Systems and methods for monitoring DP, IVRT, DiFT, diastolic function and/or HF

For use with an implantable system, a method for monitoring a patient's diastolic function and/or heart failure (HF) condition, comprising:

• obtaining a signal indicative of changes in arterial blood volume and a signal indicative of electrical activity of the patient's heart;
• detecting
• beginnings of diastolic periods based on a feature of the signal indicative of changes in arterial blood volume, and
• ends of the diastolic periods based on a feature of the signal indicative of electrical activity of the patient's heart;
• and
• estimating the patient's diastolic periods (DPs), isovolumic relaxation times (IVRTs) and/or diastolic filling times (DiFTs) based on the detected beginnings of the diastolic periods and detected ends of the diastolic periods;
• and
• monitoring the patient's diastolic function and/or HF, and/or changes in the patient's diastolic function and/or HF, based on estimates of DP, IVRT and/or DiFT.

An implantable system, comprising:

• an implantable sensor to obtain a signal indicative of changes in arterial blood volume;
• a sensing circuit to obtain a signal indicative of electrical activity of the patient's heart;
• a monitor configured to
• detect beginnings of diastolic periods based on a feature of the signal indicative of changes in arterial blood volume,
• detect ends of the diastolic periods based on a feature of the signal indicative of electrical activity of the patient's heart, and
• estimate diastolic periods (DPs), isovolumic relaxation times (IVRTs) and/or diastolic filling times (DiFTs) based on the detected beginnings of the diastolic periods and the detected ends of the diastolic periods.

For use with an implantable system, a method comprising:

• (a) using an implanted sensor to obtain a plethysmography signal indicative of changes in a patient's arterial blood volume for a period of time corresponding to one or more cardiac cycles, wherein the implanted sensor is implanted extravascularly;
• (b) detecting a beginning of a diastolic period (DP) based on a first feature of the plethysmography signal indicative of changes in arterial blood volume;
• (c) detecting an end of the DP based on a second feature of the plethysmography signal indicative of changes in arterial blood volume;
• and
• (d) detecting a maximum downward slope (MDS) of the plethysmography signal indicative of changes in arterial blood volume;
• and
• estimating an isovolumic relaxation time (IVRT) and/or a diastolic filling time (DiFT) based on the beginning of the DP as detected at step (b), the end of the DP as detected at step (c), and the MDS of the plethysmography signal as detected at step (d).

An implantable system, comprising:

• an implantable sensor to obtain a plethysmography signal indicative of changes in arterial blood volume;
• a monitor configured to
• detect beginnings and ends of diastolic periods based on features of the plethysmography signal indicative of changes in arterial blood volume,
• detect maximum downward slopes (MDSs) of the plethysmography signal indicative of changes in arterial blood volume, and
• estimate isovolumic relaxation times (IVRTs) and/or diastolic filling times (DiFTs) based on the detected beginnings of the diastolic periods, the detected ends of the diastolic periods, and the detected MDSs;
• wherein the implantable sensor is configured to be implanted extravascularly.