Arrhythmic syncope: From diagnosis to management

Figure 2 Electrophysiological study of a patient with syncope and left bundle branch blocked. Surface electrocardiogram (DI, DII, DIII, V1) (top) and intracardiac electrograms at 100 mm/seg of an electrophysiological study to evaluate infra-Hisian conduction. A diagnostic catheter was placed in the right atrium (pink register: ACp and Acd) and in the His bundle zone (yellow register: HCp, HCm and HCd). *Indicates the His deflection. HV interval, from the onset of the His deflection to the onset of the QRS, is measured with the caliper (71 milliseconds in this case).