Radiofrequency ablation of a reentrant atrial tachycardia at the superior left atrium via the pulmonary artery

Figures

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  Figure 1. Electroanatomic high-density omnipolar voltage map showing large low-voltage areas at the anterior and superior left atrium during mapping of the initial atrial tachycardia (AT1). AT = atrial tachycardia.

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  Figure 2. Twelve-lead ECG of the second atrial tachycardia (AT2) (left) and intracardiac electrograms from mapping and ablation catheters (right). The tachycardia cycle length was 370 ms with concentric activation in the CS. The HD Grid catheter was positioned in the LAA, whereas the ablation catheter was located in the pulmonary artery at the site where RF delivery immediately terminated AT2. No discernible electrograms were recorded at this location despite high amplification (magnified in the red box). AT = atrial tachycardia; CS = coronary sinus; ECG = electrocardiogram; LAA = left atrial appendage; RF = radiofrequency.

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  Figure 3. Entrainment mapping during the second atrial tachycardia (AT2). PPI–TCL values are shown for multiple atrial pacing sites, including the lateral and inferolateral LA, anterior wall, proximal/middle/distal CS, cavotricuspid isthmus, and right atrial septum. All sites demonstrated long PPI–TCL values, indicating the absence of concealed entrainment and exclusion from the tachycardia circuit. Pacing from the superior endocardial LA failed to achieve myocardial capture, resulting in ineffective entrainment. AT = atrial tachycardia; CS = coronary sinus; LA = left atrium; PPI–TCL = postpacing interval minus tachycardia cycle length.

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  Figure 4. Anterosuperior view of the LA showing the presumed localized reentry circuit of the second atrial tachycardia (AT2) (black arrow) at the superior LA. Blocked lines identified by entrainment mapping are shown in red, forming a triangular region (transparent blue) bounded by the anterior line, the posterior roof line, and the ridge, along with pulmonary vein isolation lines. Pacing sites are marked with asterisks: the shortest PPI–TCL (∼180 ms) was recorded at the inferolateral LA (blue asterisk), whereas very long PPI–TCL values (∼230–290 ms) were observed at the posterior and anteroseptal LA and in the distal coronary sinus (red asterisks). These findings suggest that the critical isthmus was confined to the superior LA, likely beneath the pulmonary artery. AT = atrial tachycardia; LA = left atrium; LAA = left atrial appendage; LSPV = left superior pulmonary veins; PPI = postpacing interval; RSPV = right superior pulmonary vein; TCL = tachycardia cycle length.

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  Figure 5. Immediate termination of the second atrial tachycardia (AT2) during epicardial-targeted ablation from the pulmonary artery, confirming a localized epicardial circuit of the tachycardia at the left atrial roof.

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  Figure 6. Key anatomic risks during ablation from the pulmonary artery. Vulnerable structures include the left main coronary artery, pulmonary valve, sinus node artery, pulmonary arterial wall, and epicardial sympathetic fibers. Awareness of these sites and titrated RF delivery are essential for procedural safety. RF = radiofrequency.