The 12 Conventional ECG Leads
These 12 leads are divided into two groups:
- six extremity (limb) leads; they are recording electrical potentials transmitted into the frontal plane;
- six chest (precordial) leads, they are recording electrical potential transmitted into horizontal plane.
There are the leads with their location and polarity:
|limb||location of the lead|
| bipolar extremity leads
|I||+||left upper limb||-||right upper limb|
|II||left lower limb||right upper limb|
|III||left lower limb||left upper limb|
| unipolar extremity leads
|aVR||right upper limb lead|
|aVL||left upper limb lead|
|aVF||left lower limb lead|
| unipolar chest leads
|V1||fourth intercostal space, just to the right of the sternum|
|V2||fourth intercostal space, just to the left of the sternum|
|V3||midway between V2 and V4, fifth intercostal space|
|V4||fifth intercostal space, midclavicular line on the left|
|V5||fifth intercostal space, anterior axillary line|
|V6||fifth intercostal space, midaxillary line|
Additional ECG Leads
These leads are used in special situations, when conventional 12-leads ECG can not reliably show the myocardial defect.
There are some examples of additional ECG leads:
|lead||location of the lead|
|unipolar chest leads||V7||posterior axillary line, on the same level as V6, on the left|
|V8||scapulary line, in the same level as V6, on the left|
|V9||paravertebral line on the left, on the same level as V6|
|VE||just to the left of processus xiphoideus|
|V3R - V6R||on the right, same location as V3–V6|
|unipolar chest leads||V1´– V6´||about 1 intercostal space above the V1–V6|
|V1´´– V6´´||about 2 intercostal space above the V1–V6|
|esophageal leads||E/Oe||for example 37.5 cm (left atrium)|
- KASPER, Dennis L – FAUCI, Anthony S – LONGO, Dan L, et al. Harrison's principles of Internal Medicine. 16th edition. New York : McGraw-Hill Companies, Inc, 2005. 2607 pp. pp. 1312-1313. ISBN 0-07-139140-1.
- WikiSkripta. Elektrokardiografie [online]. ©2011. The last revision 2011-07-2, [cit. 2011-07-03]. <http://www.wikiskripta.eu/index.php/Elektrokardiografie>.
- KASPER, Dennis L – FAUCI, Anthony S – LONGO, Dan L, et al. Harrison's principles of Internal Medicine. 16th edition. New York : McGraw-Hill Companies, Inc, 2005. 2607 pp. pp. 1311-1319. ISBN 0-07-139140-1.