Wolff‐parkinson‐white syndrome type B and left bundle‐branch block: Electrophysiologic and radionuclide study

Coinciding left bundle‐branch block and Wolff‐Parkmson‐White syndrome type B, a very rare electrocardiographic occurrence, was found in a patient with dilated cadiomyopathy. Electrophysiologic study revealed eccentric retrograde atrial activation during ventricular pacing, suggesting right‐sided accessory pathway. At programmed atrial pacing, effective refractory period of the accessory pathway was 310 ms; at shorter pacing coupling intervals, normal atrioventricular conduction with left bundle‐branch block was seen. Left bundle‐branch block was seen also with His bundle pacing. Radionuclide phase imaging demonstrated right ventricular phase advance and left ventricular phase delay; both right and left ventricular phase images revealed broad phase distribution histograms. Combined electrophysiologic and radionuclide investigations are useful to disclose complex conduction abnormalities and their mechanical correlates.