A 55-year-old woman with long-standing diabetes and hypertension with hypertrophic cardiomyopathy (diagnosed on cardiac magnetic resonance imaging) was implanted with a single-chamber, single-coil implantable cardioverter defibrillator (ICD; Abbott Laboratories) for primary prevention a few weeks previously. She presented to the emergency department with history of dyspnea and recent episodes of tachycardia. On detailed inquiry, she gave a history of multiple shocks in the last few hours and a similar episode 15 days previously. She was put on a Holter monitor at another center at that time (to confirm the diagnosis of the tachycardia) and was diagnosed as having ventricular tachycardia (VT). The Holter report tracing was interpreted to have multiple (14) episodes of VT (Figure 1). Is it VT?

Figure 1. Holter strip recorded when the patient was asleep (4 AM). N indicates normal; PTE, patient-triggered event; V, ventricular; and VT, ventricular tachycardia.

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There is a broad QRS tachycardia seen in the Holter tracing. The background of structural heart disease such as hypertrophic cardiomyopathy in this case makes interpreting this ECG strip complicated. Symptoms cannot be relied on because the episode was recorded while the patient was asleep, and the patient was asymptomatic. This Holter records only a single ECG lead strip and is thus more prone to interpretative error. There are 3 sinus beats accompanied by a splintered QRS at the start of the tracing, after which a broad QRS tachycardia seems to be starting (Figure 1). There are a change in the RR interval and a change in QRS width during the broad QRS tachycardia. If one looks carefully, one can identify the splintered QRS marching through the broad QRS tachycardia. In the lower part of the figure, there are changing QRS patterns and bizarre QRS complexes, and here the splintered QRS within them become more evident. It indicates that the broad QRS tachycardia is an artifact and that there must be some issue with the recording, either a loose lead or a loose ECG patch. If we scan through the rest of the tracing, we can make out similar deflections on the ongoing apparent wide complex rhythm, which was labeled as VT by the recording device (Figure 2).

Figure 2. Scanning for the hidden ECG activity inside the broad complex rhythm. N indicates normal; PTE, patient-triggered event; V, ventricular; and VT, ventricular tachycardia.

Two main categories of electrocardiographic artifacts have been described: simulating a variety of arrhythmia (viz pseudo–atrial flutter or pseudo-VT) or resulting in pseudopauses. The first type of artifacts, which may have been the case in our patient, can be produced by body movements, temporary impairment of skin-electrode contact, loose electrode connections, dysfunctional leads, skeletal myopotentials, or ambient noise. The second type is generally produced by electrode contact issues or recorder problems.¹ The misinterpretation can lead to inappropriate decisions for the management of arrhythmia in this patient such as in-hospital shocks, addition of antiarrhythmic medications (which may cause unwanted side effects), canceling of surgeries, and inappropriate advice for an ICD implantation.

Any physician interpreting a Holter ECG showing wide complex tachycardia, especially in the backdrop of structural heart disease, invariably starts the interpretation along the lines of differentiating the 2 common diagnoses rather than trying to look for the artifacts. This has been substantiated by an elegant study that included internists, cardiologists, and cardiac electrophysiologists.² In this study, 766 physicians were surveyed with a case simulation of a wide complex rhythm in a patient with old coronary artery disease as depicted on 2-lead ECG monitoring. The strip was not diagnosed correctly as artifact by a majority of internists (94%), more than half of the cardiologists (58%), and about one-third of electrophysiologists (38%).

In our patient, ICD interrogation suggested that the shocks were inappropriate and were delivered for atrial fibrillation, which was occurring at other times. The ICD might have misinterpreted the arrhythmia as a result of aberrant conduction during the rhythm. Inappropriate ICD shocks in a patient with hypertrophic cardiomyopathy might be due to underlying T-wave oversensing or atrial fibrillation with aberrancy. These shocks can lead to decreased quality of life (eg, episodes of phantom shocks), increased mortality, and increased cost of health care use.³ ICD programming changes were effective in avoiding any further episodes in our patient.

Our case suggests that in any rhythm in which the symptoms are inconclusive or not available and there is enough time for the interpretation of a tracing of wide complex tachycardia, it would be good to consider artifacts and recording issues as the cause of the rhythm. A multiple ECG lead Holter would reduce the chance of error in interpretation. In our patient, there was a loose lead, which led to the artifacts. This needs meticulous interpretation of the entire rhythm strip.

