Electrodes V1V2 trop hautes

Erreurs fréquentes qui génèrent des erreurs d’interprétation et de reproductibilité [1][2][3] :

  • fausse hypertrophie/dilatation atriale gauche
  • faux bloc incomplet droit
  • faux ST+ ou faux “Brugada” (aspect du ST-T en selle de cheval)
  • fausse onde Q de nécrose (Why is there ST Elevation in lead V2? Think Lead Placement)
  • microvoltage masquant une HVG
  • anomalie de repolarisation (masquée ou ajoutée, ex. T négative)

Vidéo. P. Taboulet. Comment enregistrer un ECG

Vidéo. P. Taboulet. Séquelle d’infarctus septal ?



  • En V1V2, ondes P à prédominance négative, souvent onde R’ en V1(V2) simulant un bloc incomplet droit et complexes QRS plus petits que V3 V4, ou QR simulant une séquelle de nécrose [2][4] .
  • Parfois, V1 ressemble parfaitement à VR (deux dérivations supéro-droites), ce qui doit donner l’alarme.

Rappel. Il faut poser les électrodes V1-V2 au 4e espace intercostal. Pour cela, il faut :

  • repérer l’Angle de Louis (qui identifie l’insertion des 2èmes côtes sur le sternum) [5]
  • ou (ma méthode) positionner en premier l’électrode V4 dans le sillon sous mammaire gauche sur la ligne médio-claviculaire (fossette palpable avec l’index), puis poser V2 en parasternal gauche, 1 espace intercostal plus haut, puis poser V1 en parasternal droite en regard de V2, puis V3 exactement entre V2 et V4 et on poursuit avec V5 et V6 sur la même ligne que V4 (cf. Electrodes précordiales) [6].

Une aide au repérage du mauvais positionnement des électrodes par les algorithmes d’interprétation ou “machine learning” est possible [7].

[1] Walsh B. Misplacing V1 and V2 can have clinical consequences. Am J Emerg Med. 2018;36(5):865-870

[2] Rjoob K, Bond R, Finlay D, McGilligan V, Leslie SJ, Rababah A, Guldenring D, Iftikhar A, Knoery C, McShane A, Peace A. Machine learning techniques for detecting electrode misplacement and interchanges when recording ECGs: A systematic review and meta-analysis. J Electrocardiol. 2020 Aug 19;62:116-123. doi: 10.1016/j.jelectrocard.2020.08.013. Epub ahead of print. PMID: 32866909.

[3] Maron et al (AHA 2014)12-Lead ECG as a Screening Test for Detection of Cardiovascular Disease in Healthy General Populations of Young People (12–25 Years of Age). Circulation 2014;130:1303–1334. A lire absolument –> A major source of potential technical error is misplacement of the limb or precordial electrodes, not uncommonly including inadvertent lead reversals, in which the V1 and V2 leads are placed in the second (rather than the fourth) intercostal space and the left precordial V5 and V6 leads are placed below the horizontal extensions of V4 in the fifth intercostal space. Precordial lead misplacement results in distorted precordial R-wave progression, thereby simulating anteroseptal infarction; magnifies otherwise small terminal R′ deflections and elevates the ST segments in V1 and V2; and confuses standard criteria for diagnosis of ventricular hypertrophy. Because day-to-day lead misplacement itself often varies, reproducibility of the precordial ECG is poor, and this variability can limit the ability to separate normal from abnormal tracings.

[4] MacAlpin et al. Significance of a negative sinus P wave in lead V2 of the clinical electrocardiogram. Ann Non Invasive ECG 2017. With correct precordial lead placement, negative PV2 is rare and biphasic V2 is also uncommon, and their presence should alert one to the probability of high placement of V1 and V2, which can produce ECGs that mimic LAA, septal infarction, and ventricular repolarization abnormality.

[5] Kligfield P, et al. Recommendations for the standardization and interpretation of the electrocardiogram: part I: The electrocardiogram and its technology: a scientific statement from the American Heart Association… Circulation. 2007 13;115(10):1306-24. –> A common error is superior misplacement of V 1 and V 2 in the second or third intercostal space. This can result in reduction of initial R-wave amplitude in these leads, approximating 0.1 mV (1 mm) per interspace, which can cause poor R-wave progression or erroneous signs of anterior infarction. Superior displacement of the V 1 and V 2 electrodes will often result in rSr′ complexes with T-wave inversion, resembling the complex in lead aVR. It also has been shown that in patients with low diaphragm position, as in obstructive pulmonary disease, V 3 and V 4 may be located above the ventricular boundaries and record negative deflections that simulate anterior infarction. Another common error is inferior placement of V 5 and V 6, in the sixth intercostal space or even lower, which can alter amplitudes used in the diagnosis of ventricular hypertrophy. Precordial lead misplacement explains a considerable amount of the variability of amplitude measurements that is found between serial tracings

[6] Taboulet P. Un peu de doigté pourrait simplifier la pose des électrodes précordiales d’un électrocardiogramme (Abstract FC256, Urgences 2020)

[7] Rjoob K, Bond R, Finlay D, McGilligan V, et al. Machine learning techniques for detecting electrode misplacement and interchanges when recording ECGs: A systematic review and meta-analysis. J Electrocardiol. 2020 Aug 19;62:116-123.