Aconite

Aconite (also known as monkshood or wolfsbane, as any Hogwarts first-year should know) is a genus of buttercup flowers that are found across the mountainous regions of the Northern Hemisphere. The flower, which varies in color, has a distinctive hood-like shape. Aconite has been used as both medicine and maleficent since ancient times (and still has a presence in traditional medicines), and was even briefly promoted as a cure for COVID-19 (with predictable consequences).

All parts of aconite contain toxic alkaloid compounds, most saliently aconitine. Aconitine is a terpene alkaloid that binds to voltage-dependent sodium channels and induces persistent channel opening, leading to increased cardiac, neuronal, and musculoskeletal excitability. Aconite alkaloids also demonstrate moderate cholinergic activity.

Presentation:

Patients rapidly (can be <30 minutes after ingestion) develop a mix of cardiovascular, sensorimotor, and gastrointestinal symptoms. Cardiovascular complaints can range from bradycardia and hypotension, to palpitations and chest tightness, to ectopic ventricular beats, to ventricular tachycardia or fibrillation; numbness, paresthesias, and/or weakness may development in any combination of locations in the body. Nausea, vomiting, and diarrhea can also be seen, as well as tachypnea and respiratory alkalosis.

Death is rarer in smaller-dose ingestions; the typical mechanism is sudden cardiac death resulting from ventricular arrhythmias.

Management:

The efficacy of GI decontamination is not well-established, but should be performed if the ingestion is recent.

Cardiovascular support is key to the management of the aconite-poisoned patient. Inotropic pressors (e.g. epinephrine) should be given for persistent hypotension; atropine is the treatment for persistent bradycardia.

The cardiac arrhythmias caused by aconitine typically do not respond well to cardioversion or antiarrhythmic agents. Lidocaine has been ineffective in case reviews; flecainide and amiodarone, in that order, have the highest chance of restoring regular heart rhythm. Flecainide and beta-blockers (propranolol, pindolol, oxprenolol) also had an overall mortality benefit. One case report successfully used magnesium sulfate to treat the arrhythmia.

If the patient remains unstable with refractory arrhythmias, cardiopulmonary bypass should be initiated earlier rather than later. The use of charcoal hemoperfusion — the addition of an activated charcoal cartridge to the bypass machine — to sequester circulating aconite alkaloids has been described, but the efficacy is not well-studied.