> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hopticshealth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Mastering 12-Lead ECG Placement

> An essential clinical guide for accurate cardiac diagnostics. Correct placement is the foundation of a reliable electrocardiogram.

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  <img src="https://mintcdn.com/hopticshealth/Lwmz1y-bX232JK_Q/images/ecg/ecg-placement.jpeg?fit=max&auto=format&n=Lwmz1y-bX232JK_Q&q=85&s=918b632a226cb729023f87f259bac035" alt="ECG Lead Placement" width="3999" height="2999" data-path="images/ecg/ecg-placement.jpeg" />
</Frame>

## Understanding the 12-Lead System

The 12-lead ECG is composed of two main sets of leads: `Limb Leads` and `Precordial (Chest) Leads`. Together, they provide a comprehensive three-dimensional view of the heart's electrical activity.

```mermaid theme={null}
  flowchart LR
    subgraph 6 Limb Leads
        direction TB
        top1[I, II, III] --> bottom1[aVR, aVL, aVF]
    end
    subgraph 6 Precordial/Chest Leads
        direction TB
        top2[V1, V2, V3] --> bottom2[V4, V5, V6]
    end
    %% ^ These subgraphs are identical, except for the links to them:

    %% Link *to* subgraph1: 6 Limb Leads direction is maintained
    12-Lead-ECG --> top1
    %% Link *within* subgraph2:
    %% subgraph2 inherits the direction of the top-level graph (LR)
    12-Lead-ECG ---> top2
```

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</Card>