Patent ID: 8355782

Claim:
An implantable heart stimulator comprising: an electrode arrangement adapted for placement adjacent a heart of a subject; a pulse generator adapted for connection to the electrode arrangement to deliver stimulation pulses to the heart; an impedance measurement unit that monitors, through said electrode arrangement, a chamber of the heart by measuring impedance therein to generate an impedance signal corresponding to said impedance; and a computerized processor supplied with said impedance signal, said computerized processor being configured to analyze said impedance signal according to predetermined criteria to determine a fractionation index value that represents a measure of a length of curve of the impedance signal during a predetermined measurement period of said impedance, said processor making said fractionation index value available at an output thereof as an indicator of a degree of mechanical dyssynchrony of the heart, wherein said processor determines said curve length by filtering the impedance signal to remove noise therefrom, averaging the impedance signal during the measurement period to generate an average waveform, storing the average waveform, storing an average R-R interval from heartbeats included in said impedance signal, dividing the stored average waveform by a maximum value thereof, sampling the stored average waveform to define the number of samples in a heartbeat summing a plurality of absolute difference values between adjacent samples in the stored average waveform that is divided by the maximum to obtain a sum that is a measure of the curve length during the measurement period, and dividing said sum by the stored average R-R interval to obtain a quotient that is said fractionation index value.