Case report
A 73-year-old man was referred to our hospital for ablation of a
symptomatic persistent AT. Nine years ago, the patient underwent surgery
for coronary artery bypass grafting and aortic valve replacement. During
this surgical procedure, the patient additionally received ablation
treatment performed with HIFU (Epicor™, St Jude Medical, Maple Grove,
MN) due to paroxysmal AF. At presentation, a dilated left ventricle with
moderately reduced left-ventricular ejection fraction of 32% and a left
atrial volume of 77 ml with only mild mitral regurgitation was detected.
The biological aortic valve prosthesis was in proper location and
well-functioning with a mean aortic valve pressure gradient of 21 mmHg.
During the electrophysiological procedure, a 7 French (F) 10-pole
deflectable catheter was placed into the coronary sinus (CS) via femoral
venous approach, which confirmed the left-atrial AT with a cycle length
(CL) of 280ms and a 2:1 atrioventricular conduction. After
fluoroscopy-guided double trans-septal punctures, a high-density mapping
catheter (PENTARAY©, Biosense Webster, CA, USA) and a
Smarttouch SF irrigated-tip ablation catheter (Smarttouch
SF©, Biosense Webster, CA, USA) were placed in the
left atrium (LA), respectively. EAM was performed with the CARTO 3
CONFIDENSE system (Biosense Webster, CA, USA). Low voltage zones (LVZ)
were defined as areas with a bipolar peak-to-peak voltage amplitude of
<0.5 mV. Notably, LVZ were identified along the
EpicorTM ablation line. However, there were multiple
gaps in the ablation line, particularly located among the anterior
segments of the right PV and the posterior wall (Figure 1). Activation
mapping depicted 83% of the AT-CL with the earliest activation ostial
of the LA appendage suggestive of a macro-reentry mechanism. The
integration of vector and velocity information
(COHERENTTM technology) confirmed a focal activation
with a conduction block of the LA roof, as shown in Figure 2 and
Supplement video 1. Ablation (30 Watts) was started at the earliest site
of activation, resulting in prompt termination of the AT into sinus
rhythm. Furthermore, the EpicorTM ablation line was
completed by ablating the posterior wall and the anterior segments of
the right PV. As a result, isolation of all PVs and the posterior wall
was achieved (Figure 3).