Atrial contraction detection by a ventricular leadless pacing device for atrio-synchronous ventricular pacing

Abstract

A leadless pacing device (LPD) includes a motion sensor configured to generate a motion signal as a function of heart movement. The LPD is configured to analyze the motion signal within an atrial contraction detection window that begins an atrial contraction detection delay period after activation of the ventricle, and detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window. If the LPD does not detect a ventricular depolarization subsequent to the atrial contraction, e.g., with an atrio-ventricular (AV) interval beginning when the atrial contraction was detected, the LPD delivers a ventricular pacing pulse.

What is claimed is: 
     
       1. A leadless pacing device configured to deliver atrio-synchronous ventricular pacing, the leadless pacing device comprising:
 a plurality of electrodes; 
 a motion sensor configured to generate a motion signal as a function of based on movement of a heart of a patient; 
 a stimulation module circuitry coupled to the plurality of electrodes, wherein the stimulation module circuitry is configured to generate pacing pulses and deliver the pacing pulses to a ventricle of the heart via the plurality of electrodes; 
 an electrical sensing module circuitry coupled to the plurality of electrodes, wherein the electrical sensing module circuitry is configured to detect depolarizations of the ventricle within a cardiac electrogram sensed via the plurality of electrodes; 
 a mechanical sensing module circuitry coupled to the motion sensor and configured to:
 receive the motion signal from the motion sensor; 
 identify an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiate an atrial contraction detection delay period; 
 analyze the motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period; and 
 detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; 
 
 a processing module circuitry configured to control the stimulation module circuitry to generate a pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the detection of the contraction of the atrium by the mechanical sensing module circuitry; and 
 a housing configured to be implanted within the ventricle, wherein the housing encloses the motion sensor, the stimulation module circuitry, the electrical sensing module circuitry, the mechanical sensing module circuitry, and the processing module circuitry; 
 wherein the processing module circuitry is configured to:
 determine that the electrical sensing module circuitry did not detect a depolarization of the ventricle within an atrioventricular (AV) interval beginning timed from when the mechanical sensing module circuitry detected the contraction of the atrium; and 
 control the stimulation module circuitry to generate the pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the determination; and, 
 
 wherein the mechanical sensing module circuitry is configured to detect a contraction of the ventricle based on the motion signal after delivery of the pacing pulse to the ventricle, and the processing module circuitry is configured to: determine whether the delivery of the pacing pulse to the ventricle was effective based on the detection of the contraction of the ventricle; and adjust the AV interval based on the determination of whether the delivery of the pacing pulse to the ventricle was effective. 
 
     
     
       2. The leadless pacing device of  claim 1 , wherein the processing module circuitry is configured to:
 determine that an interval from the delivery of the pacing pulse to the detection of the contraction of the ventricle is less than a threshold; and 
 decrease the AV interval in response to the determination that the interval from the delivery of the pacing pulse to the detection of the contraction of the ventricle is less than the threshold. 
 
     
     
       3. The leadless pacing device of  claim 1 ,
 wherein the mechanical sensing module circuitry is configured to:
 detect a peak of the ventricular contraction of the ventricle based on the motion signal; and 
 determine an amplitude of the motion signal at the peak, and 
 
 wherein the processing module circuitry is configured to:
 determine that the amplitude is greater than the threshold; and 
 increase the AV interval in response to the determination that the amplitude is greater than the threshold. 
 
 
     
     
       4. A leadless pacing device configured to deliver atrio-synchronous ventricular pacing, the leadless pacing device comprising:
 a plurality of electrodes; 
 a motion sensor configured to generate a motion signal as a function of based on movement of a heart of a patient; 
 a stimulation module circuitry coupled to the plurality of electrodes, wherein the stimulation module circuitry is configured to generate pacing pulses and deliver the pacing pulses to a ventricle of the heart via the plurality of electrodes; 
 an electrical sensing module circuitry coupled to the plurality of electrodes, wherein the electrical sensing module circuitry is configured to detect depolarizations of the ventricle within a cardiac electrogram sensed via the plurality of electrodes, wherein the electrical sensing circuitry is further configured to detect depolarizations of at least one atrium of the heart; 
 a mechanical sensing module circuitry coupled to the motion sensor and configured to:
 receive the motion signal from the motion sensor; 
 identify an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiate an atrial contraction detection delay period; 
 analyze the motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period; and 
 detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; 
 
