Dual Atrioventricular Nodal Non-Reentrant Tachycardia

Figures

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  Figure 1. Electrocardiogram After Pacemaker Implantation

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  Figure 2. Intracardiac Electrograms (A) Atrial and ventricular sensed events. Notably, the first ventricular complex is paced. The atrial rate is 53 per minute, and the corresponding ventricular rate is 106 per minute. The first ventricular event follows the atrial signal by 277 to 281 ms (fast pathway conduction), while the second ventricular event follows the same atrial signal by 660 to 664 ms (slow pathway conduction). (B) Atrial pacing at a rate of 55 per minute (cycle length: 1,090 ms) results in a ventricular rate of 110 per minute. The second ventricular sensed event appears with a consistent interval, similar to that observed in panel A, supporting the diagnosis of DAVNNT.

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  Figure 3. Lead V1 From the Electrocardiogram (in Figure 1) and Laddergram P waves are marked with red asterisks. Conduction through the fast (F) and slow (S) atrioventricular nodal pathways produces the characteristic “double fire” pattern. Alternating QRS morphology results from repetitive long-short cycle lengths. In the laddergram, fast-pathway conduction is depicted by a continuous line, whereas slow-pathway conduction is shown by a dashed line. A = atria; AVN = atrioventricular node; H = His bundle; V = ventricle.

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  Figure 4. Electrophysiology Study (A) A repetitive sequence of A–H1V1–H2V2 is observed with a consistent H1H2 interval. The H1V1 interval is within normal limits (42 ms), whereas the H2V2 interval is markedly prolonged (119 ms). (B) Atrial pacing from the coronary sinus (CS) 9 to 10 channel at an interval of 820 ms (73 per minute) results in fast pathway block due to a Wenckebach response. Normalization of the H2V2 interval is also observed. The subsequent AH interval is measured at 622 ms. (C) Tracing after slow pathway ablation showing elimination of 1:2 physiology. His bundle recordings (proximal, mid, and distal) are displayed in yellow; coronary sinus (CS) electrograms from CS 9 to 10 to CS 1 to 2 are shown in turquoise/blue; right ventricular apex (RVA) catheter signals are shown in green; and ablation (ABL) catheter signals in orange.

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  Figure 5. Follow-Up Electrocardiogram After Slow Pathway Ablation Sinus rhythm at a rate 67 per minute, 1:1 atrioventricular conduction with PR interval of 208 ms, incomplete right bundle branch block and left anterior fascicular block.