Patent ID: 8019415

Claim:
An implantable cardiac stimulator ( 10 ) comprising: an at least partially electrically conductive housing ( 22 ); a ventricular stimulation unit ( 56 ; 64 ) which is connected or connectable to a left ventricular stimulation electrode or a right ventricular stimulation electrode and is configured to generate and deliver ventricular stimulation pulses for stimulation of a ventricle of a heart; a terminal for a right ventricular defibrillation electrode ( 36 ); a far-field electrogram detection unit ( 90 ); a stimulation success detecting unit ( 92 ); wherein the far-field electrogram detection unit ( 90 ) has a first input that is connected to the terminal for the right ventricular defibrillation electrode and a second input that is connected to the at least partially electrically conductive housing, and wherein the far-field electrogram detection unit ( 90 ) is configured to detect a far-field electrogram based on electric potentials applied to the first and second inputs and to output the far-field electrogram to the stimulation success detecting unit ( 92 ); and, wherein the stimulation success detecting unit ( 92 ) has an electrogram input and a signal input and wherein the stimulation success detecting unit ( 92 ) is configured to receive the far-field electrogram generated by the far-field electrogram detection unit ( 90 ) via the electrogram input and to receive via the signal input a stimulation signal that indicates a ventricular stimulation pulse generated and delivered by the ventricular stimulation unit ( 56 , 64 ) and is also configured to analyze a section of a received far-field electrogram that follows immediately in time after delivery of the ventricular stimulation pulse to determine whether it represents effective or ineffective ventricular stimulation.