This case report describes a patient with heart failure in whom a biventric
ular pacing system was successfully implanted. During control of the pacing
system, three morphologies of the paced QRS complex could be elucidated. R
ight ventricular stimulation, biventricular stimulation, and biventricular
pacing with additional stimulation from the anodal electrode of the right v
entricular lead determined the morphologies.