a b s t r a c t

The precordial electrocardiogram (ECG) leads V1 and V2 are often misplaced. Such misplacement usually in- volves placing these leads too high on the chest. The resulting ECG may generate erroneous ECG patterns: e.g. in- complete Right bundle branch block, anterior T wave inversion, septal Q waves, ST-segment elevation. These features may falsely suggest acute or old cardiac ischemia, pulmonary embolism, or a type-2 Brugada pattern. On rare occasion, conversely, high placement of V1 and V2 may reveal a true type-1 Brugada pattern. The emer- gency clinician needs to be aware of the possibility of Lead misplacement, and should know how to suspect it based on unusual P wave morphology in V1 and V2.

(C) 2018

1. case presentations

The electrocardiogram (ECG) is an essential tool for identifying myr- iad cardiac and non-cardiac disorders quickly, cheaply, and non- invasively. Nonetheless, it can also be performed improperly, and thus interpreted incorrectly.

In particular, the precordial leads must be placed in the appropriate locations. V1 is placed in the 4th Intercostal space along the right margin of the sternum, V2 along the left margin of the sternum in the 4th ICS as well. V4 is placed in the 5th ICS, in the mid-clavicular line, with V3 placed midway between V2 and V4. V5 and V6 are then placed in the anterior axillary line and axillary line, respectively, at the same level as V4.

This convention has been standard for almost 80 years [1]. Neverthe- less, moving V1 and V2 upwards to the 3rd or 2nd ICS has proven to be a consistent and persistent error [1,2]. Despite the common occurrence of this misplacement, there may not be awareness of the potential impact on the patient’s clinical course.

In the following five cases V1 and V2 were placed too high. This mis- placement, in turn, directly lead to a change in the patient’s clinical course. In four of these cases, an acute cardiopulmonary process was in- correctly suspected initially. In the fifth case, a type 1 Brugada pattern was recognized only because of the high placement of V1 and V2, and appropriate identification and referral was made possible because of lead misplacement.

? These cases have not been previously published, submitted for publication, presented at conference, either in oral or poster format.

?? The author received no financial assistance from any source.

E-mail address: [email protected].

Case 1

A young adult woman presented to the emergency department (ED) with mild and Atypical chest pain, and an ECG was obtained (Fig. 1a). The physician noted the incomplete right bundle branch block (IRBBB) pattern in V2, and considered this to be concerning for pulmonary em- bolus (PE). A D-dimer was marginally elevated, and so a CT angiogram (CTA) of the chest was ordered. Care of the patient was transferred to a second physician at shift change, who wondered if the IRBB was due to lead placement, as suggested by the biphasic P wave in V2. He asked for a repeat ECG, and placed the leads himself (Fig. 1b). No IRBBB was seen. The CTA had already been performed, and was negative for PE.

Case 2

A 50-year-old woman was seen at her primary care physician’s office for a routine visit. She was noted to be hypertensive, despite apparent compliance with her anti-hypertensive medications. She had no chest pain, shortness of breath, or other potentially Ischemic symptoms, but an ECG was obtained (Fig. 2a). The precordial leads demonstrated ap- parent changes (rSr’ in V1, and T wave inversions in V1-V3) from a prior ECG. She was sent to the emergency department, based on con- cern for acute ischemia. The emergency physician felt that this change likely represented lead misplacement, and so an ECG was repeated with careful attention to the chest leads (Fig. 2b). Lastly, to rule out “si- lent” dynamic Ischemic changes, a third ECG was performed with V1 and V2 placed where the patient recalled them being done in the office. The ECG obtained with this deliberate misplacement (Fig. 2c) was

https://doi.org/10.1016/j.ajem.2018.02.006

0735-6757/(C) 2018

Fig. 1. ECGs from Case 1. Initial ECG (a), and after proper placement of precordial leads (b): ECG, Electrocardiogram.

similar to that obtained in the office. Further evaluation for ischemia was deferred, and the patient referred back to their physician.

