case_images: PMC7252680_01
case_images: Supraventricular tachycardia (SVT) with a long RP interval was recorded on electrocardiogram (ECG). Positive P-waves are seen in V1.
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case_images: Association functional classification class II). A 12-lead resting electrocardiogram (ECG) revealed regular narrow complex tachycardia (Figure 1).
case_images: A: An RF catheter is positioned in the tricuspid annulus. The first beat (1) was sinus and conducted to the ventricle through the AV node. The second beat (2) was a premature atrial conduction conducted to the ventricles by the AV node (long AV interval), which initiated (3) SVT with a cycle length (CL) of 360 ms and a constant ventriculoatrial (VA) interval of 104 ms. Aberrancy in the first tachycardic beats was recorded. B: His potential during tachycardia. The atrium to His interval was 94 ms; the His to ventricle interval was 50 ms. C: Overdrive pacing from the right ventricle was performed. Entrainment was confirmed by measurement of the AA interval during pacing (300 ms) and tachycardia (360 ms), which was also the tachycardia CL. VAV response and 492-ms PPI are illustrated. PPI-TCL = 132 ms. The earliest atrial activations were detected in CS2, positioned in the left posteroinferior wall. D: A PVC placed at the time of His bundle refractoriness advanced the atrium without changing the atrial activation sequence and reset the tachycardia, which was diagnostic for a retrograde pathway that participates in tachycardia. E: The ventricular pacing given earlier terminated tachycardia without advancing to the atrium. F: Retrograde ventriculoatrial dissociation was recorded during right ventricular pacing after ablation.
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case_images: Few sinus complexes were recorded with concentric ventricular activation (Figure 2A). The atrium to His (AH) and His to ventricle intervals were 94 ms and 50 ms, respectively (Figure 2B). The post-pacing interval was 492 ms with a ventricle-atrium-ventricle (VAV) response during overdrive pacing and entrainment of tachycardia from the right ventricle (Figure 2C). Ventricular pacing within 40 ms of the His potential advanced the atrium and the atrial activation sequence to the same as that seen during tachycardia (Figure 2D). The ventricular pacing given earlier terminated the tachycardia without advancing to the atrium (Figure 2E). Stable VA dissociation was recorded (Figure 2D).
case_images: A: Fluoroscopic imaging of catheter positions during the successful ablation (right: RAO, left: LAO). The decapolar catheter was in the coronary sinus. The Marinrs MC ablation catheter (Medtronic, Minneapolis, MN, USA) was in the mitral groove. The quadripolar catheter was in the right ventricle. B: Local activation at the successful ablation site. No VA fusion was present at the ablation site.
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case_images: Fluoroscopy time was 10 minutes (Figure 3A). Local activation at the successful ablation site is shown in Figure 3B.