Electrocardiographic findings in accessory right precordial leads in adults and seniors with notched S waves in lead V1-a preliminary study.

BackgroundAtypical right bundle branch block (RBBB) may present with an rS pattern and notched S wave in lead V-1. The notched S wave may represent slowed conduction or delayed activation of the right ventricular conduction system or ventricular myocardium. MethodsWe retrospectively analyzed the QRS patterns in accessory right precordial leads (from V3R to V5R) in 15 adults/senior individuals with notched S wave in lead V-1. ResultsIn the right accessory precordial leads, 13 showed triphasic QRS pattern with final R wave in their QRS complexes. This QRS pattern in association with notched S wave in lead V-1 is suggestive of the presence of RBBB (incomplete or complete). ConclusionsA notched S wave in lead V-1 and in the right precordial accessory leads associated with a final R wave suggests the possibility of concealed RBBB (incomplete or complete).