difference and sum of values ​​determined between depolarizations, but Figure 8The technique can be applied to instances where the processing circuit system 50 determines other values ​​(such as cross-correlation values) that indicate the degree of correlation indicative of ventricular depolarization morphology. As described herein, a greater degree of correlation is indicated by a larger cross-correlation value and a smaller difference sum value. To illustrate this difference, the morphology criteria can be modified in instances where the correlation value is a cross-correlation value rather than a difference sum value. For example, in instances where the correlation value is a cross-correlation value, the directionality of the comparisons used in Equations 3–5 (e.g., > or <) and the threshold calculation can be modified.

[0094] Figure 9 This is a flowchart illustrating an example operation used to determine whether a morphological criterion based on amplitude and slope is met to determine if the current depolarization is a PVC. Figure 9 Example operations can be Figure 8 An example implementation of element 156 is shown, and is presented as based on satisfying Figure 8 The first interval standard (150 is) is used as the starting point. In other instances, Figure 9 The example operation can be performed as part of another method for identifying PVCs.

[0095] according to Figure 9 In this example, the processing circuit system 50 determines the maximum amplitude (maxR) for each depolarization 122B–122D. n-1,n,n+1 ) and their respective minimum amplitudes (minR) n-1,n,n+1 For example, the maximum and minimum amplitudes of the cardiac EGM 120 within each window 126A–126C (170). The processing circuitry 50 further determines whether the maximum and minimum amplitudes meet one or more amplitude criteria (172). In some instances, the processing circuitry 50 compares the maximum amplitudes of depolarizations with each other, compares the minimum amplitudes of depolarizations with each other, and / or compares the difference between the maximum and minimum amplitudes of each depolarization with the differences of other depolarizations. In some instances, the amplitude criteria are:

[0096] MnMxD n-1,n+1 <60 and MnMxD n-1,n >30 and MnMxD n,n+1 >30

[0097] Among them, MnMxD xy It is the absolute value (maxR) x –maxR y ) + absolute value (minR) x –minR y Equation 6

[0098] The various thresholds in Equation 6 are examples and may differ in some instances, and may be programmable in some instances. Based on the processing circuitry 50 determining that one or more amplitude criteria (No for 172) are not met, the processing circuitry 50 may determine whether a first relevant criterion is met. Figure 8 (158). Based on the processing circuit system 50 determining that one or more amplitude criteria (172) are met, the processing circuit system 50 can determine the corresponding maximum slope and corresponding minimum slope for each depolarization 122B–122D, for example, based on the maximum slope and minimum slope of the cardiac EGM 120 within each window 126A–126C (174). The processing circuit system 50 can determine the maximum slope and minimum slope (slopeint) for each depolarization 122B–122D. n-1,n,n+1 The corresponding slope interval between (e.g., number of samples or time period) (176).

[0099] Processing circuitry 50 determines whether one or more of the maximum slope, minimum slope, or slope interval meets one or more slope criteria (178). In some instances, processing circuitry 50 determines whether one or more slope criteria are met by comparing the corresponding slope intervals of depolarizations 122B–122D with each other to determine a comparison metric, such as a difference or ratio, and determining whether the comparison metric meets one or more criteria. In some instances, processing circuitry determines whether a first comparison metric used to compare a previous adjacent ventricular depolarization 122B with a subsequent adjacent ventricular depolarization 122D meets a similarity criterion, and determines whether a second comparison metric used to compare a previous adjacent ventricular depolarization 122B with the current ventricular depolarization 122C, and a third comparison metric used to compare a subsequent adjacent ventricular depolarization 122D with the current ventricular depolarization 122C, meets a dissimilarity criterion. If the current ventricular depolarization is a PVC depolarization, its slope interval can be expected to be longer than the slope intervals of adjacent depolarizations, and therefore different from the slope intervals of adjacent depolarizations. In some instances, the slope criterion is:

[0100] SD n-1,n+1 <7 and SD n-1,n >2 and SD n,n+1 >2,

[0101] Among them, SD xy It is the absolute value (slopeint) x –slopeint y Equation 7

[0102] The various thresholds in Equation 7 are examples and may differ in some instances, and may be programmable in some instances. Furthermore, in some instances, SD... xy It may be equal to slopeint x–slopeint y Instead of the absolute value of the difference, the processing circuit system 50 determines whether one or more slope criteria (178) are not met, based on whether the first relevant criterion is met. Figure 8 Based on the processing circuit system 50 determining that one or more slope criteria (178 is met), the processing circuit system 50 can determine that the current ventricular depolarization 122C is PVC depolarization (158). Figure 7 (142).

