Site de formation à la lecture de l'ElectroCardioGramme.

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  Physiologie
  Technique
  Terminologie
  Arythmie SV
  Arythmie V
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  Coronaropathie
  Cardiopathie
  Toxique/métabolique
  Traitement
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Electrodes V1V2 trop hautes
Erreurs fréquentes qui génèrent des erreurs d'interprétation et de reproductibilité : 
- fausse hypertrophie/dilatation atriale gauche
- faux bloc incomplet droit
- faux "Brugada"
- 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 ?
 
Diagnostic
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.
Parfois, V1 ressemble parfaitement à VR (deux dérivations droites), ce qui doit donner l'alarme.
 
Walsh B. Misplacing V1 and V2 can have clinical consequences. Am J Emerg Med. 2018;36(5):865-870
 
Rappel. Il faut poser les élèctrodes V1-V2 au 4e espace intercostal. Le mieux est de repérer l'Angle de Louis (qui identifie l'insertion des 2èmes côtes sur le sternum) ou de postionner l'électrode V4 en premier dans le sillon sous mammaire gauche sur la ligne médio-claviculaire, puis de poser V2 en parasternal gauche un espace intercostal plus haut, puis de 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. Dérivations précordiales).
 

Références

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


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.

 
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.
 
 
 
 
 
 
 
Dr Pierre Taboulet
Pierre Taboulet
Cardiologue
Urgentiste
Hôpital Saint-Louis (APHP)

 
Nouveau

ISBN : 978-2-35640-183-0

Éditeur
S-EDITIONS
(Ed. 01/2018)
 
 
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