A 69-year-old man with very frequent supraventricular extrasystoles, functional class II, and mild ventricular dysfunction (48%) underwent an electrophysiology study. At baseline, he had dual antegrade atrioventricular nodal physiology (evidenced by an atrial-his [AH] jump), 2 echo beats, and dual nodal conduction (figure 1A, electrocardiogram; figure 1B, intracavitary recording during His-bundle sinus mapping with a high-density catheter; figure 1C, schematic representation and ladder diagram; A, right atrium; AVN, atrioventricular node; H, His; HP, His-Purkinje; V, right ventricle). As shown in figure 1B, atrial activation (A) caused 2 ventricular activations (V1 and V2) with a constant HV interval, both preceded by His-bundle activation (AH1fastpathway=125ms, AH2slowpathway=685ms, AH2-AH1=560ms). AH2 showed concentric retrograde atrial conduction with a short ventriculoatrial (VA) interval. The regularity of the His-His intervals distinguished them from His-bundle and atrioventricular junctional ectopics.

Figure 1

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Isoproterenol induced spontaneous regular nonsustained narrow QRS tachycardia (rendering resetting or entrainment impossible) with a cycle length of 585 ms. Additional findings were concentric retrograde atrial activation with a VA interval of 2 ms; termination, probably due to retrograde block in the fast pathway (last tachycardia beat with a different VA interval, prolongation of the atrial-atrial interval, and no variations in the ventricular-ventricular interval); and restarting of dual nodal response (figure 2A, intracavitary recording with catheters in the septal right atrium, coronary sinus, and right ventricular apex; figure 2B, nodal conduction; figure 2C, ladder diagram). A septal accessory pathway was ruled out on demonstrating the retrograde Wenckebach phenomenon during ventricular pacing at a tachycardia rate. With a diagnosis of dual atrioventricular nodal nonre-entrant tachycardia and common nodal re-entrant tachycardia, the slow pathway was ablated, resulting in disappearance of the dual response, an improvement in functional class, and normalization of ventricular function.

Figure 2

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The patient gave his consent for the publication of this case report.