Improved communication between medical devices

Abstract

This paper describes devices, systems, and methods for improving conducted communication between medical devices, such as leadless pacemakers (LCPs) and nonvascular implantable cardioverter defibrillators (NV-ICDs). To enhance channel noise immunity, inter-implant (i2i) communication can encode bit values ​​as orthogonal pseudo-noise pulse waveforms. When a first implantable device communicates with multiple devices, multiple data streams from these devices can be encoded as composite bits, each composite bit containing bits from each of the multiple intended receiving devices, and at least one bit in each data stream is encoded as an orthogonal pseudo-noise pulse waveform.

Description

[0001] Priority requirements

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 593,323, filed October 26, 2023, which is incorporated herein by reference as if fully set forth herein. Technical Field

[0003] The embodiments of the technology described herein generally relate to techniques for improving communication between implantable medical devices (IMDs). Embodiments of the technology also relate to systems and devices configured to implement such techniques. The embodiments of the technology described herein can also be used to improve conductive communication between an external device (which may also be referred to as an external medical device) and one or more IMDs. Background Technology

[0004] Active implantable medical devices (AIMDs), such as leadless pacemakers (LCPs), use implant-to-implant (i2i) communication to synchronize pacing and / or sensing events. An example of an existing solution for i2i communication is low-frequency (kHz range) conducted telemetry. There are cases where patients are implanted with both a dual-chamber LCP system (comprising a pair of LCPs) and a non-vascular ICD (NV-ICD) (such as, but not limited to, a subcutaneous implantable cardioverter-defibrillator (S-ICD)). In such cases, it may be useful for one or more LCPs to notify the NV-ICD of arrhythmic events detected by the LCPs, and for the NV-ICD to notify one or more LCPs to pause pacing during certain arrhythmic events so that the NV-ICD can provide electrical shock therapy. Therefore, providing conducted telemetry communication compatible with existing conducted telemetry i2i communication between LCPs and one or more LCPs would be useful. There are also cases where patients are exposed to noisy electromagnetic environments that may interfere with conducted telemetry. This type of noise can be misinterpreted as I2I communication signals by one or more receiving devices and processed by the device firmware, leading to undefined behavior such as changes in programming parameters. Conducted telemetry communication signals transmitted from the LCP to the NV-ICD are particularly susceptible to noise interference due to the typically weak signal reception at the NV-ICD. Summary of the Invention

[0005] Some embodiments of this technology relate to a method used by a first implantable medical device (IMD1) to generate a first bit sequence for communication from IMD1 to a second implantable medical device (IMD2), and a second bit sequence for communication from IMD1 to a third implantable medical device (IMD3). The method also includes IMD1 encoding the first and second bits into a composite bit comprising a first time slot containing the first bit and a second time slot containing the second bit, wherein IMD1 encoding the first and second bits includes IMD1 encoding the second bit into a first pseudo-noise pulse sequence corresponding to the value of the first bit or a second pseudo-noise pulse sequence corresponding to the value of the second bit, wherein the first and second pseudo-noise pulse sequences are orthogonal to each other. The method also includes IMD1 transmitting the composite bit, for example, using conducted communication.

[0006] Some embodiments of this technology relate to a method used by a first implantable medical device (IMD1) to generate a first bit sequence for communication from IMD1 to a second implantable medical device (IMD2), and to generate a second bit sequence for communication from IMD1 to a third implantable medical device (IMD3). The method further includes IMD1 encoding the first bit sequence and the second bit sequence into a composite bit sequence, each composite bit including a first time slot and a second time slot, the first time slot including a corresponding bit of the first bit sequence, and the second time slot including a corresponding bit of the second bit sequence. In some embodiments, encoding the second bit sequence includes encoding each bit in the second bit sequence as either a first pseudo-noise pulse sequence corresponding to a first bit value of the second bit sequence or a second pseudo-noise pulse sequence corresponding to a second bit value of the second bit sequence, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other. The method also includes IMD1 transmitting the composite bit sequence, for example, using conducted communication.

[0007] According to certain embodiments of the present invention, the method further includes the IMD3: receiving the composite bit series; and decoding the received composite bit series to extract a second bit series.

[0008] According to certain embodiments of the present technology, the IMD3 decodes the received composite bit series to extract the second bit series comprising the IMD3: multiplying each of the received composite bits by the first pseudo-noise pulse sequence; integrating each received composite bit in a second time slot multiplied by the first pseudo-noise pulse sequence over a duration; multiplying each received composite bit by the second pseudo-noise pulse sequence; integrating each received composite bit multiplied by the second pseudo-noise pulse sequence over the duration of the second time slot; mapping each integrated received composite bit multiplied by the first pseudo-noise pulse sequence and each integrated received composite bit multiplied by the second pseudo-noise pulse sequence to a corresponding co-channel value and a corresponding quadrature channel value; and determining the value of each bit in the second bit series based on the combination of the co-channel value and the quadrature channel value.

[0009] According to certain embodiments of the present technology, the IMD3 further includes decoding the received composite bit series to extract the second bit series by: the IMD3 determining, based on a combination of the same channel value, the orthogonal channel value, and the bit values ​​of the second bit series, that the data content of the received and decoded second bit series is corrupted.

[0010] According to certain embodiments of the present technology, the IMD1 encoding of the first bit series includes: encoding each bit of the first bit series as a flat waveform corresponding to the first bit value of the first bit series, or a pulse series corresponding to the second bit value of the first bit series.

[0011] According to certain embodiments of the present technology, the encoding of the first bit series by the IMD1 includes: encoding each bit in the first bit series as a third pseudo-noise pulse sequence corresponding to the first bit value of the first bit series or a fourth pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, wherein the first pseudo-noise pulse sequence, the second pseudo-noise pulse sequence, the third pseudo-noise pulse sequence and the fourth pseudo-noise pulse sequence are orthogonal to each other.

[0012] According to certain embodiments of the present technology, the method further includes: the IMD1 maintaining a lookup table of correspondence between the bit values ​​of the second bit series and the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence; and wherein the encoding of the first bit series and the second bit series by the IMD1 includes: the IMD1 using the lookup table to convert each bit of the second bit series into the corresponding pseudo-noise pulse sequence.

[0013] According to certain embodiments of the present technology, the composite bit series is a specified number of composite bits.

[0014] According to certain embodiments of the present technology, the method further includes the IMD1 using conductive communication to transmit the composite bit series, which includes: transmitting a wake-up pulse; and transmitting the composite bit series after transmitting the wake-up pulse.

[0015] According to certain embodiments of the present technology, the IMD1 sending the composite bit series using conductive communication further includes: waiting for a specified time period after sending the wake-up pulse and before sending the composite bit series.

[0016] According to certain embodiments of the present technology, the composite bit series includes multiple frames, each of which includes multiple composite bits.

[0017] According to certain embodiments of the present technology, the method further includes IMD3 transmitting a signal intended to be received by IMD1 using conductive communication. The signal includes an additional series of composite bits, each composite bit including a first time slot and a second time slot, the first time slot including a waveform corresponding to a data bit value, and the second time slot not containing data.

[0018] According to certain embodiments of the present technology, the method further includes IMD1: receiving a signal intended to be received by IMD1; and for each bit of a further composite bit series, determining a data value for a first time slot during a second time slot by IMD1. According to certain embodiments of the present technology, IMD1 is a first leadless pacemaker (LCP1), IMD2 is a second leadless pacemaker (LCP2), and a third device is an NV-ICD. In some implementations, IMD2 is a type of NV-ICD, also known as an S-ICD.

[0019] According to certain embodiments of the present technology, in each composite bit of the composite bit series, the first time slot precedes the second time slot.

[0020] Some embodiments of this technology relate to an implantable medical device including a conductive communication circuit configured to transmit signals to a plurality of additional implantable medical devices, and a controller connected to the conductive communication circuit. The controller is configured to: generate a first bit sequence to be communicated to a first implantable medical device in the additional implantable medical devices; generate a second bit sequence to be communicated to a second implantable medical device in the additional implantable medical devices; and encode the first bit sequence and the second bit sequence into a composite bit sequence. Each composite bit in the composite bit sequence includes a first time slot and a second time slot, the first time slot of the composite bit including a corresponding bit in the first bit sequence, and the second time slot of the composite bit including a corresponding bit in the second bit sequence. To encode the first bit sequence and the second bit sequence, the controller is configured to encode each bit in the second bit sequence into a first pseudo-noise pulse sequence corresponding to a first bit value of the second bit sequence or a second pseudo-noise pulse sequence corresponding to a second bit value of the second bit sequence, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other. The controller is also configured to control the conductive communication circuit to transmit the composite bit sequence using conductive communication.

[0021] According to certain embodiments of the present technology, in order to encode the first bit series, the controller is further configured to encode each bit of the first bit series as a flat waveform corresponding to the first bit value of the first bit series, or a pulse series corresponding to the second bit value of the first bit series.

[0022] According to certain embodiments of the present technology, the controller is further configured to: maintain a lookup table of correspondences between the bit values ​​of the second bit series and the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence; and wherein encoding the bits of the second bit series includes: the IMD1 using the lookup table to convert each bit of the second bit series into the corresponding pseudo-noise pulse sequence.

[0023] According to some embodiments, the composite bit series is a specified number of composite bits.

[0024] According to some embodiments, the controller is configured to control the conductive communication circuit to send a wake-up pulse, and after sending the wake-up pulse, to send a composite bit sequence.

[0025] According to some embodiments, the controller is configured to control the conductive communication circuit to wait for a specified period of time after sending a wake-up pulse and before sending a composite bit sequence.

[0026] According to some embodiments, the series of composite bits includes multiple frames, each frame including multiple composite bits.

[0027] According to some embodiments, the implantable medical device includes a first leadless pacemaker (LCP1), the first of a plurality of additional implantable medical devices includes a second leadless pacemaker (LCP2), and the second of a plurality of additional implantable medical devices includes a second leadless pacemaker (LCP2).

[0028] According to some embodiments, in each composite bit of the composite bit series, the first time slot precedes the second time slot.

[0029] Some embodiments of this technology relate to a system including multiple implantable medical devices, including a first implantable medical device (IMD1), a second implantable medical device (IMD2), and a third implantable medical device (IMD3). IMD1 is configured to: generate a first bit sequence to be transmitted from IMD1 to IMD2; generate a second bit sequence to be transmitted from IMD1 to IMD3; and encode the first bit sequence and the second bit sequence into a composite bit sequence, each composite bit in the composite bit sequence including a first time slot and a second time slot, the first time slot of the composite bit including a corresponding bit in the first bit sequence, and the second time slot of the composite bit including a corresponding bit in the second bit sequence. To encode the first bit sequence and the second bit sequence, IMD1 is configured to encode each bit in the second bit sequence as either a first pseudo-noise pulse sequence corresponding to a first value of the second bit sequence or a second pseudo-noise pulse sequence corresponding to a second value of the second bit sequence, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other. IMD1 is also configured to transmit the composite bit sequence using conducted communication.

[0030] According to certain embodiments of the present invention, the IMD3 is configured to: receive the composite bit series; multiply each received composite bit by a first pseudo-noise pulse sequence; integrate each received composite bit in a second time slot multiplied by the first pseudo-noise pulse sequence over a duration; multiply each received composite bit by a second pseudo-noise pulse sequence; integrate each of the received composite bits multiplied by the second pseudo-noise pulse sequence over the duration of the second time slot; map each of the integrated received composite bits multiplied by the first pseudo-noise pulse sequence and each of the integrated received composite bits multiplied by the second pseudo-noise pulse sequence to a corresponding co-channel value and a corresponding quadrature channel value; and determine the value of each bit in the second bit series based on a combination of the co-channel value and the quadrature channel value.

[0031] According to some embodiments, in order to encode the first bit series, IMD1 is configured to encode each bit of the first bit series as a flat waveform corresponding to the first bit value of the first bit series, or a pulse sequence corresponding to the second bit value of the first bit series.

[0032] According to some embodiments, in order to encode the first bit series, the IMD1 is configured to encode each bit in the first bit series as a third pseudo-noise pulse sequence corresponding to the first bit value of the first bit series, or a fourth pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, wherein the first pseudo-noise pulse sequence, the second pseudo-noise pulse sequence, the third pseudo-noise pulse sequence, and the fourth pseudo-noise pulse sequence are orthogonal to each other.

[0033] According to some embodiments, in order to encode the first bit series, IMD1 is configured to maintain a lookup table that corresponds the bit values ​​of the second bit series to the first and second pseudo-noise pulse sequences, and the lookup table is used to encode the first bit series and the second bit series to convert each bit of the second bit series into the corresponding pseudo-noise pulse sequence.

[0034] According to some embodiments, the composite bit series is a specified number of composite bits.

[0035] According to some embodiments, in order to use conductive communication to send a composite bit series, IMD1 is configured to send a wake-up pulse, and after sending the wake-up pulse, send the composite bit series.

