Pre-ejection interval (PEI) monitoring devices, systems and methods

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.

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.

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.

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.