[0103] Figure 10 and 11 This is a flowchart illustrating example operations for adjusting relevant thresholds used to determine whether ventricular depolarization is PVC depolarization. In some instances, Figure 10 and 11 The operation can usually correspond to Figure 7 Elements 138 and 144. The processing circuit system 50 can periodically update the threshold used to identify PVC depolarization based on the correlation value in order to compensate for the changes in the amplitude and morphology of the cardiac EGM 120 over time, regardless of whether the given ventricular depolarization is normal or PVC.

[0104] Figure 10 It shows instances where the correlation value is a cross-correlation value, and Figure 11 This shows instances where the relevant values ​​are the difference and sum of values. Figure 10 and 11 The two instances adjust the correlation threshold based on correlation values ​​determined during the update cycle, which represent the maximum correlation between the two depolarized forms. However, the cross-correlation value representing the maximum correlation between the two depolarized forms is the maximum cross-correlation value, while the sum of differences representing the maximum correlation between the two depolarized forms is the minimum sum of differences value.

[0105] according to Figure 10 In an example, the processing circuit system 50 determines the cross-correlation value of the depolarized 122B–122D, for example, C. n-1,n+1 C n-1,n and C n,n+1 This is used to determine whether the current ventricular depolarization 122C is a PVC depolarization based on whether one or more relevant criteria are met (190). The processing circuitry 50 further determines whether one of the current cross-correlation values ​​is greater than the maximum cross-correlation value previously identified during the current update cycle (192). In some instances, to determine the maximum cross-correlation value during the update cycle, the processing circuitry 50 considers fewer than all the relevant values ​​determined for a particular current ventricular depolarization, such as, for example, only C. n-1,n+1 C n-1,n .

[0106] Based on the determination that the current cross-correlation value is greater than the existing maximum value of the update cycle (Yes in 192), the processing circuit system 50 updates the maximum cross-correlation value of the cycle to the current correlation value (194). Regardless of whether the maximum cross-correlation value is updated (194) or not updated (No in 192), the processing circuit system 50 determines whether the end of the update cycle has been reached (196). Based on the determination that the end of the update cycle has not been reached (No in 196), the processing circuit system 50 can continue to evaluate the cross-correlation value of the next current ventricular depolarization (198). Based on the determination that the end of the update cycle has been reached (Yes in 196), the processing circuit system 50 can update one or more correlation thresholds, such as the value of aThr, based on the maximum cross-correlation value during the update cycle (200). The processing circuit system 50 can further reset the maximum cross-correlation value to a predetermined update cycle start value and begin a new update cycle (202).

[0107] according to Figure 11 In an example, the processing circuit system 50 determines the difference and sum of values ​​between depolarized 122B and 122D, for example, D. n-1,n+1 D n-1,n and D n,n+1 The processing circuitry 50 is used to determine whether the current ventricular depolarization 122C is a PVC depolarization based on whether one or more relevant criteria are met (210). The processing circuitry 50 further determines whether one of the current sums of differences is less than the minimum sum of differences previously identified during the current update cycle (212). In instances where the correlation value is the sum of differences, the maximum correlation will be represented by the minimum sum of differences. In some instances, to determine the minimum sum of differences during the update cycle, the processing circuitry 50 considers fewer than all sums of differences determined for a particular current ventricular depolarization, such as, for example, only D. n-1,n+1 D n-1,n .

[0108] Based on the determination that the current sum of differences is less than the existing minimum sum of differences in the update cycle (212 is), the processing circuitry 50 updates the minimum sum of differences in the cycle to the current sum of differences (214). Regardless of whether the minimum sum of differences is updated (214) or not (212 is not), the processing circuitry 50 determines whether the end of the update cycle has been reached (216). Based on the determination that the end of the update cycle has not been reached (216 is not), the processing circuitry 50 can continue to evaluate the sum of differences for the next current ventricular depolarization (218). Based on the determination that the end of the update cycle has been reached (216 is), the processing circuitry 50 can update one or more relevant thresholds, such as the value of aThr, based on the minimum sum of differences during the update cycle (220). The processing circuitry 50 can further reset the minimum sum of differences to a predetermined update cycle start value and begin a new update cycle (222).

