# US 8,571,642 B2 · Pre-ejection interval (PEI) monitoring devices, systems and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,642 B2 - Document ID: US8571642B2 - Status: Granted - Kind: B2 - Application number: 12/882,084 - Filed: 2010-09-14 - Published: 2012-03-15 - Granted: 2013-10-29 - Earliest claimed: 2010-09-14 - Assignees: Pacesetter, Inc. - Applicants: Jong Gill; Brian Jeffrey Wenzel; Allen Keel; Wenbo Hou; Edward Karst; Taraneh G. Farazi - Inventors: Jong Gill; Brian Jeffrey Wenzel; Allen Keel; Wenbo Hou; Edward Karst; Taraneh G. Farazi - Web page: https://patentgrep.com/patent/US8571642B2 ## CPC - A61B 5/352: Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval - A61B 5/02028: {Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction} - A61B 5/0295: using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography - A61B 5/7239: {using differentiation including higher order derivatives} - A61N 1/36843: {Bi-ventricular stimulation} - A61B 5/287: Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS] - A61B 5/686: {Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence)} - A61N 1/3684: {for stimulating the heart at multiple sites of the ventricle or the atrium} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## Abstract Provided herein are implantable systems, and methods for use therewith, for monitoring a patient's pre-ejection interval (PEI). A signal indicative of cardiac electrical activity and a signal indicative of changes in arterial blood volume are obtained. One or more predetermined features of the signal indicative of cardiac electrical activity and the signal indicative of changes in arterial blood volume are detected. The patient's PEI is determined by determining an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume. ## Claims ### Claim 1 For use with an implantable system, a method for monitoring a patient's pre-ejection interval (PEI), the method comprising: (a) using one or more electrodes implanted within and/or on the patient's heart to obtain a signal indicative of cardiac electrical activity; (b) using an implanted sensor to obtain a signal indicative of changes in arterial blood volume; (c) detecting a predetermined feature of the signal indicative of cardiac electrical activity; (d) detecting a predetermined feature of the signal indicative of changes in arterial blood volume; (e) determining an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume; (f) determining a transit time representing at least one of i) a delay from an onset of the signal indicative of cardiac electrical activity obtained at the one or more electrodes to when the signal indicative of changes in arterial blood volume arrives at the implanted sensor or ii) a time for a pressure pulse to travel from an aorta to the implanted sensor; and (g) monitoring the patient's PEI based on the interval and the transit time. ### Claim 2 (depends on 1) The method of claim 1, further comprising: (g) triggering an alert, triggering therapy and/or adjusting therapy based on the monitored PEI. ### Claim 3 (depends on 1) The method of claim 1, further comprising: (g) storing, within the implantable system, information indicative of the monitored PEI so that the stored information is available for transfer to a non-implanted system. ### Claim 4 (depends on 1) The method of claim 1, wherein: steps (a), (b), (c), (d) and (e) are performed for each of a plurality of periods of time to thereby determine, for each of the plurality of periods of time, the interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume; and step (g) comprises monitoring changes in the patient's PEI based on changes in the interval over time. ### Claim 5 (depends on 4) The method of claim 4, further comprising: (h) triggering an alert, triggering therapy and/or adjusting therapy based on the monitored changes in PEI. ### Claim 6 (depends on 4) The method of claim 4, further comprising: (h) monitoring for an indication of disease and/or disease progression based on the monitored changes in the patient's PEI. ### Claim 7 (depends on 1) The method of claim 1, wherein: step (c) comprises detecting a predetermined feature indicative of ventricular depolarization of the signal indicative of cardiac electrical activity; step (d) comprises detecting a predetermined feature corresponding to a systolic portion of the signal indicative of changes in arterial blood volume; step (e) comprises detecting an interval between the predetermined feature indicative of ventricular depolarization of the signal indicative of cardiac electrical activity and the predetermined feature corresponding to a systolic portion of the signal indicative of changes in arterial blood volume; and step (g) comprises monitoring the patient's PEI based on the interval between the predetermined feature indicative of ventricular depolarization of the signal indicative of cardiac electrical activity and the predetermined feature corresponding to a systolic portion of the signal indicative of changes in arterial blood volume. ### Claim 8 (depends on 1) The method of claim 1, wherein: step (a) comprises using one or more electrodes implanted within and/or on the patient's heart to obtain an intracardiac electrogram (IEGM) signal or an electrocardiogram (ECG) signal indicative of cardiac electrical activity; and step (b) comprises using an implanted photoplethysmography (PPG) sensor to obtain a photoplethysmography (PPG) signal indicative of changes in arterial blood volume, or using or an impedance plethysmography (IPG) sensor to obtain an impedance plethysmography (IPG) signal indicative of changes in arterial blood volume. ### Claim 9 (depends on 1) The method of claim 1, wherein the monitoring further comprises factoring the transit time out of the interval when monitoring the patient's PEI. ### Claim 10 For use with an implantable system, a method for monitoring a patient's pre-ejection interval (PEI), the method comprising: (a) using one or more electrodes implanted within and/or on the patient's heart to obtain a signal indicative of cardiac electrical activity; (b) using an implanted sensor to obtain a signal indicative of changes in arterial blood volume; (c) detecting a predetermined feature of the signal indicative of cardiac electrical activity; (d) detecting a predetermined feature of the signal indicative of changes in arterial blood volume; (e) determining an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume; and (f) monitoring the patient's PEI based on the interval, wherein: during a first one of the periods of time that steps (a), (b), (c), (d) and (e) are performed, a first measure of systolic blood pressure is obtained; during a second one of the periods of time that steps (a), (b), (c), (d) and (e) are performed, a second measure of systolic blood pressure is obtained; and at step (f), when monitoring changes in the patient's PEI from the first period of time to the second period of time, calibrating the interval corresponding to the second period of time based on the change in the measure of systolic blood pressure from the first period of time to the second period of time, if any change. ### Claim 11 For use with an implantable system, a method for monitoring a patient's pre-ejection interval (PEI), the method comprising: (a) using one or more electrodes implanted within and/or on the patient's heart to obtain a signal indicative of cardiac electrical activity; (b) using an implanted sensor to obtain a signal indicative of changes in arterial blood volume; (c) detecting a predetermined feature of the signal indicative of cardiac electrical activity; (d) detecting a predetermined feature of the signal indicative of changes in arterial blood volume; (e) determining an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume; (f) monitoring the patient's PEI based on the interval, (g) performing a calibration including: (g1) determining an echo-based measure of PEI at a point in time, (g2) at about the same point in time that the echo-based measure of PEI is determined, performing steps (a), (b), (c), (d) and (e) to determine an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume, and (g3) determining a difference between the determined echo-based measure of PEI and the determined interval; wherein when step (f) is performed after the calibration is performed, the patient's PEI is estimated based on the interval determined at step (e) and the difference determined during calibration. ### Claim 12 (depends on 11) The method of claim 11, wherein: when step (f) is performed after the calibration is performed, the patient's PEI is estimated as being equal to the interval determined at step (e) minus the difference determined during calibration. ### Claim 13 An implantable system capable of monitoring a patient's pre-ejection interval (PEI), comprising one or more electrodes configured to obtain a signal indicative of cardiac electrical activity; an implantable sensor configured to obtain a signal that is indicative of changes in arterial volume; a PEI monitor configured to detect a predetermined feature of the signal indicative of cardiac electrical activity, detect a predetermined feature of the signal indicative of changes in arterial blood volume, determine an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume, determine a transit time representing at least one of i) a delay from an onset of the signal indicative of cardiac electrical activity obtained at the one or more electrodes to when the signal indicative of changes in arterial blood volume arrives at the implanted sensor or ii) a time for a pressure pulse to travel from an aorta to the implanted sensor; and monitor the patient's PEI based on the interval and the transit time. ### Claim 14 (depends on 13) The implantable system of claim 13, wherein the PEI monitor is configured to trigger an alert, therapy and/or adjusting therapy based on the monitored PEI. ### Claim 15 (depends on 13) The implantable system of claim 13, further comprising memory, wherein the PEI monitor is also configured to store, within memory, information indicative of the monitored PEI so that the stored information is available for transfer to a non-implanted system. ### Claim 16 (depends on 13) The implantable system of claim 13, wherein the PEI monitor is configured to monitor changes in the patient's PEI by monitoring changes in the interval over time. ### Claim 17 (depends on 13) The implantable system of claim 13, wherein the predetermined feature indicative of cardiac electrical activity is selected from the group consisting of: a Q-wave; a R-wave; and a QRS complex. ### Claim 18 (depends on 13) The implantable system of claim 13, wherein the predetermined feature indicative of changes in arterial blood volume is selected from the group consisting of: a foot of the signal indicative of changes in arterial blood volume; a peak of the signal indicative of changes in arterial blood volume; and a maximum positive slope of the signal indicative of changes in arterial blood volume. ### Claim 19 (depends on 13) The implantable system of claim 13, wherein the PEI monitor is further configured to factor the transit time out of the interval when monitoring the patient's PEI. ### Claim 20 For use with an implantable system, a method for monitoring a patient's pre-ejection interval (PEI), the method comprising: (a) obtaining an ABV signal indicative of changes in arterial blood volume (ABV) at a sensor; (b) determining a transit time representing at least one of i) a delay from an onset of cardiac electrical activity (CEA) to when the ABV signal arrives at the sensor or ii) a time for a pressure pulse to travel from an aorta to the implanted sensor; and (c) monitoring the patient's PEI based on the ABV signal indicative of changes in arterial blood volume and the transit time.