 a processing module circuitry configured to control the stimulation module circuitry to generate a one or more pacing pulse pulses and deliver the pacing pulse pulses to the ventricle via the plurality of electrodes in response to the detection of the contraction of the atrium by the mechanical sensing module; and 
 a housing configured to be implanted within the ventricle, wherein the housing encloses the motion sensor, the stimulation module circuitry, the electrical sensing module circuitry, the mechanical sensing module circuitry, and the processing module circuitry; 
 wherein the processing module is configured to:
 determine that the electrical sensing module did not detect a depolarization of the ventricle within an atrioventricular (AV) interval beginning when the mechanical sensing module detected the contraction of the atrium; and   control the stimulation module to generate the pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the determination; and,   
 wherein the AV interval comprises a mechanical AV interval, 
 wherein the electrical sensing module is configured to detect depolarizations of the atrium within the cardiac electrogram sensed via the plurality of electrodes, 
 wherein, in response to the electrical sensing module circuitry detecting a depolarization of the atrium, the processing module circuitry is configured to:
 determine that the electrical sensing module circuitry did not detect a depolarization of the ventricle within an electrical atrioventricular (AV) interval beginning timed from when the electrical sensing module circuitry detected the depolarization of the atrium; and 
 control the stimulation module circuitry to generate a one of the pacing pulse pulses and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the determination that the electrical sensing module circuitry did not detect a depolarization of the ventricle, 
 
 wherein the processing module circuitry is further configured to determine that the electrical sensing module circuitry did not detect a depolarization of the atrium during a predetermined number of one or more cardiac cycles and, in response to the determination:
 control the mechanical sensing module circuitry to detect a the contraction of the atrium based on the motion signal; 
 determine that the electrical sensing module circuitry did not detect a depolarization of the ventricle within the a mechanical AV interval beginning timed from when the mechanical sensing module circuitry detected the contraction of the atrium; and 
 control the stimulation module circuitry to generate a one of the pacing pulse pulses and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the determination that the mechanical sensing module circuitry did not detect a depolarization of the ventricle, and 
 
 wherein the electrical AV interval is greater than the mechanical AV interval. 
 
     
     
       5. A leadless pacing device configured to deliver atrio-synchronous ventricular pacing, the leadless pacing device comprising:
 a plurality of electrodes; 
 a motion sensor configured to generate a motion signal as a function of based on movement of a heart of a patient; 
 a stimulation module circuitry coupled to the plurality of electrodes, wherein the stimulation module circuitry is configured to generate pacing pulses and deliver the pacing pulses to a ventricle of the heart via the plurality of electrodes; 
 an electrical sensing module circuitry coupled to the plurality of electrodes, wherein the electrical sensing module circuitry is configured to detect depolarizations of the ventricle within a cardiac electrogram sensed via the plurality of electrodes; 
 a mechanical sensing module circuitry coupled to the motion sensor and configured to:
 receive the motion signal from the motion sensor; 
 identify an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiate an atrial contraction detection delay period; 
 analyze the motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period; and 
 detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; 
 
 a processing module circuitry configured to control the stimulation module circuitry to generate a pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the detection of the contraction of the atrium by the mechanical sensing module circuitry; and 
 a housing configured to be implanted within the ventricle, wherein the housing encloses the motion sensor, the stimulation module circuitry, the electrical sensing module circuitry, the mechanical sensing module circuitry, and the processing module circuitry; 
 wherein the processing module circuitry is configured to:
 determine a heart rate of the patient based on depolarizations detected by the electrical sensing module circuitry; 
 determine that the heart rate exceeds a threshold; and 
 control the stimulation module circuitry to generate pacing pulses and deliver the pacing pulses to the ventricle according to an asynchronous ventricular pacing mode in response to based on the determination that the heart rate exceeds the threshold. 
 
 
     
     
       6. A leadless pacing device configured to deliver atrio-synchronous ventricular pacing, the leadless pacing device comprising:
 a plurality of electrodes; 
 a motion sensor configured to generate a motion signal as a function of based on movement of a heart of a patient; 
 a stimulation module circuitry coupled to the plurality of electrodes, wherein the stimulation module circuitry is configured to generate pacing pulses and deliver the pacing pulses to a ventricle of the heart via the plurality of electrodes; 
 an electrical sensing module circuitry coupled to the plurality of electrodes, wherein the electrical sensing module circuitry is configured to detect depolarizations of the ventricle within a cardiac electrogram sensed via the plurality of electrodes; 
 a mechanical sensing module circuitry coupled to the motion sensor and configured to:
 receive the motion signal from the motion sensor; 
 identify an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiate an atrial contraction detection delay period; 
 analyze the motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period; and 
 detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; 
 
