CN111714772B - Implanted medical device and ventricular fibrillation counting method - Google Patents

Abstract

The invention provides a ventricular fibrillation technical scheme of implantable medical equipment and the implantable medical equipment, wherein the implantable medical equipment comprises: a lead wire connecting the myocardial tissue with the sensing circuit and transmitting electrocardiosignals to the sensing circuit; and an execution circuit configured to perform a ventricular fibrillation count. The ventricular fibrillation count includes: acquiring a current real-time heart rate; updating a real-time heart rate data sequence according to the real-time heart rate; and calculating a ventricular fibrillation count value according to the heart rate data sequence, wherein the ventricular fibrillation count value is the number greater than a rapid ventricular rate threshold in the real-time heart rate data sequence.

Description

Implanted medical device and ventricular fibrillation counting method

Technical Field

The invention belongs to the field of medical equipment, and particularly relates to an improvement of heart disease implantable medical equipment.

Background

Such as an implantable defibrillator (ICD) or Implantable Cardiac Monitor (ICM) or cardiac pacemaker (CARDIACPACEMAKER), diagnose cardiac disease and provide therapy by monitoring cardiac electrical signals. One typical method is to determine whether ventricular tachycardia or ventricular fibrillation is present by real-time heart rate counting and to treat the heart based on the determination.

Disclosure of Invention

It is an object of the present invention to provide a method of ventricular fibrillation counting for use on an implantable medical device, the implantable medical device comprising:

a sensing circuit for sensing the electrocardiographic signal;

A lead connecting the myocardial tissue with the sensing circuit for transmitting an electrocardiosignal to the sensing circuit;

execution circuitry configured to:

Acquiring a current real-time heart rate;

Updating a real-time heart rate data sequence according to the real-time heart rate;

And calculating a ventricular fibrillation count value according to the heart rate data sequence, wherein the ventricular fibrillation count value is the number greater than a rapid ventricular rate threshold in the real-time heart rate data sequence.

The counting method converts a plurality of real-time heart rates into a data sequence, counts the number of the data sequence which is larger than the rapid ventricular rate as ventricular fibrillation counting data, and can reflect heartbeat data within a period of time.

In a preferred embodiment, the method of ventricular fibrillation counting in an implanted medical device, the real-time heart rate data sequence is 24 bits in length.

In a preferred arrangement, the real-time heart rate sequence is stored in a shift register which performs a shift after the real-time heart rate is acquired.

In a preferred embodiment, the ventricular fibrillation threshold is an alternative value in the range of 140-250 bpm.

The second purpose of the invention is to provide an implanted medical device, which calculates the ventricular fibrillation count value according to the real-time heart rate data sequence, wherein the ventricular fibrillation count value is the number greater than the ventricular rate threshold in the real-time heart rate data sequence; and if the ventricular fibrillation count value reaches a first threshold value, diagnosing ventricular fibrillation.

In a preferred scheme, judging whether a ventricular fibrillation area value exists in a heart rate backtracking window; the value of the ventricular fibrillation if present and the ventricular fibrillation if not present is rapid.

The backtracking window is the last specific heartbeats of the tail part of the real-time heart rate sequence, the heartbeats in the backtracking window reflect the heartbeat condition closest to the period of time before the real-time heartbeats of the patient, and the backtracking window is adopted to judge whether ventricular fibrillation can improve the diagnosis precision.

It is a further object of the present invention to provide a method for joint counting of cardiac events of an implantable medical device, the cardiac events including ventricular rate events and ventricular fibrillation events. The count of the heart combination counter is the algebraic sum of the ventricular fibrillation count and the ventricular rate count.

