PMC3539401_01
The four panels show intracardiac tracings during ventricular pacing. A jump in VA conduction time was observed in both twins with similar jumps at similar pacing intervals i.e. a VA jump of 84ms from S2=380ms to S2=360ms (drive chain 600ms) in twin A, and a jump of 102ms from S2=400ms to S2=390ms in twin B (drive chain 600ms).
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F1
At both cycle lengths, retrograde activation was concentric and decremental but with demonstrable dual nodal physiology as seen by a VA jump (Figure 1).
Intracardiac recordings during RF application at the slow pathway region in twin A. Fast junctional tachycardia with dissociated atrial and ventricular activity was observed leading to the curtailment of the RF application.
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F2
Many of the RF applications had to be curtailed due to fast junctional tachycardia with dissociated atrial and ventricular activity (Figure 2).
Intracardiac recordings during mapping at the slow pathway region in twin B. Junctional tachycardia with dissociated atrial and ventricular activity was observed on touch alone.
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F3
Successful slow pathway ablation was obtained after 9 RF applications and the procedure was fraught with difficulties; both transient AV block and junctional tachycardia were produced by touching the slow pathway area (Figure 3) even though this was distant from the maximal His recording (Figure 4).
Fluoroscopy during ablation of twin B. Left panel: the ablation catheter is at the point of maximal His recording. Right panel: the catheter is in the position where touch AV block and junctional tachycardia were produced.
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F4
Successful slow pathway ablation was obtained after 9 RF applications and the procedure was fraught with difficulties; both transient AV block and junctional tachycardia were produced by touching the slow pathway area (Figure 3) even though this was distant from the maximal His recording (Figure 4).