Patent ID: 7330758

Claim:
A heart monitoring device comprising: a control circuit having an electrical connection adapted for electrical connection to a first electrode surface at a first in vivo intracardiac position relative to a heart and to a second electrode surface at a second in vivo intracardiac position relative to the heart; and said control circuit deriving an impedance value indicative of an in vivo cardiac impedance between said first and second electrode surfaces, determining a linear representation of a negative rate of change of said impedance value at a first portion of a heart cycle of the heart, monitoring said linear representation of said negative rate of change over a plurality of heart cycles of the heart, and determining whether said linear representation of said negative rate of change increases or decreases over said plurality of heart cycles as an indicator of at least one of systolic or diastolic dysfunction of the heart, and said control circuit generating an electrical control signal corresponding to said indicator, in a form suitable for controlling pacing of the heart.