[0036] According to some embodiments, in order to use conductive communication to send a composite bit series, IMD1 is configured to wait for a specified period of time after sending a wake-up pulse and before sending the composite bit series.

[0037] According to some embodiments, the series of composite bits includes multiple frames, each frame including multiple composite bits.

[0038] According to some embodiments, IMD3 is configured to use conductive communication to transmit a signal intended to be received by IMD1, the signal including another series of composite bits, each composite bit including a first time slot and a second time slot, the first time slot including a waveform corresponding to a data bit value, and the second time slot not containing data.

[0039] According to some embodiments, IMD1 is configured to receive signals intended to be received by IMD1, and for each bit in another composite bit series, to determine the data value of the first time slot during the second time slot.

[0040] According to some embodiments, IMD1 includes a first leadless pacemaker (LCP1), IMD2 includes a second leadless pacemaker (LCP2), and a third device includes a non-vascular implantable cardioverter defibrillator (NV-ICD).

[0041] According to some embodiments, in each composite bit of the composite bit series, the first time slot precedes the second time slot.

[0042] Some embodiments of this technology relate to a method used by a first implantable medical device (IMD1) to generate a first bit sequence for communication from IMD1 to a second implantable medical device (IMD2). The method further includes IMD1 encoding each bit in the first bit sequence as either a first pseudo-noise pulse sequence corresponding to a first bit value of the first bit sequence or a second pseudo-noise pulse sequence corresponding to a second bit value of the first bit sequence, thereby producing an encoded bit sequence, wherein the first and second pseudo-noise pulse sequences are orthogonal to each other. The method further includes IMD1 transmitting the encoded first bit sequence using conducted communication.

[0043] According to certain embodiments of the present technology, the method further includes the IMD2: receiving the encoded first bit sequence; and decoding the received encoded bit sequence to extract the first bit sequence.

[0044] According to certain embodiments of the present technology, decoding a received coded bit series to extract the IMD2 of the first bit series includes: multiplying each received bit in the received coded bit series by a first pseudo-noise pulse sequence; integrating each of the received coded bit series multiplied by the first pseudo-noise pulse sequence over the duration of the coded bit; multiplying each received bit in the received coded bit series by a second pseudo-noise pulse sequence; integrating each of the received coded bit series multiplied by the second pseudo-noise pulse sequence over the duration of the coded bit; mapping each of the received coded bit series integrated by multiplying by the first pseudo-noise pulse sequence and each of the received coded bit series integrated by multiplying by the second pseudo-noise pulse sequence to a corresponding co-channel value and a corresponding quadrature channel value; and determining the value of each bit in the first bit series based on the combination of the co-channel value and the quadrature channel value.

[0045] According to certain embodiments of the present technology, IMD2 decoding the received encoded bit series to extract the first bit series also includes IMD2 determining that the data content of the received and decoded first bit series is corrupted based on a combination of the same channel value, the orthogonal channel value, and the determined bit values ​​of the first bit series.

[0046] According to certain embodiments of the present technology, the method further includes: selecting an IMD2 from a plurality of implantable medical devices before IMD1 encodes each bit of the first bit series into a first pseudo-noise pulse sequence or a second pseudo-noise pulse sequence, each of the plurality of implantable medical devices having a corresponding one of a plurality of mutually orthogonal first and second pseudo-noise pulse sequences; and wherein, the encoding of each bit of the first bit series into the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence by IMD1 includes: encoding each bit of the first bit series into the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence corresponding to the selected IMD2.

[0047] According to certain embodiments of the present technology, the method further includes: the IMD1 maintaining a lookup table of corresponding mutually orthogonal first and second pseudo-noise pulse sequences for each of the plurality of implantable medical devices; and the IMD1 selecting a corresponding one of the plurality of mutually orthogonal first and second pseudo-noise pulse sequences from the lookup table.

[0048] According to certain embodiments of the present technology, the method further includes, before IMD1 transmits the encoded bit series using conductive communication, IMD1 transmitting an initial bit series encoded as a third pseudo-noise pulse sequence or a fourth pseudo-noise pulse sequence, the first, second, third and fourth pseudo-noise pulse sequences being orthogonal to each other, the initial bit series specifying: a plurality of implantable medical devices IMD2; and the first pseudo-noise pulse and the second pseudo-noise pulse.

[0049] According to certain embodiments of the present invention, the method further includes the IMD2: receiving the initial bit series; and determining whether the initial bit series specifies the IMD2.

[0050] According to certain embodiments of the present technology, the method further includes the IMD2: in response to specifying the initial bit series of the IMD2, decoding the first bit value of the first bit series.

[0051] According to certain embodiments of the present technology, the method further includes IMD2: after decoding the first value of the first bit series, IMD1 is recovered using a signal encoded with first and second pseudo-noise pulses.

[0052] According to certain embodiments of the present technology, the plurality of implantable medical devices includes a third implantable medical device (IMD3), and the method further includes the IMD3: receiving the initial bit sequence; determining whether the initial bit sequence specifies the IMD3; and in response to the initial bit sequence not specifying the IMD3, not decoding the first bit value of the first sequence.

[0053] According to certain embodiments of the present technology, the first series of bits is a specified number of bits.

[0054] According to certain embodiments of the present technology, the IMD1 sending the first bit series using conductive communication includes: sending a wake-up pulse; and sending the first bit series after sending the wake-up pulse.

[0055] According to certain embodiments of the present technology, the transmission of the first sequence using conductive communication by IMD1 further includes: waiting for a specified period of time after sending the wake-up pulse and before sending the first sequence.

[0056] According to certain embodiments of this technology, IMD1 is a first leadless cardiac pacemaker (LCP1), and IMD2 is an NV-ICD. In some embodiments, IMD2 is a type of NV-ICD, also known as an S-ICD.

[0057] According to certain embodiments of the present technology, IMD1 is a first leadless pacemaker (LCP1), and IMD2 is a second leadless pacemaker (LCP2).

[0058] Some embodiments of this technology relate to a system comprising multiple implantable medical devices, including a first implantable medical device (IMD1) and a second implantable medical device (IMD2). IMD1 is configured to: generate a first bit sequence to be transmitted from IMD1 to IMD2; encode each bit in the first bit sequence as either a first pseudo-noise pulse sequence corresponding to a first bit value of the first bit sequence or a second pseudo-noise pulse sequence corresponding to a second bit value of the first bit sequence, thereby producing an encoded bit sequence, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and transmit the encoded first bit sequence using conductive communication.

[0059] According to certain embodiments of the present technology, IMD1 is further configured to: select IMD2 from a plurality of implantable medical devices before encoding each bit of the first bit series as a first pseudo-noise pulse sequence or a second pseudo-noise pulse sequence, each of the plurality of implantable medical devices having a corresponding one of a plurality of mutually orthogonal first and second pseudo-noise pulse sequences; and wherein, in order to encode each bit of the first bit series as the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence, IMD1 is further configured to encode each bit of the first bit series as the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence corresponding to the selected IMD2.

[0060] According to certain embodiments of the present technology, IMD1 is further configured to transmit an initial bit series encoded as either a third pseudo-noise pulse sequence or a fourth pseudo-noise pulse sequence before transmitting the encoded bit series using conductive communication, wherein the first, second, third, and fourth pseudo-noise pulse sequences are mutually orthogonal, and the initial bit series specifies: a plurality of implantable medical devices IMD2; and the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence.

[0061] According to some embodiments, in order to encode the first bit series, IMD1 is configured to encode each bit of the first bit series as a flat waveform corresponding to the first bit value of the first bit series, or a pulse series corresponding to the second bit value of the first bit series.

[0062] According to some embodiments, in order to encode the first bit series, the IMD1 is configured to encode each bit in the first bit series as a third pseudo-noise pulse sequence corresponding to the first bit value of the first bit series or a fourth pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, wherein the first pseudo-noise pulse sequence, the second pseudo-noise pulse sequence, the third pseudo-noise pulse sequence and the fourth pseudo-noise pulse sequence are orthogonal to each other.

[0063] According to some embodiments, in order to encode the first bit series, IMD1 is configured to maintain a lookup table that corresponds the bit values ​​of the second bit series to the first and second pseudo-noise pulse sequences, and the lookup table is used to encode the first bit series and the second bit series to convert each bit of the second bit series into the corresponding pseudo-noise pulse sequence.

[0064] According to some embodiments, the composite bit series is a specified number of composite bits.

[0065] According to some embodiments, in order to use conductive communication to send a composite bit series, IMD1 is configured to send a wake-up pulse, and after sending the wake-up pulse, send the composite bit series.

[0066] According to some embodiments, in order to use conductive communication to send a composite bit series, IMD1 is configured to wait for a specified time period after sending a wake-up pulse and before sending the composite bit series.

[0067] According to some embodiments, the series of composite bits includes multiple frames, each frame including multiple composite bits.

[0068] According to some embodiments, in each composite bit of the composite bit series, the first time slot precedes the second time slot.

[0069] Some embodiments of this technology relate to an implantable medical device including a conductive communication circuit configured to transmit signals from a first implantable medical device (IMD1) to a second implantable medical device (IMD2); and a controller connected to the conductive communication circuit. The controller is configured to: generate a first bit sequence to be communicated from IMD1 to IMD2; encode each bit in the first bit sequence as a first pseudo-noise pulse sequence corresponding to a first bit value of the first bit sequence or a second pseudo-noise pulse sequence corresponding to a second bit value of the first bit sequence, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and control the conductive communication circuit to transmit the composite bit sequence using conductive communication.

[0070] This invention is not intended to be a complete description of embodiments of the present technology. Other features and advantages of embodiments of the present technology will become apparent from the following description, in which preferred embodiments have been set forth in detail with reference to the accompanying drawings and claims. Attached Figure Description

[0071] Embodiments of the present technology relating to both the structure and the method of operation can be best understood by referring to the following description and accompanying drawings, wherein similar reference numerals denote similar elements in several views:

[0072] Figure 1 A system comprising multiple implantable medical devices (IMDs) implanted in a patient is shown.

[0073] Figure 2 This is a high-level block diagram of an example LCP.

[0074] Figure 3 An example shape factor for LCP is shown.

[0075] Figure 4 This is a high-level block diagram showing example details of an implantable cardioverter defibrillator (ICD) configured to communicate with one or more other IMDs implanted in a patient using conduction communication.

[0076] Figure 5 An example of the transmit signal waveform for one bit is shown, from one LCP to another (in time slot 1) and back to the NV-ICD (in time slot 2).

[0077] Figure 6 An example of a transmit signal waveform for one bit from NV-ICD to LCP is shown.

[0078] Figure 7 An example of a pseudo-noise pulse-coded data frame format layout is shown.

[0079] Figure 8An example of the waveforms of a pair of orthogonal pseudo-noise pulse sequences {PN0, PN1} that satisfy the pseudo-noise condition is shown.

[0080] Figure 9 It is used to encode the bits of two series to be transmitted into a format such as... Figure 5 A block diagram illustrating an embodiment of the compound bit.

[0081] Figure 10 Is using Figure 5-9 A flowchart illustrating an embodiment of encoding signals for implant-to-implant communication from a first device to a pair of other devices.

[0082] Figure 11 This is a diagram of an embodiment of a pseudo-noise pulse demodulation system.

[0083] Figure 12 This shows the location at the receiving IMD (e.g., NV-ICD). Figure 11 Decoding constellation diagram of the IQ channel in the diagram.

[0084] Figure 13 This describes an example of a data frame format used for the public-private {PN0, PN1} pair method.

[0085] Figure 14 It is public-private {PN0, PN} l A flowchart of an embodiment of the method.

[0086] Figure 15 An embodiment of a distributed implant-to-implant communication network using a public-private {PN0, PN1} pair method is shown.

[0087] Figure 16 An embodiment of a master / slave implant-to-implant communication network with a public-private {PN0, PN1} pair arrangement is shown.

[0088] Figure 17 This describes an embodiment of the data frame format used for the dedicated {PN0, PN1} pair method.

[0089] Figure 18 This is a flowchart of an implementation of the method with private {PN0, PN1} pairs. Figure 19 An embodiment of a distributed implant-to-implant communication network using a dedicated {PN0, PN1} pair method for a three-device embodiment is shown.

[0090] Figure 20 An embodiment of a master / slave implant-to-implant communication network with a public-private {PN0, PN1} pair arrangement is shown.

[0091] Figure 21 and 22The pseudo-noise encoding / decoding with and without noise with additive Gaussian noise are shown respectively. Detailed Implementation

[0092] Embodiments of this technology can be used to improve conduction communication between IMDs, such as between multiple LCPs and / or between an implantable cardioverter-defibrillator and one or more LCPs, but are not limited thereto. Some embodiments provide conduction telemetry communication between an LCP and an NV-ICD, which is compatible with certain LCP-to-LCP communication systems. The communication link from the NV-ICD to the LCP can use the same information encoding / decoding techniques as certain existing LCP implant-to-implant communication systems, while the communication link from the LCP to the NV-ICD uses pseudo-random noise information encoding / decoding techniques with enhanced noise immunity. Figure 1-4 An example cardiac pacing system that can be used with embodiments of the present technology is shown, wherein pacing and sensing operations can be performed by multiple IMDs. Such IMDs may include, for example, one or more LCPs, ICDs (such as NV-ICDs), and / or other implantable devices, such as insertable cardiac monitors (ICMs) or pulmonary artery pressure monitoring devices. In cases where the system includes an ICD, the system is also capable of performing defibrillation.

