Cardiac ICU · Flat-reference ECG atlas

Where the Electrodes Go

Every precordial electrode has a standardized anatomical address. Find the sternal angle, count the interspaces, and place V4 before aligning V5 and V6. Select a lead to connect placement with the view it records.

Anterior: facing the patient Axial: both viewing directions shown R / L always mean patient side
Placement guideFour-step sequence
  1. 01
    Find the sternal angleIt meets the second rib.
  2. 02
    Count to the fourth spacePlace V1 right and V2 left of the sternum.
  3. 03
    Place V4, then V3V3 sits midway between V2 and V4.
  4. 04
    Stay horizontalAlign V5 and V6 with V4, not the rib curve.
Evidence checked September 4, 2026 Scope Adult standard placement and hospital telemetry Use Educational reference

Surface placement and frontal axis

Pair where the electrodes sit with the frontal-plane direction each limb lead records.

Anterior chest wall

You are facing the patient. Find the sternal angle, count to the correct interspace, then follow the horizontal plane of V4.

Frontal plane · limb lead axes

A standardized, idealized frontal-plane model. Arrows point toward each lead’s positive pole; their angles do not come from the pads’ drawn positions.

Standard 12-lead ECG paperRegional correlations and illustrative waveforms

Classic 3 × 4 display with a long lead-II rhythm strip. Select any tracing to connect it with the anatomical views above.

25 mm/s · 10 mm/mV · illustrative waveforms
InferiorII · III · aVF Often RCA-related; LCx is possible with left dominance.
Septal / right precordialV1 · V2 Common teaching group: septal; V1 also samples right-precordial forces.
Anterior / apicalV3 · V4 Often LAD-related; use the full pattern and clinical context.
LateralI · aVL · V5 · V6 Often LCx/obtuse marginal or LAD diagonal-related.
aVRrightward cavity vector No single myocardial or coronary territory.

Contiguous means anatomically adjacent viewpoints, not simply neighboring boxes on the printout. A single lead does not localize an infarct. Interpret patterns across contiguous and reciprocal leads with symptoms, serial ECGs, and clinical context. Right-ventricular and posterior assessment may require V3R–V4R or V7–V9.

Real ECG galleryTwelve measured PTB-XL records

Read the unmarked tracing first, then reveal the normalized teaching label.

PTB-XL v1.0.3 · CC BY 4.0

These records are examples for pattern recognition, not a diagnostic test set. Source reports may be clinician- or device-generated; the displayed teaching labels are normalized for readability.

Sources & scope

Built around placement standards, not shortcuts

Landmarks and monitoring distinctions were checked against AHA/ACCF/HRS standards and supporting placement research. Regional labels are orientation aids, not vessel-level diagnoses.

AHA / ACCF / HRSStandard ECG technology and lead placementCirculation, 2007 American Heart AssociationHospital ECG monitoring practice standardsCirculation, 2017 Placement researchAccuracy of precordial lead placementInt J Clin Pract, 2008 Placement researchEffect of precordial displacement on morphologyMed Biol Eng Comput, 2014 PhysioNet · CC BY 4.0PTB-XL measured ECG datasetVersion 1.0.3 · DOI 10.13026/kfzx-aw45 European Society of CardiologyAcute coronary syndrome guidelineClinical interpretation and management context American College of CardiologyRight-ventricular myocardial infarctionRight-sided ECG and hemodynamic context