Editing Electrocardiography (section)

=== 12-Lead ECG ===
Leads are broken down into three types: limb; augmented limb; and precordial or chest. The 12-lead ECG has a total of three ''limb leads'' and three ''augmented limb leads'' arranged like spokes of a wheel in the [[coronal plane]] (vertical), and six ''precordial leads'' or ''chest leads'' that lie on the perpendicular [[transverse plane]] (horizontal).<ref name="EKGInterp">{{Cite web |url=https://www.nurseslearning.com/courses/nrp/nrp1619/Section%205/index.htm |title=EKG Interpretation |website=Nurses Learning Network |access-date=2019-05-27}}</ref>

Electrodes should be placed in standard positions, with 'left' or 'right' referring to [[anatomical]] directions, being the patient's left or right. Exceptions due to emergency or other issues should be recorded to avoid erroneous analysis.<ref>{{cite journal |last1=Jowett |first1=N I |last2=Turner |first2=A M |last3=Cole |first3=A |last4=Jones |first4=P A |title=Modified electrode placement must be recorded when performing 12-lead electrocardiograms |journal=Postgraduate Medical Journal |date=February 2005 |volume=81 |issue=952 |pages=122–125 |doi=10.1136/pgmj.2004.021204 |pmid=15701746 |pmc=1743200 }}</ref>

The 12 standard ECG leads and electrodes are listed below.<ref>{{Cite journal |last1=Drew |first1=Barbara J. |last2=Califf |first2=Robert M. |last3=Funk |first3=Marjorie |last4=Kaufman |first4=Elizabeth S. |last5=Krucoff |first5=Mitchell W. |last6=Laks |first6=Michael M. |last7=Macfarlane |first7=Peter W. |last8=Sommargren |first8=Claire |last9=Swiryn |first9=Steven |last10=Van Hare |first10=George F. |date=2004-10-26 |title=Practice Standards for Electrocardiographic Monitoring in Hospital Settings: An American Heart Association Scientific Statement From the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: Endorsed by the International Society of Computerized Electrocardiology and the American Association of Critical-Care Nurses |url=https://www.ahajournals.org/doi/10.1161/01.CIR.0000145144.56673.59 |journal=Circulation |language=en |volume=110 |issue=17 |pages=2721–2746 |doi=10.1161/01.CIR.0000145144.56673.59 |pmid=15505110 |issn=0009-7322}}</ref> All leads are effectively bipolar, with one positive and one negative electrode; the term "unipolar" is not true, nor useful.<ref name="AHA_ECG_pt1" />

{| class="wikitable collapsible"
|+ ECG Electrodes and positioning
|-
! Type
! Name ([[American Heart Association|AHA]])
! Color ([[American Heart Association|AHA]])
! Placement
! Name ([[International Electrotechnical Commission|IEC]])
! Color ([[International Electrotechnical Commission|IEC]])
|-
! scope=rowgroup rowspan=4 | Limb
| RA (Right Arm)
| White
| On the right arm, below the shoulders, avoiding thick [[muscle]].
| R (Right)
| Red
|-
| LA (Left Arm)
| Black
| Symmetrical to the placement of the RA.
| L (Left)
| Yellow
|-
| RL (Right Leg)
| Green
| On the right leg, below the hips.
| N (Neutral)
| Black
|-
| LL (Left Leg)
| Red
| Symmetrical to the placement of the RL.
| F (Foot)
| Green
|-
! scope=rowgroup rowspan=6 | Precordial
| V1
| Brown & Red
| Fourth [[intercostal space]] on the right [[sternal]] border.
| C1
| White & Red
|-
| V2
| Brown & Yellow
| Fourth intercostal space on the left sternal border (symmetrical to V1).
| C2
| White & Yellow
|-
| V3
| Brown & Green
| Halfway between electrodes V2 and V4 (in a straight line).
| C3
| White & Green
|-
| V4
| Brown & Blue
| Fifth intercostal space on the [[midclavicular line]].
| C4
| White & Brown
|-
| V5
| Brown & Orange
| Left [[anterior axillary line]] on the same horizontal plane as V4. If the anterior axillary line is ambiguous, place halfway between V4 and V6.
| C5
| White & Black
|-
| V6
| Brown & Purple
| Left [[midaxillary line]] on the same horizontal plane as V4.
| C6
| White & Purple.
|}