[0093] As used herein, a conducted communication pulse refers to a voltage pulse generated by a device (e.g., by its pulse generator) and emitted between at least one pair of electrodes corresponding to a conducted communication vector, such that the conducted communication pulse is conducted through patient tissue and can be sensed by at least another pair of electrodes of a second device or electrically coupled to a second device. As used herein, a conducted communication message may include, for example, a sequence of conducted communication pulses that collectively convey information after being decoded and / or demodulated. As used herein, a conducted communication signal may include one or more conducted communication pulses that collectively constitute one or more conducted communication messages, or collectively constitute at least a portion of at least one conducted communication message; that is, a conducted communication signal includes one or more conducted communication pulses. Conducted communication may also be interchangeably referred to as conducted communication. Similarly, a conducted communication pulse may also be interchangeably referred to as a conducted communication pulse.

[0094] Figure 1A system 100 configured for at least partial implantation in a heart 101 is shown. The system 100 includes LCPs 102a and 102b located in different chambers of the heart 101. LCP 102a is located in the right atrium, while LCP 102b is located in the right ventricle. LCPs 102a and 102b can communicate with each other to notify each other of various local physiological activities, such as local intrinsic events and / or local pacing events, etc. LCPs 102a and 102b can be constructed in a similar manner, but operate differently depending on which chamber LCP 102a or 102b is located in. LCPs 102a and 102b may sometimes be collectively referred to herein as LCP 102, or individually as LCP 102.

[0095] In some embodiments, LCPs 102a and 102b communicate with each other via conductive communication through the same electrodes used for sensing and / or delivering pacing therapy, and / or with ICD 106, and / or with additional devices such as insertable cardiac monitors (ICMs) or external devices. Although not shown (and not preferred, as it would increase the size and power consumption of LCPs 102a and 102b), LCPs 102a and 102b may potentially include antennas and / or telemetry coils, which would enable them to communicate with each other, with ICD 106, and / or non-implantable devices using RF and / or inductive communication. Figure 1 Only two LCPs 102 are shown, but more than two LCPs can be implanted in a patient. For example, to provide biventricular pacing and / or cardiac resynchronization therapy (CRT), in addition to implanting LCPs in or above the right atrium (RA) and right ventricle (RV) chambers, additional LCPs can be implanted in or above the left ventricle (LV). A single LCP can also be implanted in a patient, for example, in or above the RV, RA, or LV chambers, but is not limited thereto. More than one LCP can also be implanted in or above the same heart chamber. ICD 106 is shown connected to lead 103, on which multiple electrodes are positioned. Figure 1 In this configuration, the conductive canister (also known as the housing or casing) of the ICD (or a portion thereof) provides canister or casing electrodes 125a. Leads 103 are shown as including a distal annular (or tip) electrode 125b, a proximal annular electrode 125c, a distal coil electrode 125d (also known as a parasternal coil electrode 125d), and a proximal coil electrode 125e (also known as a transverse coil electrode 125e). Leads 103 may include more or fewer electrodes than shown. The ICD 106 may also be connected to more than one lead and / or patch electrode.

[0096] Each LCP 102a, 102b uses two or more electrodes located inside, above, or within a few centimeters of the pacemaker housing for pacing and sensing in the heart chambers, and additionally for bidirectional conductive communication with each other and / or with the ICD 106.

[0097] Each LCP 102a, 102b and / or other type of IMD can from time to time use at least two electrodes of the IMD (e.g., LCP) to transmit advertising pulse sequences, such that an external device (e.g., having or communicatively coupled to an external electrode (where one or more LCPs and / or one or more other IMDs are implanted) in contact with the patient. Figure 1 An external programmer or remote monitor (not shown) can detect the presence of one or more IMDs and optionally establish a communication session with one or more IMDs. For a more specific example, the LCP (or other type of IMD) may send an advertising pulse sequence every specified number of cardiac cycles (e.g., every eight cardiac cycles) or every specified time period (e.g., every 5 seconds), but is not limited thereto. According to some embodiments, the advertising pulse sequence is a predetermined pulse sequence that instructs an external device (e.g., an external programmer or remote monitor) that the LCP (or other type of IMD) has been implanted into the patient. The advertising pulse sequence may also be referred to as a sniffing pulse sequence, or more simply as sniffing.

[0098] refer to Figure 2 The block diagram illustrates example embodiments of the electronics within LCPs 102a and 102b, configured to provide conductive communication via the same electrodes used for cardiac pacing and / or sensing. Each of LCPs 102a and 102b includes two leadless electrodes configured to deliver cardiac pacing pulses, sense induced and / or natural electrocardiographic signals, and provide unidirectional and / or bidirectional conductive communication. Figure 2 (and Figure 3 In the diagram, the two electrodes shown are labeled 108a and 108b. Such electrodes may be collectively referred to as electrode 108, or individually as electrode 108. Depending on the implementation, LCP 102 or other types of IMD may include more than two electrodes. However, unless otherwise stated, for most of the following description, it is assumed that each LCP 102 includes only two electrodes, also referred to as a pair of electrodes.

[0099] exist Figure 2In the diagram, each of LCPs 102a and 102b is shown to include a conductive communication receiver 120, which is coupled to electrodes 108a and 108b and configured to receive conductive communication signals from another LCP 102 and / or ICD 106, but is not limited thereto. Electrodes 108a and 108b may be collectively referred to as electrode 108, or individually as electrode 108. The conductive communication receiver 120 and electrode 108 can also be used to receive conductive communication signals from an external device (not shown). Figure 2 A receiver 120 is depicted, but in other embodiments, each LCP 102a, 102b may also include one or more additional receivers. For example, each LCP 102 may include a low-frequency (LF) receiver and a high-frequency (HF) receiver, for example, as described in US2022 / 0370810 entitled "Implant to Implant Communication for use with Implantable Medical Devices". Figure 2 The descriptions and facts presented herein are incorporated by reference as if fully set forth herein. For example, in US2022 / 0370810, Figure 1Receivers 120 and 122 can be referred to as low-frequency (LF) receiver 120 and high-frequency (HF) receiver 122, respectively, because receiver 120 is configured to monitor one or more signals in a relatively low frequency range (e.g., below 100 kHz), and receiver 122 is configured to monitor one or more signals in a relatively high frequency range (e.g., above 100 kHz). In some embodiments, receiver 120 (and more specifically, at least a portion thereof) is always enabled and monitors for wake-up notifications within a specific low-frequency range (e.g., between 1 kHz and 100 kHz), which may simply be a wake-up pulse; and receiver 122 is selectively enabled by receiver 120. Receiver 120 is configured to consume less power than receiver 122 when both the first and second receivers are enabled. Therefore, receiver 120 can also be referred to as low-power receiver 120, and receiver 122 can also be referred to as high-power receiver 122. Low-power receiver 120 cannot receive signals in a relatively high frequency range (e.g., above 100 kHz), but consumes significantly less power than high-power receiver 122. Thus, low-power receiver 120 can always monitor wake-up notifications without significantly depleting the LP's battery (e.g., 114). According to some embodiments, in response to low-power receiver 120 receiving a wake-up notification, high-power receiver 122 is selectively enabled by low-power receiver 120, allowing high-power receiver 122 to receive signals at higher frequencies, thereby handling the higher data throughput required for effective i2i communication without unnecessarily and rapidly depleting the LP's battery (which high-power receiver 122 might do if it were always enabled). As will be further described in detail below, pulse generator 116 can be used as a transmitter to transmit conducted communication signals using electrodes 108 under the control of controller 112. Controller 112 can modulate and / or encode such pulses, or the modulation and / or encoding of pulses can be performed externally to controller 112, but at least partially under the control of controller 112, depending on the specific implementation.

[0100] In some embodiments, LCPs 102a and 102b can be manufactured by means of... Figure 1The multiple communication channels indicated herein communicate. For example, in some embodiments, LCPs 102a and 102b may communicate via a common communication channel 107, communicate with ICD 106 via channels 105 and 115 respectively, and communicate with other devices (e.g., ICMs or external devices) via channels 111 and 113 respectively. More specifically, LCPs 102a and 102b may communicate conductively over a common physical channel via the same electrode 108, which is also used to deliver pacing pulses. The use of electrode 108 for conductive communication enables one or more LCPs 102a and 102b to perform communication without antennas or inductors. In cases where multiple implantable devices (such as LCPs 102a and 102b) communicate with each other using conductive communication, such conductive communication may be referred to as implant-to-implant (i2i) conductive communication, or more simply as i2i conductive communication.

[0101] Optionally, an LCP (or other IMD) receiving any conducted communication signal from another LCP (or other IMD) or from a non-implantable device (e.g., a programmer or other external device) may send a reception acknowledgment indicating that the receiving LCP (or other IMD, or external device) has received the conducted communication signal. In some embodiments, if an IMD expects to receive the conducted communication signal within a window and fails to do so, the IMD may send a reception failure acknowledgment indicating that the receiving IMD has failed to receive the conducted communication signal. Other variations are also possible and are within the scope of the embodiments described herein. Each conducted communication signal may include one or more sequences of conducted communication pulses. According to some embodiments, the conducted communication pulses are preferably sent during a cardiac refractory period identified or detected by one or more LCPs and / or one or more other IMDs. According to some embodiments, the conducted communication pulses are preferably subthreshold, i.e., they are below the patient's cardiac capture threshold.

[0102] LCPs 102a and 102b can exchange event messages within an i2i conduction communication signal to enable synchronized therapy and additional support features (e.g., measurements, etc.). To maintain synchronized therapy, each of the LCPs 102a and 102b needs to know (via event messages) when an event occurs in the chamber containing the other LCPs 102a and 102b. Event messages can be used, for example, by one LCP to notify another LCP (and / or NV-ICD) of inherent events sensed by the LP and / or pacing events caused by the LP, etc. Additional details of example i2i event messages transmitted between LCPs 102 are provided in US 2022 / 0370810, which is incorporated herein by reference above.

[0103] For synchronous event signaling, LCPs 102a and 102b can remain synchronized and communicate periodically at specific intervals. Synchronous event signaling allows the transmitters (e.g., pulse generator 116) and receivers in each LCP 102a, 102b to use limited (or minimal) power, as each LCP 102a, 102b is powered only for a small fraction of the time relevant to transmission and reception. For example, LCPs 102a, 102b can transmit / receive (Tx / Rx) communication messages in time slots with a duration of 10-20 μs, where the Tx / Rx time slots occur periodically (e.g., every 10-20 ms). Such time slots can also be referred to as windows.

[0104] Still referencing Figure 2 Each LCP 102a, 102b is shown as including a controller 112 and a pulse generator 116. The controller 112 may include, but is not limited to, a microprocessor (or equivalent control circuitry), RAM and / or ROM memory, logic and timing circuitry, state machine circuitry, and I / O circuitry. The controller 112 may also include, for example, timing control circuitry to control the timing of stimulation pulses (e.g., pacing rate, atrioventricular (AV) delay, atrial (AA) conduction delay, or interventricular (VV) conduction delay, etc.). This timing control circuitry system can also be used for timing refractory periods, blanking intervals, noise detection windows, evoked response windows, alarm intervals, marker channel timing, etc. The controller 112 may further include other dedicated circuitry and / or firmware / software components to assist in monitoring various conditions of the patient's heart and managing pacing therapy. The controller 112 and pulse generator 116 can be configured to send an event message via electrode 108 in a manner that does not unintentionally capture the heart in the chamber where the LCPs 102a and 102b are located (e.g., when the associated chamber is not in an inactive state). Additionally, the LCPs 102a and 102b that receive the event message can enter an "event inactive" state (or event blanking state) after receiving the event message. The event inactive / blanking state can be set to extend a defined time period after receiving the event message to prevent the receiving LCPs 102a and 102b from unintentionally sensing another signal as an event message that could lead to re-triggering. For example, the receiving LCPs 102a and 102b can detect measurement pulses from another LCP 102a or 102b or an external device.

[0105] In some embodiments, the individual LCP 102 may include an hermetically sealed housing 110 and at least two leadless electrodes 108. The hermetically sealed housing 110 is configured to be placed on or attached to the interior or exterior of a heart chamber. The at least two leadless electrodes 108 are located near the housing 110 and are configured to conduct communication with at least one other device inside or outside the body. Depending on the specific implementation and / or the other device with which the LCP communicates, the conduction communication may be unidirectional or bidirectional.

