Abstract
A 50-year-old man with long-standing persistent atrial fibrillation received radiofrequency catheter ablation after electrical cardioversion. The second radiofrequency application on anterior antrum of the right superior pulmonary vein induced sinus arrest following a sinus cycle length prolongation. Sinus arrest persisted. Right ventricular pacing was required for 3 min until a sinus rhythm was restored. Preprocedural contrast-enhanced computed tomography revealed that the ablation site was near the right sinus node artery (SNA). Retrospective analysis during catheter ablation confirmed a direct anatomical relationship between the ablation site and the right SNA. In the present case, rapid recovery without coronary intervention suggests a transient and reversible mechanism, such as SNA spasm. This case highlights the importance of preprocedural anatomical assessment of the SNA and performing ablation under sinus rhythm, which may facilitate early recognition of sinus node dysfunction and help prevent irreversible injury.
Learning objective
A right sinus node artery might be close to the right superior pulmonary vein and can be affected by right pulmonary vein isolation. In cases of persistent atrial fibrillation, performing ablation under sinus rhythm allows immediate recognition of sinus node dysfunction and may help prevent irreversible sinus node injury.
Keywords: Atrial fibrillation, Catheter ablation, Pulmonary vein isolation, Sinus node dysfunction, Sinus node artery
Introduction
The sinus node artery (SNA) perfuses the sinus node, and it can originate from either the right coronary artery (RCA) or left circumflex artery. The right SNA branches from the RCA [1]. Although many reported cases of sinus node dysfunction during atrial fibrillation (AF) ablation have involved left-sided ablation or left/posterior SNA anatomy, only a limited number of cases have described sinus arrest during right pulmonary vein isolation related to right SNA involvement. Here, we report a case of sinus arrest during right superior pulmonary vein isolation in which electroanatomical mapping combined with contrast-enhanced computed tomography (CT) demonstrated close anatomical proximity between the ablation site and the right SNA. It is important to be aware of the potential for injury to the SNA and to check its origin and course of the SNA in advance. Furthermore, we performed ablation during sinus rhythm after electrical cardioversion, and allowed early recognition of the right SNA injury.
Case report
A 50-year-old man presented to our hospital with exertional dyspnea. He was diagnosed with persistent AF and hypertension during his annual check-up 2 years prior. AF was persistent on arrival at our hospital (Fig. 1A), and he was diagnosed with long-standing persistent AF. After obtaining informed consent, catheter ablation of AF was performed under deep sedation.
Fig. 1.
(A) The 12-lead electrograms before ablation. The rhythm was atrial fibrillation with a heart rate of 68 bpm. (B) The12-lead electrograms after ablation. The rhythm was sinus rhythm with first-degree atrioventricular block. The heart rate was 74 bpm.
Contrast CT scan revealed a pouch on the anterior wall near the right pulmonary vein (RPV) with no significant coronary stenosis or cardiovascular malformation (Fig. 2A). His SNA branched only from the RCA (Fig. 2B). Before undergoing ablation, the patient underwent intracardiac cardioversion. His rhythm was restored to sinus rhythm without any bradycardia.
Fig. 2.
Preprocedural contrast-enhanced CT demonstrating the anatomy of the right sinus node artery. (A) Axial CT images. The upper panel shows the close anatomical proximity between the right sinus node artery and the anterior antrum of the right superior pulmonary vein. The lower panel shows the course of the right sinus node artery branching from the right coronary artery. (B) Three-dimensional reconstructed CT image demonstrating the anatomical relationship between the right sinus node artery and the anterior antrum of the right superior pulmonary vein.
CT, computed tomography; SNA, sinus node artery; RCA, right coronary artery; LCA, left coronary artery.
