Patent ID: 8565866

Claim:
An implantable medical device comprising: an electrode connecting arrangement connectable to at least two electrodes; an impedance determiner that determines an impedance signal associated with a heart of a subject over at least a diastolic phase of a heart beat based on electric signals sensed by said at least two electrodes; a signal analyzer configured to identify a global maximum in said impedance signal during said heart beat, and to identify first local maximum in said impedance signal during the diastolic phase following the identified global maximum in the impedance signal; a parameter calculator that calculates, based on said impedance signal, an impedance parameter by applying a non-zero first weight to a diastolic portion of said impedance signal corresponding to a portion of said diastolic phase immediately preceding said identified first local maximum and up to directly following said identified first local maximum and applying a second weight to a non-diastolic portion of said impedance signal corresponding to a non-diastolic phase of said heart beat, said first weight being larger than said second weight; and an acute decompensated heart failure, ADHF, monitor that monitors an ADHF status based on said impedance parameter.