[0106] Figure 2 Example LCP 102a (or 102b) is depicted, and the functional elements of the LCP, substantially enclosed in an airtight housing 110, are shown. LCP 102a (or 102b) has at least two electrodes 108 located within, on, or near the housing 110 for delivering pacing pulses to the muscles of the heart chambers and sensing electrical activity from the muscles of the heart chambers, and for conductive communication with at least one other device inside or outside the body. Airtight feedthroughs 130, 131 transmit electrode signals through the housing 110. The housing 110 contains a primary battery 114 for powering pacing, sensing, and communication. The housing 110 also includes a sensing amplifier 132 for sensing cardiac activity from the electrodes 108, a receiver 120 (as described above) for receiving information from at least one other device via the electrodes 108, and a pulse generator 116 for generating pacing pulses for delivery via the electrodes 108 and also for transmitting information via the electrodes 108 to at least one other device. The housing 110 may also include circuitry for monitoring the health of the device, such as an optional battery ammeter 136 and an optional battery voltmeter 138, and may include circuitry for controlling operation in a predetermined manner.

[0107] Electrode 108 can be configured to communicate bidirectionally between multiple leadless pacemakers and / or implanted ICDs 106 to coordinate pacing pulse communication and optional additional therapeutic or diagnostic features using messages that identify events at the location of the individual pacemaker initiating the message, and the pacemaker receiving the message can respond according to the message's indication based on the message's source. LCPs 102a, 102b receiving event messages respond according to the event message's indication based on the message's source or location. In some embodiments or cases, two or more leadless electrodes 108 can be configured to communicate bidirectionally between one or more LCPs and / or ICDs 106 and transmit data including a designated code for an event detected or created by a single pacemaker. Each pacemaker can be configured to issue a unique code corresponding to the event type and the location of the sending pacemaker. The electrodes can also be used to send and / or receive conducted communication signals from external devices.

[0108] like Figure 2As shown, each LCP 102a, 102b may include two (or more) leadless electrodes 108 configured to deliver cardiac pacing pulses, sense induced and / or natural electrocardiographic signals, and communicate bidirectionally with each other and / or with the co-implanted ICD 106. Figure 2 As shown, the primary battery 114 has a positive terminal 140 and a negative terminal 142. Current from the positive terminal 140 of the primary battery 114 flows through an optional shunt 144 to an optional regulator circuit 146 to generate a positive voltage source 148 suitable for powering the remaining circuitry of the pacemaker 102. The optional shunt 144 enables an optional battery ammeter 136 to provide an indication of battery current consumption to the controller 112 and indirectly to an indication of device health. The illustrative power source may be the primary battery 114. The LCP is also shown to include an optional temperature sensor 152 and an optional accelerometer 154.

[0109] In various embodiments, each LCP 102a, 102b can manage power consumption to draw limited power from the battery, thereby reducing device size. Each circuit in LCP 102 can be designed to avoid large peak currents. For example, cardiac pacing can be achieved by discharging a tank capacitor (not shown) across the pacing electrodes. Recharging of the tank capacitor is typically controlled by a charge pump circuit. In a particular embodiment, the charge pump circuit is throttled to recharge the tank capacitor at a constant power from the battery.

[0110] In some embodiments, a controller 112 in an LCP 102 can access signals on electrode 108 and can examine the duration of an output pulse from another pacemaker as a signature for determining the validity of trigger information, and for a signature arriving within a predetermined limit, activate the delivery of a pacing pulse after a predetermined delay of zero or more milliseconds. The predetermined delay can be preset at manufacturing time, programmed via an external programmer, or determined by adaptive monitoring to facilitate the identification of the trigger signal and its differentiation from noise. In some embodiments or in some cases, the controller 112 can examine the waveform of an output pulse from another leadless cardiac pacemaker as a signature for determining the validity of trigger information, and for a signature arriving within a predetermined limit, activate the delivery of a pacing pulse after a predetermined delay of zero or more milliseconds.

[0111] Figure 3Example form factors of LCPs 102a and 102b are shown. The LCP may include an airtight housing 202 (110) on which electrodes 108a and 108b are disposed. As shown, electrode 108a may be separable from but partially surrounded by a fixation mechanism 205, and electrode 108b may be disposed on the housing 202. The fixation mechanism 205 may be a fixation spiral, multiple hooks, barbs, or other attachment features configured to attach the pacemaker to tissue (e.g., cardiac tissue). Electrodes 108a and 108b are... Figure 2 As shown in and referenced above Figure 2 Examples of electrodes 108 discussed. The housing may also include an electronics compartment 210 within the housing, containing electronic components required for the operation of the pacemaker, including, for example, a pulse generator, receiver, battery, and processor for operation. The hermetically sealed housing 202 may be adapted for implantation on or within a human heart and may be, for example, cylindrical, rectangular, spherical, or any other suitable shape. The housing may comprise conductive, biocompatible, inert, and anolyte-safe materials, such as titanium, 316L stainless steel, or other similar materials. The housing 202 may also include an insulator disposed on the conductive material to separate electrodes 108a and 108b. The insulator may be an insulating coating on a portion of the housing between the electrodes and may comprise materials such as silicone, polyurethane, parylene, or another biocompatible electrical insulator commonly used in implantable medical devices. Figure 3 In some embodiments, a single insulator 208 is disposed along a portion of the housing between electrodes 108a and 108b. In some embodiments, the housing itself may comprise an insulator instead of a conductor, such as alumina ceramic or other similar material, and the electrodes may be disposed on the housing.

[0112] like Figure 3 As shown, the pacemaker may further include a head assembly 212 to isolate electrodes 108a and 108b. The head assembly 212 may be made of PEEK, tecothane, or other biocompatible plastics and may contain ceramic-to-metal feedthroughs, glass-to-metal feedthroughs, or other suitable feedthrough insulators known in the art. As used herein, the term metal also includes conductive alloys. Electrodes 108a and 108b may include pacing / sensing electrodes or return electrodes. Low-polarity coatings may be applied to the electrodes, such as sintered platinum, platinum-iridium, iridium, iridium oxide, titanium nitride, carbon, or other materials commonly used to reduce polarization effects. Figure 3 In this configuration, electrode 108a can be a pacing / sensing electrode, and electrode 108b can be a return electrode. Electrode 108b can be a portion of the conductive housing 202 excluding the insulator 208.

[0113] Several techniques and structures can be used to attach the housing 202 to the inner or outer wall of the heart. A spiral fixation mechanism 205 allows the device to be inserted into the endocardium or epicardium via a guiding catheter. A rotatable catheter can be used to rotate the housing and force the fixation device into the heart tissue, thereby securing the device (and...) Figure 2 Electrode 108a) is attached to contact the stimulable tissue. Electrode 108b can be used as an independent electrode for sensing and pacing. The fixation mechanism can be partially or entirely coated for electrical insulation and can include a steroid-eluting matrix on or near the device to minimize fibrotic reactions, as is known in conventional pacing electrode leads.

[0114] exist Figure 1-3 In this embodiment, each of the LCPs 102 is shown and described as comprising two electrodes 108. In alternative embodiments, one or more of the LCPs 102 may comprise more than two electrodes, such as three electrodes 108. When the LCP 102 comprises at least three electrodes, the LCP 102 can perform conductive communication using multiple different conductive communication vectors, wherein each of the multiple different conductive communication vectors comprises different combinations of at least three electrodes. Reference is made to co-assigned U.S. Patent Application No. 16 / 241,389, filed January 7, 2019 and published as U.S. 2020 / 0215536 ​​A1, entitled “Leadless Pacemakers and Methods for Use Therewith”. Figure 9 A and 9B describe examples of LCPs comprising at least three electrodes, which are incorporated herein by reference as if fully illustrated herein.

[0115] refer to Figure 4The diagram illustrates an example block diagram of ICD 106, which can communicate with one or more other IMDs (e.g., LCPs) within the patient's body using conductive communication, and / or with external devices using conductive and / or RF communication. For the purposes of this discussion, it is assumed that ICD 106 is an NV-ICD, such as, but not limited to, a subcutaneous ICD (S-ICD). ICD 106 can communicate with one or more LCPs 102 and / or ICMs. ICD 106 is shown as including a controller 412, a battery / power regulator 426, an ECG amplifier and / or filter 414, a memory 419, a conductive communication receiver (RX) 442, a conductive communication transmitter (TX) 432, an RF telemetry circuit 464, an electric shock circuit 462, and an electrode configuration switch 413. The battery and / or power regulator 426 provides one or more constant voltages to the various components of ICD 106. In this example embodiment, receiver 442 is shown as including message amplifier and / or filter 440 and message decoder 438, and is configured to receive conducted communication signals from one or more LCPs (e.g., 102a and / or 102b) and, in some embodiments, from ICM and / or external devices. Controller 412 for controlling the operation of ICD 106 may include, but is not limited to, one or more processors (or equivalent control circuitry), RAM and / or ROM memory, logic and timing circuitry, state machine circuitry, and / or I / O circuitry. Controller 412 may also include clock circuitry, or a separate clock circuit (not shown) may provide clock signals to controller 412.

[0116] The controller 412 is shown to include a timing control module 418, an arrhythmia detector module 420, and an optional arrhythmia discriminator module 422, but may also include alternative and / or additional modules not specifically shown. The timing control module 418 can control the timing of conducted communication windows, conducted communication pulses, impulse pulses, etc. The timing control module 418 can also be used for timing refractory periods, blanking intervals, noise detection windows, evoked response windows, alarm intervals, marker channel timing, etc. The arrhythmia detector 420 can be used to detect arrhythmias, and the optional arrhythmia discriminator 422 can be used to distinguish different types of arrhythmias and / or determine whether an arrhythmia detection should be classified as a false positive. For example, the arrhythmia detector 420 and / or the arrhythmia discriminator 422 can analyze a patient's heart rate and rhythm, and based on this analysis determine whether the patient is experiencing or about to experience fibrillation. The arrhythmia detector 420 and / or arrhythmia discriminator 422 may also diagnose ventricular tachycardia and atrial tachycardia based on the EGM sensed by the ICD 106 and / or on messages provided to the ICD 106 by one or more LCPs 102, but are not limited thereto.

[0117] exist Figure 4In the illustrated embodiment, the ICD 106 is shown electrically connected to five electrode terminals 425a, 425b, 425c, 425d, and 425e, each terminal electrically connected to a corresponding electrode. For example, electrode terminal 425a may be electrically connected to a housing electrode (e.g., 125a), which is also referred to as a can or can electrode. Electrode terminals 425b, 425c, 425d, and 425e are electrically connected to electrodes coupled to one or more leads (e.g., 103) of the ICD 106. In an exemplary embodiment, electrode terminal 425b is electrically connected to a distal annular or tip electrode (e.g., 125b), electrode terminal 425c is electrically connected to a proximal annular electrode (e.g., 125c), electrode terminal 425d is electrically connected to a distal coil electrode (e.g., 125d) (also referred to as a parasternal coil electrode), and electrode terminal 425e is electrically connected to a proximal coil electrode (e.g., 125e) (also referred to as a transverse coil electrode). Electrode terminals 425a, 425b, 425c, 425d, and 425e may be collectively referred to as electrode terminal 425, or individually as electrode terminal 425. Electrodes 125a, 125b, 125c, 125d, and 125e may be collectively referred to as electrode 125, or individually as electrode 125. Electrode 125 (via electrode terminal 425) is connected to electrode configuration switch 413, which may also be referred to herein as switch 413. Electrode configuration switch 413, under the control of controller 412, can connect any two or more of electrodes 125 to ECG amplifier and / or filter 414, conductive communication RX 442, conductive communication TX 432, or shock circuit 462. As will be described in more detail below, electrodes 125 can be used to send and receive conductive communication signals to / from one or more LCPs, one or more other types of IMDs, and / or external devices (e.g., programmers or bedside monitors), and can also be used to sense electrocardiogram (ECG).

[00120] In some embodiments, amplifiers and / or filters 414, 440, and 436 are each differential circuits designed to be connected to a pair of electrodes 125 via a switch 413 under the control of controller 412. For example, switch 413 can be controlled to connect any pair of electrodes 125a, 125b, 125c, 125d, 125e to message amplifier and / or filter 440. Switch 413 can also connect two electrodes 125 directly to each other. For example, switch 413 can connect electrode 125a to a first input of message amplifier / filter 440, and connect electrodes 125b and 125c to each other and to a second input of message amplifier / filter 440.Advantageously, connecting two or more electrodes (e.g., 125b and 125c) together to the same node (e.g., the same input node connected to the message amplifier / filter 440) can effectively average or create a virtual vector between the two or more electrode locations, which makes it possible to sense a signal that is actually the average of the signals detected at two separate electrodes.

[0118] A conducted communication receiver 442, shown as including a message amplifier and / or filter 440 and a message decoder 438, is configured to receive conducted communication signals from one or more LCPs (e.g., 102a and / or 102b) or external devices.