The Rhythmia three-dimensional mapping system (Boston Scientific, Marlborough, MA, USA) and Intellanav Stablepoint ablation catheter (Boston Scientific) were used. We started the pulmonary vein isolation (PVI) from the anterior wall antrum of the right superior pulmonary vein (RSPV) near the anterior pouch. The anterior power setting of 50 W for 20 s and the posterior power setting of 50 W for 15 s were applied. A radiofrequency application at the second point resulted in sinus arrest after prolongation of the sinus cycle length (Fig. 2B). The application setting for the second point was 50 W for 16 s, resulting in an impedance drop of 39 Ohms (from 165 to 126 Ohms). The average contact force was 14 g. He did not complain of pain during the high-frequency application. Sinus arrest persisted, requiring right ventricular back-up pacing at 40 pulses per minute. Three minutes later, sinus rhythm was restored and exceeded the pacing rate. After reviewing the preoperative CT scan, we recognized that the application sites on antrum of the anterior wall were remarkably close to the right SNA (Figs. 2B, 3B). We redesigned the ablation line closer to the RPV, and accomplished PVI. He complained of pain during radiofrequency application to the posterior wall of the left pulmonary vein, but bradycardia was not induced. The electrocardiogram after ablation exhibited normal sinus rhythm (Fig. 1B). During the one year of follow-up, the patient experienced neither tachyarrhythmia nor bradycardia recurrence. A CT scan after ablation showed an intact right SNA.
Fig. 3.
(A) The PVI line with a CT image of the LA. We started the radiofrequency application on the anterior antrum of the LA near the RSPV (#1). The second application (#2) induced sinus arrest. We redesigned the PVI line and accomplished PVI. (B) Ablation tag#1 and tag#2 were remarkably close to the pouch. (C) Intracardiac cardiograms during the second application. The second application induced sinus arrest (4498 ms) following a sinus cycle length prolongation.
CT, computed tomography; LA, left atrium; RSPV, right superior pulmonary vein; SNA, sinus node artery; PVI, pulmonary vein isolation; RA, right atrium; CS, coronary sinus.
Discussion
SNAs are classified into three types. A previous study using cardiac CT reported the following proportions: right SNA (65.7%), left SNA (30.7%), posterior SNA (6.5%), and dual supply (5.9%) [2]. Although contrast-enhanced CT may facilitate visualization of the SNA before ablation, the detectability of the SNA by contrast-enhanced CT depends on multiple factors, including vessel caliber, contrast enhancement (iodine delivery rate and timing), cardiac output, heart rate, and image resolution, as described in prior coronary CT angiography studies.
Previously reported cases of sinus node dysfunction related to SNA injury during AF ablation are summarized in Table 1 [3], [4], [5], [6], [7], [8]. In many cases, recovery was delayed, required percutaneous coronary intervention, or resulted in persistent dysfunction. In contrast, the present case demonstrated rapid recovery within 3 min without the need for coronary intervention, which is consistent with a transient and reversible process. In a previous report, sinus node dysfunction resolved promptly after cessation of ablation and recurred reproducibly with repeated applications at the same site, suggesting a reversible mechanism such as transient SNA spasm [3]. Recognition of this mechanism may be clinically important, as early identification and prompt cessation of ablation could potentially prevent progression to permanent sinus node dysfunction.
Table 1.
Comparison of previously reported cases of sinus node dysfunction related to sinus node artery injury during AF/AT ablation.
| Author | Ablation site | Rhythm during ablation | Suspected mechanism | Outcome |
|---|---|---|---|---|
| Leftheriotis et al. [8] | RSPV antrum | Sinus rhythm | Modulation of ganglionated plexi | Pacemaker required |
| Aerts et al. [3] | LSPV–LAA ridge | Sinus rhythm | Posterior SNA spasm | Immediate recovery |
| Kitamura et al. [5] | Septal SVC-RA junction | Sinus rhythm | Left SNA occlusion | Recovery after 13 days |
| Miyazaki et al. [6] | Anterior wall of the LA | Perimitral flutter | Left SNA occlusion | PCI at day 2; immediate recovery |
| Yamaji et al. [7]-1 | Lateral mitral isthmus | Sinus rhythm | Posterior SNA occlusion | Immediate PCI; recovery after 1 day |
| Yamaji et al. [7]-2 | Roof of the LA | Sinus rhythm | Left SNA occlusion | PCI after 1 h; immediate recovery |
| Sakamoto et al. [4] | Septal SVC-RA junction; 4 LPV–LAA ridge; 3 RSPV; 1 PLSVC; 1 |
Not reported | SNA occlusion or severe narrowing (CAG-confirmed in 8/9) |
Recovery after PCI (8/8); Persistent SND (no CAG 1/1) |
| Present case | Anterior RSPV antrum | Sinus rhythm | Right SNA spasm | Recovery within 3 min |
AF, atrial fibrillation; AT, atrial tachycardia; CAG, coronary angiography; PCI, percutaneous coronary intervention; PVI, pulmonary vein isolation; RSPV, right superior pulmonary vein; LSPV, left superior pulmonary vein; LPV, left pulmonary vein; LAA, left atrial appendage; LA, left atrium; RA, right atrium; PLSVC, persistent left superior vena cava; SNA, sinus node artery; SND, sinus node dysfunction; SVC, superior vena cava.