Specifically, the joint counting method comprises the steps of:

Acquiring a current real-time heart rate;

Updating a ventricular fibrillation count and a ventricular rate count according to the real-time heart rate, the ventricular fibrillation count comprising the steps of: updating a real-time heart rate data sequence according to the real-time heart rate roll; calculating a ventricular fibrillation count value according to the real-time heart rate sequence, wherein the ventricular fibrillation count value is the number greater than a rapid ventricular speed threshold in the real-time heart rate data sequence;

If the ventricular fibrillation count reaches a first threshold, updating the joint count, wherein the joint count is algebraic sum of the ventricular rate count and the ventricular fibrillation count.

The combined meter uses the sum of ventricular fibrillation and ventricular tachycardia to prevent the heart rate from being fluctuated by the boundary between the ventricular fibrillation and ventricular tachycardia, and the ventricular fibrillation or ventricular tachycardia count is only relied on to reach the threshold for triggering diagnosis or treatment.

The fourth object of the present invention is to provide an implantable medical device for diagnosing arrhythmia using a joint counting method,

The implanted medical device is configured to: and performing arrhythmia diagnosis when the joint counter reaches a second threshold, wherein the arrhythmia diagnosis comprises: :

Judging whether a ventricular fibrillation area value exists in a heart rate backtracking window; judging that the ventricular fibrillation exists if the value of the ventricular fibrillation area exists; if not, judging the chamber speed;

judging whether the value of the rapid ventricular zone exists in the heart rate backtracking window, if so, judging that the rapid ventricular zone value is rapid, otherwise, judging that the rapid ventricular zone value is ventricular.

Drawings

Fig. 1 is a schematic view of an implantable medical device.

Fig. 2 is a schematic diagram of an implantable medical device ventricular fibrillation count flow.

Fig. 3 is a logic structure diagram of a real-time heart rate data sequence.

Fig. 4 is a schematic diagram of a ventricular fibrillation diagnosis flow of an implantable medical device.

Fig. 5 is a schematic diagram of an implantable medical device joint count flow.

Fig. 6 is a flow chart of a ventricular rate count for use in joint counting of implantable medical devices.

Fig. 7 is a flow chart of arrhythmia diagnosis by an implantable medical device using joint counts.

Detailed Description

The implantable medical device of the present invention is a cardiac medical device including, but not limited to, an Implantable Cardiac Defibrillator (ICD), an Implantable Cardiac Monitor (ICM), an implantable cardiac pacemaker (LEAD LESS PACEMAKER), a leadless implantable cardiac defibrillator, a Subcutaneous Implantable Cardiac Defibrillator (SICD). The implanted medical device can sense electrocardiosignals, diagnose heart diseases of patients according to the electrocardiosignals and store key heart data. Wherein the ICD and pacemaker are also capable of providing defibrillation/pacing or like therapy based on the diagnostic results.

The invention uses an Implantable Cardiac Defibrillator (ICD) as an illustration of the application of a ventricular fibrillation (ventricular fibrillation for short) counting method, a ventricular tachycardia (ventricular tachycardia for short) counting method and a combined counting method, and a corresponding diagnosis method. It is apparent that those skilled in the art can easily apply these methods to implantable cardiac medical devices such as implantable cardiac pacemakers, implantable cardiac monitors, and the like.

ICD overall structure

Fig. 1 illustrates the internal structural modules of ICD104, and where the leads and electrodes are located after implantation into a human heart. The ICD includes a body portion 104 and a lead 105 connected to the ICD. The body portion is formed of a metal housing 102 and a connector 106 disposed on the metal housing, the connector 106 for electrically connecting an ICD hybrid 108 and leads. The metal housing 102 is typically a biocompatible titanium metal shell and the ICD hybrid is disposed inside the metal housing 102. ICD lead 105 is used to connect cardiac tissue 116 to ICD hybrid circuit 108, and ICDs are used to deliver cardiac electrical signals to the hybrid circuit 108. While the ICD delivers therapies including pacing, defibrillation, anti-tachycardia pacing, etc. through the hybrid circuit 108.