[0119] Message amplifier and / or filter 440 is configured to amplify and / or filter conducted communication signals received from another IMD or external device. The amplifier section can be used to increase the relatively small amplitude of such conducted communication signals. The filter section can be a high-pass or band-pass filter suitable for separating electrocardiogram (ECG) signals from conducted communication signals. Message decoder 438 can be configured to decode the conducted communication signals received from another IMD or external device into a format understandable by controller 412. The specific type of decoding performed by message decoder 438 can depend on the specific encoding of the conducted communication signals received from another IMD or external device, such as, but not limited to, on / off keying, frequency shift keying, frequency modulation, or amplitude shift keying. Message decoder 438 can also be implemented as a comparator that compares the output of message amplifier and / or filter 440 with a threshold and outputs binary 1s and 0s based on the comparison result, thereby providing a bit stream to controller 412. Controller 412 can then perform a specific type of decoding, depending on how the transmitting device encodes the conducted communication message.

[0120] In some embodiments, ICD 106 includes one, two, or more additional instances of a conducted communication receiver 442, wherein example additional instances of the conducted communication receiver are designated 442b and 442c. Each additional instance of receiver 442 may include its own corresponding message amplifier and / or filter 440 and its own corresponding message decoder 438, and may provide its own bitstream to controller 412. Using a switch 413 controlled by controller 412, each of the different receivers (e.g., 442, 442b, and 442c) may be electrically coupled to different pairs or combinations of external electrodes 125a, 125b, 125c, 125d, and 125e, and thus may be electrically coupled to different conducted communication vectors.

[0121] Conductive communication transmitter 432 is configured (under the control of controller 412) to transmit conducted communication signals to one or more IMDs implanted in a patient and / or external device. The conducted communication signals can also be used for programming, querying, and / or obtaining notifications and / or other types of diagnostic information from one or more IMDs. In this example embodiment, transmitter 432 is shown as including a message encoder and / or modulator 430 and an amplifier 436. Transmitter 432 may also be referred to as a pulse generator due to its output conducted communication pulses.

[0122] One or more conductive communication receivers 442 and conductive communication transmitters 432 are example components of the conductive communication circuitry 452 of the ICD 106. Figure 4 In this configuration, switch 413 is located between conductive communication circuit 452 and electrodes 125a, 125b, 125c, 125d, and 125e, which are either part of or communicatively coupled to ICD 106. Under the control of controller 412, switch 413 enables different conductive communication vectors to be electrically coupled to conductive communication circuit 452 or portions thereof. Although in Figure 4 Five electrodes 125 are shown, but more or fewer electrodes 125 may be part of or communicatively coupled to ICD 106.

[0123] A controller 412, which may include one or more processors, can perform operations based on firmware stored in non-volatile memory (flash memory). The non-volatile memory can also be used to store parameters or values ​​to be retained when power is lost. The controller 412 can use volatile memory or RAM as a general-purpose memory for information such as ECG data, status information, swap memory, and other data. This type of memory (in...) Figure 4 The memory (shown as 419) may be included within the controller 412 and / or may be communicatively coupled to the controller 412.

[0124] Switch 413 can also connect various combinations of electrodes to impedance measurement circuit 450. Impedance measurement circuit 450 includes inputs to collect multiple measurement impedances among corresponding multiple electrode combinations. For example, impedance measurement circuit 450 can collect the measurement impedance of each or a subset of active sensing vectors. Optionally, impedance measurement circuit 450 can measure respiration or minute ventilation; measure chest impedance to determine shock threshold; detect when the device has been implanted; measure stroke volume; and / or detect the opening of heart valves, etc.

[0125] Impact circuit 462 generates impact pulses of low energy (e.g., up to 0.5 joules), medium energy (e.g., 0.5-10 joules), or high energy (e.g., 11-80 joules) selected by controller 412. These impact pulses are applied to the patient's heart via, for example, at least two shock electrodes selected from various electrodes 125. The electrodes selected for delivering the shock may be referred to herein as shock vectors. Example electric shock vectors include, but are not limited to, the following: a distal (also called parasternal) coil electrode 125d to a proximal (also called lateral) coil electrode 125e; the distal (also called parasternal) coil electrode 125d and the proximal (also called lateral) coil electrode 125e electrically coupled to each other (to form the anode of the carrier) to a housing (also called can or can) electrode 125a (which provides the cathode of the carrier); a distal annular (or tip) electrode 125b electrically coupled to the distal (also called parasternal) coil electrode 125d (to form the anode of the vector) to a housing (also called can or can) electrode 125a (which provides the cathode of the vector); and a distal (also called parasternal) coil electrode 125d to a housing (also called can or can) electrode 125a. Other variations are also possible and are within the scope of the embodiments described herein.

[0126] As described above, there exist situations where patients are exposed to noisy electromagnetic environments, and conducted telemetry channels 105, 107, 111, 113, and 115 between LCPs 102a and 102b, NV-ICD 106, and possibly other devices in the system are interfered with by noise. Noise signals may be misinterpreted by the receiving device as erroneous I2I signals and processed by the device's firmware, leading to undefined behavior such as changes in programming parameters. Due to the relative alignment and placement of NV-ICD 106 with respect to LCPs 102a and 102b, signal reception on NV-ICD 106 is weaker, making signals transmitted from LCPs 102a or 102b to NV-ICD 106 particularly susceptible to noise interference.

[0127] The embodiments described herein are generally intended to improve communication between two or more IMDs. However, it should be noted that the embodiments described below can also be used to improve communication between an external medical device (EMD) and one or more IMDs. Such an EMD can be an external programmer, a bedside monitor, a remote monitor, etc. For a specific example, if an EMD attempts to communicate with one or two IMDs, there is a potential risk that data frames sent by the EMD may collide with data frames sent between the IMDs when the two IMDs are communicating with each other. The embodiments described herein can reduce the risk of data frame collisions in this situation. This is merely one example of how to use the embodiments described herein to improve communication between an EMD and one or more IMDs, and this example is not intended to be limiting. More generally, the embodiments described herein can be used to improve communication between two or more devices, where at least one device is an IMD. In the following discussion, when at least two devices are described as communicating with each other, it is assumed that at least one of the devices includes an IMD. While it is possible and likely that all devices are IMDs, it is also possible that at least one device is an EMD.

[0128] The following discussion presents a conductive telemetry communication system between LCPs 102a, 102b, and NV-ICD 106, which is compatible with currently used LCP-to-LCP communication systems. The communication link from NV-ICD 106 to LCP 102a or 102b can use the same information encoding / decoding method as existing LCP implant-to-implant communication systems, while the communication link from LCP to NV-ICD uses an embodiment of an information encoding / decoding method with enhanced noise immunity. This newly introduced information encoding / decoding method can be implemented with minimal changes to the existing LCP firmware and requires no hardware changes on LCPs 102a and 102b. If hardware and firmware changes are made, this technology can also be applied to multiple LCP communications. The same technology can also be applied to other implant-to-implant communications with two or more implantable medical devices (IMDs).

[0129] More specifically, the following embodiments present examples of an implant-to-implant communication system between an LCP 102a or 102b and an NV-ICD 106, which is compatible with currently available i2i communication systems between LCPs 102a and 102b. In this embodiment of the communication system, each bit of the LCP transmission signal is encoded in two consecutive time slots, such as... Figure 5 As shown.

[0130] Figure 5An example of a transmitted signal waveform is shown, which includes one bit (in time slot 1) for communication from one LCP to another, and another bit (in time slot 2) for communication to the NV-ICD, which are combined to form a composite bit. More generally, Figure 5 An example of a transmitted signal waveform is shown, which includes one bit (in time slot 1) to be transmitted from a first implantable medical device (IMD1) to a second IMD (IMD2), and another bit (in time slot 2) to be transmitted from IMD1 to a third IMD (IMD3), which are combined to form a composite bit. As used herein, a composite bit is a bit of a signal having multiple (i.e., at least two) time slots, each time slot carrying bits of signal for a different device. Figure 5 The embodiments include two time slots (for IMD2 and IMD3, respectively), but other embodiments may include additional time slots to accommodate communication with an attached implantable medical device. According to embodiments, the allocation of the device to time slots 1 and 2 can be in any order, and additional time slots can be added to the composite bit for communication with the attached device. Figure 5 In this embodiment, for composite bits, the signal waveform in slot 1 can be compatible with certain existing conducted i2i communication systems and can be decoded by the receiving LCP (or more generally, IMD2) into a set of square wave pulses (“bit 1” in this embodiment) or a flat waveform (“bit 0” in this embodiment). Figure 5The “bit 1” in time slot 1 is shown. (In an alternative embodiment, a square wave pulse in time slot 1 can represent “bit 0”, and a flat waveform in time slot 1 can represent “bit 0”.) The signal waveform in time slot 2 is encoded as the corresponding “bit 0” and “bit 1” using one of two orthogonal pseudo-noise (PN) pulse sequences PN0 and PN1. The waveform in time slot 2 will be decoded by the receiving NV-ICD 106 (or more generally, IMD3). The terms “bit 0” and “bit value 0” are used interchangeably herein, and the terms “bit 1” and “bit value 1” are used interchangeably herein. Encoding bit values ​​“1” and bit values ​​“0” using the corresponding PN pulse sequences provides enhanced noise immunity for the receiving NV-ICD 106 (or more generally, the receiving IMD3). The decoding process at both the receiving LCP (e.g., 102b, for transmitting LCP 102a) and the receiving NV-ICD 106 will be synchronized with the wake-up signal pulse of the transmitting LCP. More generally, the decoding process at IMD2 and IMD3 will be synchronized with the transmission of the IMDT wake-up signal pulse, as will be described in more detail below. Note that the pseudo-noise (PN) waveforms are not used to encode or modulate another signal, but are themselves "1" and "0" bit values.

[00134] The composite bits of the message can be assembled into a series of frames, wherein the number of composite bits per frame can be a fixed number or can vary depending on the embodiment. In some embodiments, the wake-up pulse signal is followed by a series of payload frames for implant-to-implant communication, and each payload frame includes multiple composite bits, including a data stream encoded by a {PN0,PN1} pulse sequence in one time slot. An embodiment of this data frame format layout is described in Figure 7 As shown in the diagram, this will be discussed further below.

[0131] Figure 6 An example of a communication signal waveform (one bit) from NV-ICD to LCP, or more generally, from IMD3 to IMD1 or IMD2, is explained. Each bit of the signal transmitted by NV-ICD 106 (or more generally, IMD3) can be the same as the signal available in existing i2i communication systems used to receive LCP102a and / or 102b (or more generally, for receiving IMD1 and / or IMD2). For example, as Figure 6 As shown, time slot 1 is used for the data value to be transmitted, where, as Figure 5As shown, this can be a square wave pulse sequence (again, a "1" bit value in this example) or a flat waveform (a "0" bit value in this example), where the square wave pulse sequence may also be referred to herein as a square wave pulse waveform. In other words, time slot 1 includes a waveform corresponding to the data value (e.g., a square wave pulse waveform or a flat waveform). Time slot 2 is used by (one or more) receiving LCPs 102a and / or 102b to determine whether a "0" or "1" is detected during time slot 1. In other words, (multiple) receiving IMDs perform decoding during time slot 2. In each figure showing an example signal waveform, for example... Figure 5 and Figure 6 Unless otherwise stated, the vertical axis represents voltage and the horizontal axis represents time.

[0132] Figure 7 An embodiment of a pseudo-noise (PN) pulse-coded data frame format layout is shown, wherein each frame includes Figure 5 or Figure 6 A composite bit of a specified number m in the form of a signal. The specified number m can be fixed or programmable, depending on the specific implementation. In this embodiment, the signal begins with a wake-up pulse, followed by a specified silence period, after which a specified number N frames, frames 1 to N, each frame having a composite bit of the form of a signal of the specified number m. Figure 5 or Figure 6 The formatted data consists of multiple (specified number m) composite bits, depending on the communication direction. The specified silent period can be fixed or programmable, depending on the specific implementation. The specified number N of frames can be fixed or programmable, depending on the specific implementation. As shown in Frame 1, each frame consists of a specified number m of composite bits cb1 to cbm, each composite bit having a first timeslot and a second timeslot, as shown by the dashed lines in each composite bit (cb). As mentioned above, depending on the specific implementation, the specified number m can be fixed or programmable. These techniques can help mitigate false alarm detection of I2I messages, which can disrupt I2I communication between IMDs in noisy signal environments.

[0133] Further consideration is given to pseudo-noise (PN) pulse sequences, which can be used to encode bit values ​​"0" and "1" in the communication link from LCP 102a or 102b to NV-ICD106 (and more generally, from IMD1 or IMD2 to IMD3), such as... Figure 5 As shown. Typically, each PN pulse sequence comprises a sequence of time-orthogonal pulses. More specifically, each PN pulse sequence comprises a pulse sequence whose integral over the duration of the pulse sequence is equal to zero. In the embodiment presented herein, the PN pulse sequence has the following characteristics (i.e., satisfies the following pseudo-noise condition):

[0134] 1) The time integral of each PN sequence PN0 and PN1 over its PN sequence duration should be zero:

[0135]

[0136] 2) The inner product of the PN0 and PN1 pulse sequences over the duration of the PN sequence should be zero, meaning the PN0 and PN1 pulse sequences are orthogonal to each other:

[0137]

[0138] 3) The inner product of each pulse in the PN0 and PN1 pulse sequences with itself over the duration of the PN sequence should be non-zero:

[0139]

[0140] The requirement that the inner product of the PN0 and PN1 pulse sequences over the duration of the PN sequence should be zero effectively reduces random noise during decoding and distinguishes between bit value "1" and bit value "0" waveforms. The requirement that the inner product of each of the PN0 or PN1 pulse sequences with itself over the duration of the PN sequence should be non-zero allows for reference below. Figure 11 Decoding the description.