Case 3

A 20-year-old man had an ECG performed during his annual medical evaluation to renew his commercial driver’s license (Fig. 3a). The com- puter interpretation noted “Right-precordial ST elevation, consider acute ischemia.” Despite the absence of any symptoms, he was sent im- mediately to the emergency department. The emergency physician doubted cardiac ischemia, and repeated the ECG after placing the pre- cordial leads personally (Fig. 3b). Given the thin, muscular habitus of the patient, the ST elevation was felt to be normal male variant. When asked where the clinic staff had placed the precordial leads, he pointed to just below his clavicles. No further testing was required, and his pa- perwork for his commercial driver’s license was signed.

Case 4

A 41-year-old man was seen by his primary care physician for an an- nual exam, and an ECG was obtained for unclear reasons (Fig. 4a). The patient reported excellent health, with no symptoms to suggest cardiac disease. Nonetheless, because of the computer interpretation of acute ST segment elevation MI (STEMI), 911 was called, and the patient was transferred to the emergency department by ambulance. The emergen- cy physician thought that ischemia was unlikely, and repeated the ECG after placing the precordial leads (Fig. 4b). No further testing was performed.

Case 5

A 20-year-old man presented to the emergency department with fe- vers, chills, and occasional dizziness. An ECG was obtained to evaluate for syncope (Fig. 5a).

The emergency physicians noted an apparent type 1 Brugada pat- tern in V1, and type 2 Brugada pattern in V3. The evolution of the QRS and T waves, however, suggested both lead misplacement and lead switch problems. (The progression of the R wave suggested V2 had been switched with V3.) The physician ordered a repeat ECG, and placed the precordial electrodes himself (Fig. 5b). This confirmed that V2 and V3 had been switched in the first ECG (V3 in Fig. 5b is identical to V2 in Fig. 5a), but the Brugada pattern is significantly attenuated. Nonethe- less, despite the likely high placement of V1 and V2 in the first ECG, car- diology agreed this was very likely Brugada.

1. Discussion

Precordial leads have been applied with poor technique for over half a century [3]. Despite this long-standing recognition, lead misplacement remains a concern [1,4]. In particular, V1 and V2 are commonly misplaced [5-7] usually too high (although there can be a great deal of variability) [2].

This misplacement is likely due to multiple factors: e.g. poor initial training, patient obesity, not removing clothing. Misplacement may be more common in women [8], perhaps due to concerns with preserving patient modesty [9]. Lastly, examples of lead placement obtained from the Internet are often incorrect, and may not include illustrations of placement on women or people with different body types [10].

Fig. 2. ECGs from Case 2. Initial ECG (a), ECG after proper placement of precordial leads (b), and then after deliberate upwards misplacement of V1 and V2 (c): ECG, Electrocardiogram.

Unfortunately, errors in placement of the precordial leads can gener- ate errors in ECG interpretation [11,12]. On the other hand, modest up- wards misplacement might not affect ECG interpretation significantly [13], and might even increase the sensitivity of computer detection of STEMI and NSTEMI, without a change in specificity [14].

Spurious ECG abnormalities are frequently generated by superior misplacement of V1 and V2. IRBBB is commonly seen in precordial lead misplacement [1], and was seen in all 5 of the initial ECGs in these cases. In each case the IRBBB resolved with proper lead placement. Unfortunately, the false IRBB pattern can suggest pulmonary embolism, as seen in Case 1 [15]. Although not seen in our cases, this false pattern of IRBBB can also suggest type 2 Brugada [16]. Certain features may dis- tinguish these mimics from a true Brugada pattern [17,18]. Lastly, the false IRBBB, when combined with the true (but benign) “male variant” anterior ST segment elevation [19], incorrectly suggested anterior STEMI in Cases 3 and 4.

