Heart sound based syncope detection
Systems and methods are disclosed to detect a potential syncope event using cardiac acceleration information of a patient and to transition a medical device from a first low-power mode to a second high-power mode in response to the detected potential syncope event.
1 . A medical device system, comprising:
a signal receiver circuit configured to receive cardiac acceleration information of a patient, wherein the cardiac acceleration information is determined using an accelerometer or a microphone; and
an assessment circuit configured to detect a potential syncope event in a first low-power mode using the cardiac acceleration information of the patient, and to transition a medical device of the medical device system from the first low-power mode to a second high-power mode in response to the detected potential syncope event,
wherein to detect the potential syncope event, the assessment circuit is configured to compare the cardiac acceleration information to at least one threshold, and to transition the medical device to the second high-power mode comprises in response to the cardiac acceleration information exceeding the at least one threshold.
2 . The system of claim 1 , wherein the signal receiver circuit is configured to receive cardiac electrical information of the patient, and
wherein the assessment circuit is configured to detect the potential syncope event using the cardiac acceleration information and the cardiac electrical information of the patient.
3 . The system of claim 2 , wherein the cardiac acceleration information comprises heart sound information of the patient,
wherein the cardiac electrical information of the patient comprises heart rate information of the patient, and
wherein the assessment circuit is configured to detect the potential syncope event using an increase in first heart sound (S1) information of the patient greater than a first threshold and an increase in the heart rate information of the patient greater than a second threshold.
4 . The system of claim 3 , wherein the assessment circuit is configured to detect an indication of a neurally mediated syncope (NMS) event using a decrease in second heart sound (S2) information of the patient greater than a third threshold in a first time period following the detected potential syncope event.
5 . The system of claim 4 , wherein the assessment circuit is configured to detect the indication of the NMS event using the decrease in S2 information of the patient greater than the third threshold and a decrease in the S1 information of the patient greater than a fourth threshold in the first time period following the detected potential syncope event, and a subsequent decrease in the heart rate information greater than a fifth threshold in a second time period following the first time period.
6 . The system of claim 4 , wherein the assessment circuit is configured to trigger a patient alert indicative of the detected indication of the NMS event and a patient inquiry to receive patient feedback of the detected indication of the NMS event in response to the detected indication of the NMS event.
7 . The system of claim 4 , comprising:
a therapy circuit configured to alter or provide one of a drug therapy or a pacing therapy in response to the detected indication of the NMS event.
8 . The system of claim 2 , wherein the signal receiver circuit is configured to receive activity or posture information of the patient, and
wherein the assessment circuit is configured to detect a high risk syncope position of the patient using the activity or posture information of the patient, and in response to the detected high risk syncope position, to detect the potential syncope event using an increase in the cardiac acceleration information greater than a first threshold and an increase in the cardiac electrical information greater than a second threshold.
9 . The system of claim 8 , wherein the assessment circuit is configured to detect the high risk syncope position of the patient as:
a detected change in patient posture from a horizontal thoracic position to a vertical thoracic position; or
a detected vertical thoracic position and patient activity information below an activity threshold.
10 . The system of claim 8 , wherein the signal receiver circuit is configured to receive the cardiac acceleration information and activity or posture information of the patient using a signal accelerometer in non-overlapping time periods.
11 . The system of claim 2 , wherein the first low-power mode comprises an ambulatory monitoring mode,
wherein the second high-power mode comprises a higher-power monitoring mode including storing received cardiac acceleration information and the received cardiac electrical information in long-term storage, and
wherein the medical device comprises an implantable medical device comprising the signal receiver circuit and the assessment circuit.
12 . The system of claim 1 , wherein the cardiac acceleration information comprises heart sound information of the patient,
wherein the assessment circuit is configured to determine, in the second high-power mode, a composite heart sound parameter including first heart sound (S1) information of the patient over second heart sound (S2) information of the patient, (S1/S2), and to detect an indication of a syncope event in the second high-power mode using the determined composite heart sound parameter.
13 . The system of claim 1 , wherein the assessment circuit is configured to store, in the low-power mode, received cardiac acceleration information in short-term storage, and to store, in the second high-power mode, sequential time-period windows of the received cardiac acceleration information leading up to and including the detected potential syncope event in long-term storage.
14 . The system of claim 1 , wherein the assessment circuit is configured to detect the potential syncope event using an increase in first heart sound (S1) of the patient greater than a first threshold and an increase in the second heart sound (S2) information of the patient greater than a second threshold.
15 . A method comprising:
receiving, using a signal receiver circuit, cardiac acceleration information of a patient, wherein the cardiac acceleration information is determined using an accelerometer or a microphone;
detecting, using an assessment circuit in a first low-power mode, a potential syncope event using the cardiac acceleration information of the patient; and
transitioning, using the assessment circuit, a medical device from the first low-power mode to a second high-power mode in response to the detected potential syncope event,
wherein detecting the potential syncope event comprises comparing the cardiac acceleration information to at least one threshold and transitioning the medical device to the second high-power mode comprises in response to the cardiac acceleration information exceeding the at least one threshold.
16 . The method of claim 15 , comprising:
receiving, using the signal receiver circuit, cardiac electrical information of the patient,
wherein detecting the potential syncope event comprises using the cardiac acceleration information and the cardiac electrical information of the patient.
17 . The method of claim 16 , wherein the cardiac acceleration information comprises heart sound information of the patient,
wherein the cardiac electrical information of the patient comprises heart rate information of the patient, and
wherein detecting the potential syncope event comprises using an increase in first heart sound (S1) information of the patient greater than a first threshold and an increase in the heart rate information of the patient greater than a second threshold.
18 . The method of claim 17 , comprising:
detecting, using the assessment circuit, an indication of a neurally mediated syncope (NMS) event using a decrease in second heart sound (S2) information of the patient greater than a third threshold in a first time period following the detected potential syncope event.
19 . The method of claim 18 , wherein detecting the indication of the NMS event comprises using the decrease in S2 information of the patient greater than the third threshold and a decrease in the S1 information of the patient greater than a fourth threshold in the first time period following the detected potential syncope event, and using a subsequent decrease in the heart rate information greater than a fifth threshold in a second time period following the first time period.
20 . The method of claim 16 , comprising:
receiving, using the signal receiver circuit, activity or posture information of the patient; and
detecting, using the assessment circuit, a high risk syncope position of the patient using the activity or posture information of the patient,
wherein detecting the potential syncope event comprises using an increase in the cardiac acceleration information greater than a first threshold and an increase in the cardiac electrical information greater than a second threshold, further in response to the detected high risk syncope position,
wherein detecting the high risk syncope position of the patient comprises using:
a detected change in patient posture from a horizontal thoracic position to a vertical thoracic position; or
a detected vertical thoracic position and patient activity information below an activity threshold.