Systems and methods for detecting atrial tachyarrhythmia
Systems and methods for detecting cardiac arrhythmia are discussed. A medical-device system includes an arrhythmia detector circuit and an event prioritizer circuit. The arrhythmia detector circuit can detect an atrial activation event from a cardiac electrical signal sensed from the patient, and determine an atrial fibrillation (AF) confidence indicator based on a signal characteristic of the atrial activation event. The event prioritizer circuit can generate an event priority for the AF event based on the AF confidence indicator. Multiple AF events may be prioritized in a specific order and presented to a user or a process.
1 . A medical-device system for detecting cardiac arrhythmia in a patient, the system comprising:
an atrial fibrillation (AF) detector circuit configured to determine a ventricular rate parameter for the patient using the received cardiac signal and to detect an AF event using the determined ventricular rate parameter;
an atrial characteristic generator circuit configured to determine an ensemble average of multiple segments of the cardiac electrical signal corresponding to a plurality of cardiac cycles, and to generate a signal characteristic of a P wave for the plurality of cardiac cycles using the determined ensemble average;
an AF confidence calculator configured to determine an AF confidence indicator indicating a confidence level of the detected AF event based on the ventricular rate parameter of the detected AF event and the signal characteristic of the P wave for the plurality of cardiac cycles comprising the detected AF event;
an event prioritizer circuit configured to receive the detected AF event in a time-based order corresponding to a time of the detected AF event and to generate an event priority for the detected AF event based on the AF confidence indicator, the event priority different than the time-based order; and
a controller circuit configured to dynamically control allocation of resources of the medical-device system to process or store information about the AF event, in accordance with the generated event priority, including increasing allocation of resources in response to the generated event priority indicating a high confidence or a numerical confidence score above a threshold in contrast to the generated event priority indicating a low confidence or the numerical confidence score below the threshold,
wherein to detect the AF event comprises using information of the cardiac electrical signal separate from the detected absence or presence of the P wave.
2 . The system of claim 1 , wherein the atrial characteristic generator circuit is further configured to generate the signal characteristic including a peak intensity or a signal power of the detected P wave.
3 . The system of claim 1 , wherein the atrial characteristic generator circuit is further configured to detect a plurality of P waves respectively from segments of the cardiac electrical signal corresponding to a plurality of cardiac cycles; and
generate signal characteristics respectively from the plurality of P waves; and
wherein the AF confidence calculator is configured to determine the AF confidence indicator based on a variability of the signal characteristics of the plurality of P waves.
4 . The system of claim 3 , wherein the atrial characteristic generator circuit is further configured to generate the signal characteristics including similarity metrics between (1) an ensemble-averaged morphology of the plurality of P waves and (2) respective signal morphologies of the plurality of P waves; and
wherein the AF confidence calculator is configured to determine the AF confidence indicator based on a variability of the similarity metrics.
5 . The system of claim 3 , wherein the atrial characteristic generator circuit is further configured to generate the signal characteristics including similarity metrics between (1) an atrial morphology template acquired during a specific type of cardiac rhythm and (2) respective signal morphologies of the P waves; and
wherein the AF confidence calculator is configured to determine the AF confidence indicator based on a variability of the similarity metrics.
6 . The system of claim 1 , wherein the atrial fibrillation (AF) detector circuit is further configured to detect two consecutive ventricular activation events from the cardiac electrical signal;
wherein the atrial characteristic generator circuit is configured to detect the presence or absence of P wave between the detected two consecutive ventricular activation events; and
wherein the AF confidence calculator is configured to determine, for the AF event detected using information of the cardiac electrical signal separate from the detected absence or presence of the P wave, the AF confidence indicator including a first AF confidence level in the detected presence of one or more P waves between the detected two consecutive ventricular activation events, and a second AF confidence level in the detected absence of the P wave, the first AF confidence level being lower than the second AF confidence level.
7 . The system of claim 6 , wherein the atrial fibrillation (AF) detector circuit is further configured to detect an atrial flutter event when more than one P wave is detected to be present between the detected two consecutive ventricular activation events.
8 . The system of claim 1 , wherein:
the AF confidence calculator is further configured to determine respective AF confidence indicators for two or more AF events detected from the patient; and
the event prioritizer circuit is further configured to prioritize the two or more AF events in a descending order of the AF confidence indicators.
9 . The system of claim 1 , wherein the arrhythmia detector circuit is configured to determine, for the AF event detected using the information of the cardiac electrical signal separate from the detected absence or presence of the P wave, the AF confidence indicator including a first AF confidence level in the detected presence of the P wave and a second AF confidence level in the detected absence of the P wave, the first AF confidence level being lower than the second AF confidence level.
