Why complicate an important task? An orderly display of the limb leads in the 12-lead electrocardiogram and its implications for recognition of acute coronary syndrome

Figures

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  Fig. 1. A figurative description of the illogical presentation of limb leads in the ECG standard format by the use of an X-ray image of a bimalleolar ankle fracture. The radiological image is divided into six parts with lead annotations to the right of each image in order to illustrate both the orderly and non-orderly lead sequences. To the left, the image is presented with the skeletal parts and the lead annotations in their orderly anatomical sequence. The right image is presented in scrambled order representing the standard, non-orderly presentation of the frontal plane sequence of the 12-lead ECG

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  Fig. 2. ECG presentation using the Cabrera sequence for limb leads (to the left), i.e. the limb leads are presented in an anatomically, contiguous sequence. The Cabrera sequence only affects the presentation of limb leads (aVL, I, -aVR, II, aVF, III). As in the standard display, the precordial leads are presented in contiguous order

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  Fig. 3. Panel A shows the Cabrera presentation of leads. The leads are presented in contiguous order. Compared to the standard format, aVR is replaced by –aVR. The relation between the limb leads according to the frontal axis is evident in Panel B. The Cabrera sequence is demarcated by the dashed lines above lead aVL and to the left of lead III. Lead aVR, which is included in standard display, is completely different from the other leads, with its positive pole in the upper right quadrant of the thorax. In the Cabrera display, the inverted version −aVR instead bridges the gap between lead I and II, resulting in a smooth waveform progression. This ECG, from a patient with RCA occlusion, shows significant ST elevation in only one lead, lead III, but reciprocal ST depression in aVL. Since −aVL is opposite to aVL and next to III, significant ST elevation can be considered to be present in two contiguous leads, III and − aVL

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  Fig. 4. Three ECGs presented with both the standard presentation of limb leads (a) and the Cabrera sequence (b). Precordial leads are presented in columns c. 1. ECG from a patient with RCA occlusion. The myocardium at risk was large (37%) according to cardiac magnetic resonance imaging. There is ST elevation in II, III, aVF, V3 − V6 and ST depression in aVL, I and V1-V2. In the standard format, ECG shows significant ST elevation in two contiguous limb lead pairs; II/aVF and III/aVF. In the Cabrera format, ST depression in aVR is replaced by ST elevation in −aVR and ST elevation is thus evident in one additional lead pair, −aVR/II. The ST depression is larger in aVL than in I and the ST elevation is larger in III than in II. The inferior STEMI is easily recognized with the standard format, but in the Cabrera sequence, with −aVR presented adjacent to lead II, the extent of the infarction is more easily appreciated. 2. ECG from a patient with left main stenosis. Precordial leads show ST depression in V2 − V6 (c). In the standard format (a), ECG shows ST depression in I, II, III, aVF and ST elevation in aVR. In the Cabrera display (b), ST elevation in aVR is replaced by ST depression in −aVR…

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  Fig. 5. 1. ECG from a patient with LAD occlusion. ECG shows ST elevation in V1 − V4 (c) and ST depression in II, III and aVF. In the standard format (a), slight ST elevation in aVR is present, displayed as ST depression in −aVR in the Cabrera sequence (b). 2. ECG from a patient with takotsubo cardiomyopathy. The ECG shows ST elevation in precordial leads (c) V3 − V6 and also ST elevation in II, III and aVF. In the standard format (a), ST depression in aVR is present, displayed as ST elevation in −aVR in the Cabrera sequence (c). ST depression in inferior leads and ST elevation in aVR (ST depression in −aVR) is more common in patients with LAD occlusion than in patients with takotsubo cardiomyopathy [37]. Kosuge et al. suggested that these differences were more easily visualized, and thus not as easily neglected, when −aVR was used and the leads were presented in contiguous order [37]