[0141] Figure 8 An example of an embodiment of the waveforms of a pair of pseudo-noise pulse sequences {PN0, PN1} that satisfy the pseudo-noise conditions given above is shown. Figure 8 The PN1 waveform at the top and middle Figure 8 The PN0 waveform at the bottom of the middle segment is zero on average across the time slot intervals (i.e., the time integral of each PN sequence over its pulse duration is equal to zero), and it can be seen by comparing when PN1 and PN0 are high and low that they are orthogonal to each other in terms of intervals. An alternative embodiment may also use pseudo-noise in time slot 1 for LCP-to-LCP (or other i2i) communication, in which case an additional pair of pseudo-noise pulse sequences {PN0', PN1'} may be used, where all four pseudo-noise pulse sequences are orthogonal to each other.

[0142] Figure 9 It is used for compounding components such as Figure 5The diagram shows a block diagram of an embodiment where composite bits are encoded using two example bit series for transmission. At block 901, the controller 112 of LCP 102a (or more generally, IMD1) can generate the bit series to be transmitted from LCP 102a to LCP 102b (or more generally, from IMD1 to IMD2), and encode it at block 903 (e.g., using a lookup table (LUT), but not limited thereto) as a pulse series ("p") of "1" bit values ​​or a flat waveform ("f") of "0" bit values. For example, the transmit bit series [0, 1, 1, 1] becomes the transmit pulse series [f, p, p, p] in block 905. In one embodiment, for the transmit bit series in block 911 to be transmitted from LCP 102a to NV-ICD 106 (or more generally, from IMD1 to IMD3), the corresponding transmit pulse group in block 915 can be determined using the lookup table LUT at block 913. For example, the transmitted bit sequence [0, 1, 0, 1] at block 911 is encoded as a PN sequence [PN0, PN1, PN0, PN1] at block 915. In some embodiments, the pseudo-random noise pulse sequence can be predefined and hard-coded as a lookup table (LUT) in the firmware transmitting the LCP (or more generally, the IMD). For each bit value (bit value "1" or "0"), the LCP firmware can then retrieve the corresponding PN pulse sequence for {PN1 or PN0} from the lookup table at block 913, and... Figure 5 The waveform is encoded in time slot 2. Then, the composite drill bit is assembled at box 921, as follows. Figure 5 As shown. For example, at block 921, the composite bit (corresponding to the bits in blocks 901 and 911) can be [f / PN0, p / PN1, p / PN0, p / PN1], where " / " is used to separate the time slots of the composite bit. The pulses of the composite bit can then be assembled into a pulse generator 116 of LCP 102a. Figure 7 The data frame format (for transmission). Other embodiments may reverse which device is assigned to time slots 1 and 2. If both time slots use pseudo-noise coding, then coding block 903 may also be or utilize a lookup table (LUT) similar to the LUT used at block 913, with a second pair of mutually orthogonal pseudo-noise pulse sequences.

[0143] Figure 10 Is using Figure 5-9This is a flowchart illustrating an embodiment of encoding signals for implant-to-implant communication from a first implantable medical device (IMD1) to a pair of other implantable medical devices (IMD2 and IMD3) in multiple formats. Starting at step 1001, the transmitting device IMD1 generates a first sequence of bits to communicate to IMD2. In this example, IMD1 and IMD2 are LCP 102a and LCP 102b, respectively, and the steps performed by IMD1 can be performed by the controller 112 and pulse generator 116 of LCP 102a. Then, according to... Figure 5 In one embodiment, in step 1003, the first sequence to be transmitted is encoded into time slot 1 of the composite bits as a square wave pulse and / or a flat waveform sequence. Steps 1001 and 1003 correspond to Figure 9 Boxes 901, 903, and 905 in the diagram. In step 1005, transmitting device IMD1 generates a second bit sequence to be communicated to IMD3, where in this example, IMD3 is NV-ICD 106. Then, in step 1007, the second bit sequence to be transmitted is encoded into a pair of orthogonal pseudo-noise (PN) waveforms, where steps 1005 and 1007 correspond to... Figure 9 Boxes 911, 913, and 915 in the diagram can be used, and pseudo-noise coding can be performed using lookup tables (LUTs), for example, as described regarding the LUT used in box 913. It should be noted that... Figure 10 The order of steps 1001, 1003, 1005, and 1007 shown can be changed, as long as step 1001 is executed before step 1003 and step 1005 is executed before step 1007. For example, step 1005 can be executed substantially simultaneously with step 1001, or before step 1001. In another example, step 1007 can be executed substantially simultaneously with step 1003, or before step 1003.

[0144] Still referencing Figure 10 At step 1009, IMD1 can combine two series of transmitted pulses (which have already been encoded) into a single group. Figure 5 The composite bit format, corresponding to Figure 9 The composite bit 921. In step 1011, the composite bit (as referenced) Figure 5 (Formatted as described) can then be formatted by IMD1 as Figure 7 The frame format is then used. Then, in step 1013, the formatted frame is sent using conductive communication.

[0145] Now we move on to demodulating the pseudo-noise pulse sequence at the receiving device. Figure 11 This is a diagram of an embodiment of a pseudo-noise pulse demodulation system. For example, in Figure 4In the NV-ICD embodiment, these components may be part of the conducted communication RX 442, and more specifically, part of the message decoder 438. Demodulation of the spurious noise pulse sequence at NV-ICD 106 (or more generally, IMD3) is accomplished by utilizing the orthogonality of PN0 and PN1. Individual bits of the received signal can be buffered at buffer 1121 and provided to signal separator 1123, which then provides the received signal to multipliers 1103 and 1113. The NV-ICD 106 receiver will also be aware of this pair of spurious noise pulse signals and can provide the PN1 signal from signal generator 1101 and the PN0 signal from another signal generator 1111 to the corresponding multipliers 1103 and 1113. The corresponding integrators 1105 and 1115 then integrate the outputs of multipliers 1103 and 1113 over the duration of time slot 2. Due to the orthogonality of PN1 and PN0 (and ignoring noise), if the received bit is PN1, the output X of integrator 1105 will be 1, and the output Y of integrator 1115 will be 0. Conversely, if the received bit is PN0, the outputs will be X=0 and Y=1. The X and Y values ​​are then converted to, for example, in-phase (I) / orthogonal (Q) format at IQ channel mapper 1125. Multiple mappings can be used to map to the I and Q channels, such as the example embodiment of I channel = log(XA') and Q channel = log(Y / X). This set of logarithmic IQ channel mappings is just one implementation of IQ channel constellation mapping. Other mapping algorithms based on other functions can also be considered based on the actual device hardware characteristics, while remaining within the scope of the embodiments described herein. If multiple pairs of mutually orthogonal pseudo-noise pulse waveforms are used, such as when slot 1 is also encoded with pseudo-noise, or in the multi-device communication embodiments discussed below, different mappings can be used for each pair.

[0146] Used to implement Figure 11 Regarding the circuitry of the pulse demodulation system, many different embodiments are possible. For example, the IQ channel mapper 1125 can be digitally implemented, and... Figure 11 The components to its left (e.g., components 1101, 1103, 1104, 1111, 1113, 1115, 1121, and 1123) can be implemented as analog circuits. Analog-to-digital conversion can be accomplished by introducing one or more ADCs (not shown) between integrators 1105 and 1115 and IQ mapper 1125 or at other points in the system. For example, integrators 1105 and 1115 can operate in the digital domain after an ADC following each multiplier 1103 and 1113. Other variations are also possible and are within the scope of the embodiments described herein.

[0147] Figure 12This shows the location at the receiving NV-ICD (or more generally, at IMD3). Figure 11 An example of a decoding constellation diagram for the IQ channel is provided. If the demodulated (I, Q) value pairs fall within the "bit 0" region, they are decoded as "0" bit values, and if they fall within the "bit 1" region, they are decoded as "1" bit values. If the (I, Q) value pairs fall within the "empty" region, they are decoded as "null" bits. "Null" means that neither "0" nor "1" is reliably decoded. If "Null" is decoded in a message, the entire message can be considered corrupted and discarded. In this case, the noise search count in the receiving IMD (e.g., NV-ICD) firmware can be increased by one to prepare for a noise recovery event. As the received signal-to-noise ratio (SNR) deteriorates, the resulting "bit 0" and "bit 1" regions can be extended to the "empty" region to increase the acceptable range of "bit 0" and "bit 1". This decoding mechanism can help reduce the likelihood of incorrectly decoded implant-to-implant messages being processed by the receiving IMD (e.g., NV-ICD) because noise-contaminated bits are ignored as "empty" bits instead of false alarm bits with the opposite polarity. For example, when decoding a received bit string, if the result falls into an "empty" region, the decoded value will have low confidence, and the data frame may be discarded as corrupted, and an error signal will be returned to the transmitting device, which may cause the transmitting device to retransmit the message. This decoding system also has improved performance for low receive SNR values, as discussed further below.

[00145] In use for Figure 6 In the transmission signal of the NV-ICD 106 in the embodiment, the signal can be transmitted via conducted communication as a broadcast signal that can be received by LCP 102a or LCP 102b. When there are more than two implantable medical devices (IMDs), it may be beneficial to establish a private session between each pair of individual devices so that communication between a pair of IMDs does not interfere with other IMDs within the telemetry reception range. The following figures consider embodiments for implementing such private sessions.

[0148] More specifically, these embodiments use more than one pair of PN0 and PN1 to encode bit 1 and bit 0 values, where each of these {PN0, PN1} pairs is also orthogonal to the other {PN0, PN1} pairs. All available mutually orthogonal {PN0, PN1} pair options can be stored in the device firmware and assigned a unique pair ID. Multiple {PN0, PN1} pairs can be used to implement a private session between two devices without sharing the communicated information with other implanted devices. Two methods for constructing private sessions with multiple {PN0, PN1} pairs are proposed: a public-private {PN0, PN1} pair method; and a private {PN0, PN1} pair method.

[0149] Figure 13An example of a data frame format for the public-private {PN0, PN1} pair method is shown. Figure 7 As shown, the frame format again begins with a wake-up pulse, followed by a specified silence period. Following the silence period are one or more data payload frames, each with two parts: a "common frame" and a "private frame." In the example embodiment, there is one common frame and one private frame, each with a specified number of bits; however, other embodiments may have additional common or private frames. The common frame is encoded with a common {PN0, PN1} pair shared with each IMD (e.g., LCP or NV-ICD). Each IMD is programmed to use the common {PN0, PN1} pair to decode the payload of the common frame time slot. The common frame includes the ID of the intended receiving device, or, if multiple receiving devices are to use the same channel in a broadcast manner, the device ID, and the private {PN0, PN1} pair ID that the transmitting device will use to encode the private frame, thereby allowing the transmitting device to dynamically assign the private {PN0, PN1} pair to other devices. Note that including the private {PN0, PN1} pair ID in the common frame may be optional if each device is pre-configured with a private {PN0, PN1} pair. After the transmitting device finishes sending the common frame, it will switch to the private {PN0, PN1} pair to encode and send the private frame. The intended receiving device will also switch to the private {PN0, PN1} pair to decode the upcoming private frame data and use it to communicate back to the first device. Therefore, once the private {PN0, PN1} pair is established between the two devices, it is not necessary to include the common frame in subsequent exchanges.

[0150] Figure 14 This is a flowchart of an implementation of a public-private {PN0, PN1} technology pair. Figure 14 The diagram shows the steps for the transmitting device on the left and the steps for the receiving device on the right. On the transmitting side, the process begins at 1401, a wake-up pulse is sent at 1403, and then the transmitting device waits for a specified silence period at 1405. The specified silence period can be fixed or programmable, depending on the specific implementation. On the receiving side, the process begins at 1431 with a wake-up pulse received at 1433, and then the receiving device waits for a specified silence period at 1435. After waiting for the specified silence period, at 1407, the transmitting device encodes a common frame for a specified receiving device ID, and optionally encodes private {PN0,PN1} pairs, and then transmits the common frame at 1409. In one embodiment, the encoding performed at 1407 occurs during the waiting period at 1405, such that the common frame can be transmitted at 1409 as soon as the silence period expires.

