Closed-loop adaptive adjustment of pacing therapy based on cardiogenic impedance signals detected by an implantable medical device

A system for controlling therapy provided by an implantable cardiac stimulation device to reduce the system comprising:

• a cardiogenic impedance (ZC) detector operative to detect an interventricular cardiogenic impedance signal (ZC) associated with individual heartbeats, the interventricular cardiogenic impedance signal having an interventricular waveform morphology, the interventricular cardiogenic impedance signal having sufficient resolution to detect a notch within an individual heartbeat occurring even in the absence of mechanical dyssynchrony, the interventricular waveform morphology of individual heartbeats having additional features corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• a cardiac function evaluation system operative to derive a measure of interventricular fractionation from the interventricular waveform morphology, wherein interventricular fractionation quantifies the features of the interventricular waveform morphology of individual heartbeats corresponding to the periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• and
• a cardiogenic impedance-based therapy adjustment system operative to adjust therapy provided by the device based on the interventricular cardiogenic impedance signal (ZC) to improve the measure of interventricular fractionation and reduce periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• wherein the features of the interventricular waveform morphology corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony include a plurality of additional notches within an individual heartbeat arising due to mechanical dyssynchrony and wherein the therapy adjustment system operates to adjust therapy to reduce at least one of the plurality of additional notches within the individual heartbeat to reduce interventricular fractionation and reduce mechanical dyssynchrony.

A system for controlling therapy provided by an implantable cardiac stimulation device to reduce mechanical dyssynchrony, the system comprising:

• means for detecting an interventricular cardiogenic impedance signal (ZC) associated with individual heartbeats, the interventricular cardiogenic impedance signal having an interventricular waveform morphology, the interventricular cardiogenic impedance signal having sufficient resolution to detect a notch within an individual heartbeat occurring even in the absence of mechanical dyssynchrony, the interventricular waveform morphology of individual heartbeats having additional features corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• means for deriving a measure of interventricular fractionation from the interventricular waveform morphology, wherein interventricular fractionation quantifies the features of the interventricular waveform morphology of individual heartbeats corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• and
• means for adjusting therapy provided by the device based on the interventricular cardiogenic impedance signal (ZC) so as to improve the measure of interventricular fractionation and reduce periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• wherein the features of the interventricular waveform morphology corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony include a plurality of additional notches within an individual heartbeat arising due to mechanical dyssynchrony and wherein the means for adjusting therapy operates to adjust therapy to reduce at least one of the plurality of additional notches within the individual heartbeat to reduce interventricular fractionation and reduce mechanical dyssynchrony.

A method for controlling therapy provided by an implantable cardiac stimulation device, the method comprising:

• detecting an interventricular cardiogenic impedance signal (ZC) associated with individual heartbeats with the interventricular cardiogenic impedance signal having an interventricular waveform morphology, the interventricular waveform morphology of individual heartbeats having features corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• deriving a measure of interventricular fractionation from the interventricular waveform morphology, wherein interventricular fractionation quantifies the features of the interventricular waveform morphology of individual heartbeats corresponding to the periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• adjusting therapy provided by the device based on the interventricular cardiogenic impedance signal (ZC) to improve the measure of interventricular fractionation and reduce periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• and
• wherein the features of the interventricular waveform morphology corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony include higher spectral frequencies compared to spectral frequencies associated with periods of time when chambers of the heart are beating uniformly and wherein therapy is adjusted to reduce at least some of the higher spectral frequencies to reduce interventricular fractionation.

A system for controlling therapy provided by an implantable cardiac stimulation device, the system comprising:

• a cardiogenic impedance (ZC) detector operative to detect an interventricular cardiogenic impedance signal (ZC) associated with individual heartbeats, the interventricular cardiogenic impedance signal having an interventricular waveform morphology, the interventricular waveform morphology of individual heartbeats having features corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• a cardiac function evaluation system operative to derive a measure of interventricular fractionation from the interventricular waveform morphology, wherein interventricular fractionation quantifies the features of the interventricular waveform morphology of individual heartbeats corresponding to the periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• and
• a cardiogenic impedance-based therapy adjustment system operative to adjust therapy provided by the device based on the interventricular cardiogenic impedance signal (ZC) to improve the measure of interventricular fractionation and reduce periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony;
• wherein the features of the interventricular waveform morphology corresponding to periods of time when chambers of the heart are not beating uniformly due to mechanical dyssynchrony include higher spectral frequencies compared to spectral frequencies associated with periods of time when chambers of the heart are beating uniformly and wherein the therapy adjustment system operates to adjust therapy to reduce at least some of the higher spectral frequencies to reduce interventricular fractionation.