None.

Disclosures None.

For Sources of Funding and Disclosures, see page 1055.

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

一名 55 岁女性，患有长期糖尿病和高血压，患有肥厚性心肌病（经心脏磁共振成像诊断），被植入单腔、单线圈植入式心脏复律除颤器（ICD；雅培实验室）用于一级预防。几周前。她因呼吸困难病史和最近发作的心动过速而到急诊科就诊。经过详细询问，她提供了过去几个小时内多次电击的历史以及 1​​5 天前的类似经历。当时她在另一个中心接受了动态心电图监测（以确认心动过速的诊断），并被诊断为室性心动过速（VT）。 Holter 报告追踪被解释为有多次 (14) 次 VT 发作（图 1）。是VT吗？

图 1. 患者睡眠时（凌晨 4 点）记录的动态心电图。 N表示正常； PTE，患者触发事件； V，心室；和 VT，室性心动过速。

请翻页阅读诊断书。

动态心电图 (Holter) 描记中可见广泛的 QRS 心动过速。该病例的结构性心脏病（例如肥厚性心肌病）的背景使得解释此心电图条变得复杂。不能依赖症状，因为该事件是在患者睡觉时记录的，并且患者没有症状。该动态心电图仅记录单个心电图导联带，因此更容易出现解释错误。描记开始时有 3 次窦性搏动，伴有 QRS 波碎片，之后似乎开始出现宽 QRS 波心动过速（图 1）。宽QRS波心动过速期间，RR间期有变化，QRS波宽度也有变化。如果仔细观察，就可以识别出穿过宽 QRS 波心动过速的分裂 QRS 波。在图的下半部分，有不断变化的QRS波型和奇异的QRS波群，而这里其中的QRS波群分裂变得更加明显。它表明广泛的 QRS 心动过速是一种伪影，并且记录一定存在一些问题，要么是引线松动，要么是心电图片松动。如果我们扫描跟踪的其余部分，我们可以在持续的明显宽复杂节奏上找出类似的偏转，该节奏被记录设备标记为 VT（图 2）。

图 2. 扫描广泛的复杂心律内隐藏的心电图活动。 N表示正常； PTE，患者触发事件； V，心室；和 VT，室性心动过速。

心电图伪影的两个主要类别已被描述：模拟各种心律失常（即假性心房扑动或假性 VT）或导致假性暂停。第一种类型的伪影可能是我们患者的情况，可能是由身体运动、皮肤电极接触的暂时损伤、电极连接松动、引线功能障碍、骨骼肌电位或环境噪音产生的。第二种通常是由电极接触问题或记录仪问题产生的。¹这种误解可能会导致对该患者的心律失常治疗做出不适当的决定，例如院内休克、添加抗心律失常药物（可能会导致不良副作用）、取消手术以及对植入 ICD 的不适当建议。

任何医生在解释显示广泛复杂性心动过速的动态心电图时，尤其是在结构性心脏病的背景下，总是会按照区分两种常见诊断的方式开始解释，而不是试图寻找伪影。一项包括内科医生、心脏病专家和心脏电生理学家在内的优雅研究证实了这一点。²在这项研究中，对 766 名医生进行了调查，对患有陈旧冠状动脉疾病的患者进行了广泛复杂心律的病例模拟，如 2 导联心电图监测所示。大多数内科医生 (94%)、超过一半的心脏病专家 (58%) 和约三分之一的电生理学家 (38%) 没有将试纸正确诊断为伪影。

在我们的患者中，ICD 询问表明电击不合适，是因为心房颤动而进行的，这种情况在其他时间也发生过。 ICD 可能会误解心律失常，因为心律期间传导异常。对肥厚型心肌病患者进行不适当的 ICD 电击可能是由于潜在的 T 波过度敏感或心房颤动异常所致。这些电击可能导致生活质量下降（例如幻觉电击发作）、死亡率增加以及医疗保健使用成本增加。³ ICD 编程的改变有效地避免了患者的任何进一步发作。

我们的案例表明，在任何症状不确定或不可用的心律中，并且有足够的时间来解释广泛复杂的心动过速的追踪，最好将伪影和记录问题视为心律的原因。多心电图导联动态心电图将减少解释错误的可能性。在我们的患者中，导线松动，导致出现伪影。这就需要对整个节奏条进行细致的解读。

没有任何。

披露无。

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