ICD hybrid circuit

ICD hybrid circuit 108 includes a sensing unit 110, an execution unit 114, a therapy unit 112, and a communication unit 126. The sensing unit 110 is configured to receive an electrocardiographic signal transmitted through the lead 105, and the sensing unit 119 includes a signal processing circuit, where the electrocardiographic signal passes through an amplifying module, a filtering module, and an ADC conversion module, and finally forms a digital signal that can be read and processed by the executing unit 114. The sensing unit 110 may further include any other known signal processing method besides signal processing, for example, the filtering module may include a digital filtering unit, and the sensing unit may also be an ASIC.

Hybrid circuit therapy unit

The treatment unit 112 includes a charge and discharge control circuit and a capacitor. The charge-discharge control circuit charges the electrical circuitry in the ICD battery into the capacitor through the transformer and the discharge control circuit discharges the electrical energy in the capacitor through the lead 106 into the myocardial tissue 116. The energy released by the pacing therapy is approximately in the range of 0.25 muj-6 muj and the defibrillation is approximately in the range of 20J-40J, with the above treatment being able to restore sinus rate in patients suffering from ventricular tachycardia or ventricular fibrillation, etc.

Hybrid circuit communication unit

The communication unit 126 includes circuitry and an antenna for communication, and the communication unit 126 is configured to communicate with an ICD programmer or other recorder or remote follow-up device. The ICD program control instrument is equipment used by doctors in diagnosis and treatment, and is provided with a display and an input device, so that the doctors can check an electrocardiogram perceived by the ICD on the program control instrument and check parameters of the ICD. These parameters include sensing parameters, diagnostic parameters, or therapeutic parameters, among others. The ICD communicates with the programmer via known wireless communication techniques including, but not limited to, NFC near field communication, bluetooth communication, wireless local area network technology, or ultrasonic communication, among others. The electrocardiogram, sensing parameters, diagnostic parameters and the like are transmitted between the ICD and the program control instrument in a data packet mode through the communication protocol.

Hybrid circuit execution unit

ICD execution unit 114 is an execution circuit disposed on ICD hybrid circuit 108, including but not limited to a special purpose processor, a general purpose processor, an ASIC (application specific integrated circuit), a CPLD (complex programmable logic device), or an FPGA (field programmable logic array), typically a processor chip. In the preferred scheme, the processor chip is an MCU singlechip, and the inside of the processor chip comprises a storage circuit which is used for storing the QRS waveform template. Besides diagnostic functions, the execution unit can also complete signal sensing, ventricular fibrillation diagnosis and treatment. The above-mentioned functions can also be implemented by computer instruction code, and the described computer instruction code is formed from source program which is compiled and burned into the storage circuit of the described MCU. It should be noted that the memory circuit in the MCU is not necessary, and the memory circuit may also be stored in a separate module. The MCU communicates with the memory module via reserved pins, which are typically used to connect the bus of the ICD hybrid. Including but not limited to address buses, communication buses, and control buses. In the present invention, the storage circuit is further configured to store a patient QRS waveform template for SVT matching.

The execution unit is used for realizing all functions of the ICD, including but not limited to electrocardiosignal sensing, transceiving of communication data, diagnosis and treatment. The execution unit cooperates by controlling the sensing unit 110, the communication unit 126, the treatment unit 112, etc. to realize diagnosis, treatment, report data or status of the patient, and simultaneously receive prescription parameters set by a doctor on the ICD programmer and transmit data to the programmer.

Algorithm population

The machine code stored in the memory includes methods that may enable ventricular fibrillation counts, methods that utilize the ventricular fibrillation counts in combination with joint counts of ventricular rate counts. It is noted that the memory unit in the ICD may store one or more of the above methods, and the execution unit is configured to execute one or more of the above methods, i.e. the ICD programmer may be able to perform different types of counting or diagnosis simultaneously.

These algorithms are described below with reference to fig. 2-6, respectively.

