• heart rate variability;
  • tachycardia detection

PAUL, V.E., ET AL.: Variability of the Intracardiac Electrogram: Effect on Specificity of Tachycardia Detection. Correlation has been described as a method of high sensitivity to distinguish ventricular arrhythmias from sinus rhythm but the specificity of this algorithm has not been assessed. Ten patients with a history of chronic ventricular tachycardia were studied. The ventricular endocardial electrogram was recorded during sinus rhythm at rest immediately following exercise and during their clinical ventricular tachycardia. Each complex recorded during these sample periods was correlated with a template constructed during sinus rhythm at rest. Although for each patient the range of correlation values obtained at rest were clearly separated from those obtained during ventricular tachycardia, in 69% of cases there was overlap of the range in sinus tachycardia and ventricular tachycardia.