Patent ID: 7844335

Claim:
A heart stimulator for biventricular pacing of a heart, comprising: a. at least one stimulation pulse generator for pacing at least a left ventricle of a heart, b. an impedance determination unit for determining an intracardiac impedance value reflecting cardiac output, c. a control unit connected to the stimulation pulse generator and to the impedance determination unit, the control unit being adapted to: (1) trigger the stimulation pulse generator to generate and deliver at least left ventricular stimulation pulses when triggered, and (2) perform a quality factor test procedure for determining a quality factor, wherein: (a) a first intracardiac impedance value or impedance curve is determined for an intrinsic heart cycles sequence comprising a predetermined first number N intrinsic of consecutive intrinsic heart cycles wherein no left ventricular stimulation pulses are delivered, (b) a second intracardiac impedance value or impedance curve is determined for a paced heart cycles sequence comprising a predetermined second number N paced of consecutive paced heart cycles wherein at least left ventricular stimulation pulses are delivered, and (c) the first and second intracardiac impedance values or curves are compared to each other.