Patent ID: 8135455

Claim:
An implantable heart monitoring system comprising: a housing configured for implantation in a subject having a heart beating in successive heart cycles each having a diastolic portion and a systolic portion; at least one sensor member implanted relative to the heart of the subject to detect an electrical signal related to cardiac activity of the heart; a control circuit in said housing; a memory accessible by said control circuit; and said control circuit being configured to derive, from said electrical signal, a first value related to a volume of a first part of the heart and to derive a second value related to a volume of a second part of the heart, and to monitor variation of said first value over time in at least a substantial portion of heart cycle selected from said diastolic portion and said systolic portion, and by representing said first value along a first axis of a Cartesian coordinate system and representing said second value along a second axis of said Cartesian coordinate system, to form a substantially complete loop in the Cartesian coordinate system; said control unit being configured to determine from said loop, a volume of said first part of the heart or a normalized value thereof and to determine a volume of the second part of the heart or a normalized value thereof, and to determine a difference or a ratio between the volume of said first part of the heart or a normalized value thereof and the volume of the second part of the heart or a normalized value thereof, and to determine, from said difference or ratio, a degree of synchrony between said first part of the heart and said second part of the heart in said substantial portion of the heart cycle; and said control unit being configured to emit said indication of said degree of synchrony as an output signal from the control circuit and to store said indication of said degree of synchrony in a memory.