Rare narrow QRS tachycardia with atrioventricular dissociation: A case report

Figure 1 The first tachycardia and premature ventricular beats. A: The first tachycardia, the cycle length was 360 ms, with VA 1: 1 conduction; B: Premature ventricular beats during His refractory period advanced the following atrial potential.

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.

Figure 3 The ablation target was just before the ostium of coronary sinus around the area of slow pathway of the atrial ventricular node.