Ventricular fibrillation counting method

Referring to fig. 2 and 3, the method of ventricular fibrillation counting includes the steps of:

202, acquiring a current real-time heart rate;

204 updating a real-time heart rate data sequence 300 based on the real-time heart rate;

206 calculating a ventricular fibrillation count value according to the heart rate data sequence, wherein the ventricular fibrillation count value is the number of the real-time heart rate data sequence which is larger than a rapid ventricular speed threshold.

The real-time heart rate is the heart rate x (n) of the last beat of the electrocardiograph signal perceived by the perceiving unit in the process 202. Where the x (n) function represents the real-time heart rate calculation method, a typical real-time heart rate calculation method, is obtained by calculating the time interval between the last hop (n hops) and the previous hop (n-1 hops). The execution unit searches the position of the R wave crest of the last jump when determining the real-time heart rate, then searches the position of the R wave crest of the previous jump, calculates the interval between the two R wave crests and determines the time t used for the jump, wherein the real-time heart rate is 1/t (t is in seconds), or 1000/t (t is in milliseconds).

The real-time heart rate is stored as a data sequence 300 in the process 204 with reference to fig. 3. Typically the length of the data sequence is 10-24, i.e. the real-time heart rate value storing the last 24 hops is denoted x (n-23), x (n-22), x (n-21). The data sequence may be represented as an array in the source program, that is, a continuous address space in the MCU memory, and the data storage sequence may also be a shift register, where the forefront data in the data sequence of each shift action of the shift register is shifted out, and the real-time heart rate is stored in the last bit of the sequence of the real-time heart rate, that is, the new real-time heart rate data sequence is x (n-22), x (n-21), x (n-20).

The number of real-time heart rates greater than the fast ventricular rate threshold is counted as a ventricular fibrillation count in the process 206. Whether each jump in the real-time heart rate data sequence belongs to ventricular fibrillation or not is obtained by comparing the heart rate with a rapid ventricular rate threshold. The fibrillation count value is stored in process 206 using variable y, and it is apparent that the real-time heart rate data sequence changes every hop, so that the fibrillation count value y may change after every fibrillation count statistics.

The ventricular rate threshold is a critical value of a treatment-free heart rate partition and a ventricular rate partition, and the fast ventricular rate threshold is a critical value of a slow ventricular rate partition and a fast ventricular rate partition. In the ICD algorithm the heart rate of the patient is divided into, in order of decreasing arrival, a slow ventricular rate zone, a ventricular rate zone, and a ventricular fibrillation zone. Preferably, the value range of the ventricular rate threshold is 90-200bpm, the value range of the ventricular rate threshold is 140-250bpm, and the value of the ventricular fibrillation threshold is more than 250bpm. Assuming that the slow chamber speed threshold value is 150bpm, the fast chamber speed threshold value is 200bpm, and the ventricular fibrillation threshold value is 250bpm; then the real-time heart rate x (n) <150bpm is considered a treatment-free heart rate if 150.ltoreq.x (n) <200bpm is considered to be in the ventricular tachycardia region if 200.ltoreq.x (n) <250 is considered to be in the rapid ventricular tachycardia region if x (n) >250 is considered to be in the ventricular fibrillation region. The rapid ventricular rate threshold may be different for different patients. The specific threshold value needs to be set by the doctor in the prescription parameters of the program control instrument according to the condition of the patient.

Referring to fig. 4, which illustrates a flow of an implantable medical device for ventricular fibrillation diagnosis using ventricular fibrillation counts based on fig. 2, an execution unit of the implantable medical device is configured to implement the functions of the flow of fig. 4.

Where the flows 402-406 are all identical to the flows 202-206 of fig. 2, the execution completes 402-406. Flow 408 a defibrillation diagnostic flow 410 is performed if the defibrillation count value reaches a threshold t 0.

In the process 408, the threshold t0 is set to 18, and it is obvious that the counting person skilled in the art can adjust the threshold t0 according to the knowledge of the person skilled in the art.

The diagnosis of ventricular fibrillation: a value 410 that includes determining if a ventricular fibrillation zone exists in the heart rate backtracking window; the value of the ventricular fibrillation if present and the ventricular fibrillation if not present is rapid.

