Interpretation Made Easy. LEAD PLACEMENT LIMB LEADS MUST BE PLACED ON THE LIMBS Uses both positive and negative electrodes Current towards positive,

Interpretation Made Easy

LEAD PLACEMENTLIMB LEADS MUST BE PLACED ON THE

LIMBSUses both positive and negative electrodesCurrent towards positive, view from negative

Precordial Leads

Acquisition & Transmission

Acquisition & TransmissionSkin Preparation

Helps obtain a strong signalSkin oils reduce adhesion of electrode

and hinder penetration of electrode gelDead, dried skin cells do not conduct

well

Acquisition & Transmission

Rubbing skin with a

gauzepad can

reduce skin oil

and remove some of

dead skin cells

Acquisition & TransmissionOther causes of artifact

Patient movement

Cable movement

Vehicle movement

Electromagnetic Interference (EMI)

Acquisition & TransmissionPatient 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”

Acquisition & TransmissionCable 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

Acquisition & TransmissionElectromagnetic Interference (EMI)

Can interfere with electronic equipment60 cycle interference is a type of EMILook for nearby cell phones, radios or

electrical devicesNo contact between cables & power

cordsTurn off or move away from AC devicesUse shielded cables; inspect for cracks

Limb Lead PlacementTraditional Placement

Acceptable Placement

Avoid placing on the trunk!!!

Chest Lead PlacementV1: fourth intercostal space

to right of sternumV2: fourth intercostal space

to left of sternumV3: directly between leads

V2 and V4V4: fifth intercostal space at

left midclavicular lineV5: level with V4 at left

anterior axillary lineV6: level with V5 at left

midaxillary line

Acquisition & TransmissionThings to look for

Little or no artifactSteady baseline

Acquisition & Transmission

12-Lead ValidationLead I – Global Negativity?

P, QRS and T Wave inverted?R Wave Progression?

R Wave size increases in V leadsTransition Zone?

R Wave should be predominately positive in V3 and V4

12-Lead ValidationLimb leadsP wave, QRS, and

T wave upside down in Lead I

Global negativityUpper limb leads

switched

12-Lead ValidationR wave

progressionR waves progress

in size from V1 to V4

If poor progression, check lead placement on electrodes

normal poor