 a processing module circuitry configured to control the stimulation module circuitry to generate a pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the detection of the contraction of the atrium by the mechanical sensing module circuitry; and 
 a housing configured to be implanted within the ventricle, wherein the housing encloses the motion sensor, the stimulation module circuitry, the electrical sensing module circuitry, the mechanical sensing module circuitry, and the processing module circuitry; 
 wherein the motion sensor comprises a plurality of accelerometers, each of the plurality of accelerometers oriented along a respective axis and configured to generate a respective accelerometer signal, 
 wherein mechanical sensing module circuitry derives the motion signal based on a first one or more of the accelerometer signals according to a first sensing vector, and 
 wherein the processing module circuitry is configured to:
 determine that the mechanical sensing module circuitry did not detect a contraction of the atrium during a predetermined number of one or more cardiac cycles; and 
 control the mechanical sensing module circuitry to derive the motion signal based on a second one or more of the accelerometer signals according to a second sensing vector in response to based on the determination. 
 
 
     
     
       7. A method for delivering atrio-synchronous ventricular pacing by a leadless pacing device implanted within a ventricle of a heart of a patient, the method comprising:
 identifying an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiating an atrial contraction detection delay period; 
 analyzing a motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period, wherein the motion signal is generated by a motion sensor of the leadless pacing device as a function of based on movement of the heart; 
 detecting a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; and 
 delivering a pacing pulse to the ventricle in response to the detection of the atrial contraction; 
 determining that a depolarization of the ventricle resulting from the depolarization of the atrium that caused the contraction of the atrium was not detected within an atrioventricular (AV) interval beginning when the contraction of the atrium was detected; 
 delivering the pacing pulse to the ventricle in response to the determination; 
 determining that a depolarization of the ventricle resulting from the depolarization of the atrium that caused the contraction of the atrium was not detected within an atrioventricular (AV) interval beginning timed from when the contraction of the atrium was detected; and 
 delivering the a pacing pulse to the ventricle in response to the determination; 
 detecting a contraction of the ventricle based on the motion signal after delivery of the pacing pulse to the ventricle; and  
 determining whether the delivery of the pacing pulse to the ventricle was effective based on the detection of the contraction of the ventricle; and 
 adjusting the AV interval based on the determination of whether the delivery of the pacing pulse to the ventricle was effective. 
 
     
     
       8. The method of  claim 7 , further comprising:
 determining that an interval from the delivery of the pacing pulse to the detection of the contraction of the ventricle is less than a threshold; and 
 decreasing the AV interval in response to the determination that the interval from the delivery of the pacing pulse to the detection of the contraction of the ventricle is less than the threshold. 
 
     
     
       9. The method of  claim 7 , further comprising:
 detecting a peak of the ventricular contraction of the ventricle based on the motion signal; 
 determining an amplitude of the motion signal at the peak; 
 determining that the amplitude is greater than the threshold; and 
 increasing the AV interval in response to the determination that the amplitude is greater than the threshold. 
 
     
     
       10. A method for delivering atrio-synchronous ventricular pacing by a leadless pacing device implanted within a ventricle of a heart of a patient, the method comprising:
 identifying an activation of the ventricle; 
 upon identification of the activation of the ventricle, initiating an atrial contraction detection delay period; 
 analyzing a motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period, wherein the motion signal is generated by a motion sensor of the leadless pacing device as a function of movement of the heart; 
 detecting a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; and 
 delivering a pacing pulse to the ventricle in response to the detection of the atrial contraction; 
 determining that a depolarization of the ventricle resulting from the depolarization of the atrium that caused the contraction of the atrium was not detected within an atrioventricular (AV) interval beginning when the contraction of the atrium was detected; 
 delivering the pacing pulse to the ventricle in response to the determination; 
 determining that a depolarization of the ventricle resulting from the depolarization of the atrium that caused the contraction of the atrium was not detected within an atrioventricular (AV) interval beginning when the contraction of the atrium was detected; and 
 delivering the pacing pulse to the ventricle in response to the determination; 
 wherein the leadless pacing device is configured to detect depolarizations of the atrium, and the AV interval comprises a mechanical AV interval, the method further comprising: 
 in response to detecting a depolarization of the an atrium of the heart:
 determining that a depolarization of the ventricle was not detected within an electrical atrioventricular (AV) interval beginning when the electrical sensing module detected timed from the detection of the depolarization of the atrium; and 
 delivering a pacing pulse to the ventricle in response to the determination that a depolarization of the ventricle was not detected, and 
 