10 . The system of claim 9 , wherein, in response to the determined AF confidence indicator for the AF event being the first AF confidence level, the arrhythmia detector circuit is configured to confirm the AF event using additional processing that is more computationally intensive than to detect the AF event.
11 . The system of claim 1 , wherein the medical-device system includes an implantable medical device including the AF detector circuit, the atrial characteristic generator circuit, the AF confidence calculator, the event prioritizer circuit, the controller circuit, and memory.
12 . The system of claim 11 , wherein the controller circuit is configured to implement dynamic memory management by removing AF events with lower confidence indicators from the memory before removing AF events with higher confidence indicators when memory space needs to be released.
13 . The system of claim 1 , wherein the controller circuit is configured to dynamically allocate memory space to store the detected AF event based on the generated event priority, including in response to the generated event priority indicating the high confidence or the numerical confidence score above the threshold in contrast to the generated event priority indicating the low confidence or the numerical confidence score below the threshold.
14 . A system for detecting cardiac arrhythmia in a patient, comprising:
an ambulatory medical device including a communication circuit and circuitry configured to sense a cardiac electrical signal from the patient, to detect a ventricular rate parameter for the patient using the sensed cardiac electrical signal, and to detect an atrial fibrillation (AF) event using the detected ventricular rate parameter; and
an external system communicatively coupled to the ambulatory medical device, the external system including:
an arrhythmia detector circuit configured to:
determine an ensemble average of multiple segments of the sensed cardiac electrical signal corresponding to a plurality of cardiac cycles and to generate a signal characteristic of a P wave for the plurality of cardiac cycles using the determined ensemble average; and
determine an AF confidence indicator indicating a confidence level of the detected AF event based on the ventricular rate parameter of the detected AF event and the signal characteristic of the P wave for the plurality of cardiac cycles comprising the detected AF event;
an event prioritizer circuit configured to generate an event priority for the detected AF event based on the AF confidence indicator; and
a controller circuit configured to dynamically control allocation of resources of the ambulatory medical device to process or store information about the detected AF event, in accordance with the generated event priority, including increasing allocation of ambulatory medical device resources in response to the generated event priority indicating a high confidence or a numerical confidence score above a threshold in contrast to the generated event priority indicating a low confidence or the numerical confidence score below the threshold,
wherein to detect the AF event comprises using information of the cardiac electrical signal separate from the detected absence or presence of the P wave.
15 . The system of claim 14 , wherein the ambulatory medical device is an implantable cardiac monitor.
16 . The system of claim 14 , wherein: the arrhythmia detector circuit is further configured to determine respective AF confidence indicators for two or more AF events from the patient;
the event prioritizer circuit is further configured to generate event priorities for the two or more AF events based on the respective AF confidence indicators; and
the controller circuit is configured to dynamically control allocation of ambulatory medical device resources for the two or more AF events based on the generated event priorities.
17 . A method for detecting cardiac arrhythmia in a patient using a medical-device system, comprising:
receiving a cardiac electrical signal sensed from the patient;
determining a ventricular rate parameter for the patient using the received cardiac electrical signal;
detecting, using an arrhythmia detector circuit, an atrial fibrillation (AF) event using the determined ventricular rate parameter;
detecting, using the arrhythmia detector circuit, a signal characteristic of a P wave from an ensemble average of multiple segments of the received cardiac electrical signal corresponding to a plurality of cardiac cycles;
determining an AF confidence indicator indicating a confidence level of the detected AF event based on the ventricular rate parameter of the detected AF event and the signal characteristic of the P wave for the plurality of cardiac cycles comprising the detected AF event;
receiving the detected AF event in a time-based order corresponding to a time of the detected AF event;
generating, using an event prioritizer circuit, an event priority for the detected AF event based on the AF confidence indicator, the event priority different than the time-based order; and
via a controller circuit, dynamically allocating resources of the medical-device system to process or store information about the AF event, in accordance with the generated event priority, including increasing allocation of resources in response to the generated event priority indicating a high confidence or a numerical confidence score above a threshold in contrast to the generated event priority indicating a low confidence or the numerical confidence score below the threshold,
wherein detecting the AF event comprises using information of the cardiac electrical signal separate from the detected absence or presence of the P wave.
18 . The method of claim 17 , wherein the signal characteristic includes a peak intensity or a signal power of the P wave, and the atrial fibrillation (AF) confidence indicator is determined to be inversely proportional to the peak intensity or the signal power of the P wave.
19 . The method of claim 17 , comprising: sensing, using a sensor of an implantable medical device, the cardiac electrical signal from the patient,
wherein the implantable medical device comprises the arrhythmia detector circuit, the event prioritizer circuit, and the controller circuit,
wherein dynamically allocating resources of the medical-device system comprises dynamically allocating resources to the implantable medical device, including memory of the implantable medical device to store information about the detected AF event.