A 33-years old female patient was transferred to the emergency department after out-of-hospital cardiac arrest. The prehospital ECG showed a regular bradycardia with wide QRS complex (see Figure 1) that subsequently converted into ventricular fibrillation requiring cardiopulmonary resuscitation. The patient was intubated and sedated. The medical history of the patient was negative for chronic disease. The patient’s personal belongings included a box with aromatic green plant needles. Acute myocardial infarction, acute aortic syndrome, and pulmonary embolism were excluded by coronary angiography and computed tomography. Cerebral computed tomography excluded bleeding and did not provide evidence of acute ischemia. During coronary angiography, the patient developed a hemodynamically relevant bradycardia requiring cardiac pacing. The temporarily implanted endocardial pacing lead had intermittent loss of capture. With increasing need for catecholamine support, the patient was transferred to the intensive care unit to evaluate the option of extracorporeal life support.

Figure 1. Prehospital ECG showing sinus bradycardia, 40 bpm, extreme axis deviation (Northwest axis), intraventricular conduction delay (QRS duration 370 ms), prolonged QT duration, premature ventricular contractions (bigeminy) with superior axis, and R/S transition in leads V₂ and V₃.

What are the possible causes of the baseline bradycardia with wide QRS? What was the final diagnosis?

Please turn the page to read the diagnosis.

The prehospital ECG showed sinus bradycardia with 40 bpm as baseline rhythm. The heart axis was extremely deviated. The QRS complex was wide, lasting 370 ms and demonstrating a significant intraventricular conduction delay. The QT duration was prolonged and ventricular bigeminy was present. These premature ventricular contractions had a superior axis and an early R/S transition in leads V₂/V₃. The ECG diagnosis was regular wide complex bradycardia with ventricular bigeminy.

Given the patient’s young age and blank past medical history, a suicide attempt and subsequent intoxication was suspected. Considering the extremely wide QRS complex, sodium channel blockers such as flecainide, propafenone, and tricyclic antidepressants, or cardiac glycosides were reasonable candidates. However, sodium channel intoxication is usually associated with baseline tachycardia. Instead, our patient presented with bradycardia as a sign of additional calcium channel block, leading to the clinical diagnosis of yew intoxication.

Taxine alkaloids as in yew needles block both calcium and sodium channels in cardiac myocytes, explaining both bradycardia and wide QRS complex followed by tachycardia, but also the observed loss of capture during internal pacing.^1,2 Bradycardia might result from sinus bradycardia, but might also be a consequence of delayed atrioventricular conduction with total heart block in some cases.³ Deviation of heart axis is also associated with blockade of sodium channels. The clinical presentation of taxine alkaloid intoxication is nonspecific, ranging from nausea, vomiting, and dizziness to abdominal pain (see Table).^1,3

Table. Cardiac and Systemic Effects of Taxus baccata

All parts of the plant contain taxine alkaloids, and our patient consumed shredded needles (see Figure 2).¹ Post hoc analysis resulted in an estimated dose of 0.3 g yew needles per kg body weight. The postulated lethal dose ranges from 0.6 to 1.3 g yew needles per kg body weight.¹ After oral treatment with activated charcoal, the patient returned to stable sinus rhythm the next day without additional measures. General treatment strategies include gastroscopy, pacemaker implantation, dialysis, or extracorporeal life support.^2,3 In the absence of a specific antidote, prior studies evaluated the effect of digoxin-specific Fab fragments.² The mechanism depends on a cross-reaction between these fragments and taxine alkaloids; it might be beneficial in patients refractory to conservative treatment.²

Figure 2. Yew plant with needles.

The patient’s suicide attempt was inspired by a crime novel she had read previously. She could be discharged after 2 days and was transferred to psychiatry.

Unexplained wide QRS-complex bradycardia and sudden onset of wide complex tachycardia, especially in previously healthy patients, should raise the suspicion of yew intoxication. Exploration of the patient’s surrounding area at point of first medical contact is important and might contribute to the diagnosis. These patients require treatment in an intensive care unit and, in some cases, extracorporeal life support might be needed as a bridge-to-recovery.

None.

