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One Pill Can Kill: Yew Toxicity
It’s Christmas eve, and you’re betting on a quiet night when the dispatch phone rings. You’re sent to a residential address right around the corner from your suburban base, where a frantic father has called 9-1-1 for his 6-year-old son, whom he thinks ate berries from a Christmas tree. He’s convinced the berries are highly toxic.
On your arrival the panicked man explains that his husband bought a yew tree for the holidays and their 11-year-old daughter told him she saw her younger brother pick shiny red berries from the tree and eat them a few hours ago. The father turned to Google and found articles that said yew berries are highly toxic.
He insists his son, who has normal vital signs and an unremarkable physical exam, be transported to the hospital. You oblige, attaching the monitor to the child once you secure him on your transport stretcher. His ECG tracing, as you expected, is perfectly normal.
En route to the hospital, the child remains well, without any complaints of nausea, chest pain, or belly pain. You notice some ectopy on the monitor—a few PVCs—and wonder if there’s anything to the father’s anxious claims.
You report to the triage nurse, who asks you to wait in the hallway. During your offload delay you notice an increased frequency in the PVCs, and on closer inspection his QRS looks wide. You decide to do a 12-lead ECG and find the boy has a QRS of 165 ms. You show your ECG to the triage nurse, who isn’t sure what to make of it. You remain in the hallway, eyes fixed on the monitor—is there anything to this?
Pretty But Deadly
The common yew (Taxus baccata) is a common evergreen tree. While it’s admired for being ornamental, the tree’s aesthetics conceal its toxic nature. Yew berries, needles, and bark contain toxic taxine alkaloids, which cause cardiotoxicity through a mechanism similar to calcium channel blockers like verapamil. Taxines block both sodium and calcium channels of cardiac myocytes.
The early signs of yew toxicity are electrocardiographic. ECG tracings show multiple extrasystoles, followed by persistent ventricular tachycardias and ventricular fibrillation. This progresses to a bizarre widened QRS complex with bradycardia, not unlike in hyperkalemia. Death is marked by irreversible pulseless electrical activity. As toxicity progresses heart failure produces dyspnea, and seizures can precede a loss of consciousness.
Back to the Case
After 30 minutes you begin to feel alarmed. The ECG is now visibly wide, and the heart rate has slowed to 65. For a 6-year-old, you know that’s not right. You look at the child, who still looks perfectly well. You assess for subtle signs of hypoperfusion but find no evidence of delayed capillary refill, cool extremities, or mottling.
You again talk to the triage nurse, who becomes increasingly frustrated. The ER is swamped, and he’s struggling to manage the barrage of ambulances. While you’re engaged in the conversation, your partner hollers out: The child has gone into v-tach but still has a pulse. You rush to the bedside while the triage nurse runs to open a resus bed. The child is now cool in the peripheries and looks less alert. You lie him flat and regret not starting a fluid bolus. The triage nurse yells to go to resus bed #2.
ECMO for Survival
The main principle in management of yew toxicity is supportive care until the taxines release their grip on myocyte ion channels. The half-life of the toxin is about 12 hours; if we use the principle that five half-lives are required to eliminate a drug from someone’s system, yew clears in about 60 hours. Sadly, the toxicity is so severe that for many patients, maximum supports are insufficient, and cardiac output cannot be maintained.
There is no antidote for yew, and resuscitation is rarely effective. Extracorporeal membrane oxygenation offers the only chance of survival for severe cases that progress to asystole. While patients may have normal vital and laboratory values early on, they can decompensate within minutes about 2–5 hours after ingestion. It is recommended to consider ECMO early for patients with significant yew ingestion; given their precipitous decline, consider transporting directly to ECMO-capable centers.
Resuscitation consists of decontamination efforts; sodium bicarbonate administration to narrow the QRS (like in amitriptyline toxicity); cardiovascular support, including transcutaneous and transvenous pacing; and management of arrhythmia. It has been suggested that lidocaine is more effective than amiodarone to reverse ion channel toxicity.1 Renal replacement therapy, like dialysis, does not remove taxines from the blood but can help temporize acidosis. Despite these efforts yew may be deadly.
Case Conclusion
In the resuscitation bay the emergency doctor and on-call pediatrician consult with the local poison control center while the nurses initiate IV access. Lidocaine and sodium bicarbonate pushes are prepared as the child progresses into ventricular fibrillation. Despite defibrillation and ACLS resuscitation, the child then slips into asystole. The code is called not even two hours after you were dispatched.
Historically yew needle extracts were used for assassinations. Nowadays victims of yew poisoning are most often young children who consume the bright red berries of the yew plant; occasionally victims are adults who attempt suicide. There are several poisonous plants paramedics should be aware of, but perhaps none as toxic as yew.
Reference
1. Piskač O, Stříbrný J, Rakovcová H, Malý M. Cardiotoxicity of yew. ScienceDirect, 2015; www.sciencedirect.com/science/article/pii/S0010865014000952.
After a decade working as a helicopter paramedic, Blair Bigham, MD, MSc, EMT-P, completed medical school in Ontario, Canada, where he is now a resident physician in the emergency department. He has authored over 30 scientific articles, led major national projects to advance prehospital research and participated in multiple collaboratives, including the Resuscitation Outcomes Consortium.
Comments
I read something from 1998 that said it is not fatal 1 out of 100 times. This sounds amateurish and like propaganda to scare people. Beside my suspicion this case never happened anyway.
No one should eat it, but look it up, it isn't fatal the vast majority and 99th percentile of the time.
—J Beel