Figure 3 Left panel, in case 3, the 2nd beat conducting over the SP with CRBBB induced ORT, followed by A-H showing SP perpetuation. Right panel, AV conduction was over FP in the first 3 beats, with resolution of CRBBB in the next ones, followed by shortened VA interval and subsequent marked AV prolongation in the 6th beat. Note the subtle change in right bundle conduction. See text for discussion. CRBBB=complete right bundle branch block; CS=coronary sinus; FP=fast pathway; iCRBBB=incomplete right bundle branch block; NCT=narrow complex tachycardia; PVC=premature ventricular contraction; RV=right ventricle; SP=slow pathway.