case_images: PMC10904613_01
case_images: Timeline of the patient's medical history with corrective surgeries (Kawashima procedure, lateral Fontan procedure, cardiac catheterisation) and current symptoms. At admission baseline ECG and TTE were performed. Baseline electrocardiogram: sinus rhythm with slightly wide QRS complex suggestive of non-specific intraventricular conduction delay, left anterior fascicular block and diffuse negative T waves. Transthoracic echocardiography: one ventricle with conserved systolic function, 50%-55% visually estimated; minimal regurgitation of the atrioventricular valve. Apparently only one atrium (the interatrial septum was not visualized); inside of it was present the venous conduct with laminarly flux. It was also viewed the rudiment of the right ventricle. The aorta had complete dextroposition and was slightly more anterior than the pulmonary artery. The aortic valve was tricuspid, with no significant regurgitation. At the left of the aorta, it was also visible the pulmonary artery with a hypoplastic pulmonary valve.
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case_images: PMC10904613_01_fped-12-1358505-g001.jpg
case_images: F1
case_images: Signs of heart failure have reappeared in the last years due to recurrent episodes of rapid and regular palpitations with supraventricular tachyarrhythmia documented (Figure 1). Prior to the procedure transthoracic echocardiography (Figure 1) and multi-slice computed tomography angiography were performed in order to gain an enhanced comprehension of the patient's anatomy, especially taking into account the history of corrective surgeries.
case_images: (A) ECG during arrhythmia: regular tachycardia, cycle length (CL) of 340 msec, 1:1 ventriculoatrial conduction, RP interval longer than 90 msec, negative P waves in inferior leads, narrow QRS complex without pseudo-R in V1 and pseudo-S in DII-DIII. (B) Intraprocedural recording during radiofrequency applications (56 C, 50 W) with arrythmia termination within seconds. (C) ECG during second arrhythmia: regular tachycardia, CL of 400 msec, 1:1 ventriculoatrial conduction, long RP interval, positive P waves in inferior leads, narrow QRS complex. (D) Intraprocedural recording during radiofrequency applications (56 C, 50 W) with arrythmia termination within seconds.
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case_images: PMC10904613_01_fped-12-1358505-g002.jpg
case_images: F2
case_images: Diagnostic maneuvers like atrial stimulation were performed at a base cycle of 500 ms with progressive decrease of the extra stimulus from 400 ms resulting in the induction of a supraventricular tachycardia with a 1/1 ventriculoatrial relationship, cycle length of 340 ms, RP'~120 ms< and negative axis of the P' waves in the inferior leads (Figure 2A). Radiofrequency applications at 56 degrees Celsius and 50 Watts promptly terminated the AVRT (Figure 2B), resulting in a block in the retrograde loop in less than 5 s. Following this, programmed atrial stimulation (500 ms, 400 ms) induced a second supraventricular tachycardia with a 1/1 ventriculoatrial relationship, cycle length of 400 msec RP'~180 ms < P'R and positive P' waves in the inferior leads (Figure 2C), and entrainment studies again confirmed ortho-AVRT. AVRT (Figure 2D). At the end of the procedure, there were no other inducible tachyarrhythmias.
case_images: (A) Fluoroscopic imagine showing the position of the decapolar deflectable catheter into the intra-atrial conduct, with no puncture of the dacron conduit and the position of the thermocool RMT catheter (B,C) electroanatomical CARTO 3 map showing the position of the two accessory pathways in relation to the His bundle (yellow dot). (D) Electroanatomical reconstruction using computed tomography. (E) Intraprocedural electrogram of the His bundle.
case_images: fped-12-1358505-g003.jpg
case_images: PMC10904613_01_fped-12-1358505-g003.jpg
case_images: F3
case_images: It was possible to record and pace the right atrium without the need to puncture the Dacron conduit (Figure 3). The electroanatomical CARTO 3 maps provided further substantiation of this hypothesis by revealing the existence of two accessory pathways, both situated in close proximity to the atretic tricuspid valve and the His bundle (Figure 3).