A previously healthy 14-year-old male patient reported shortness of breath and near syncope during a basketball game. His initial evaluation by a pulmonologist included an exercise pulmonary function test that was reported as normal. The patient presented for cardiac evaluation for persistent symptoms. On general physical examination, his vital signs and clinical cardiac examination were normal. His ECG was interpreted as normal (Figure 1). His echocardiogram demonstrated normal structural cardiac anatomy and normal biventricular systolic function. A 48-hour Holter monitor (Zio patch) was placed and while wearing this monitor, he experienced shortness of breath with near syncope during a basketball game, which prompted a patient-triggered event recording.

Figure 1. A 12-lead ECG during cardiology evaluation.

Figure 2 shows the patient-triggered continuous rhythm ECG from the Holter monitor.

Figure 2. Continuous rhythm ECG of the patient-triggered episode.* *Two-minute episode from onset to termination; time displayed at upper left of the rhythm.

What is the diagnosis, mechanism, and treatment of this arrhythmia?

Please turn the page to read the diagnosis.

His ECG was interpreted as normal during pulmonology and cardiology visits. However, a subtle ventricular preexcitation was noted on subsequent review (Figure 3, arrow). He demonstrated a fast, wide QRS tachycardia with ventricular rate of 300 to 360 bpm. The tachycardia was regular at initiation and before spontaneous termination with a transient period of irregularity interposed by narrow QRS beats. Figure 4 shows the patient-triggered continuous rhythm ECG from the Holter (with annotations).

Figure 3. 12-Lead ECG during cardiology evaluation. The arrow indicates subtle delta waves.

Figure 4. Continuous rhythm ECG of the patient-triggered episode.* A, Initiation of the wide QRS tachycardia (strip 6, arrow). B, Irregular wide QRS tachycardia from spontaneous atrial fibrillation/flutter (strip 7 and 8). Interposed QRS beats shows ventricular preexcitation (strip 7, arrow). C, Shortest preexcited RR intervals during atrial fibrillation <200 msec (strip 7, with asterisks) which is a measure of the refractory period of the pathway. D, Regular wide QRS tachycardia with 1:1 QRS to P’ waves (notch on the upslope of T waves indicate retrograde P’ waves) indicating supraventricular tachycardia from reentry (strips 9 and 10). E, Spontaneous termination of the wide QRS tachycardia (strip 10, long arrow). F, Post conversion to sinus rhythm showing ventricular preexcitation (strip 10, short arrows point to the delta waves). *Two-minute episode from onset to termination shown with all salient electrophysiologic events highlighted.

Wide QRS tachycardia in children is either from ventricular tachycardia or supraventricular tachycardia. Ventricular tachycardia is rare in children with a structurally normal heart. Conditions such as congenital QTc syndrome, Brugada syndrome, and idiopathic ventricular tachycardia were considered and ruled out for lack of supportive findings on either ECG or Holter study. Similarly, supraventricular tachycardia presenting as wide QRS tachycardia from rate-dependent aberrancy, a bystander pathway, or antidromic reentry via an accessory pathway were considered in the differential diagnosis.

Clinical diagnosis is often a challenge when the sole source of causal arrhythmia is a rhythm ECG as in this case. At first glance, the rhythm mimicked polymorphic ventricular tachycardia with fast ventricular rate. However, critical review of the entire episode, from initiation to termination, led to revision of the initial diagnosis. In fact, the wide QRS tachycardia is from preexcited atrial fibrillation—that is, atrial fibrillation occurring in the setting of ventricular preexcitation is responsible for fast, irregular, wide QRS tachycardia with varying QRS morphologies (Figure 4; rhythm strips 7 and 8). Often, the atria can discharge at higher rates (>300 bpm) during atrial fibrillation to obscure the delta waves, a key electrocardiographic feature in the diagnosis of preexcited atrial fibrillation. Demonstration of ventricular preexcitation (delta waves) during the wide QRS tachycardia and in isolated QRS beats provided an invaluable clue in support of preexcited atrial fibrillation (Figure 4; arrow depicts preexcited beat in rhythm strip 7).