[0151] On the receiving device, a public frame is received and decoded in step 1437, which allows any receiving device to obtain the ID of one or more expected receiving devices. Step 1439 checks whether the receiving device is the expected receiving device (i.e., the expected receiver) based on whether the decoded device ID matches the receiving device's device ID. If not, the receiver-side process ends at step 1445 for any unintended implantable device to receive the public signal. If the ID received and decoded in step 1439 matches the receiving device's ID, the receiver switches to a private {PN0, PN1} pair for subsequent communication. In a dynamic embodiment, a private frame will specify a private {PN0, PN1} pair, which is then stored by the designated receiver for use in decoding subsequent private frames for the initial communication and any subsequent communication.

[0152] On the transmitting side, in step 1411, dedicated session data is encoded in a dedicated frame with dedicated {PN0, PN1} pairs and transmitted in step 1413. In step 1443, on the receiving side, the dedicated {PN0, PN1} pairs are used to receive and decode the dedicated frame. Then, the transmission and reception of data frames end at corresponding steps 1415 and 1445 of the transmitting and receiving devices. Subsequent exchanges between devices can continue using the established private {PN0, PN1} pairs. Note that the encoding in step 1411 can be performed at least partially concurrently with steps 1407 and / or 1409. Further, it should be noted that steps 1411 and 1407 can be interleaved or reversed, assuming the receiving IMD has a buffer of sufficient size to store the received waveform data. More generally, the order of various steps can be modified while still remaining within the scope of the embodiments described herein.

[0153] Reference Figure 13 and 14 The described public-private {PN0, PN1} pair technology can be used to implement distributed implant-to-implant communication networks between implanted devices, because any device can utilize it. Figure 15 The illustrated workflow initiates a private communication session with any intended receiving device. This method can also be used to implement master / slave implant-to-implant communication networks, where only the master device can send public frames and determine which slave device to communicate with, such as... Figure 16 As shown. Regarding the implementation on the device, on the sending side, this can be as described above regarding... Figure 9 and Figure 10 As stated above, and on the receiving side, as mentioned above regarding Figure 11 and Figure 12The lookup table can be used again for pseudo-noise coding, but incorporates mutually orthogonal public and private pulse pairs, wherein, when private pairs are dynamically allocated, the receiving device can store the received private {PN0, PN1} pairs in memory for later use.

[00152] Figure 15 It shows how to use such Figure 1 The three-device embodiment of devices 1 1501, 2 1502, and 3 1503 is an embodiment of a distributed implant-to-implant communication network topology using a public-private {PN0, PN1} pairing method, although it may include more devices. In a distributed topology, any device can initiate a private channel with any other device by using a public-private pair arrangement. Figure 15 As shown, device 1 1501 can send (public frame + private frame) to designated device 2 1502, and then communication between device 1 1501 and device 2 1502 can be encoded using the private {PN0, PN1} pairs. Although in Figure 15 Not shown, but device 2 1502 can similarly initiate a communication channel by initially transmitting a (public frame + private frame) to specify device 1 1501. Device 2 1502 can similarly initiate a communication channel with device 3 1503, and (although not shown) the reverse, and device 3 1503 can initiate a communication channel with device 1 1501, and (although not shown) the reverse.

[00153] Figure 16 An embodiment using a public-private {PN0, PN1} pair for a master / slave implant-to-implant communication network is illustrated. Return to Reference Figure 1 For example, depending on the embodiment, any of LCP 102a, LCP 102b, or NV-ICD 106 can be the master device 1601, but in some embodiments, the larger size of ICD 106 may make it better suited as a master device. In a master / slave arrangement, master device 1 1601 sends (common frames + private frames) to slave device 1 1611 or slave device 1612 to establish a private {PN0,PN1} pair for subsequent conduction communication using the private {PN0,PN1} pair between the device pairs.

[0154] Figure 17 This describes an embodiment of the data frame format in the dedicated {PN0, PN1} pair method. In these embodiments, each device in the implanted system includes a lookup table of private {PN0, PN1} pairs for each device in the implanted system. The transmitting device encodes the data payload frame using the dedicated {PN0, PN1} pairs of one or more intended receiving devices. The receiving device decodes the private session data using the corresponding private {PN0, PN1} pairs. Figure 7 and 13As shown, the frame format again begins with a wake-up pulse, followed by a first silence period. One or more data payload frames will contain dedicated session data encoded with the {PN0, PN1} pairs of the intended receiving device. According to some embodiments, a group of IMDs may share private {PN0, PN1} pairs. For example, LCP102a and 102b may both use the same private pair, while NV-ICD 106 uses a different private pair.

[0155] Figure 18 This is a flowchart of an embodiment of the dedicated {PN0, PN1} pair technology. Figure 18 In this diagram, the steps of the transmitting device are shown on the left, and the steps of the receiving device are shown on the right. On the transmitting side, the process begins at 1801, a wake-up pulse is sent at 1803, and then the transmitting device waits for a specified silence period at 1805. On the receiving side, the process begins at 1831 with the wake-up pulse received at 1833, and then the receiving device waits for a specified silence period at 1835. After waiting for the specified silence period, at 1807, the transmitting device searches for the {PN0, PN1} pair of the expected receiving device (or multiple devices), and at 1809, it encodes the data frame (or multiple data frames) using the {PN0, PN1} pair of the expected receiving device (or multiple devices).

[0156] After the silent period expires, at step 1811, one or more encoded private frames are sent, and then the process of the transmitting device ends at 1813. In one embodiment, the lookup performed at step 1807 and the encoding performed at step 1809 occur during the waiting period at step 1805, so that a private frame can be sent at step 1811 as soon as the silent period expires. In one set of embodiments, the frame may have a specified number of bits. At step 1841, the expected receiving device receives and decodes the private frame using the device's private {PN0, PN1} pairs, and then the process of the receiving device ends at step 1843. Due to the mutual orthogonality of the different {PN0, PN1} pairs, if an unexpected receiving device attempts to decode the private frame, it will find that the bits of the frame will provide an empty output for the "1" and "0" channels during demodulation. In this way, if each device has a complete {PN0, PN1} pair lookup table for other devices, then Figure 19 and Figure 20 This method can be used to implement distributed implant-to-implant communication networks. Figure 13-16 Similar to the public-private arrangement, the private {PN0, PN1} pair method can be implemented as both a distributed implant-to-implant communication network and a master / slave implant-to-implant communication network.

[0157] Figure 19An embodiment of a distributed implant-to-implant communication network using a dedicated {PN0, PN1} pair method is shown for a three-device embodiment including device 1 1901, device 2 1902, and device 3 1903 (e.g., Figure 1 (In the context of the text), although it may include more devices. Each device is arranged symmetrically and uses corresponding private {PN0, PN1} pairs to encode private session data for the intended device or multiple devices.

[0158] Figure 20 An embodiment of a master / slave implant-to-implant communication network with a public-private {PN0, PN1} pair arrangement is illustrated. In the master / slave arrangement, only the master device needs to have a complete {PN0, PN1} pair lookup table for the slave devices, and each slave device needs to have a master device {PN0, PN1} pair.

[0159] For any of the embodiments presented above, the use of pseudo-noise coding of the data signal can improve the receiving device's ability to decode the data content of conducted communications. This can be referred to... Figure 21 and Figure 22 Please provide an explanation.

[0160] Figure 21 and 22 Explain the pseudo-noise encoding / decoding methods, both with and without noise, and with the included additive Gaussian noise. Figure 21 and Figure 22 The top of each graph represents the coded waveform with and without noise, and with added Gaussian noise, respectively. The corresponding decoded constellation diagrams for the IQ channels are shown below. Figure 21 and Figure 22 In the simulation, Figure 8 The pseudo-noise pulse sequence shown is used to encode the "bit 1" and "bit 0" values ​​of a random sequence of bit values, where in Figure 21 The top shows the result of a pseudo-noise pulse-end encoded waveform with no noise and exhibiting well-defined values. Figure 22 At the top, Gaussian noise is added with a signal-to-noise ratio (SNR) of 0 dB, so the definitions of these values ​​are much worse. Then, the two waveforms are Figure 11 and Figure 12 The corresponding inputs to the decoding system, such as Figure 21 and Figure 22 As shown at the bottom. Figure 21 and 22 In the bottom curve chart, according to Figure 12 The condition for the zero region defined by the acceptable ratio max{X / Y,Y / X} is less than 1.5. Figure 21 and Figure 22The image shows two versions of the PN pulse coded waveform at the top, and the corresponding decoded constellation diagrams on the IQ channel are shown below for both cases. Figure 21 In the text, the values ​​of "bit 0" and "bit 1" are well separated from each other and well separated from empty regions. Figure 22 At the bottom, the distribution of "bit 0" and "bit 1" decoded values ​​is not clearly defined, but it still allows the system to successfully decode the waveform.

[0161] The embodiments described above are generally used to improve communication between two or more IMDs. However, it should be noted that the embodiments described above can also be used to improve communication between an external medical device (EMD) and one or more IMDs. For example, when an EMD communicates with multiple IMDs, it is also useful for the EMD to use pseudo-noise pulse sequences. Such an EMD could be an external programmer, a bedside monitor, a remote monitor, etc. For a specific example, if an EMD attempts to communicate with one or two IMDs, there is a potential risk that data frames sent by the EMD may collide with data frames sent between the IMDs when the two IMDs communicate with each other. Using two pairs of different pseudo-noise pulse sequences can reduce the risk of data frame collisions in this case. This is merely one example of how to use the embodiments described herein to improve communication between an EMD and one or more IMDs, and this example is not intended to be limiting. More generally, the embodiments described herein can be used to improve communication between two or more devices, where at least one device is an IMD.

[0162] It should be understood that the subject matter described herein is not limited in its application to the details of the construction and arrangement of the components set forth in the description or shown in the accompanying drawings. The subject matter described herein can have other embodiments and can be practiced or performed in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The use of “comprising,” “including,” or “having,” and variations thereof herein is intended to cover the items listed thereafter and their equivalents, as well as additional items. Moreover, it should be noted that, unless otherwise stated, the term “based on” as used herein should be interpreted as meaning at least partially based on, implying the existence of one or more additional factors upon which the decision or similar decision is based. For example, if a decision is based on the results of a comparison, then in addition to being based on the results of the comparison, the decision may also be based on one or more other factors.

[0163] The embodiments have been described above using functional building blocks that illustrate the performance of specified functions and their relationships. For ease of description, the boundaries of these functional building blocks are generally defined herein. Alternative boundaries can be defined as long as the specified functions and their relationships are performed appropriately. Therefore, any such alternative boundaries are within the scope and spirit of the claimed invention. For example, some steps shown in the various flowcharts can be combined or separated. It is also possible to perform only a subset of the steps shown in the various flowcharts. For another example, it is possible to change some boundaries in the block diagrams and flowcharts. Within the scope of the embodiments described herein, the order of some steps in the various flowcharts can also be changed.

[0164] It should be understood that the above description is intended to be illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) can be used in combination with each other. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the embodiments without departing from their scope. While the dimensions and types of materials and coatings described herein are intended to define parameters of embodiments of the technology, they are by no means restrictive but rather exemplary embodiments. Many other embodiments will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of embodiments of the technology should be determined by reference to the appended claims and the full scope of their equivalents. In the appended claims, the terms “comprising” and “wherein” are used as concise English equivalents of the corresponding terms “including” and “wherein”. Furthermore, in the following claims, the terms “first,” “second,” and “third,” etc., are used only as designations and are not intended to impose numerical requirements on their objects.

Claims

1. A method comprising: The first implantable medical device (IMD1) generates a first bit sequence to communicate from IMD1 to the second implantable medical device (IMD2), and generates a second bit sequence to communicate from IMD1 to the third implantable medical device (IMD3); The IMD1 encodes the first bit series and the second bit series into a composite bit series. Each composite bit in the composite bit series includes a first time slot and a second time slot. The first time slot of the composite bit includes a corresponding bit in the first bit series, and the second time slot of the composite bit includes a corresponding bit in the second bit series. The encoding of the first bit series and the second bit series by IMD1 includes: IMD1 encoding each bit in the second bit series as a first pseudo-noise pulse sequence corresponding to the first bit value of the second bit series, or a second pseudo-noise pulse sequence corresponding to the second bit value of the second bit series, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and The IMD1 uses conductive communication to transmit the composite bit series.

2. The method of claim 1, further comprising the IMD3: Receive the composite bit series; and The received composite bit sequence is decoded to extract the second bit sequence.

3. The method according to claim 2, wherein, The IMD3 decodes the received composite bit sequence to extract the second bit sequence including the IMD3: Multiply each received composite bit by the first pseudo-noise pulse sequence; Integrate each received composite bit of the second time slot multiplied with the first pseudo-noise pulse sequence over the duration; Multiply each received composite bit by the second pseudo-noise pulse sequence; Integrate each of the received composite bits multiplied with the second pseudo-noise pulse sequence over the duration of the second time slot; Each of the received composite bits of the integral multiplied by the first pseudo-noise pulse sequence and each of the received composite bits of the integral multiplied by the second pseudo-noise pulse sequence are mapped to the corresponding co-channel value and the corresponding quadrature channel value. and The value of each bit in the second bit series is determined based on the combination of the same channel value and the orthogonal channel value.

