Transcript Acquiring an ECG

Acquiring a Resting ECG
ECG
• An ECG is the recording of the electrical
activity generated by the cells of the heart
that reaches the body surface.
• This electrical activity initiates the heart’s
muscular contraction that pumps the blood to
the body
12 Lead ECG
• In a conventional 12 lead ECG, ten electrodes are
placed on the patient's limbs and on the surface
of the chest.
• The overall magnitude of the heart's electrical
potential is then measured from twelve different
angles ("leads") and is recorded over a period of
time (usually 10 seconds).
• In this way, the overall magnitude and direction
of the heart's electrical depolarization is captured
at each moment throughout the cardiac cycle.
Lead placement
Lead placement
Electrode
Placement
V1
4th Intercostal space to the right of the
sternum
V2
4th Intercostal space to the left of the
sternum
V3
Midway between V2 and V4
V4
5th Intercostal space at the
midclavicular line
V5
Anterior axillary line at the same level as
V4
V6
Midaxillary line at the same level as V4
and V5
RL
Anywhere above the ankle and below
the torso
RA
Anywhere between the shoulder and
the elbow
LL
Anywhere above the ankle and below
the torso
LA
Anywhere between the shoulder and
the elbow
Lead Placement
Additional Chest Leads
• Right sided chest lead: V4R
– 5th intercostal space, right midclavicular line
V4R
Do standard 12 Lead ECG
Remove V4 lead wire and place on V4R electrode
12 Lead will be the same except V4 is now V4R
Must be documented on the ECG
V4R
Left Posterior Leads
• Leave on V1, V2, V3 lead wires
• Take off V4, V5, V6 lead wires
• Rule of Three
– V4 lead wire connected to V7 electrode
– V5 lead wire connected to V8 electrode
– V6 lead wire connected to V9 electrode
• Now you are looking directly at the left
ventricular posterior wall
• ECG will print: V1, V2, V3, V7, V8, V9
Posterior ECG
Posterior Lead Placement
• V7 – Left posterior axillary line, in the same
horizontal plane as V6
• V8 – Tip of the left scapula, in the same
horizontal plane as V6
• V9 – Left paraspinal region, in the same
horizontal plane as V6
Importance of correct lead placement
• Incorrect placement can lead to a false
diagnosis of infarction or negative changes on
the ECG
– Electrode misplacement
• Up to 50% of cases have the V1 and V2 electrodes in a
more superior location, which can mimic an anterior MI
and cause T wave inversion.
• Up to 33% of cases have the precordial electrodes (V1V6) inferiorly or laterally misplaced, which can alter the
amplitude and lead to misdiagnosis.
Equipment
• ECG Analysis System
– Keyboard
– Acquisition Module
– Lead wires
• Electrodes
• Razor (if applicable)
• Power “On” machine
• Verify and enter patient data
• Place electrodes on patient, prepping skin if
needed (i.e. shave)
• Attach lead wires to electrodes, ensure correct
lead wire labels correlate with position of
electrodes
• A quality resting ECG is established when all
three hookup advisor circles are full
• Press “ECG” to initiate recording of the ECG
Reducing Artifact
• Patient Positioning
– Place the patient in a supine or semi-Fowler’s position.
– Instruct the patient to place their arms down by their side
and to relax their shoulders.
– Make sure the patient’s legs are uncrossed.
• Skin Preparation
– Dry the skin if it is moist or diaphoretic.
– Shave any hair that interferes with electrode placement.
This will ensure a better electrode contact with the skin.
• Electrode Application
– Check the electrodes to make sure the gel is still moist.
– Do not place the electrodes over bones.
– Do not place the electrodes over areas where there is a lot
of muscle movement