His electrophysiologic study confirmed ventricular preexcitation with earliest ventricular activation in the distal coronary sinus indicating a left sided pathway. During atrial stimulation, there were echo beats with nonsustained runs of wide QRS tachycardia. Risk stratification or induction of supraventricular tachycardia was deemed unnecessary, and he underwent ablation of a left lateral pathway with no clinical relapses or symptoms during follow-up.

This case exemplifies interesting clinical and electrophysiologic features, including (1) missed or subtle ventricular preexcitation on surface ECG; (2) near syncope from a fast and wide QRS tachycardia; and (3) fast ventricular rate with varying cycle lengths and varying QRS morphologies during the tachycardia with evidence of ventricular preexcitation (delta waves) in multiple QRS beats is sine qua non for preexcited atrial fibrillation. Additionally, the shortest preexcited RR interval was <200 msec during the wide QRS tachycardia, indicating a fast-conducting pathway. Such pathways can facilitate 1:1 atrioventricular conduction during atrial fibrillation and are deemed high-risk pathways with propensity for sudden cardiac death from life-threatening arrhythmias. In our case, spontaneous termination of the wide QRS tachycardia averted a sudden death. Last, successful ablation of the pathway eliminated the substrate for arrhythmias and sudden cardiac death, although atrial fibrillation can recur even after successful ablation of the pathway in adults.

Patients with ventricular preexcitation from an atrioventricular accessory pathway (also called the bundle of Kent) demonstrate a short PR interval with wide QRS complex from a pathognomonic delta wave and, if present on the surface ECG, is referred to as overt ventricular preexcitation. In a select few, the delta waves can be too subtle to be recognized on the surface ECG. Spontaneous atrial fibrillation in such patients may confound the electrocardiographic features of the presenting arrhythmia, misleading physician diagnosis. Furthermore, preexcited atrial fibrillation may not be considered in the differential diagnosis. Multiple pathways, pathways with functional retrograde limb, or unique pathway morphology with multifiber atrial insertion are responsible for rapid atrial stimulation and for triggering atrial fibrillation.^1,2

In summary, this is Wolff–Parkinson–White syndrome presenting as irregular, fast, and wide QRS tachycardia from spontaneous atrial fibrillation, resulting in near syncope in an otherwise healthy child with unapparent and unsuspected ventricular preexcitation on baseline ECG. Concerns related to persistent symptoms led to successful management and hence, the alternate designation “When–Patients–Worry syndrome” is apt for our case.

None.

Disclosures None.

Circulation is available at www.ahajournals.org/journal/circ

For Sources of Funding and Disclosures, see page 1971.

一名既往健康的 14 岁男性患者在一场篮球比赛中报告呼吸急促和近乎晕厥。肺科医生对他的初步评估包括一项运动肺功能测试，结果显示正常。患者因持续症状而接受心脏评估。在一般体格检查中，他的生命体征和临床心脏检查均正常。他的心电图被解释为正常（图 1）。他的超声心动图显示正常的心脏解剖结构和正常的双心室收缩功能。放置了一个 48 小时动态心电图监测器（Zio 贴片），在佩戴该监测器时，他在一场篮球比赛中出现呼吸急促和近乎晕厥的症状，这促使患者触发了事件记录。

图 1. 心脏病学评估期间的 12 导联心电图。

图 2 显示了来自 Holter 监视器的患者触发的连续心律心电图。

图 2. 患者触发发作的连续心律心电图。* *从发作到结束的两分钟发作；时间显示在节奏的左上角。

这种心律失常的诊断、机制和治疗是什么？

请翻页阅读诊断。

在肺病学和心脏病学就诊期间，他的心电图被解释为正常。然而，在随后的检查中发现了轻微的心室预激（图 3，箭头）。他表现出快速、宽 QRS 心动过速，心室率为 300 至 360 bpm。心动过速在开始时和自发终止前是规律的，并有短暂的不规则时期，由窄 QRS 节拍插入。图 4 显示了来自 Holter 的患者触发的连续心律心电图（带注释）。

