Fatal ingestion of Taxus brevifolia (Pacific yew): a case report

Abstract Taxus brevifolia, the Pacific yew, is an evergreen shrub that is common to the Pacific Northwest of North America. The Taxus spp. are often seen in decorative hedging and topiary, though historically have been referred to as the “death tree” for its known toxicity. The yew contains cardiotoxic alkaloids including taxine A and B, which are present in all parts of the plant except the red arils. Deliberate ingestions can result in life threatening effects including cardiac dysrhythmias, hemodynamic instability, and death without intervention. Serious toxicity following accidental ingestion is rare. A 38 year old woman was assessed on scene after ingesting yew needles in a suicide attempt. Shortly after Emergency Medical Services (EMS) arrival, she became unresponsive and pulseless. A wide complex ventricular tachycardia followed by bradycardia was reported. She received epinephrine, atropine, amiodarone, and several cardiac defibrillations but ultimately expired in the field thirty minutes later. Postmortem serum samples confirmed the presence of taxine B and isotaxine B. This case highlights the severe and rapid characteristics of taxine poisoning, despite being generally considered less toxic than other Taxus spp. Patients require aggressive and immediate medical care following intentional ingestions.


Background
Taxus brevifolia, also known as the Pacific or Western yew, is a species of ornamental yew tree native to the Pacific Northwest of North America.It is easily accessible in public areas, and readily available for purchase at plant nurseries and from online retailers.This accessibility contributes to its modern use in self harm attempts although many historical and ancient texts document the known toxicity of Taxus spp.[1].Ingestion can be lethal as all parts of the plant, except the red fleshy aril, contain cardiotoxic alkaloids taxine A and B. Taxine alkaloids antagonize myocardial sodium and calcium channels as well as increase myocardial cellular calcium concentrations resulting in bradycardia, hypotension, and refractory cardiac instability [2].Though overall rare, accidental ingestions often require minimal intervention while deliberate ingestions can be difficult to treat requiring aggressive supportive care and advanced therapies [3,4].We present, in accordance with the CARE Guidelines (https://www.care-statement.org),a fatal case of intentional T. brevifolia ingestion.

Case report
Family members of a 38 year-old female summoned paramedics for a safety check after receiving a concerning text message from the patient.Paramedics found her sitting in a parked car and appearing pale and weak.On their initial assessment, the patient was alert and oriented.Her vital signs included a heart rate of 80 beats per minute, a respiratory rate of 24 breaths per minute, and a pulse oxygen saturation of 100% on room air.Blood pressure and physical exam were not documented.The patient stated she intentionally ingested three cups of brewed yew needles from an insulated flask 30 min prior to evaluation.She stated she had researched the yew plant to confirm there was no available antidote and had premedicated for nausea with 4 mg oral ondansetron.She also described collecting the Pacific yew material from a nearby park.A thermos and plastic bag of evergreen needles visually consistent with yew needles was collected from the patient's car.
Five minutes after EMS arrival, she became unresponsive and pulseless.Compressions were initiated followed by a total of 4 mg intraosseous (IO) epinephrine, 0.5 mg IO atropine, 300 mg IO amiodarone, and three cardiac defibrillations at 360 joules.Cardiac rhythm strips revealed a wide complex tachycardia that quickly decompensated into a broad complex bradycardia, followed by an agonal rhythm and asystole (Figure 1).The patient expired in the field 32 min after EMS arrival.
The medical examiner sent serum samples for postmortem analysis.Stomach volume and contents were not examined.Comprehensive drug screening for illicit substances and medications identified ondansetron and acetaminophen.Liquid chromatography-quadrupole time of flight (LC-QTOF) and liquid chromatograph tandem mass spectrometry (LC-MS-MS) confirmed the presence of taxine B and isotaxine B. Unavailability of a reference standard precluded quantification.We obtained consent from family in the reporting of this case.

Discussion
Ingestion of the yew plant can result in life threatening toxicity which may present with complex cardiac rhythms and difficult to treat hemodynamic instability.While fatal cases of yew ingestion have been well documented in the literature, most accounts describe poisoning by T. canadensis and T. baccata rather than T. brevifolia which has been reported to have lower concentrations of taxine [2,5,6].We describe a case of a large ingestion of Pacific yew needles which resulted in rapid clinical decompensation of the patient, and death approximately one hour post ingestion.While taxine A and B are the most prevalent yew constituents, taxine B exhibits the greatest toxicity and is highly arrhythmogenic.Myocardial toxicity results from sodium and calcium channel blockade producing AV conduction block, prolonged QRS interval and decreased myocardial contractility [2].
While conventional resuscitative strategies are typically employed, purposeful ingestions often do not respond to sympathomimetic and antidysrhythmic agents.In this case the patient decompensated prior to EMS transport, limiting available resources.Even in an intensive care setting, resuscitation of the taxine poisoned patient is extremely challenging and advanced interventions demonstrate little benefit in the literature.Taxine mediated bradycardia is frequently resistant to atropine and amiodarone [1] and sodium bicarbonate has failed to demonstrate effectiveness in limited animal studies [7].Digoxin specific Fab fragments have been cited in reports for cross reactivity of taxine with digoxin assays, however clinical improvement has been variable [1,8].Extracorporeal life support and digoxin Fab fragments were successful in a similar case with refractory dysrhythmias and shock [8].Although it appears extracorporeal oxygenation therapy may provide the best outcomes in intentional taxus ingestions, there are inherent limitations in case reporting of interventional strategies.It is unclear whether transport to the emergency department and initiation of extracorporeal therapies would have affected the clinical course of this patient.

Conclusion
This case demonstrates fatal taxine poisoning secondary to intentional ingestion of T. Brevifolia, despite being regarded as less toxic than other Taxus spp.The ineffectiveness of traditional resuscitation strategies highlights the gravity of severe yew toxicity which requires advanced medical care that is best managed in an inpatient setting.