Referring back to fig. 3, the window W refers to a number of real-time heart rate values from the last real-time heart beat onwards. For example, the backtracking window size is set to 8, and the backtracking windows are x (n-7), x (n-1), x (n). If there is a real-time heart rate value of the ventricular fibrillation region (e.g., a heart rate greater than 250 bpm) in the 8 heart rates, it is diagnosed as ventricular fibrillation in flow 410, and if there is no real-time heart rate value of the ventricular fibrillation region, it is diagnosed as fast ventricular tachycardia. And the execution unit controls the treatment to select an appropriate treatment mode according to the diagnosis result.

The backtracking window W is used for confirming the heartbeat condition of the patient in a period of time, and preventing the patient from generating false treatment after the heart rate of the patient is recovered by self. It is apparent that the size of the backtracking window is adjustable, but the backtracking window cannot exceed the length of the real-time heart rate data sequence 300.

Joint counting method population

Referring to fig. 5, a method of joint counting is shown, which combines the method of defibrillation counting and the method of ventricular rate counting, and adds the defibrillation counting and the ventricular rate counting to obtain a joint counting, wherein the joint counting can quickly converge when the real-time heart rate fluctuates between ventricular rate and rapid ventricular rate relative to ventricular fibrillation or ventricular rate counting.

Combined counting method

Method for joint counting of cardiac events, comprising

502 Obtaining a current real-time heart rate;

504 updating a ventricular fibrillation count and a ventricular rate count based on the real-time heart rate, the ventricular fibrillation count comprising the steps of: updating a real-time heart rate data sequence according to the real-time heart rate roll; calculating a ventricular fibrillation count value according to the real-time heart rate sequence, wherein the ventricular fibrillation count value is the number greater than a rapid ventricular speed threshold in the real-time heart rate data sequence;

If 506 the ventricular fibrillation count reaches the first threshold t1, then a process 508 updates the joint count, which is the algebraic sum of the ventricular rate count and the ventricular fibrillation count.

Wherein the flow 502 is the same as the method used by the flow 202 in fig. 2. The method of updating the ventricular fibrillation counter in process 504 is the same as the processes of processes 204 and 206 in fig. 2, and in process 506 the joint counter, i.e. the ventricular fibrillation count, is updated to 18 only when the velocity of the ventricular fibrillation counter reaches a first threshold t1, preferably 18, and if the joint counter is not reached, the process returns to process 102 of acquiring a real-time heart rate. It should be noted that the ventricular fibrillation count and the ventricular rate count use the same real-time heart rate x (n) data and are counted independently, and the values of the ventricular fibrillation count and the ventricular rate count are respectively stored in different variable values.

Chamber speed counting method in combined counting method

The method of chamber speed counting described with reference to fig. 6 further includes the steps of:

602 obtain a real-time heart rate, which corresponds to the process 102 of fig. 5, which may be one process.

604, When the real-time heart rate is smaller than the ventricular rate threshold, clearing the ventricular rate count;

606, counting self-increment when the real-time heart rate is larger than the room speed threshold and smaller than the shutter threshold;

the count is unchanged when the chamber speed counter is greater than a fast chamber speed threshold.

The chamber speed threshold is preferably an alternative value of 90-200bpm, for example 150bpm;

taking the above-mentioned room speed threshold of 150bpm and the fast room speed threshold of 200bpm as an example, when the real-time heart rate is smaller than the room speed threshold of 150bpm in the process 604, the real-time heart rate is considered to be a normal heart rate, and thus is not counted as the room speed heart rate. If not, the process proceeds to 606.

When the real-time heart rate is less than the fast room speed threshold 200 once in the process 606, the room speed count value is self-incremented by 1, i.e., the process 608 is executed.

When greater than the fast ventricular speed threshold 200 occurs, it is deemed to be outside the range of ventricular speeds into the count range of ventricular fibrillation or fast-time in flow 606.