Disclosures None.

https://www.ahajournals.org/journal/circ

For Sources of Funding and Disclosures, see page 661.

Informed Consent: The patient gave informed consent.

一名 33 岁女性患者在院外心脏骤停后被转入急诊室。院前心电图显示有规律的心动过缓和宽 QRS 波群（见图 1），随后转变为需要心肺复苏的心室颤动。患者被插管并镇静。患者的病史为慢性病阴性。病人的个人物品包括一个装有芳香绿色植物针的盒子。冠状动脉造影和计算机断层扫描排除了急性心肌梗塞、急性主动脉综合征和肺栓塞。脑计算机断层扫描排除了出血，并且没有提供急性缺血的证据。在冠状动脉造影期间，患者出现了与血流动力学相关的心动过缓，需要心脏起搏。临时植入的心内膜起搏导线间歇性失去捕获。随着对儿茶酚胺支持的需求增加，患者被转移到重症监护室以评估体外生命支持的选择。

图 1. 院前心电图显示窦性心动过缓，40 bpm，电轴极度偏离（西北轴），心室内传导延迟（QRS 持续时间 370 ms），QT 持续时间延长，室性早搏（二联），电轴上移，R/S 转换导致V ₂和V ₃。

宽 QRS 波的基线心动过缓的可能原因是什么？最后的诊断是什么？

请翻页阅读诊断。

院前心电图显示窦性心动过缓，基线节律为 40 bpm。心轴严重偏离。QRS 波群很宽，持续 370 毫秒，显示出明显的心室内传导延迟。QT 持续时间延长，并存在心室二联律。这些室性早搏在导联 V ₂ /V _{3 中}具有上轴和早期 R/S 转换。心电图诊断为规则性宽复合波心动过缓伴心室二重心律。

鉴于患者年龄小，既往病史空白，怀疑有自杀企图和随后的中毒行为。考虑到极宽的 QRS 波群，钠通道阻滞剂如氟卡尼、普罗帕酮和三环类抗抑郁药或强心苷是合理的候选药物。然而，钠通道中毒通常与基线心动过速有关。相反，我们的患者出现心动过缓作为额外钙通道阻滞的迹象，导致临床诊断为红豆杉中毒。

紫杉针中的紫杉碱生物碱阻断心肌细胞中的钙和钠通道，解释了心动过缓和宽 QRS 波群，然后是心动过速，但也解释了在内部起搏过程中观察到的捕获损失。^1,2心动过缓可能由窦性心动过缓引起，但在某些情况下也可能是房室传导延迟伴心脏传导阻滞的结果。³心轴的偏离也与钠通道的阻滞有关。紫杉碱生物碱中毒的临床表现是非特异性的，范围从恶心、呕吐、头晕到腹痛（见表）。^1,3

桌子。红豆杉的心脏和全身作用

植物的所有部分都含有紫杉碱生物碱，我们的病人食用了切碎的针叶（见图 2）。¹事后分析得出的估计剂量为每公斤体重 0.3 克红豆杉针。假定的致死剂量范围为每公斤体重 0.6 至 1.3 克红豆杉针。¹口服活性炭治疗后，患者第二天无需额外措施即可恢复稳定的窦性心律。一般治疗策略包括胃镜检查、心脏起搏器植入、透析或体外生命支持。^2,3在没有特定解毒剂的情况下，先前的研究评估了地高辛特异性 Fab 片段的效果。²该机制取决于这些片段与紫杉碱生物碱之间的交叉反应；它可能对保守治疗无效的患者有益。²

图 2. 带针的红豆杉植物。

病人的自杀企图是受到她之前读过的一本犯罪小说的启发。2天后即可出院，转入精神病院。

不明原因的宽 QRS 波群心动过缓和突然出现的宽波群心动过速，特别是在既往健康的患者中，应引起红豆杉中毒的怀疑。在第一次医疗接触时探索患者周围区域很重要，可能有助于诊断。这些患者需要在重症监护室接受治疗，在某些情况下，可能需要体外生命支持作为康复的桥梁。

没有任何。

披露无。

https://www.ahajournals.org/journal/circ

有关资金来源和披露信息，请参见第 661 页。

知情同意：患者知情同意。