The invention is directed to a heart stimulator for left-ventricular
pacing comprising a left ventricular stimulation pulse generator
connected or connectable to a single electrode lead for left ventricular
stimulation having one or more electrodes for delivery of stimulation
pulses to left ventricular myocardial heart tissue, said stimulation
pulse generator being adapted to generate and deliver stimulation pulses
of switchable polarity. The heart stimulator further comprises a control
unit connected to the stimulation pulse generator for controlling the
stimulation pulse generator and to trigger generation and delivery of
stimulation pulses having a polarity controlled by said control unit,
wherein the control unit is adapted to control said left ventricular
stimulation pulse generator so as to deliver at least a pair of
suprathreshold stimulation pulses of opposite polarity.