In our case, a radiofrequency application to the RSPV induced sinus arrest. A ganglionated plexus (GP)-mediated reflex is unlikely, as ablation of the right anterior GP typically accelerates heart rate. A vasovagal reflex associated with pain was possible. However, it was unlikely because no bradycardia was seen during ablation at the posterior wall of the left atrium, where pain was more severe. The long duration of sinus arrest was also atypical for vasovagal reflexes. We considered that the cause of the sinus arrest was spasm of the right SNA. Transient sinus arrest and immediate sinus restoration during the right PVI, and the intact right SNA on post-ablation CT supported spasm of the SNA. Nakamura et al. reported that coronary spasms sites during radiofrequency applications all occur near the left superior PV and left inferior PV [9]. The notable point of our case was that sinus arrest occurred during the radiofrequency application to RSPV. Applications at not only the left PV but also the right PV can induce spasms or injury to the SNA during PVI. Although the right SNA may course close to the RSPV in some patients, sinus node dysfunction during RPV isolation appears to be relatively uncommon. This may be explained by interindividual variability in SNA origin and course, protective epicardial fat, atrial wall thickness, and the fact that the SNA does not consistently run adjacent to the standard ablation line. The upper panel of Fig. 2A demonstrates the close anatomical proximity between the anterior RSPV antrum and the right SNA. Leftheriotis et al. reported that ablation to the ostium of the RSPV resulted in bradycardia followed by sinus arrest [8]. In the report, coronary CT scan after 2 months showed the intact right SNA and the patient required permanent pacemaker implantation. The authors ruled out coronary artery involvement. However, the coronary occlusion can be spontaneously reperfused after myocardial infarction. Sakamoto et al. reported that percutaneous coronary intervention improved persistent sinus arrest in 8 of 9 patients, thereby avoiding pacemaker implantation [4]. In the case of persistent sinus arrest, coronary angiography should be considered. If sinus arrest is caused by SNA occlusion, sinus restoration can be expected through coronary angioplasty. Coronary spasms during pulse-field ablation using solid tip catheters have already been reported [10]. PFA to the RSPV may also need attention paid to the SNA spasms.
When preprocedural imaging demonstrates close anatomical proximity of the SNA to the anticipated ablation line, the optimal ablation strategy should be individualized based on its anatomical course. In some cases, shifting the lesion set toward the pulmonary vein side may reduce the risk of SNA injury, whereas in others, a more antral ablation approach may be safer. Such anatomical considerations may help minimize the risk of SNA injury while maintaining procedural efficacy.
Our case had long-standing persistent AF, and we performed ablation during sinus rhythm after electrical cardioversion. If we had performed PVI during an AF rhythm, we could not have recognized the right SNA injury. In our case, the radiofrequency application was discontinued immediately after sinus arrest, which might lead to SNA spasm without progressing to SNA injury. Based on our experience from this case, SNA injury could be one of the causes of sick sinus syndrome after catheter ablation of persistent AF. PVI during sinus rhythm may be safer than PVI during AF or atrial pacing.
Consent statement
The authors have received written consent from the patient for this case report, including images.
Declaration of Generative AI and AI-assisted technologies in the writing process
None declared.
Funding
The authors did not receive support from any organization for the submitted work.
Declaration of competing interest
Authors have no conflict of interest related to this article.
Acknowledgments
We thank Mr. John Martin for his linguistic assistance with the manuscript.
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