4. The method according to claim 3, wherein, The IMD3 decodes the received composite bit sequence to extract the second bit sequence, which further includes the IMD3: Based on the combination of the same channel value, the orthogonal channel value, and the bit values ​​of the second bit series, it is determined that the data content of the received and decoded second bit series is corrupted.

5. The method according to any one of claims 1 to 4, wherein, The IMD1 encodes the first bit series, including the IMD1: Each bit in the first bit series is encoded as a flat waveform corresponding to the first bit value of the first bit series or a pulse series corresponding to the second bit value of the first bit series.

6. The method according to any one of claims 1 to 4, wherein, The IMD1 encodes the first bit series, including the IMD1: Each bit in the first bit series is encoded as a third pseudo-noise pulse sequence corresponding to the first bit value of the first bit series or a fourth pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, wherein the first pseudo-noise pulse sequence, the second pseudo-noise pulse sequence, the third pseudo-noise pulse sequence and the fourth pseudo-noise pulse sequence are orthogonal to each other.

7. The method according to any one of claims 1 to 6, further comprising: The IMD1 maintains a lookup table that establishes the correspondence between the bit values ​​of the second bit series and the first and second pseudo-noise pulse sequences. and The encoding of the first bit series and the second bit series by IMD1 includes: IMD1 using the lookup table to convert each bit of the second bit series into a corresponding pseudo-noise pulse sequence.

8. The method according to any one of claims 1 to 7, wherein, The composite bit series is a specified number of composite bits.

9. The method according to any one of claims 1 to 8, wherein, The IMD1 uses conductive communication to transmit the composite bit series including the IMD1: Send wake-up pulse; and After sending the wake-up pulse, the composite bit sequence is sent.

10. The method according to claim 9, wherein, The IMD1 uses conductive communication to transmit the composite bit series, and also includes the IMD1: After sending the wake-up pulse and before sending the composite bit sequence, wait for a specified period of time.

11. The method according to claim 10, wherein, The composite bit series includes multiple frames, and each frame includes multiple composite bits.

12. The method according to any one of claims 1 to 11, further comprising the IMD3: The signal intended to be received by the IMD1 is transmitted using conductive communication. The signal includes an additional series of composite bits, each composite bit including a first time slot and a second time slot. The first time slot includes a waveform corresponding to a data bit value, and the second time slot does not contain data.

13. The method of claim 12, further comprising the IMD1: Receive the signal intended to be received by the IMD1; and For each bit in the additional composite bit series, the data value of the first time slot is determined by IMD1 during the second time slot.

14. The method according to any one of claims 1 to 13, wherein, The IMD1 includes a first leadless pacemaker (LCP1), the IMD2 includes a second leadless pacemaker (LCP2), and the third device includes a non-vascular implantable cardioverter defibrillator (NV-ICD).

15. The method according to any one of claims 1 to 14, wherein, In each composite bit of the composite bit series, the first time slot precedes the second time slot.

16. An implantable medical device, comprising: Conductive communication circuitry configured to transmit conductive communication signals to multiple additional implantable medical devices; and A controller, coupled to the conductive communication circuit and configured to: Generate a first-order sequence for the first additional implantable medical device among the plurality of additional implantable medical devices to communicate with; Generate a second bit sequence for the second additional implantable medical device among the plurality of additional implantable medical devices to communicate with; The first bit series and the second bit series are encoded into a composite bit series. Each composite bit in the composite bit series includes a first time slot and a second time slot. The first time slot of the composite bit includes a corresponding bit in the first bit series, and the second time slot of the composite bit includes a corresponding bit in the second bit series. In order to encode the first bit series and the second bit series, the controller is configured to encode each bit in the second bit series as a first pseudo-noise pulse sequence corresponding to the first bit value of the second bit series or a second pseudo-noise pulse sequence corresponding to the second bit value of the second bit series, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and The conductive communication circuit is controlled to use conductive communication to transmit the composite bit series.

17. The implantable medical device according to claim 16, wherein, In order to encode the first bit series, the controller is further configured to: Each bit in the first bit series is encoded as a flat waveform corresponding to the first bit value of the first bit series or a pulse series corresponding to the second bit value of the first bit series.

18. The implantable medical device according to any one of claims 16 or 17, wherein, The controller is further configured to: A lookup table is used to maintain the correspondence between the bit values ​​of the second bit series and the first and second pseudo-noise pulse sequences. and The controller is configured to encode the first bit series and the second bit series using the lookup table to convert each bit of the second bit series into a corresponding pseudo-noise pulse sequence.

19. A system comprising: Multiple implantable medical devices, including a first implantable medical device (IMD1), a second implantable medical device (IMD2), and a third implantable medical device (IMD3), wherein IMD1 is configured as follows: Generate the first series to communicate from IMD1 to IMD2; Generate a second bit sequence to be transmitted from IMD1 to IMD3; The first bit series and the second bit series are encoded into a composite bit series. Each composite bit in the composite bit series includes a first time slot and a second time slot. The first time slot of the composite bit includes a corresponding bit in the first bit series, and the second time slot of the composite bit includes a corresponding bit in the second bit series. In order to encode the first bit series and the second bit series, the IMD1 is configured to encode each bit in the second bit series as a first pseudo-noise pulse sequence corresponding to the first bit value of the second bit series or a second pseudo-noise pulse sequence corresponding to the second bit value of the second bit series, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and The composite bit series is transmitted using conductive communication.

20. The system according to claim 19, wherein, The IMD3 is configured to: Receive the composite bit series; Multiply each received composite bit by the first pseudo-noise pulse sequence; Integrate each received composite bit of the second time slot multiplied with the first pseudo-noise pulse sequence over the duration; Multiply each received composite bit by the second pseudo-noise pulse sequence; Integrate each of the received composite bits multiplied with the second pseudo-noise pulse sequence over the duration of the second time slot; Each of the received composite bits of the integral multiplied by the first pseudo-noise pulse sequence and each of the received composite bits of the integral multiplied by the second pseudo-noise pulse sequence are mapped to the corresponding co-channel value and the corresponding quadrature channel value. and The value of each bit in the second bit series is determined based on the combination of the same channel value and the orthogonal channel value.

21. A method comprising: The first implantable medical device (IMD1) generates the first series of data to communicate from IMD1 to the second implantable medical device (IMD2); The IMD1 encodes each bit in the first bit series into a first pseudo-noise pulse sequence corresponding to the first bit value of the first bit series or a second pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, thereby generating an encoded bit series, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and The IMD1 uses conductive communication to send the encoded first bit sequence.

22. The method of claim 21, further comprising the IMD2: Receive the encoded first bit sequence; and The received encoded bit sequence is decoded to extract the first bit sequence.

23. The method according to claim 22, wherein, The IMD2 decoder receives the encoded bit sequence to extract the first bit sequence, which includes the IMD2: Multiply each received bit in the received coded bit sequence by the first pseudo-noise pulse sequence; Integrate each of the received coded bit series multiplied with the first pseudo-noise pulse sequence over the duration of the coded bit; Multiply each received bit in the received coded bit sequence by the second pseudo-noise pulse sequence; Integrate each of the received coded bit sequence multiplied with the second pseudo-noise pulse sequence over the duration of the coded bit sequence; Each of the received coded bit series of the integral multiplied by the first pseudo-noise pulse sequence and each of the received coded bit series of the integral multiplied by the second pseudo-noise pulse sequence are mapped to the corresponding co-channel value and the corresponding orthogonal channel value. and The value of each bit in the first bit series is determined based on the combination of the same channel value and the orthogonal channel value.

24. The method according to claim 23, wherein, The IMD2 decoding of the received encoded bit sequence to extract the first bit sequence further includes the IMD2: Based on the combination of the same channel value, the orthogonal channel value, and the determined bit values ​​of the first bit series, it is determined that the data content of the received and decoded first bit series is corrupted.

25. The method according to any one of claims 21 to 24, further comprising: Before IMD1 encodes each bit in the first bit series into a first pseudo-noise pulse sequence or a second pseudo-noise pulse sequence, IMD1 selects IMD2 from a plurality of implantable medical devices, each of the plurality of implantable medical devices having a corresponding pseudo-noise pulse sequence from a plurality of mutually orthogonal first pseudo-noise pulse sequences and second pseudo-noise pulse sequences. and The process of encoding each bit in the first bit series into the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence by IMD1 includes: encoding each bit in the first bit series into the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence corresponding to the selected IMD2.

26. The method of claim 25, further comprising: The IMD1 maintains a lookup table for the corresponding mutually orthogonal first and second pseudo-noise pulse sequences for each of the plurality of implantable medical devices. and The IMD1 selects one of a plurality of mutually orthogonal first pseudo-noise pulse sequences and second pseudo-noise pulse sequences from the lookup table.

27. The method according to any one of claims 21 to 24, further comprising: Before IMD1 transmits the encoded bit series using conducted communication, IMD1 transmits an initial bit series encoded as a third or fourth pseudo-noise pulse sequence, wherein the first, second, third, and fourth pseudo-noise pulse sequences are orthogonal to each other, and the initial bit series specifies: IMD2 between multiple implantable medical devices; and First pseudo-noise pulse and second pseudo-noise pulse.

28. The method of claim 27, further comprising the IMD2: Receive the initial bit sequence; and Determine whether the initial bit series specifies the IMD2.

29. The method of claim 28, further comprising the IMD2: In response to the initial bit series specified by the IMD2, the first bit value of the first bit series is decoded.

30. The method of claim 29, further comprising the IMD2: After decoding the first bit value of the first bit series, the IMD1 is responded to using a signal encoded with the first pseudo-noise pulse and the second pseudo-noise pulse.

31. The method according to claim 27, wherein, The plurality of implantable medical devices includes a third implantable medical device (IMD3), and the method further includes the IMD3: Receive the initial bit sequence; Determine whether the initial bit series specifies the IMD3; and In response to the initial bit series not specifying the IMD3, the first bit value of the first bit series is not decoded.

32. The method according to any one of claims 21 to 31, wherein, The first bit series is a specified number of bits.

33. The method according to any one of claims 21 to 32, wherein, The IMD1 uses conductive communication to transmit the first bit series including the IMD1: Send wake-up pulse; and After sending the wake-up pulse, the first bit sequence is sent.

34. The method according to any one of claims 21 to 33, wherein, The IMD1 uses conductive communication to transmit the first bit series, which also includes the IMD1: After sending the wake-up pulse and before sending the first bit sequence, wait for a specified period of time.

35. The method according to any one of claims 21 to 34, wherein, The IMD1 includes a first leadless pacemaker (LCP1), and the IMD2 includes a non-vascular implantable cardioverter defibrillator (NV-ICD).

36. The method according to any one of claims 21 to 34, wherein, The IMD1 includes a first leadless pacemaker (LCP1), and the IMD2 includes a second leadless pacemaker (LCP2).

37. A system comprising: Multiple implantable medical devices, including a first implantable medical device (IMD1) and a second implantable medical device (IMD2), wherein IMD1 is configured to: Generate the first series to communicate from IMD1 to IMD2; Each bit in the first bit series is encoded into a first pseudo-noise pulse sequence corresponding to the first bit value of the first bit series or a second pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, thereby generating an encoded bit series, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and Conductive communication is used to send the encoded first bit sequence.

38. The system according to claim 37, wherein, The IMD1 is further configured as follows: Before encoding each bit in the first bit series into a first pseudo-noise pulse sequence or a second pseudo-noise pulse sequence, the IMD2 is selected from a plurality of implantable medical devices, each of the plurality of implantable medical devices having a pseudo-noise pulse sequence corresponding to one of a plurality of mutually orthogonal first pseudo-noise pulse sequences and second pseudo-noise pulse sequences. and In order to encode each bit in the first bit series as the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence, the IMD1 is further configured to encode each bit in the first bit series as the first pseudo-noise pulse sequence or the second pseudo-noise pulse sequence corresponding to the selected IMD2.

39. The system according to any one of claims 37 or 38, wherein, The IMD1 is also configured as follows: Before transmitting the encoded bit series using conducted communication, an initial bit series encoded as a third or fourth pseudo-noise pulse sequence is transmitted, wherein the first, second, third, and fourth pseudo-noise pulse sequences are orthogonal to each other, and the initial bit series specifies: IMD2 between multiple implantable medical devices; and The first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence.

40. An implantable medical device, comprising: A conductive communication circuit is configured to transmit signals from a first implantable medical device (IMD1) to a second implantable medical device (IMD2). and A controller, coupled to the conductive communication circuit and configured to: Generate the first series to communicate from IMD1 to IMD2; Each bit in the first bit series is encoded as either a first pseudo-noise pulse sequence corresponding to the first bit value of the first bit series or a second pseudo-noise pulse sequence corresponding to the second bit value of the first bit series, wherein the first pseudo-noise pulse sequence and the second pseudo-noise pulse sequence are orthogonal to each other; and The conductive communication circuit is controlled to use conductive communication to transmit the composite bit series.

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