Atypical form of sinoatrial node reentrant tachycardia: Should the traditional diagnostic criteria be modified?

Figures

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  Figure 1. A: Induction of tachycardia by programmed atrial extrastimulation under isoproterenol infusion. Surface electrocardiograms and intracardiac electrograms from the RAA, CS, His, and RVA are shown. B: Termination of the tachycardia with a bolus injection of adenosine triphosphate. Note that the atrial activation sequence and P-wave morphology were different during tachycardia and sinus rhythm. CS = coronary sinus; His = His-bundle region; RAA = right atrial appendage; RVA = right ventricular apex.

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  Figure 2. A: Activation maps of the right atrium during sinus rhythm and tachycardia during isoproterenol administration. The arrow indicates the earliest atrial activation site. B: P-wave morphology and intracardiac atrial activation sequence during sinus rhythm and tachycardia under isoproterenol infusion and during sinus rhythm at baseline. Note that the P-wave morphology and atrial activation sequence during tachycardia (blue tracings) perfectly match those during sinus rhythm at baseline without isoproterenol (orange tracings), as shown in the superimposed image. IVC = inferior vena cava; SVC = superior vena cava; TA = tricuspid annulus. Other abbreviations are as in Figure 1.

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  Figure 3. A: Manifest entrainment of the tachycardia during overdrive pacing from the RAA (pacing cycle length 340 ms). Prepotentials (P) were recorded with an Abl positioned just above the earliest atrial activation site. Note that the prepotentials and atrial electrograms from the Abl and CS catheters were orthodromically captured (blue arrows), whereas the atrial electrograms in the RAA and His-bundle region were captured antidromically (red arrow), with constant P-wave fusion (open arrows). B: Tracings during RF application at the successful site. The tachycardia terminated immediately after the initiation of RF delivery, followed by acceleration of sinus rhythm. C: Schematic representation of the presumed electrical activation during sinus rhythm and SANRT under isoproterenol infusion and sinus rhythm at baseline. Abl = ablation catheter; RF = radiofrequency; SAN = sinoatrial node; SACP = sinoatrial conduction pathway. Other abbreviations are as in Figure 1.