Magnetic‐guided catheter ablation of twin AV nodal reentrant tachycardia in a patient with left atrial isomerism, interrupted inferior vena cana, and Kawashima‐Fontan procedure

Figures

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  Figure 1. Cardiac anatomy and catheter trajectory. A coronal view of cine‐cardiac magnetic resonance (CMR) imaging is shown in Panel A. Flow from a confluence of suprahepatic veins is directed to the pulmonary artery (PA) by means of an intracardiac lateral tunnel Fontan variant. Bilateral superior vena cavae are connected to the PA. LSVC denotes left superior vena cava. Panel B displays an anteroposterior fluoroscopic view of the reference catheter placed in the intracardiac lateral tunnel by a right jugular venous approach, and the magnetic‐guided ablation catheter positioned at the superior atrioventricular (AV) node via a retrograde aortic approach. An axial view of cine‐CMR imaging in Panel C shows the intracardiac Fontan in the center of a large common atrium. A common AV valve guards the entrance of a functionally univentricular heart, where right (RV) and left (LV) ventricles communicate through a nonrestrictive bulboventricular foramen. Shown in Panel D is an inferior view of merged electroanatomic mapping with CMR imaging, displaying the position of the reference catheter within the intracardiac Fontan.

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  Figure 2. Twin AV nodes. Twin AV nodes are schematically depicted bordering the margins of a complete AV septal defect. Each has its own His‐Purkinje structure, with a so‐called Mönckeberg's sling (orange) of conduction tissue connecting the two systems. Intracardiac and surface ECG recordings in sinus rhythm are shown with electrical conduction coursing along superior (Panel A; purple) and inferior (Panel B; light blue) AV nodes. The top portion of both panels depicts surface ECG recordings from leads I, II, aVF, V1, and V6 along with intracardiac electrocardiograms from the magnetic‐guided ablation catheter positioned to record a His signal. A denotes atrium; H, His; V, ventricle. HV intervals were 58 and 40 msec with conduction across superior and inferior AV nodes, respectively. Twelve‐lead ECGs are shown in the bottom portion of both panels. Note the inferior QRS axis with conduction across the superior AV node, and superior QRS axis with conduction across the inferior AV node.

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  Figure 3. Electroanatomic mapping and catheter ablation. Panel A shows a three‐dimensional electroanatomic map merged with cardiac magnetic resonance imaging. Purple and blue spheres indicate sites with the best His recordings near superior and inferior AV nodes, respectively. Mapping was performed during clinical tachycardia. Local activation times are color‐coded, from red to orange, yellow, green, light blue, dark blue, and purple. A reentrant circuit courses antegrade down the superior AV node, along Mönckeberg's sling, and retrograde across the inferior AV node. The intracardiac Fontan is shown in green, double‐outlet right ventricle (RV) in yellow, and aorta with the pulmonary stump connected to the aortic root (i.e., Damus‐Kaye‐Stansel) in red. Panel B captures surface ECG recordings from leads I, II, aVF, V1, and V6 and intracardiac recordings from the distal (Map1‐2) and proximal (Map3‐4) magnetic‐guided ablation catheter, and reference (Ref) catheter in the intracardiac conduit. Radiofrequency ablation of the inferior AV node is performed in sinus rhythm during inferior AV conduction. Upon successful ablation, the QRS axis transitions from superior to inferior (asterisk) as…