Authors: Vidovich C et al.
A & A Practice, November 2025
Summary
This case report describes the successful termination of refractory supraventricular tachycardia (SVT) using neostigmine in a critically ill patient undergoing emergent endoscopic retrograde cholangiopancreatography (ERCP) under general anesthesia. The report revisits an older, largely abandoned pharmacologic approach and reframes it as a potential rescue strategy when guideline-directed therapies fail and vagal stimulation appears beneficial.
The patient was a 69-year-old man with pancreatic head adenocarcinoma who presented in septic shock from presumed acute obstructive cholangitis. Shortly after induction of anesthesia, he developed hemodynamically unstable narrow-complex SVT with heart rates between 180 and 200 bpm. The arrhythmia proved refractory to repeated synchronized cardioversion, vagal maneuvers, adenosine, esmolol, magnesium, and escalating doses of amiodarone. Laboratory evaluation showed no acute metabolic or electrolyte derangements that would otherwise explain the arrhythmia.
Concerned that β-adrenergic stimulation was exacerbating SVT, the anesthesia team transitioned vasopressor support from norepinephrine to phenylephrine and angiotensin II, which improved rate control and hemodynamic stability but did not restore sinus rhythm. During the procedure, transient resolution of SVT was repeatedly observed during gastric insufflation and biliary manipulation, suggesting a vagally mediated mechanism. Based on this observation, the team elected to pharmacologically augment vagal tone using neostigmine.
Neostigmine was administered intravenously in incremental doses of 0.5 to 1.0 mg, spaced no faster than every two minutes, to a cumulative dose of 3.5 mg. With careful titration, continuous monitoring, and pacing pads in place, the SVT converted to stable sinus rhythm at approximately 80 bpm without adverse effects such as heart block or profound bradycardia. The restored hemodynamic stability allowed completion of biliary source control procedures, after which the patient remained in sinus rhythm and returned to the ICU on minimal vasopressor support.
The discussion places this intervention in historical context. Neostigmine, a reversible acetylcholinesterase inhibitor, was used in the mid-20th century as a treatment for SVT due to its vagomimetic effects on sinoatrial and atrioventricular nodal conduction. Its use fell out of favor after reports of severe bradyarrhythmias and fatalities, and it is not included in contemporary SVT management guidelines. However, this case illustrates that in select circumstances—particularly when vagal maneuvers show transient efficacy and standard therapies fail—carefully titrated neostigmine may serve as an effective off-label rescue therapy.
The authors emphasize several critical considerations: exclusion of reversible metabolic causes, adherence to guideline-directed therapy before deviation, early cardiology consultation, minimization of catecholamine-driven chronotropy, and heightened vigilance for drug-induced adverse effects. Incremental dosing was deliberately chosen to reduce parasympathetic complications, with immediate availability of anticholinergics and external pacing.
Key Points
• Neostigmine can terminate refractory SVT by augmenting vagal tone when conventional therapies fail
• Transient response to vagal stimulation may predict benefit from vagomimetic pharmacologic strategies
• Incremental dosing and full monitoring are essential to mitigate risks of bradycardia or asystole
• Vasopressor selection may influence arrhythmia control in septic shock
• Off-label neostigmine use should be reserved for highly selected, closely monitored settings
Thank you to A & A Practice for allowing us to summarize and discuss this instructive case highlighting an unconventional but potentially lifesaving approach to refractory supraventricular tachycardia.