Demonstration of diffuse conduction disturbance in sick sinus syndrome utilizing simultaneous His bundle electrogram and timed vectorcardiogram.

he sick sinus syndrome is a clinical entity charTacterized by disturbances of sinoatial impulse formation and conduction.13 Recent studies have demonstrated that abnormalities of conduction and automaticity at other specialized anatomic sites are common in subjects with symptomatic sinus node disease.'^^.^ We describe here the use of combined His bundle electrography and timed vectorcardiography as a method for detecting panconduction tissue disease in such a patient. Figure 1 shows the simultaneously recorded His bundle electrogram and leads 1, 2, and VI of the electrocardiogram, along with frontal and horizontal timed biplane Frank vector~ardiograms~.~ in a 63-