A PITFALL IN USING FAR-FIELD BIPOLAR ELECTROGRAMS IN ARRHYTHMIA DISCRIMINATION IN A PATIENT WITH AN IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR

NAYAK, H.M., ET AL.: A Pitfall in Using Far-Field Bipolar Electrograms in Arrhythmia Discrimination in a Patient with an Implantable Cardiov erter Defibrillator. Analysis of stored electrograms from bipolar far- field electrodes is considered to be useful in differentiating suprarv entricular from ventricular arrhythmias. A case of inappropriate ICD s hocks for sinus tachycardia is presented whereby successive shocks cau sed marked widening of the ventricular electrograms. Analysis of these stored electrograms, recorded from far-field bipolar electrodes, gave the false impression of ventricular tachycardia. The widening was due to the current of injury effects, probably a consequence of the large amount of intervening myocardium between the bipoles. While analyzing recordings from far-field bipolar electrodes is generally useful, it is not always reliable, for changes in electrogram morphology, relativ e to baseline rhythm, may result from other factors like current of in jury.