System and method for evaluating diastolic function based on cardiogenic impedance using an implantable medical device

Abstract

Diastolic function is monitored within a patient based on dynamic cardiogenic impedance as measured by a pacemaker or other implantable medical device. In one example, the device uses ventricular cardiogenic impedance values to detect E-wave parameters representative of passive filling of the ventricles. Atrial cardiogenic impedance values are used to detect A-wave parameters representative of active filling of the ventricles. Diastolic function is then assessed or evaluated based on the E-wave and A-wave parameters. Various functions of the implantable device are then controlled based on the assessment of diastolic function, such as by adjusting atrioventricular delay parameters to improve diastolic function. In some examples, the detection of E- and A-wave parameters is achieved by aligning impedance signals to atrial activation, and separately to ventricular activation, during asynchronous VOO pacing or while artificially inducing a 2:1 block.

What is claimed is: 
     
         1 . A system for use with an implantable medical device for implant within a patient, the system comprising:
 a ventricular cardiogenic impedance measurement system operative to measure values representative of ventricular cardiogenic impedance;   an E-wave parameter derivation system operative to derive E-wave parameters representative of passive filling of the ventricles of the heart of the patient from the ventricular cardiogenic impedance values;   an atrial cardiogenic impedance measurement system operative to measure values representative of atrial cardiogenic impedance;   an A-wave parameter derivation system operative to derive A-wave parameters representative of active filling of the ventricles from the atrial cardiogenic impedance values; and   a diastolic function assessment system operative to assess diastolic function based on the E-wave parameters and the A-wave parameters.   
     
     
         2 . A system for use with an implantable medical device for implant within a patient, the system comprising:
 means for measuring values representative of ventricular cardiogenic impedance;   means for deriving E-wave parameters representative of passive filling of the ventricles of the heart of the patient from the ventricular cardiogenic impedance values;   means for measuring values representative of atrial cardiogenic impedance;   means for deriving A-wave parameters representative of active filling of the ventricles from the atrial cardiogenic impedance values; and   means for assessing diastolic function based on the E-wave parameters and the A-wave parameters.