An unusual atrial tachycardia resulting from two levels of conduction block within the arrhythmogenic superior vena cava

A 60-year-old woman underwent catheter ablation for atrial tachycardia (AT) [cycle length (CL), 260 ms]. The site of earliest activation was identified in the high superior vena cava (SVC) where a rapid tachycardia (CL, 130 ms) was observed, suggesting 2:1 block between the SVC and right atrium. The constant P-wave morphology and atrial activation sequence indicated a single electrical connection in the cavoatrial junction (CAJ). The atrial CL spontaneously became prolonged from 260 to 520 ms (Panel A). In the low SVC (LSVC), activation sequence was unidirectional and there were two different sites of 2:1 block in the lateral and anterior wall of the LSVC (Panel B). Radiofrequency application at the CAJ successfully terminated the AT. The SVC tachycardia was not inducible after isolation of the SVC.

Source: Europace - September 7, 2020 Category: Cardiology Source Type: research