[0109] In some instances, the processing circuitry 50 determines the difference D used to determine whether the current ventricular depolarization 122C is a PVC depolarization. n-1,n+1 D n-1,n Is it less than the existing minimum sum of differences during an update cycle of N cardiac cycles (e.g., 12 cardiac cycles)? After evaluating 2N sums of differences (e.g., 2 sums of differences from each cardiac cycle without noise), the processing circuitry 50 can update the adaptive threshold (aThr) by running the minimum value and resetting the running minimum value to a predetermined update cycle start value, such as 5000. In some instances, the processing circuitry 50 can update aThr based on the following:

[0110] For n = 1 to 12, minCorr = minimum value {5000; D} n-1,n+1 ;D n-1,n Equation 8

[0111] aThr = (minCorr – 25) / 2, where the minimum allowable value of aThr is -120.

[0112] And the maximum value is 230. (Equation 9)

[0113] In some instances, the values ​​of 5000, 12, 25, -120, and 230 can be fixed or programmable.

[0114] The techniques described in this disclosure can be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, aspects of these techniques can be implemented in one or more processors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic QRS circuit systems, and any combination of such components embodied in external devices (such as doctor or patient programmers, simulators, or other devices). The terms "processor" and "processing circuit system" can generally refer to any of the aforementioned logic circuit systems, alone or in combination with other logic circuit systems, or any other equivalent circuit system, alone or in combination with other digital or analog circuit systems.

[0115] For each aspect implemented in software, at least some of the functions of the systems and apparatus described in this disclosure can be embodied as instructions on a computer-readable storage medium, such as RAM, DRAM, SRAM, magnetic disk, optical disk, flash memory, or various forms of EPROM or EEPROM. The instructions can be executed to support one or more aspects of the functions described in this disclosure.

[0116] Furthermore, in some aspects, the functions described herein can be housed within dedicated hardware and / or software modules. Describing different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. Rather, the functions associated with one or more modules or units can be performed by separate hardware or software components, or integrated into shared or separate hardware or software components. Moreover, the techniques can be implemented entirely within one or more circuit or logic elements. The techniques disclosed herein can be implemented in a wide variety of devices or apparatuses, including IMDs, external programmers, combinations of IMDs and external programmers, integrated circuits (ICs) or collections of ICs, and / or discrete circuit systems residing in IMDs and / or external programmers.

Claims

1. A medical system comprising: Multiple electrodes configured to sense a patient’s cardiac electrogram; as well as Processing circuitry system, the processing circuitry system being configured to: Identify multiple ventricular depolarizations within the aforementioned cardiac electrorecord; For each of the plurality of ventricular depolarizations, identify the maximum slope point, the minimum slope point, and the interval from the maximum slope point to the minimum slope point; as well as For each of the multiple ventricular depolarizations that constitute the current ventricular depolarization: Determine from the current ventricular depolarization, the previous adjacent ventricular depolarizations of the plurality of ventricular depolarizations, and The interval between the maximum slope point and the minimum slope point of the subsequent adjacent ventricular depolarizations of the plurality of ventricular depolarizations satisfies one or more slope criteria; and Based on the interval from the maximum slope point to the minimum slope point that satisfies one or more slope criteria, the current ventricular depolarization is determined to be ventricular premature beat (PVC) depolarization.

2. The medical system according to claim 1, wherein, To determine whether the interval from the maximum slope point to the minimum slope point satisfies one or more slope criteria, the processing circuitry is configured to: Compare the intervals with each other; Determine a separate comparison metric for each comparison; and Determine whether the comparison metric satisfies one or more slope criteria.

3. The medical system according to claim 2, wherein, To determine whether the comparison metric satisfies one or more slope criteria, the processing circuitry is configured to: The first comparison metric used to compare the previous adjacent ventricular depolarization with the subsequent adjacent ventricular depolarization is determined to meet a similarity criterion; and A second comparison metric for comparing the previous adjacent ventricular depolarization with the current ventricular depolarization, and a third comparison metric for comparing the subsequent adjacent ventricular depolarization with the current ventricular depolarization, are determined to satisfy a dissimilarity criterion.

4. The medical system of claim 2, wherein the comparison metric includes a corresponding difference between each of the intervals, and in order to determine that the comparison metric satisfies the one or more slope criteria, the processing circuitry is configured to: A first difference between the interval of the previous adjacent ventricular depolarization and the subsequent adjacent ventricular depolarization is determined to be less than a first threshold; and A second difference between the interval of the previous adjacent ventricular depolarization and the current ventricular depolarization, and a third difference between the interval of the subsequent adjacent ventricular depolarization and the current ventricular depolarization, are determined to exceed a second threshold.

