Dual atrioventricular nodal nonreentrant tachycardia with alternating 1:1 and 1:2 AV conduction: mechanistic hypotheses and total suppression using right atrial pacing

Abstract

Dual atrioventricular (AV) nodal nonreentrant tachycardia is an uncommon arrhythmia with several pattern types. The primary therapy is ablation of the slow AV nodal pathway. A rare pattern type demonstrates alternating 1:2 and 1:1 AV ratios with longer PR intervals during 1:1 conduction. We report the second intracardiac study of this variant and the first case of using right atrial pacing as the ultimate therapy for any pattern type.

Figure 1

The 12‐lead ECG with rhythm strips from leads V1, II, and V₅ are shown.

Figure 2

Surface leads I, II, III, V1, and V₆ are displayed with electrograms from the right atrium (RA), His bundle (His), proximal coronary sinus (CSp), distal coronary sinus (CSd), and right ventricle (RV). The AH intervals to the first His electrograms (upper numbers and arrows) and to the second His electrograms (lower numbers and arrows) are measured.

Figure 3

ECG lead V₁ rhythm strips four months after slow pathway ablation demonstrated (A) DAVNNT pattern type 1, (B) DAVNNT pattern type 2, (C) intermittent dual AV nodal response with right atrial pacing at 60 bpm, and (D) total suppression of dual AV nodal response with right atrial pacing at 70 bpm.

Figure 4

ECG lead V₁ rhythm strip and ladder diagrams demonstrate potential mechanisms. The ERP of the AV node distal common pathway or His‐Purkinje system is represented by the shaded rectangles. See text for discussion.