# AI instructs placement of V1 and V2 ECG leads in the 2nd intercostal space instead of the 4th, leading to misdiagnosis of anterior myocardial infarction or right ventricular hypertrophy

- **ID:** `medical/ecg-lead-placement-v1-v2-error`
- **Domain:** medical
- **Category:** config_error
- **Error Code:** `MED-ECG-002`
- **Verification:** ai_generated
- **Fix Rate:** 78%

## Root Cause

Standard ECG lead placement requires V1 and V2 in the 4th intercostal space (right and left of sternum). Placing them in the 2nd intercostal space (higher) alters the QRS axis and R-wave progression, mimicking anterior MI (poor R-wave progression) or right ventricular hypertrophy (tall R in V1).

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| GE MAC 5500 1.0 | active | — | — |
| Philips PageWriter TC70 2.0 | active | — | — |
| Mortara ELI 280 3.0 | active | — | — |

## Workarounds

1. **Use anatomical landmarks: 1) Palpate the angle of Louis (sternal angle) where the 2nd rib attaches. 2) Count down two intercostal spaces to the 4th intercostal space. 3) Place V1 at the right sternal border, V2 at the left sternal border, both at the 4th intercostal space. For verification, V1 and V2 should be at the same horizontal level as V4 (mid-clavicular line).** (92% success)
   ```
   Use anatomical landmarks: 1) Palpate the angle of Louis (sternal angle) where the 2nd rib attaches. 2) Count down two intercostal spaces to the 4th intercostal space. 3) Place V1 at the right sternal border, V2 at the left sternal border, both at the 4th intercostal space. For verification, V1 and V2 should be at the same horizontal level as V4 (mid-clavicular line).
   ```
2. **Implement ECG lead placement training module with augmented reality feedback: use a tablet app that overlays correct positions on patient's chest using camera and shows intercostal space numbers. Example: 'Correct V1 position: 4th intercostal space, right sternal border.'** (88% success)
   ```
   Implement ECG lead placement training module with augmented reality feedback: use a tablet app that overlays correct positions on patient's chest using camera and shows intercostal space numbers. Example: 'Correct V1 position: 4th intercostal space, right sternal border.'
   ```

## Dead Ends

- **Place V1 and V2 at the 2nd intercostal space because 'it's easier to find'** — The 2nd intercostal space is easily palpated at the angle of Louis, but it is incorrect; the 4th intercostal space is the standard, and deviation causes diagnostic errors (85% fail)
- **Use the nipple line for V4 and then count down two spaces for V1 and V2** — The nipple line is not a reliable landmark (varies with breast size, position); the correct method is to find the angle of Louis (2nd rib), then count down to 4th intercostal space (70% fail)
- **Place V1 and V2 at the sternal border at the level of the 3rd intercostal space as a compromise** — Even 3rd intercostal space placement is non-standard and can cause false positive anterior MI patterns; only 4th intercostal space is correct (60% fail)