Elsevier

Heart Rhythm

Volume 13, Issue 6, June 2016, Pages 1238-1245
Heart Rhythm

Strategies for phrenic nerve preservation during ablation of inappropriate sinus tachycardia

https://doi.org/10.1016/j.hrthm.2016.01.021Get rights and content

Background

Radiofrequency (RF) ablation can alleviate drug-refractory inappropriate sinus tachycardia (IST). However, phrenic nerve (PN) injury and other complications limit its use.

Objective

The purpose of this study was to characterize the maneuvers used to avoid PN injury and the long-term clinical outcomes.

Methods

The study consisted of a retrospective analysis of consecutive patients who underwent ablation for IST.

Results

RF ablation was performed on 13 consecutive female patients with drug-refractory IST. Eleven patients exhibited PN capture at desired ablation sites. In 1 patient, PN capture was not continuous throughout the respiratory cycle and ventilation holding sufficed to avoid PN injury. In 10 patients, pericardial access (PA) and balloon insertion was required. Initially (n = 4) a posterior PA was used, which was replaced by an anterior PA in the subsequent 6 cases. PA to optimal balloon positioning time was significantly lower in anterior vs posterior PA (16.3 ± 6 minutes vs 58 ± 21.3 minutes, P = .01), as was fluoroscopy time (15.66 ± 16.72 min vs 35.9 ± 1.8 min, P = .03). RF ablation successfully reduced sinus rate to <90 bpm in 13 of 13 patients. Procedure times and total RF times were not significantly different in anterior vs posterior PA. Major complications occurred in 2 patients, including unremitting pericardial bleeding requiring open-chested repair in 1 patient and sinus pauses mandating pacemaker implantation in the other patient. Long-term symptom control after follow-up of 811 ± 42 days was successful in 84.6%.

Conclusion

Ventilation holding and/or pericardial balloon insertion are frequently warranted in IST ablation. Anterior PA appears to facilitate the procedure over posterior PA.

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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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.

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