Atrioventricular block (AVB) is frequently seen following atrio-His (AH) interval lengthening after adenosine injection during sinus rhythm when both the fast and slow pathways are blocked in patients with dual atrioventricular nodal physiology (DAVNP). However, the condition also occurs in patients without DAVNP. Therefore, an AH jump may not indicate DAVNP if AVB is accompanied. The goal of this study was to use a low dose (6-9 mg) of adenosine to determine whether an AH jump truly represents DAVNP when the presence or absence of AVB following the AH jump is taken into consideration.

This study included 78 patients (male:female=47:31, age 40.0±15.7 years, DAVNP group, n=46, control group, n=32). Adenosine (6-9 mg) was administered intravenously during sinus rhythm. The inclusion criteria of DAVNP were either induced AVNRT (n=37:common type, n=35, uncommon, n=2) or identification of AH jump (n=9) during elctrophysiology study (EPS). The control group consisted of patients without evidence of DAVNP and noninducible AVNRT on EPS. In all subjects, the electrophysiologic parameters of the AV nodal properties were tested.

In the DAVNP group, intravenous adenosine during sinus rhythm resulted in an AH jump without AVB (8/46, 17.4%), an AH jump followed by AVB (9/46, 19.6%), an AH jump accompanied by induced AVNRT (1/46, 2.1%), or no significant changes in the AH interval (28/46, 60.9%). In the control group, none of the subjects showed an AH jump without AVB, however an AH jump with subsequent AVB was observed in 4 of 32 subjects (12.5%). If the finding of an AH jump without AVB alone was considered as a positive criteria of DAVNP, its specificity (87.5% to 100%) and positive predictive value (81.8% to 100%) increased compared to the criteria defined by an AH jump regardless of the presence or absence of AVB, however, its sensitivity decreased from 39.1% to 19.6%.

AH jump induced by adenosine injection may not indicate DAVNP if AVB follows.