Patent ID: 6473650
Filing Date: 2002-10-29
Classification: A61N

Abstract:
A heart stimulator comprising:a pulse generator which emits stimulation pulses, each having an amplitude; an electrode lead connected to said pulse generator and adapted for introduction int a patient to deliver said stimulation pulses to the patient's heart, and for picking up respective signals representing polarization of the heart immediately after each of said stimulation pulses; a control unit connected to said pulse generator for controlling said pulse generator to emit at least two stimulation pulses having different amplitudes, at least one of said two stimulation pulses having a high amplitude which exceeds a stimulation threshold value for the heart; an evoked response detector including a measuring unit connected to said electrode lead, a calculating unit connected to an output of said measuring unit, and an analyzing unit connected to an output of said calculating unit; said measuring unit measuring respective signals picked up by said electrode lead immediately following said two stimulation pulses; said calculating unit calculating a polarization Polhigh for said stimulation pulse having a high amplitude and determining a measured signal Umeaslow from said electrode lead for a lowest possible stimulation amplitude; and said analyzing unit setting a threshold value ERLimit for a measured signal Umeas for evoked response detection according to ERLimit=Umeslow-Polhighn+Polhighwherein n is a number greater than 1 with Umeaslow being less than Polhigh, and with |Umeaslowâˆ’Polhigh|>Y, wherein Y is a predetermined value.