{| class="wikitable collapsible"
|+ ECG Leads and Views
|-
! Type
! Name
! Lead view
|-
! rowspan=3 | Limb
| I
| From the RA to the LA. Along the frontal and horizontal planes at 0° (directly to the left).
|-
| II
| From the RA to the LL. Along the frontal plane at 60° clockwise from I.
|-
| III
| From the LA to the LL. Along the frontal plane at 120° clockwise from I.
|-
! rowspan=3 | Augmented Limb
| aVL
| From WCT to the LA. Along the frontal plane at -30° (which is 330° clockwise from I).
|-
| aVR
| From WCT to the RA. Along the frontal plane at -150° (which is 210° from I).
|-
| aVF
| From WCT to the LL. Along the front plane at 90°.
|-
! rowspan=6 | Precordial
| V<sub>1</sub>
| In the fourth [[intercostal space]] (between ribs 4 and 5) just to the right of the [[sternum]] (breastbone)
|-
| V<sub>2</sub>
| In the fourth intercostal space (between ribs 4 and 5) just to the left of the sternum.
|-
| V<sub>3</sub>
| Between leads V<sub>2</sub> and V<sub>4</sub>.
|-
| V<sub>4</sub>
| In the fifth intercostal space (between ribs 5 and 6) in the [[mid-clavicular line]].
|-
| V<sub>5</sub>
| Along the same horizontal line as V<sub>4</sub>, in the left [[anterior axillary line]].
|-
| V<sub>6</sub>
| Along the same horizontal line as V<sub>4</sub> and V<sub>5</sub> in the [[midaxillary line|mid-axillary line]].
|}

Two types of electrodes in common use are a flat paper-thin sticker and a self-adhesive circular pad.
The former are typically used in a single ECG recording while the latter are for continuous recordings as they stick longer.
Each electrode consists of an [[electrically conductive]] electrolyte gel and a [[Silver chloride electrode#Biological electrode systems|silver/silver chloride]] conductor.<ref>{{cite book |doi=10.1007/978-1-4613-2323-5_15 |chapter=Advances in Body Surface Potential Mapping (BSPM) Instrumentation |title=Pediatric and Fundamental Electrocardiography |series=Developments in Cardiovascular Medicine |date=1987 |last1=Kavuru |first1=Madhav S. |last2=Vesselle |first2=Hubert |last3=Thomas |first3=Cecil W. |volume=56 |pages=315–327 |isbn=978-1-4612-9428-3 }}</ref>
The gel typically contains [[potassium chloride]] – sometimes [[silver chloride]] as well – to permit [[electron]] conduction from the skin to the wire and to the electrocardiogram.<ref>{{cite journal |last1=Tsukada |first1=Yayoi Tetsuou |last2=Tokita |first2=Miwa |last3=Murata |first3=Hiroshige |last4=Hirasawa |first4=Yasuhiro |last5=Yodogawa |first5=Kenji |last6=Iwasaki |first6=Yu-ki |last7=Asai |first7=Kuniya |last8=Shimizu |first8=Wataru |last9=Kasai |first9=Nahoko |last10=Nakashima |first10=Hiroshi |last11=Tsukada |first11=Shingo |title=Validation of wearable textile electrodes for ECG monitoring |journal=Heart and Vessels |date=July 2019 |volume=34 |issue=7 |pages=1203–1211 |doi=10.1007/s00380-019-01347-8 |pmid=30680493 |pmc=6556171 }}</ref>