 in response to determining that a depolarization of the atrium was not detected during a predetermined number of one or more cardiac cycles:
 detecting a contraction of the atrium based on the a motion signal; 
 determining that a depolarization of the ventricle was not detected within the a mechanical AV interval beginning timed from when the contraction of the atrium was detected; and 
 delivering a pacing pulse to the ventricle in response to the determination that a depolarization of the ventricle was not detected, and 
 
 wherein the electrical AV interval is greater than the mechanical AV interval, and 
 wherein detecting the contraction of the atrium based on the motion signal comprises:
 identifying an activation of the ventricle; 
 in response to identification of the activation of the ventricle, initiating an atrial contraction detection delay period; 
 analyzing a motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period, wherein the motion signal is generated by a motion sensor of the pacing device based on movement of the heart; and 
 detecting the contraction of the based on the analysis of the motion signal within the atrial contraction detection window. 
 
 
     
     
       11. A method for delivering atrio-synchronous ventricular pacing by a leadless pacing device implanted within a ventricle of a heart of a patient, the method comprising:
 identifying an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiating an atrial contraction detection delay period; 
 analyzing a motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period, wherein the motion signal is generated by a motion sensor of the leadless pacing device as a function of based on movement of the heart; 
 detecting a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; and 
 delivering a pacing pulse to the ventricle in response to the detection of the atrial contraction;, wherein the motion signal is further generated by the motion sensor based on motion of the patient, the method further comprising:
 determining an amount of motion of the patient based on the motion signal; and 
 delivering the pacing pulses to the ventricle according to an asynchronous ventricular pacing mode in response to based on the amount of motion of the patient exceeding a threshold. 
 
 
     
     
       12. A method for delivering atrio-synchronous ventricular pacing by a leadless pacing device implanted within a ventricle of a heart of a patient, the method comprising:
 identifying an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiating an atrial contraction detection delay period; 
 analyzing a motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period, wherein the motion signal is generated by a motion sensor of the leadless pacing device as a function of based on movement of the heart; 
 detecting a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; and 
 delivering a pacing pulse to the ventricle in response to the detection of the atrial contraction;, the method further comprising: 
 determining a contraction of the atrium was not detected during a predetermined number of one or more cardiac cycles; and 
 delivering pacing pulses to the ventricle according to an asynchronous ventricular pacing mode in response to based on the determination. 
 
 
     
     
       13. A method for delivering atrio-synchronous ventricular pacing by a leadless pacing device implanted within a ventricle of a heart of a patient, the method comprising:
 identifying an activation of the ventricle; 
 uponin response to identification of the activation of the ventricle, initiating an atrial contraction detection delay period; 
 analyzing a motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period, wherein the motion signal is generated by a motion sensor of the leadless pacing device as a function of based on movement of the heart; 
 detecting a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; and 
 delivering a pacing pulse to the ventricle in response to the detection of the atrial contraction;, the method further comprising:
 determining that a heart rate of the heart exceeds a threshold; and 
 delivering the one or more additional pacing pulses to the ventricle according to an asynchronous ventricular pacing mode in response to based on the determination that the heart rate exceeds the threshold. 
 
 
     
     
       14. The leadless pacing device of claim 1, wherein the AV interval begins when the mechanical sensing circuitry detected the contraction of the atrium. 
     
     
       15. The leadless pacing device of claim 1, wherein the processing circuitry is configured to adjust the AV interval based on the determination of whether the delivery of the pacing pulse to the ventricle was effective. 
     
     
       16. The leadless pacing device of claim 4, wherein the electrical sensing circuitry is configured to detect the depolarizations of the at least one atrium via the plurality of electrodes. 
     
     
       17. The leadless pacing device of claim 4, wherein the processing circuitry is configured to control the mechanical sensing circuitry to detect the contraction of the atrium based on the motion signal in response to determining that the electrical sensing circuitry did not detect a depolarization of the atrium during a predetermined number of one or more cardiac cycles. 
     
     
       18. The method of claim 7, further comprising adjusting the AV interval based on the determination of whether the delivery of the pacing pulse to the ventricle was effective. 
     
     
       19. The method claim 10, wherein detecting the contraction of the atrium based on the motion signal comprises detecting the contraction of the atrium in response to determining that the depolarization of the atrium was not detected during a predetermined number of one or more cardiac cycles. 
     
     
       20. The method of claim 12, wherein determining the contraction of the atrium was not detected during one or more cardiac cycles comprises determining the contraction of the atrium was not detected during a predetermined number of one or more cardiac cycles. 
     
