Patent ID: 6920353

Claim:
A cardiac pacemaker comprising: a pulse generator which emits stimulation pulses respectively separated by stimulation intervals, each having a stimulation interval duration and collectively having an average duration; a lead connected to said pulse generator and adapted to deliver said stimulation pulses to a heart and to receive a signal containing action potential information from the heart; a modulation device connected to said pulse generator which alternatingly shortens and lengthens said stimulation interval duration without changing said average duration, thereby causing said pulse generator to emit modulated stimulation pulses; a detector connected to said lead to detect said signal after each modulated stimulation pulse, thereby producing a detector output; an evaluation unit having access to an electric restitution curve, said evaluation unit being connected to said detector for analyzing said detector output to determine an electric restitution of said heart, from said electric restitution curve, at the average duration by measuring a duration of said action potential from said action potential information, said action potential duration having a measuring variable associated therewith, and for identifying a relationship between changes in said measuring variable, caused by modulation of said stimulation interval, and said average duration, and for comparing said relationship to at least one predetermined value to obtain a comparison result; and said modulation device controlling said average duration dependent on said comparison result.