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A case of a permanent form of junctional reciprocating tachycardia with negative linking on atrial differential pacing

2024; Elsevier BV; Volume: 40; Issue: 4 Linguagem: Inglês

10.1002/joa3.13109

1883-2148

Keisuke Suzuki, Kosuke Aoki, Eiji Sato, Akihiko Ishida, Tetsuo Yagi,

Atrial Fibrillation Management and Outcomes

This case of PJRT shows negative linking on ventriculoatrial intervals after atrial differential pacing. Interpreting the results of atrial differential pacing may be challenging in cases where the pacing site affects retrograde conduction or when retrograde conduction is unstable. A 76-year-old woman exhibited palpitations during a follow-up appointment because of a comorbid condition (breast cancer). Electrocardiography (ECG) revealed evidence of paroxysmal supraventricular tachycardia, leading to a referral to our department. The 12-lead ECG showed long RP' tachycardia with a heart rate of 147 bpm (Figure 1A), characterized by negative retrograde P waves in the inferior leads. Following the rapid administration of 20 mg of adenosine triphosphate (ATP), the tachycardia terminated in the QRS complex. A 12-lead ECG during sinus rhythm revealed no apparent delta waves. Blood tests and transthoracic echocardiography revealed no significant abnormalities. Treatment options, including catheter ablation (CA) or medication, were presented to the patient who ultimately chose CA. The catheters used included the high right atrium (HRA)-coronary sinus (CS) 20-pole (20336RACS-80, Japan Lifeline, Tokyo, Japan), His 4-pole (5555HIS-120R, Japan Lifeline), right ventricular apex (RVA) 4-pole (IBI-81246, Abbott, St. Paul, MN, USA), and an ablation catheter (ThermoCool SmartTouch, Biosense Webster Inc., CA, USA). The three-dimensional (3D) mapping system used was CARTO 3 version 7.2 (Biosense Webster Inc.). No evident "jump-up phenomenon" was observed in the control study of the anterograde and retrograde decremental conduction curve (Figure 2A,B). Evaluation of retrograde conduction involved constant pacing with simultaneous ventriculoatrial (VA) pacing, followed by extra right ventricular apex (RVA) pacing. Atrial pacing during simultaneous pacing was applied from the HRA or mid-CS. Simultaneous pacing from the mid-CS resulted in prolonged VA intervals compared with simultaneous pacing from the HRA (Figure 2B). Only one retrograde atrial sequence was observed after RVA pacing and the site of the earliest retrograde atrial activation (EAAS) was the proximal CS (Figure 3A,B). The atrial effective refractory period (ERP) near the CS ostium was measured at 220 ms, while that for retrograde conduction was 400 ms. Clinical tachycardia was easily induced with RVA extra pacing. RVA stimulation was performed in the His refractory period of the tachycardia, and delayed A wave was observed immediately afterward (Figure 3A). After RVA entrainment, pacing showed a VAV pattern and corrected postpacing interval—tachycardia cycle length = 189 ms (Figure 3B). During the same tachycardia episode, the atrial differential overdrive pacing method was applied,1 resulting in nearly matched VA intervals after pacing from the distal CS and HRA sites (Figure 4A,B). However, pacing from the proximal CS repeatedly resulted in a prolonged VA interval after pacing cessation (Figure 4C). The tachycardia cycle length returned to its original cycle length without any sequence alterations by the gradually shortened VA interval. The rapid administration of a small dose of ATP (2 mg) during the tachycardia resulted in gradual prolongation of the AH and VA intervals, leading to tachycardia termination (Figure 2C). Based on previous reports, in cases of long RP' tachycardia, distinguishing between atrial tachycardia (AT), fast/slow atrioventricular nodal reentrant tachycardia, nodo-fascicular reentrant tachycardia, and permanent junctional form of reciprocating tachycardia (PJRT) also known as orthodromic reciprocating tachycardia (ORT) through the decremental VA accessory pathway (AP) is necessary.2 The response to RVA stimulation during the His bundle refractory period in the present patient suggested the presence of a decremental VA accessory pathway or bystander concealed nodo-ventricular/nodo-fascicular pathway. RVA entrainment pacing for tachycardia provided negative evidence of AT or ORT without decremental-concealed AP. The patient's response to ATP indicated the possibility of ATP-sensitive retrograde conduction. The difference between AH intervals during the atrial entrainment pacing and the tachycardia was less than 20 ms, suggesting PJRT. Considering these findings, PJRT was considered among the top differential diagnoses for this patient. However, the observation of a ∆VA >20 ms after atrial over differential pacing for the tachycardia suggested findings indicative of AT. As pacing from the proximal CS failed to match on multiple occasions. The present patient underwent successful ablation targeting the EAAS. Postablation, retrograde conduction disappeared (Figure 3C), with no impact on antegrade conduction. No tachycardia was observed after ablation, finally confirming a diagnosis of PJRT. In this case, observation revealed that the pacing site in the atrium influenced the ATP-sensitive AP, which in turn affected retrograde conduction and altered conduction time. Two patterns have been reported in PJRT cases: those with the incessant type and those with the paroxysmal type.3 In the case of paroxysmal type PJRT, the tachycardia is initiated and sustained by a premature contraction. In this case, pacing-induced retrograde decremental conduction in the AP resulted in sustained tachycardia initiated by RVA extra pacing, suggesting paroxysmal type of PJRT. Although the details remain unclear, the development of PJRT may involve: (1) rate-dependent shortening of atrial ERP or AP ERP during retrograde conduction, and (2) the influence of anterograde concealed Wenckebach block on atrial or AP conduction, which affects retrograde conduction and prolongs conduction time.4 Potential mechanisms for decremental conduction include: (1) retrograde conduction through AV node-like tissue, (2) complex morphology or course of the AP, and (3) impedance mismatch5; however, these specifics could not be evaluated in this case. Additionally, the anterograde conduction time through the AP may have been significantly longer than that through the AV node, resulting in the anterograde AP conduction being undetectable. In such cases, anterograde conduction may influence retrograde conduction or the refractory period, thereby affecting conduction time. The original article on atrial differential pacing noted the prolongation of VA conduction time after atrial overdrive pacing, which probably affects the retrograde decremental conduction.1 Interpreting the results of atrial differential pacing may be challenging in cases where the pacing site affects retrograde conduction or when retrograde conduction is unstable, especially in cases like ATP-sensitive decremental AP. This article was edited by Editage. None. Authors declare no conflict of interests for this article. The research related to human use complied with all relevant national regulations and institutional policies and is in accordance with the tenets of the Helsinki Declaration. Informed consent was obtained from the featured patient for the publication of this report. The patient was fully informed about the purpose, risks, and benefits of the report and provided voluntary consent to participate. The patient's privacy would be protected, and personal information would remain confidential. The datasets generated and/or analyzed during this study are available from the corresponding author upon reasonable request.