To present a case of refractory sinus tachycardia with cardio-vagal reflex failure after intra-operative neurapraxic injury of the left vagus nerve.

The vagus nerve is known to carry the parasympathetic innervation to the heart. It is commonly accepted that the right vagus nerve supplies the parasympathetic innervation to regulate the SA node of the right atrium, while the left vagus supplies the parasympathetic innervation for regulation of the AV node.¹

 1. Liu Q, Chen D, Wang Y, Zhao X, Zheng Y. Cardiac autonomic nerve distribution and arrhythmia. Neural Regeneration Research. 2012;7(35):2834-2841. doi:https://doi.org/10.3969/j.issn.1673-5374.2012.35.012

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 A 26-year-old woman was found to have a malignant peripheral nerve sheath tumor of the left T1 nerve root and scheduled for resection. Pre-operative imaging revealed no evidence of situs inversus or other variant anatomy. Intra-operatively, the tumor was found to be in contact with the left vagus nerve but had not infiltrated the nerve itself. Given its proximity to the tumor, the left vagus nerve required dissection and retraction to facilitate tumor resection, but did not sustain any operative damage, according to visual inspection. Post-operatively, the patient experienced persistent sinus tachycardia which remained refractory despite fluid resuscitation and optimal pain control. Neurology was consulted to evaluate for vagus nerve injury as the etiology for the tachycardia. Quantitative autonomic testing was performed and demonstrated impaired cardio-vagal reflexes during deep breathing and Valsalva. The patient’s autonomic testing was repeated 3 months later and showed resolution of the cardio-vagal reflex failure. 10 months after surgery, the patient’s resting heart rate had recovered to their pre-operative baseline.

We propose two conclusions: 1. The left vagus nerve may contribute more to the SA node and atrial regulation than previously understood. 2. There may be variability in the laterality of vagal contribution to atrial regulation.