Patent ID: 7215996

Claim:
An implantable heart stimulating device comprising: a housing adapted for implantation in a subject; a pulse generator contained in said housing for interacting with a first ventricle and a second ventricle of a heart of the subject to stimulate said first ventricle and said second ventricle; sensing circuitry contained in said housing adapted to obtain sensed signals from two different positions relative to the heart; and a control circuit contained in said housing and connected to said pulse generator and to said sensing circuitry, said control circuit controlling said pulse generator to emit respective stimulating pulses to the first and second ventricles within a same heart cycle with a time interval between the respective pulses that is variable by said control circuit, said control circuit receiving said sensed signals from said sensing circuitry and deriving an impedance value therefrom indicative of an impedance between said two different positions, said control circuit determining a minimum value magnitude and a maximum value magnitude of said impedance value during said heart cycle and determining a relationship between said minimum value magnitude and said maximum value magnitude, said control circuit varying said time interval and monitoring said relationship over a plurality of heart cycles, and said control circuit setting said time interval to cause said relationship to satisfy a predetermined requirement.