Strategies for phrenic nerve preservation during ablation of inappropriate sinus tachycardia
Introduction
Inappropriate sinus tachycardia (IST) syndrome is a tachyarrhythmia characterized by unexpectedly increased and symptomatic heart rates (HRs) during sinus rhythm, at rest, or in response to minimal physical activity and psychological stress.1, 2, 3 It has been shown to be more prevalent in middle-aged women4 and is associated with significant loss of quality of life.1, 5 Pharmacologic treatment aims to reduce HR and ameliorate clinical symptoms. Empirical first-line therapy with beta-adrenergic blocker, calcium channel blockers, or ivabradine has yielded low-to-moderate success.2, 6 Endocardial ablation/modification of the sinoatrial node (SAN) is a viable alternative in refractory cases of IST.4, 7 Limitations of this procedure stem from the predominantly epicardial location of the SAN,8 in close proximity to the right phrenic nerve (PN), which could be damaged during radiofrequency (RF) delivery.1, 9, 10 Information regarding the best approach to avoid PN injury remains scarce. Furthermore, gaps of knowledge persist regarding long-term symptom recurrence after IST ablative procedures.11
We sought to characterize the maneuvers used to avoid PN injury and the long-term clinical outcomes in a series of consecutive patients referred for IST ablation/modification.
Section snippets
Patient selection
This retrospective analysis included consecutive patients (n = 13) who underwent ablation for IST between September 2008 and August 2015 in a single tertiary center. IST was defined as HR >100 bpm at rest or with mild physical activity/psychological stimuli and associated symptoms.7 Primary causes of sinus tachycardia were ruled out, as were other mechanisms of supraventricular tachycardia. Every patient underwent 12-lead ECG to confirm normal P-wave morphology. Additional evaluations included
Baseline characteristics
A total of 13 consecutive female patients were enrolled (mean age 34.2 years, range 20–49 years). Symptoms of IST included baseline sinus tachycardia, palpitations, syncope, presyncope, and unresponsiveness to medical therapy. All patients had failed maximum tolerated doses of beta-blockers, calcium channel blockers, sotalol, or ivabradine, either as the sole therapy or in combination (Table 1). Twelve of thirteen patients were also on anxiolytic medication. A 2-dimensional echocardiogram
Discussion
Our study provides novel insights into the merits of different strategies to prevent PN injury, a known common complication of IST ablation. (1) Ventilation holding can be sufficient in a minority of patients to avoid PN damage when phasic variations of PN capture are present. (2) PA and balloon insertion are necessary in the majority of patients (81%) and achieves 100% success at avoiding PN injury. (3) The anterior PA approach allows for a straightforward balloon positioning at the SVC–RA
Conclusion
IST modification carries significant risks of PN injury. Maneuvers designed to avoid these sequelae, including ventilation holding and/or PB insertion, are frequently warranted. An anterior epicardial approach appears to be more effective in complication prevention, prompt optimal balloon positioning, and fluoroscopy time reduction compared to the posterior approach.
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Cited by (14)
Inappropriate Sinus Tachycardia: Etiology, Pathophysiology, and Management: JACC Review Topic of the Week
2022, Journal of the American College of CardiologyCitation Excerpt :The anatomic structures relevant to the hybrid treatment of IST are the right phrenic nerve, the CT, the caval veins (SVC or inferior vena cava [IVC]), right-sided pulmonary veins, the RA, the ganglionated plexi, the pericardial space and sinuses, and the esophagus. Direct thoracoscopic visualization of these important structures can help minimize collateral injury during the ablation51 (Figure 4). To perform the thoracoscopy procedure, the right chest is accessed with 3 working ports: a port for camera access and 2 for instruments.
Sinus Node Sparing Hybrid Thoracoscopic Ablation Outcomes in Patients with Inappropriate Sinus Tachycardia (SUSRUTA-IST) Registry
2022, Heart RhythmCitation Excerpt :Adjunct endocardial ablation was performed in select patients (46% of patients) to complete the linear ablation procedure along the CT connecting the SVC and IVC (Figure 3). The end point of ablation was at least a 25% reduction in HR acutely or accelerated junctional rhythm as defined in multiple previous studies.4,5,8,12–14 After the completion of the lesion set, junctional rhythm ensues, with subsequent recovery of slow sinus rhythm.
Catheter ablation for inappropriate sinus tachycardia: Clinical outcomes of sinus node ablation
2020, HeartRhythm Case ReportsCitation Excerpt :The establishment of such a generally accepted endpoint should be the objective of further studies. Prior studies reported considerably high complications rates.8–13 In the present study, permanent pacemaker implantation occurred as the only complication.
Novel method of superior vena cava electrical isolation with close proximity to the phrenic nerve
2019, HeartRhythm Case ReportsAblation of Inappropriate Sinus Tachycardia: A Systematic Review of the Literature
2017, JACC: Clinical ElectrophysiologyCitation Excerpt :However, SVC occlusion and clinical signs of SVC syndrome were not observed. After using ICE to evaluate this endpoint, Ibarra-Cortez et al. (14) observed no incidence of acute SVC syndrome after ablation. Fifteen patients (9.8%) required PCM implantation.
Treatment of inappropriate sinus tachycardia using endocardial sinus node modification with epicardial phrenic nerve deviation
2023, Journal of Interventional Cardiac Electrophysiology
This work was funded by the NIH/NHLBI (R21HL097305 and R01 HL115003 (to MV), the Charles Burnett III endowment and the Antonio Pacifico, MD fellowship support. Drs. Ibarra-Cortez and Rodríguez-Mañero contributed equally to this manuscript.