图 3. 心脏病学评估期间的 12 导联心电图。箭头表示细微的三角波。

图 4. 患者触发事件的连续心律心电图。* A，宽 QRS 心动过速的起始（条带 6，箭头）。B，自发性心房颤动/扑动引起的不规则宽 QRS 波心动过速（条带 7 和 8）。中间的 QRS 搏动显示心室预激（条带 7，箭头）。C，心房颤动期间最短的预激 RR 间期 <200 毫秒（带 7，带星号），这是通路不应期的量度。D，规则的宽 QRS 心动过速与 1:1 QRS 到 P' 波（T 波上坡上的缺口表示逆行 P' 波）表明来自折返的室上性心动过速（条带 9 和 10）。乙, 宽 QRS 心动过速的自发终止（条带 10，长箭头）。F，转换为窦性心律后显示心室预激（条带 10，短箭头指向 delta 波）。*显示从开始到结束的两分钟情节，突出显示所有显着的电生理事件。

儿童的宽 QRS 心动过速要么来自室性心动过速，要么来自室上性心动过速。心脏结构正常的儿童很少发生室性心动过速。先天性 QTc 综合征、Brugada 综合征和特发性室性心动过速等病症被考虑并排除，因为在 ECG 或 Holter 研究中缺乏支持性发现。同样，室上性心动过速表现为宽 QRS 心动过速，源于心率依赖性异常、旁观者通路或通过旁路逆行折返，在鉴别诊断中被考虑在内。

当致病性心律失常的唯一来源是本例中的心律心电图时，临床诊断通常是一个挑战。乍一看，节律类似于多形性室性心动过速，心室率快。然而，对从开始到结束的整个事件的严格审查导致对初始诊断的修改。事实上，宽 QRS 波心动过速是由预激心房颤动引起的——也就是说，在心室预激情况下发生的心房颤动是导致具有不同 QRS 形态的快速、不规则、宽 QRS 波心动过速的原因（图 4；节律带 7 和 8）。通常，心房在心房颤动期间可以以更高的速率 (>300 bpm) 放电以掩盖 δ 波，这是诊断预激性心房颤动的一个关键心电图特征。

他的电生理学研究证实了心室预激，远端冠状窦中最早的心室激活表明左侧通路。在心房刺激期间，出现回声搏动和非持续性宽 QRS 波心动过速。风险分层或室上性心动过速的诱发被认为是不必要的，他接受了左侧通路的消融术，在随访期间没有临床复发或症状。

该病例体现了有趣的临床和电生理特征，包括：(1) 体表 ECG 上遗漏或轻微的心室预激；(2) 快而宽的 QRS 心动过速导致近乎晕厥；(3) 心动过速期间具有不同周期长度和不同 QRS 形态的快速心室率以及多个 QRS 搏动中心室预激（δ波）的证据是预激心房颤动的必要条件。此外，在宽 QRS 心动过速期间，最短预激 RR 间期 <200 毫秒，表明存在快速传导通路。此类通路可促进心房颤动期间的 1:1 房室传导，并被视为高风险通路，有可能因危及生命的心律失常而导致心源性猝死。在我们的例子中，宽 QRS 波心动过速的自发终止避免了猝死。最后，该通路的成功消融消除了心律失常和心源性猝死的基础，尽管即使在成人成功消融该通路后心房颤动也可能复发。

来自房室旁路（也称为肯特束）的心室预激患者表现出短的 PR 间期和来自特征性 delta 波的宽 QRS 波群，如果出现在体表 ECG 上，则称为明显的心室预激。在少数情况下，δ波可能太细微而无法在表面 ECG 上识别。此类患者的自发性心房颤动可能会混淆所呈现的心律失常的心电图特征，误导医生的诊断。此外，在鉴别诊断中可能不考虑预激房颤。多条通路、具有功能性逆行肢体的通路或具有多纤维心房插入的独特通路形态负责快速心房刺激和触发心房颤动。^1,2

总之，这是沃尔夫-帕金森-怀特综合征，表现为自发性心房颤动引起的不规则、快速和宽 QRS 心动过速，导致一名其他方面健康的儿童近乎晕厥，基线心电图上没有明显和未被怀疑的心室预激。与持续症状相关的担忧导致了成功的管理，因此，替代名称“当-患者-担心综合征”适用于我们的病例。

没有任何。

披露无。

流通可在 www.ahajournals.org/journal/circ

有关资金来源和披露信息，请参见第 1971 页。