case_images: PMC11750785_01
case_images: ECG and imaging presentation of the patient. (A) ECG presented a tachycardia at rate of 157 bpm. (B-B') Echocardiography presented enlarged left atrium of 35 mm and left ventricle of 57 mm (B), and a PFO (B'). (C) Cardiac MRI presented a dilated left ventricle which was absent from any signaling myocardial fibrosis against the diagnosis of dilated cardiomyopathy. (D) ECG demonstrated an atrial rate of 124 bpm after amiodarone treatment, and Wenckebach block was identified which lead to a slower ventricular rate at about 82 bpm.
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case_images: F1
case_images: The 12-lead electrocardiogram (ECG) revealed a narrow QRS complex tachycardia at 157 beats per minute (bpm) without discernible P waves, but notable high-peaked T waves (Figure 1A). Echocardiography indicated severe systolic dysfunction with a left ventricular ejection fraction of 22%, an enlarged left atrium measuring 35 mm, and a dilated left ventricle measuring 57 mm (Figure 1B), with a patent foramen ovale (PFO) confirmed (Figure 1B'). Cardiac MRI supported the findings of left ventricular dilation but did not show evidence of myocardial fibrosis, ruling out the diagnosis of dilated cardiomyopathy (Figure 1C). After initiation of amiodarone therapy, ECG showed a reduction in the atrial rate to 124 bpm with the development of a Wenckebach block, resulting in a slower ventricular rate of approximately 82 bpm (Figure 1D). The biphasic P wave in lead V1 (-/+), along with positive, pointed P waves in leads I, II, III, and aVF and negative P waves in lead aVR (Figure 1D), pointed to a focal origin in the high right atrium, such as the superior vena cava or right atrial appendage.
case_images: Identifying the originating of FAT in the patient. (A) Activating mapping suggested the earliest site at the interatrial septum in right atrium on left lateral view with EnSite Velocity system. (B) The catheter slipped into the left atrium through PFO and ablation performed at the anterior wall of left atrium. (C) The catheter retreated into the right side to continue the procedure at the vicinity of the earliest site along the limbus of PFO. (D) The tachycardia had been terminated and converted to sinus rhythm when ablation performing at the limbus of PFO.
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case_images: F2
case_images: The earliest atrial signals were 65 ms ahead of the surface P wave with QS unipolar electrograms and appeared to be an anterior limbus of PFO (Figure 2A). However, due to the anatomical characteristics of the mobile limbus of the PFO, optimal catheter-tissue contact was challenging to maintain, with contact force readings remaining suboptimal at 1-2 g (Figure 2A). Next, we performed the procedure with the contact force for 10-20 g at 30 W and 30 cc/min flow for 30 s per lesion at the anterior wall of the left atrium opposite to the earliest site on the right side with LSI values of 4.0-4.5 (Figure 2B). Tachycardia was eventually terminated and converted to sinus rhythm (Figures 2C,D).
case_images: Multipath ablation strategy in the patient. (A) Ablation performed additional lesions in the non-coronary aortic sinus of Valsalva near to the earliest activate site in the right interatrial septum. (B) All ablation lesions for this patient, as the gray region is part of right atrium, the blue region is part of left atrium, and the green is part of noncoronary cusp.
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case_images: PMC11750785_01_fcvm-11-1424187-g003.jpg
case_images: F3
case_images: Furthermore, additional lesions around this region that had been identified as the foci of FAT, including the opposite side of the earliest site in the non-coronary aortic sinus of Valsalva (Figures 3A,B) also received radiofrequency at a force of 10-20 g at 30 W and 30 cc/min flow for 30 s per lesion with LSI values of 4.0-4.5 to ensure enhanced treatment efficacy via multipath strategy.
case_images: Electrocardiogram after ablation. (A) An Intracardiac electrocardiogram for the sinus rhythm, the ablation catheter placed at the target, and the right ventricular catheter was placed at high right atrium. (B) ECG with rate of 96 bpm after ablation, and AV 1:1 conducted.
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case_images: PMC11750785_01_fcvm-11-1424187-g004.jpg
case_images: F4
case_images: The ablation electrode was ultimately positioned at the anterior limbus of the PFO, while the right ventricular electrode, serving as a high right atrial reference, demonstrated that the electrical signals at the high right atrium preceded those at the ablation target site (Figures 4A,B).