     
       21. A leadless pacing device configured to deliver atrio-synchronous ventricular pacing, the leadless pacing device comprising:
 a plurality of electrodes;   a motion sensor configured to generate a motion signal based on movement of a heart of a patient;   stimulation circuitry coupled to the plurality of electrodes, wherein the stimulation circuitry is configured to generate pacing pulses and deliver the pacing pulses to a ventricle of the heart via the plurality of electrodes;   electrical sensing circuitry coupled to the plurality of electrodes, wherein the electrical sensing circuitry is configured to detect depolarizations of the ventricle within a cardiac electrogram sensed via the plurality of electrodes;   mechanical sensing circuitry coupled to the motion sensor and configured to:
 receive the motion signal from the motion sensor; 
 identify an activation of the ventricle; 
 in response to identification of the activation of the ventricle, initiate an atrial contraction detection delay period; 
 analyze the motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period; and 
 detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; 
   processing circuitry configured to:
 determine that the electrical sensing circuitry did not detect a depolarization of the ventricle within an atrioventricular (AV) interval timed from when the mechanical sensing circuitry detected the contraction of the atrium; and 
 control the stimulation circuitry to generate a pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the determination; and 
   a housing configured to be implanted within the ventricle, wherein the housing encloses the motion sensor, the stimulation circuitry, the electrical sensing circuitry, the mechanical sensing circuitry, and the processing circuitry;   wherein the processing circuitry is further configured to:
 determine a heart rate of the heart; and 
 adjust the atrial contraction detection delay period based on the determined heart rate. 
   
     
     
       22. A leadless pacing device configured to deliver atrio-synchronous ventricular pacing, the leadless pacing device comprising:
 a plurality of electrodes;   a motion sensor configured to generate a motion signal based on movement of a heart of a patient;   stimulation circuitry coupled to the plurality of electrodes, wherein the stimulation circuitry is configured to generate pacing pulses and deliver the pacing pulses to a ventricle of the heart via the plurality of electrodes;   electrical sensing circuitry coupled to the plurality of electrodes, wherein the electrical sensing circuitry is configured to detect depolarizations of the ventricle within a cardiac electrogram sensed via the plurality of electrodes;   mechanical sensing circuitry coupled to the motion sensor and configured to:
 receive the motion signal from the motion sensor; 
 identify an activation of the ventricle; 
 in response to identification of the activation of the ventricle, initiate an atrial contraction detection delay period; 
 analyze the motion signal within an atrial contraction detection window that begins upon completion of the atrial contraction detection delay period; and 
 detect a contraction of an atrium of the heart based on the analysis of the motion signal within the atrial contraction detection window; 
   processing circuitry configured to:
 determine that the electrical sensing circuitry did not detect a depolarization of the ventricle within an atrioventricular (AV) interval timed from when the mechanical sensing circuitry detected the contraction of the atrium; and 
 control the stimulation circuitry to generate a pacing pulse and deliver the pacing pulse to the ventricle via the plurality of electrodes in response to the determination; and 
   a housing configured to be implanted within the ventricle, wherein the housing encloses the motion sensor, the stimulation circuitry, the electrical sensing circuitry, the mechanical sensing circuitry, and the processing circuitry;   wherein the processing circuitry is further configured to:
 identify a condition inconsistent with atrio-synchronous ventricular pacing; and 
 control the stimulation circuitry to deliver one or more additional pacing pulses to the ventricle according to an asynchronous ventricular pacing mode based on the identification of the condition. 
   
     
     
       23. The leadless pacing device of claim 22, wherein the motion sensor is configured to generate the motion signal based on motion of the patient and, to identify the condition inconsistent with atrio-synchronous ventricular pacing, the processing circuitry is configured to determine, based on the motion signal, that an amount of motion of the patient satisfies a threshold. 
     
     
       24. The leadless pacing device of claim 22, wherein, to identify the condition inconsistent with atrio-synchronous ventricular pacing, the processing circuitry is configured to determine that a contraction of the atrium was not detected during one or more cardiac cycles. 
     
     
       25. The leadless pacing device of claim 22, wherein, to identify the condition inconsistent with atrio-synchronous ventricular pacing, the processing circuitry is configured to determine that a heart rate of the heart satisfies a threshold. 
     
     
       26. The leadless pacing device of claim 22, wherein, to identify the condition inconsistent with atrio-synchronous ventricular pacing, the processing circuitry is configured to determine that a heart rate irregularity of the heart satisfies a threshold.