The correct placement of V1 and V2 pericordial leads of the electrocardiogram (ECG) is on the fourth intercostal space to the right and the left margins of the sternum (Walsh, 2020). Misplacement of V1 and V2 leads where leads are placed higher than the fourth intercostal space is a common technical error in clinical practice (Walsh, 2018). Unfortunately, this has a negative impact on ECG interpretation as it could generate few false-positive findings such as old septal myocardial infarction (MI), acute anterior ST-segment elevation myocardial infarction (STEMI) pattern, and incomplete right bundle branch block (RBBB) (Walsh, 2018). The misinterpretation of the false ECG findings could lead to unnecessary medical management and intervention (Ilg and Lehmann, 2012). Interestingly, the morphology of P wave in V1 and V2 is a key factor which could help the physicians to differentiate between leads misplacement and true ECG findings. When V1 and V2 leads are placed correctly, in majority of healthy individuals P wave in V1 has a biphasic morphology (Walsh, 2020), whereas in V2 the shape of P wave is expected to be upright (Ilg and Lehmann, 2012). When V2 lead is placed higher than the fourth intercostal space, the positive amplitude of the P wave in V2 can be lost, and abnormal P wave shapes can be observed, such as flat, biphasic, and negative P waves based on the degree of the lead misplacement (Ilg and Lehmann, 2012). Furthermore, a predominantly negative P wave in V1 should raise the suspicion of V1 and V2 leads misplacement (García-Niebla et al., 2012).

Herein, we present three ECG examples done in the preassessment clinic at Spire Fylde Coast Hospital for patients undergoing elective surgical procedures where misplacement of V1 and V2 leads generated false-positive findings (Figure 1) resulted in delay of their surgical procedures pending further cardiological assessment. When the ECGs were repeated after careful and correct placement of V1 and V2 leads, all the ECG findings were fully resolved. In all the three examples, the P wave shape in V1 was predominantly negative, whereas in V2 the positive amplitude of P wave was lost. When the leads are placed correctly, biphasic, and positive, P waves in V1 and upright P waves in V2 can be clearly seen in addition to full resolution of the false-negative ECG findings.

In conclusion, the main learning point of presenting these ECG examples is to raise the awareness of the importance of careful and correct pericordial leads placement when performing the ECG as pericordial leads misplacement has negative consequences which could affect accurate ECG interpretation and the quality of care delivered to the patients. Furthermore, the morphology of P wave in V1 and V2 is a useful tool to detect pericordial leads misplacement so physicians can avoid ordering further investigations or interventions unnecessarily.

心电图 (ECG) 的 V1 和 V2 心包导联正确放置在胸骨右侧和左侧边缘的第四肋间（Walsh，2020 年）。将 V1 和 V2 导联放置在高于第四肋间的位置错位是临床实践中常见的技术错误（Walsh，2018）。不幸的是，这对心电图解释有负面影响，因为它几乎不会产生假阳性结果，例如陈旧性室间隔心肌梗死 (MI)、急性前 ST 段抬高心肌梗死 (STEMI) 模式和不完全右束支传导阻滞 (RBBB) ）（沃尔什，2018 年）。对错误心电图结果的误解可能导致不必要的医疗管理和干预（Ilg 和 Lehmann，2012 年）。有趣的是，V1 和 V2 中 P 波的形态是一个关键因素，可以帮助医生区分导联错位和真实的心电图结果。当 V1 和 V2 导联放置正确时，在大多数健康个体中，V1 中的 P 波具有双相形态（Walsh，2020 年），而在 V2 中，P 波的形状预计为直立（Ilg 和 Lehmann，2012 年）。当V2导联置于第四肋间隙以上时，V2中P波正幅消失，可观察到异常P波形状，根据P波的程度不同，可观察到平坦、双相、负P波等。铅错位（Ilg 和 Lehmann，2012）。此外，V1 中主要为负的 P 波应引起对 V1 和 V2 导联错位的怀疑（García-Niebla 等，2012）。

在此，我们展示了在 Spire Fylde Coast 医院的预评估诊所为接受选择性外科手术的患者所做的三个心电图示例，其中 V1 和 V2 导联的错位产生了假阳性结果（图 1）导致他们的手术延迟，等待进一步的心脏评估. 当仔细正确放置 V1 和 V2 导联后重复进行心电图检查时，所有心电图结果都得到了完全解决。在所有三个例子中，V1 中的 P 波形状主要是负的，而在 V2 中，P 波的正振幅丢失了。当导联放置正确、双相和阳性时，除了假阴性心电图结果的完全分辨率外，还可以清楚地看到 V1 中的 P 波和 V2 中的直立 P 波。

总之，展示这些心电图示例的主要学习点是提高对心包导联放置时小心和正确放置心电图的重要性的认识，因为心包导联错位会影响准确的心电图解释和提供的护理质量给病人。此外，V1 和 V2 中 P 波的形态是检测心包导联错位的有用工具，因此医生可以避免进行不必要的进一步检查或干预。