Successful Atrioventricular Nodal Reentrant Tachycardia Ablation in a 2-year-old Girl with Discordant Criss-Cross Heart

Figures

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  Figure 1. Cardiac structure. A: Schema of the cardiac structure: The RA drains through the MA to the posteroinferior morphological LV. The LA lying superior and to the left of the RA drains through the TA to the anterosuperior morphological RV, from which the Ao originated anteriorly. The RSVC and LSVC are anastomosed to the PA. B: Contrast-enhanced CT demonstrating the spatial relationship of both atria and ventricles. C: Cine angiography showing the superior location of the RV and inferior location of the LV, with a VSD connecting the 2 ventricles. Ao = aorta; AP = anteroposterior; CT = computed tomography; LA = left atrium; LAO = left anterior oblique; LAT = lateral; LSVC = left superior vena cava; LV = left ventricle; MA = mitral annulus; PA = pulmonary artery; RA = right atrium; RAO = right anterior oblique; RSVC = right superior vena cava; RV = right ventricle; TA = tricuspid annulus; VSD = ventricular septal defect.

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  Figure 2. Changes in QRS morphology during sinus rhythm, atrial pacing, and tachycardia. During sinus rhythm, the QRS complex primarily conducts through the anterior His bundle (forming an M-shaped wave in lead II). However, during atrial pacing or tachycardia, the QRS complex conducts through the posterior His bundle (forming an rS wave in lead II). Anterior His bundle potentials were identified at the 7 o’clock position of the tricuspid annulus, and posterior His bundle potentials were identified at the 3 o’clock position of the mitral annulus. HISa = anterior His catheter; HISp = posterior His catheter; PA = pulmonary artery.

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  Figure 3. Induction of tachycardia. A: 12-lead electrocardiogram showing the change in QRS morphology after tachycardia (rS in lead II). B: Tachycardia was induced by ventricular pacing, with a tachycardia cycle length of 272 ms, characterized by long RP′ tachycardia and QRS morphology, consistent with conduction via the posterior His bundle. The earliest atrial site (arrow) was located near the posterior His lesion. A quadripolar electrophysiological catheter was placed in the LPA through the LSVC to activate the atrium. ECG = electrocardiogram; HISa = anterior His catheter; HISp = posterior His catheter; LPA = left pulmonary artery; LSVC = left superior vena cava; PA = pulmonary artery; S = stimulus; STIM = stimulation; RV = right ventricle; V = ventricular electrogram; Vp = ventricular pacing.

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  Figure 4. Fluoroscopy and activation mapping. A: Fluoroscopy of the successful ablation site. B: Activation mapping during tachycardia. C: Intracardiac electrocardiography of tachycardia termination during RF application. The earliest atrial activation site (arrow) was at the 3 o’clock of the MA during fast-slow AVNRT at the posterior AVN. The posterior His electrogram was recorded near the successful ablation site. The RF energy was delivered during tachycardia while confirming atrioventricular conduction, and tachycardia was terminated by VA block (solid triangle). D: Schema of conduction system and slow pathway. The His potential electrogram was recorded at the 7 o’clock position of the TA (aHis) and 3 o’clock position of the MA (pHis). The slow pathway associated with fast-slow AVNRT in this case was located at the 3 o’clock of the MA. ABL = ablation catheter; aHis = anterior His; pHis = posterior His; AVN = atrioventricular node; AVNRT = atrioventricular nodal reentrant tachycardia; EAS = early activation site; HBE = His bundle electrogram; HISa = anterior His catheter; HISp = posterior His catheter; LA = left atrium; LAO = left anterior oblique; LAT = lateral; LV = left ventricle; MA…