Patent ID: 8535215

Claim:
An implantable heart monitoring device comprising: a control circuit having an input that receives a signal from at least one electrode that senses a parameter related to cardiac activity; a memory in communication with said control circuit; and said control circuit being configured to (a) detect the heart rate of the subject from said signal (b) derive information correlated to the stroke volume of the heart at the detected heart rate, and (c) store the detected heart rate and the derived information correlated to the stroke volume in said memory, and said control circuit being configured to automatically execute (a), (b) and (c) at a plurality of different occasions for different, naturally varying heart rates, to enter information into said memory to produce a representation in said memory of the stroke volume as a function of the heart rate; wherein said control circuit is configured to operate said electrode to execute a measurement as to how an amount of blood in the left ventricle of the heart varies with time, and to derive said information correlated to the stroke volume of the heart from a result of said measurement; wherein said control circuit is configured to generate a curve, as said result of said measurement, indicating how said amount of blood in the left ventricle varies with time, and to derive said information correlated with the stroke volume from the curve or by an operation on said curve selected from the group consisting of filtering said curve, analyzing a template based on different curves for different heartbeats, and generating and analyzing a template based on filtering different curves for respectively different heartbeats; and wherein said control circuit is configured to derive said information correlated to the stroke volume from a characteristic of said curve, said filtered curve or said template, selected from the group consisting of an area and a peak-to-peak value.