A system and method for improving heart contractions during a heart function cycle (heartbeat) of a patient requires detecting a local electrical event (depolarization) during the cycle. This local electrical event is then used to trigger a stimulation interval Δ；t at a time t0. Importantly, the stimulation interval Δ；t is set to end at a time t1 during the absolute refractory period of the heart function cycle. At the time t1, a stimulator is triggered to stimulate a local sympathetic nerve on the epicardial surface of the heart. With this stimulation the sympathetic nerve secretes norepinephrine to improve a subsequent contraction of the heart.
