Transient entrainment by ventricular and atrial stimulation was achieved in 11 and 8 of 13 bundle-branch reentrant tachycardias, respectively, aiding differentiation from other wide-QRS mechanisms.
Observational (n=9)
Can transient entrainment by atrial and ventricular stimulation differentiate bundle-branch reentrant tachycardia from other wide-QRS-complex tachycardias?
Analysis of ECGs during transient entrainment by atrial and ventricular stimulation can help differentiate bundle-branch reentrant tachycardia from other wide-QRS-complex tachycardias.
BACKGROUND: Different responses to entrainment have been reported in relation to the pacing site of a variety of tachycardias. However, transient entrainment of bundle-branch reentrant tachycardia (BBRT) has not been investigated systematically. METHODS AND RESULTS: We attempted entrainment of 13 BBRTs in 9 patients by pacing first the right ventricle and then the right atrium. The initial pacing cycle length (CL) was 10 ms faster than the tachycardia CL. Subsequent pacing sequences were performed with 5- to 10-ms CL decrements until tachycardia termination or loss of postatropine 1:1 AV conduction. Both full ventricular-paced and AV-conducted QRS complex references were obtained during sinus rhythm pacing from the same sites and with similar CL as during entrainment. Transient entrainment was achieved by ventricular and atrial stimulation in 11 and 8 tachycardias, respectively. Constant fusion was always present during entrainment by ventricular stimulation. There was no change in the QRS complex (orthodromically concealed fusion) during entrainment by atrial stimulation in 6 of 6 tachycardias with left bundle-branch block morphology and in 1 of 2 tachycardias with right bundle-branch block morphology. CONCLUSIONS: BBRT, especially if it has a left bundle-branch block morphology, can be differentiated from other wide-QRS-complex tachycardia mechanisms through analysis of the ECGs recorded during tachycardia entrainment by atrial and ventricular stimulation. This diagnostic approach may be especially useful when it is difficult to record a stable or sufficiently sized His bundle electrogram or when spontaneous changes in the ventricular CL precede similar changes in the His bundle CL.
Merino et al. (Tue,) conducted a observational in Bundle-branch reentrant tachycardia (BBRT) (n=9). Atrial and ventricular stimulation was evaluated on Achievement of transient entrainment and QRS complex morphology changes. Transient entrainment by ventricular and atrial stimulation was achieved in 11 and 8 of 13 bundle-branch reentrant tachycardias, respectively, aiding differentiation from other wide-QRS mechanisms.