From the above-described flow of combined count and ventricular rate count, it can be seen that the real-time heart rate counts ventricular rate in the ventricular rate zone, and if outside the ventricular rate zone limit, counts ventricular fibrillation while the ventricular rate count is suspended. Meanwhile, the value of the joint count is algebraic sum of the real-time heart rate and the ventricular fibrillation, so that the real-time heart rate can be normally calculated by the joint count no matter whether the real-time heart rate is ventricular fibrillation or ventricular fibrillation, and the problem that the real-time heart rate is slowly converged in the vertical fluctuation of the ventricular fibrillation threshold and the ventricular fibrillation threshold can be avoided.

Referring to fig. 7, a diagnostic method of an implantable medical device based on a joint counting method is illustrated, the execution unit of the implantable medical device being configured to implement all of the functions in the flow shown in fig. 7.

The flow 702-708 therein is the same as the flow 504-508 in fig. 5.

The count value of the joint count is obtained after the joint count is updated after the execution of flow 708, i.e., after reaching flow 710.

If the joint count reaches a second threshold t2, arrhythmia diagnosis is performed in flow 710. The second threshold t2 is preferably 21 when a heart rate data sequence length of 24 is implemented.

The arrhythmia diagnosis comprises the following steps:

Flow 712 determines whether a ventricular fibrillation zone value exists in the heart rate backtracking window W; judging that the ventricular fibrillation exists if the value of the ventricular fibrillation area exists; if not, judging the chamber speed;

Flow 714 determines whether there is a fast room speed region in the heart rate backtracking window W, if so, determines that the room speed is fast, otherwise, determines that the room speed is fast.

The backtracking window in flows 712 and 714 is the same as the backtracking window in fig. 3, and functions the same.

One or more of these functions may be implemented in an implantable medical device, and the particular implementation requires the physician to use a programmable logic device to set the device according to the patient's physical condition. Similarly, parameters and data used in the algorithm can be set according to the program controller. The implantable cardiac monitor ICM can be configured with a ventricular rate counting algorithm, a fibrillation counting algorithm, and a joint counting algorithm. The implantable cardiac defibrillator can also cooperate with corresponding therapies, such as pacing therapies, anti-tachycardia therapies, defibrillation therapies, etc., based on the above-described algorithms.

Claims (4)

1. An implantable medical device, comprising:

A sensing circuit for sensing an electrocardiographic signal;

A lead connecting the myocardial tissue with the sensing circuit for transmitting an electrocardiosignal to the sensing circuit;

Execution circuitry configured to perform:

Acquiring a current real-time heart rate;

Updating a ventricular fibrillation count and a ventricular rate count according to the real-time heart rate, the ventricular fibrillation count comprising: updating a real-time heart rate data sequence according to the real-time heart rate; calculating a ventricular fibrillation count value according to the real-time heart rate data sequence, wherein the ventricular fibrillation count value is the number of the real-time heart rate data sequence which is larger than a rapid ventricular speed threshold;

If the ventricular fibrillation count reaches a first threshold, updating the joint count, wherein the joint count is the sum of the ventricular rate count and the ventricular fibrillation count;

And if the joint count reaches a second threshold, performing arrhythmia diagnosis, wherein the arrhythmia diagnosis comprises: judging whether a ventricular fibrillation area value exists in a heart rate backtracking window; judging that the ventricular fibrillation exists if the value of the ventricular fibrillation area exists; if not, judging the chamber speed;

judging whether a value of a rapid room area exists in a heart rate backtracking window; judging the rapid room if the value of the rapid room area exists; if not, the chamber speed is determined.

2. The implantable medical device of claim 1, wherein the real-time heart rate data sequence is stored in a shift register that performs a shift after the real-time heart rate is acquired.

3. The implantable medical device of claim 2, wherein the real-time heart rate data sequence is 24 bits in length.

4. The implantable medical device of claim 1, wherein the fast room speed threshold is an alternative value in the range of 140-250 bpm.