Abstract: A method and apparatus for performing impedance plethysmography on a living heart for diagnostic and therapy purposes involves placement of plural leads where at least one is disposed within a coronary vein traversing the myocardium on the left side of the heart with another lead having plural electrodes thereon disposed in the right ventricle. By appropriate selection of electrodes on the first and second leads for driving with an AC carrier signal and other such electrodes coupled to a sensing amplifier, an impedance vs. time signal can be derived that when signal processed provides useful information concerning cardiac performance. The multi-site impedance sensing has been found to yield more robust data especially in patients having CHF.

Abstract: An apparatus and method for assessing the status of well-being of patients being treated for CHF using cardiac pacing as a therapy. By sampling the output from an activity sensor or the like, and by noting the frequency with which the averaged rectified sensor output exceeds a preset threshold following changes in the pacing mode, the efficacy of the new mode compared to the previous one can be evaluated.

Abstract: An apparatus and method for assessing the status of well-being of patients being treated for CHF using cardiac pacing as a therapy. By sampling the output from an activity sensor or the like, and by noting the frequency with which the averaged rectified sensor output exceeds a preset threshold following changes in the pacing mode, the efficacy of the new mode compared to the previous one can be evaluated.

Abstract: The respiratory function of a patient is measured for diagnostic purposes using a cardiac rhythm management device. Monitoring of the respiratory activity is initiated after a microprocessor in the cardiac rhythm management device determines that the patient has been at rest for a predetermined length of time. A respiration related signal is derived from either an accelerometer signal or from an impedance sensor, depending upon which produces a signal has the higher signal-to-noise ratio. The signal from either the accelerometer or impedance measuring mechanism is low-pass filtered to obtain a respiratory signal component. The respiratory signal component is digitized and sent to the microprocessor for analysis. The microprocessor can be programmed in either of two modes of analysis. In the first mode, the peak-to-peak values of the respiratory signal component over a number of fixed time interval is summed, obtaining the minute volume.

Abstract: An implantable monitor for collecting and storing for later telemetric readout physiologic data relating to cardiopulmonary performance. The monitor device includes an accelerometer and associated signal processing circuitry for analyzing the accelerometer output signal and deriving therefrom activity, respiratory, pulse pressure and heart sound information helpful in assessing the efficacy of therapy being rendered to the patient.