5. The medical system according to any one of claims 1-4, wherein the processing circuitry is further configured to: For each of the plurality of ventricular depolarizations, identify the maximum and minimum amplitudes; and For each of the plurality of ventricular depolarizations that constitute the current ventricular depolarization: The maximum and minimum amplitudes of the current ventricular depolarization, the previously adjacent ventricular depolarization, and the subsequent adjacent ventricular depolarization are determined to satisfy one or more amplitude criteria; and Based on the maximum and minimum amplitudes that satisfy one or more amplitude criteria, the current ventricular depolarization is determined to be PVC depolarization.

6. The medical system of claim 5, wherein the processing circuitry is configured to pair one of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization with each of the other of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization: Compare the maximum amplitudes of the depolarizations with each other; and The minimum amplitudes of the depolarizations are compared with each other. in, In order to determine whether the current ventricular depolarization is PVC depolarization, the processing circuitry is configured to determine whether the comparison satisfies one or more amplitude criteria.

7. The medical system according to any one of claims 1-4, wherein the processing circuitry is further configured to, for each of the plurality of ventricular depolarizations, determine a depolarization interval, and for each of the plurality of ventricular depolarizations that is the current ventricular depolarization: The depolarization intervals of the current ventricular depolarization, the previously adjacent ventricular depolarization, and the subsequent adjacent ventricular depolarization are determined to satisfy one or more depolarization interval criteria; and Based on the depolarization interval that satisfies one or more of the depolarization interval criteria, the current ventricular depolarization is determined to be PVC depolarization.

8. The medical system according to any one of claims 1-4, wherein the processing circuitry is further configured to, for each of the plurality of ventricular depolarizations as the current ventricular depolarization: Determine the correlation value between one of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization and each pair of the other of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization; The relevant values ​​are determined to meet one or more relevant criteria; and Based on the relevant values ​​that satisfy one or more of the relevant criteria, it is determined that the current ventricular depolarization is PVC depolarization.

9. The medical system according to claim 8, wherein, In order to determine the relevant value, the processing circuitry is configured to determine the sum of differences between each pair of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization and the other of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization.

10. The medical system of claim 8, wherein the one or more relevant criteria include one or more thresholds, and the processing circuitry is configured to: For a plurality of correlation values ​​determined during the update cycle prior to the current depolarization, one of the plurality of correlation values ​​representing the largest correlation among the plurality of correlation values ​​is identified; and The one or more thresholds are adjusted based on one of the identified multiple relevant values.

11. The medical system according to claim 1, wherein, To identify the plurality of ventricular depolarizations, the processing circuitry is configured to apply a primary sensing channel and a secondary sensing channel to the cardiac electrogram, wherein the primary sensing channel and the secondary sensing channel have different blanking periods and amplitude thresholds.

12. The medical system of claim 1, wherein the plurality of ventricular depolarizations comprises a subset of depolarizations identified by the processing circuitry system, wherein the processing circuitry system is configured to exclude ventricular depolarizations from the subset based on excluded ventricular depolarizations that satisfy one or more noise criteria, wherein the one or more noise criteria include one or more of a depolarization interval criterion, an amplitude criterion, and a sign change criterion.

13. A medical system comprising: Multiple electrodes configured to sense a patient’s cardiac electrogram; as well as Processing circuitry system, the processing circuitry system being configured to: Identify multiple ventricular depolarizations within the cardiac electrorecord; and For each of the multiple ventricular depolarizations that constitute the current ventricular depolarization: Determine the correlation value between each pair of the current ventricular depolarization, the previous adjacent ventricular depolarization, and the subsequent adjacent ventricular depolarization and the other of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization; The relevant value is determined to satisfy one or more relevant criteria, including one or more thresholds; and Based on the correlation values ​​that meet one or more of the aforementioned relevant criteria, it is determined that the current ventricular depolarization is ventricular premature beat (PVC) depolarization. The processing circuit system is further configured to: For a plurality of correlation values ​​determined during the update cycle prior to the current depolarization, one of a plurality of correlation values ​​representing the greatest correlation among the plurality of correlation values ​​is identified; and The one or more thresholds are adjusted based on one of the identified multiple relevant values.

14. The medical system according to claim 13, wherein, In order to determine the relevant value, the processing circuitry is configured to determine the sum of differences between each pair of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization and the other of the previous adjacent ventricular depolarization, the current ventricular depolarization, and the subsequent adjacent ventricular depolarization.

15. The medical system of claim 14, wherein one of the identified plurality of relevant values ​​includes a minimum difference sum determined during the update cycle.

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