Rare narrow QRS tachycardia with atrioventricular dissociation: A case report

Figure 2 Electrophysiology study. A: In sinus rhythm, AH interval was 75, His bundle-ventricular (HV) interval was 45, tachycardia could be induced both by stimulating atrium and ventricle; B: This tachycardia showed complete atrioventricular dissociation with ventricular rate faster than atrial rate; C: During tachycardia, HV interval remained the same in right bundle branch block pattern as in sinus rhythm, HV interval prolonged about 20 ms in left bundle branch block pattern; D: Intra His refractory period stimulation advanced the next H wave.