Translational Anatomy of the Sinoatrial Node: Myoarchitecture and its Relevance for Catheter Ablation

Figures

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  Figure 1. Sinus Node Modification Procedure for Inappropriate Sinus Tachycardia (A) 3D activation maps of the RA at baseline (left) and isoproterenol infusion (middle and right). Note inferior shift in activation near the arcuate ridge (yellow asterisk). (B) RA activation maps (left) and ablation lesions (right; blue tags are projected points and green tags are points with >10 Ω drop). Middle insert shows intracardiac electrograms in the isochrone corresponding to 8 μg/min isoproterenol and unipolar signals with QS morphology and pre–P-wave activation. Target heart rate during ablation was achieved at the caudal end at the arcuate ridge. (C) Heart rate plot from implantable cardiac rhythm monitor with reduction in average heart rates before (on 15 mg ivabradine daily) and after (off medication) ablation. Red dashed line marks day of ablation. (D, E) 12-lead electrocardiogram (D) before and (E) after sinus node modification procedure. Note shift in P-wave axis after ablation. (F) Intracardiac echocardiography images of the region of the arcuate ridge between the right atrial appendage (RAA) and the right atrium (RA)–superior vena cava (SVC) junction (yellow arrow, left). Ablation catheter…

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  Figure 2. Ablation of Atrial Tachycardia From the High Terminal Crest Case of atrial tachycardia (AT) arising from the high crista terminalis (CT) in a patient with recurrent palpitations despite treatment with metoprolol. (A) 12-lead electrocardiogram (ECG) in sinus rhythm. (B) 12-lead ECG during AT. (C) 3D isochronal map with earliest activation in the high CT at the posterior SVC-RA junction. Insert shows local electrogram (EGM) at earliest activation site, obtained from a multispline catheter during AT, with QS unipolar EGM preceding P-wave activation. (D) ECG showing catheter suppression of AT at earliest activation site, at which point ablation was turned on, followed by intermittent automaticity and termination during ablation. Other abbreviations as in Figure 1.

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  Figure 3. Ablation of Atrial Tachycardia From the Superior Vena Cava Example of AT arising from the SVC in a patient with previous pulmonary vein isolation for paroxysmal atrial fibrillation. (A) On 5 μg/min isoproterenol, AT from the SVC was induced (cycle length of 320 ms) and mapped. SVC bipolar electrograms were highly fractionated, and unipolar EGMs had a pre–P-wave QS morphology indicative of site of origin. (B) During sequential ablation from high to low (blue dots), caudal migration of AT activation was observed with acceleration before termination in the SVC-RA junction. (C) Continuous ECG tracings during ablation in the SVC-RA junction, where AT broke (red arrow) with subsequent sinus tachycardia due to isoproterenol effect. Abbreviations as in Figures 1 and 2.