1. Interpretation Made Easy
12-LEAD EKG
Interpretation Made Easy

3. LEAD PLACEMENT LIMB LEADS MUST BE PLACED ON THE LIMBS
Uses both positive and negative electrodes
Current towards positive, view from negative

4. Precordial Leads

5. Acquisition & Transmission
Read the clipper manufacture’s recommendations. This is one model designed for medical applications and may be used near oxygen. In addition the head is disposable, avoiding de-contamination issues.

6. Acquisition & Transmission
Skin Preparation
Helps obtain a strong signal
Skin oils reduce adhesion of electrode and hinder penetration of electrode gel
Dead, dried skin cells do not conduct well
When measured from the patient’s skin, the heart’s electrical signal is extremely small, about to volts.
That’s as small as one-ten thousandth of a volt. Compare this with energy from a nine volt battery.
Good skin prep will make the ECG signal as strong as possible, and make the artifact signals as small as possible.

7. Acquisition & Transmission
Rubbing skin with a gauze
pad can reduce skin oil
and remove some of dead skin cells
Simply rubbing the skin with a gauze pad can have a noticeable effect on ECG clarity by:
• Reducing skin oil
• Removing part of the stratum corneum

8. Acquisition & Transmission
Other causes of artifact
Patient movement
Cable movement
Vehicle movement
Electromagnetic Interference (EMI)
Once the skin has been prepped and the electrodes applied, there are still other sources of artifact to consider.

9. Acquisition & Transmission
Patient Movement
Make patient as comfortable as possible
Supine preferred
Look for subtle movement
toe tapping, shivering
Look for muscle tension
hand grasping rail, head raised to “watch”
It is important to place the patient in a position of comfort. The reduction in muscle tension will help to prevent artifact.
When possible, the patient should be in the supine position for a 12-lead ECG.
Sometimes this is not feasible, practical or desirable.
If ECG is not recording in supine position, simply note this on ECG.

10. Acquisition & Transmission
Cable Movement
Enough “slack” in cables to avoid tugging on the electrodes
Many cables have clip that can attach to patient’s clothes or bed sheet
It is important to place the patient in a position of comfort. The reduction in muscle tension will help to prevent artifact.
When possible, the patient should be in the supine position for a 12-lead ECG.
Sometimes this is not feasible, practical or desirable.
If ECG is not recording in supine position, simply note this on ECG.

11. Acquisition & Transmission
Electromagnetic Interference (EMI)
Can interfere with electronic equipment
60 cycle interference is a type of EMI
Look for nearby cell phones, radios or electrical devices
No contact between cables & power cords
Turn off or move away from AC devices
Use shielded cables; inspect for cracks
It is important to place the patient in a position of comfort. The reduction in muscle tension will help to prevent artifact.
When possible, the patient should be in the supine position for a 12-lead ECG.
Sometimes this is not feasible, practical or desirable.
If ECG is not recording in supine position, simply note this on ECG.

12. Traditional Placement
Limb Lead Placement
Traditional Placement
Avoid placing on the trunk!!!
Limb leads should be placed on the limbs. The traditional placement is near the ankles and wrists.
Acceptable Placement

13. Chest Lead Placement V1: fourth intercostal space to right of sternum
V2: fourth intercostal space to left of sternum
V3: directly between leads V2 and V4
V4: fifth intercostal space at left midclavicular line
V5: level with V4 at left anterior axillary line
V6: level with V5 at left midaxillary line
V1 fourth intercostal space to the right of the sternum
V2 fourth intercostal space to the left of the sternum
V3 directly between leads V2 and V4
V4 fifth intercostal space at left midclavicular line
V5 level with lead V4 at left anterior axillary line
V6 level with lead V5 at left midaxillary line

14. Chest Lead Placement
Here is what lead placement looks like on a patient.

15. Acquisition & Transmission
Things to look for
Little or no artifact
Steady baseline

16. Acquisition & Transmission
Note how the baseline straightened out by simply repositioning the patient cables and clipping them onto the sheet.
What technique(s) would you consider in order to resolve the muscle artifact?

17. 12-Lead Validation Lead I – Global Negativity? R Wave Progression?
P, QRS and T Wave inverted?
R Wave Progression?
R Wave size increases in V leads
Transition Zone?
R Wave should be predominately positive in V3 and V4

18. 12-Lead Validation Limb leads
P wave, QRS, and T wave upside down in Lead I
Global negativity
Upper limb leads switched
12-leads should be validated for correct lead placement. First, look at Lead I. The P, QRS, and T waves are typically upright. If the P, QRS, and T waves are all inverted, this is a sign of global negativity and the RA and LA leads are switched.

19. 12-Lead Validation R wave progression
normal
poor
12-Lead Validation
R wave progression
R waves progress in size from V1 to V4
If poor progression, check lead placement on electrodes
R wave progression is the way to validate a 12-lead for precordial leads. The insert on your left (viewing) has normal R wave progression where the one on your right has poor progression. If this is seen, check to see that Leads V1–V6 are snapped on the right location. In this example on the right, Leads V2 and V4 have been switched.
Poor R wave progression can be caused by pathology as well. It is important that the acute care provider double check the lead placement before disconnecting the V leads following the 12-lead acquisition.

20. QUESTIONS?