A‐V‐V‐A response to single atrial premature depolarization in a narrow QRS tachycardia: What is the mechanism?

Figures

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  FIGURE 1. (A) An A‐V‐V‐A response after the cessation of atrial overdrive pacing at a pacing cycle length of 300 ms. (B) Tachycardia persisted with ventriculoatrial dissociation. The sequence of atrial potentials was identical to that during sinus rhythm, with a cycle length of 615 ms. (C) Responses to atrial premature depolarizations during tachycardia with coupling interval of 280 ms. II, V1, surface electrogram; CS d, distal coronary sinus; CS p, proximal coronary sinus; His d, distal His‐bundle region; His p, proximal His‐bundle region; HRA, high right atrium; RV, right ventricle.

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  FIGURE 2. The tracing is shown in Figure 1A,C and its corresponding laddergram. II, V1, surface electrogram; A, atrium; APD, atrial premature depolarizations; AVN, atrioventricular node; CS d, distal coronary sinus; CS p, proximal coronary sinus; FP, fast pathway; His d, distal His‐bundle region; His p, proximal His‐bundle region; HRA, high right atrium; RV, right ventricle; SP, slow pathway; UCP, upper common pathway; V, ventricle.