Superior misplacement of precordial leads can also produce a false pattern of anterior T wave inversion (TWI) [1]. In a patient without lead misplacement, anterior TWI can suggest Acute cardiac ischemia. Anterior T wave inversion could also incorrectly suggest arrhythmogen- ic right ventricular cardiomyopathy (ARVC) [20]. Lastly, as seen in Case 1, anterior TWI not only can suggest the diagnosis of PE [21], but also

predicts RV dysfunction and worse outcomes in those patients with a known PE [15].

Misplacement of precordial leads can produce false poor R wave pro- gression [1], a pattern which can suggest an old anterior myocardial in- farction. Similarly, although not demonstrated in this case series, a “septal MI” pattern (QS wave in V1 and V2), can also be produced in healthy subjects with upwards misplacement of V1 & V2 [22].

Placement of V1 and V2 in the 3rd or 2nd intercostal spaces is a stan- dard diagnostic maneuver in the evaluation of type 1 Brugada syndrome [23]. High placement of V1 & V2 is more sensitive than standard place- ment for interrogating the Right ventricular outflow tract area, where the arrythmogenic focus is usually found. This increase in sensitivity does not seem to imply decreased specificity in the diagnosis of type 1 Brugada syndrome. Type 1 Brugada pattern is very unlikely to be found with “high leads” in healthy subjects [16,24]. In cases like ours, where type 1 Brugada pattern seen with high placement of V1 and V2, but not with standard placement, further investigation is obligatory [23]. Indeed, type 1 Brugada found only with high placement may be as dangerous as that seen with standard placement [25,26].

These cases are only a sampling of the potential clinical ramifications associated with misplacement of the precordial leads; others can be seen [27].

Fig. 3. ECGs from Case 3. Initial ECG from medical clinic (a), and the emergency department ECG after proper placement of precordial leads (b): ECG, Electrocardiogram.

Fig. 4. ECGs from Case 4. Initial ECG from primary care physician’s office (a), and the emergency department ECG after proper placement of precordial leads (b): ECG, Electrocardiogram.

Fig. 5. ECGs from Case 5. Initial ECG (a), and after proper placement of precordial leads (b): ECG, Electrocardiogram.

1. Identifying high placement of V1 and V2

Precordial lead misplacement can often be identified from the ECG. When the leads are properly placed on a healthy patient in the 4th ICS, V2 will show a biphasic P wave in 2% of cases, while V1 will essen- tially never show a fully negative P wave [28]. Upwards misplacement of the lead may be strongly suspected when the P wave in V2 is biphasic, and presumed when the P wave is fully negative [28,8].

This can be demonstrated in the ECGs in our series. Examples of the misplaced V2 and properly placed V2 are compared in Fig. 6 for each case. (In Case 5, where the initial ECG likely had a V2-V3 lead switch, the example is from V3.) With the exception of Case 2, the P waves are biphasic in the initial ECG, but clearly positive in the second ECG.

Nonetheless, it may not be mandatory to repeat the ECG with prop- erly position precordial leads, as the author did, in order to clarify the di- agnosis of lead misplacement. Awareness of the possibility of V1 and V2

misplacement, along with recognition of the patterns generated by such misplacement, could suffice (e.g., if the pre-test-probability of disease is very low, and there are impediments to obtaining a repeat tracing).

1. Conclusion

The leads V1 and V2 are frequently misplaced, but the electrocardio- graphic manifestations of this error may not be recognized. The cases here illustrate how these erroneous ECG patterns can affect patient management. Patients may be inappropriately investigated for cardio- pulmonary conditions, receive unneeded testing, and incur expense and anxiety. Only in one circumstance did misplaced leads likely facili- tate investigation for a serious (but rare) condition. Clinicians should be aware of the common “mimics” that lead misplacement can gener- ate, and also the features of the ECG, such as P wave morphology, that can suggest misplacement.

Fig. 6. Detail of ECGs from Cases 1-5, showing lead V2 before and after proper precordial lead positioning.

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