W10 D2 - 12 Lead ECG Flashcards
How many leads are in frontal and horizontal leads?
6 frontal plane leads
* front and back half
* 3 bipolar: lead I-III Einthoven’s triangle
* 3 unipolar: lead aVR, VL, VF
6 horizontal plane leads
* top and bottom half
* 6 unipolar: V1-V6
What is Einthoven’s triangle?
Frontal plane leads I-III form a triangle from right to left arm to left foot
Which portion of the heart is lead I, II, II looking at?
frontal planes
Lead I - lateral portions
Lead II - right inferior ?
Lead III - left inferior ?
What portion of the heart are V1-6 looking at?
horizontal plane
V1- anterior septum (middle)
V2 - anterior septum
V3 - anterior LV
V4 - anterior LV
V5 - lateral, 30 degrees
V6 - lateral, 0 degrees direct side view
V1-4: anterior views
V5-6: lateral (left) side
What leads are looking at the lateral portions of the heart?
AVL
Lead I
V5
V6
What leads are looking at the inferior portion of the heart?
Lead II
Lead III
AVF
What leads are looking at the anterior portion of the heart?
V1-V4
What is a vector?
An arrow which provides size/magnitude and direction of the electrical activity in the heart
Which coronary artery perfuses the lateral side of the heart?
What leads does this include?
Circumflex
via V5, V6, Lead I, aVL
Which coronary artery perfuses the inferior portion of the heart?
What leads does this inlcude?
RCA
via leads II, III, AVF
Which coronary artery supplies the anterior portion of the heart?
What leads does this include?
LAD
via V1 & V2 (septum)
V3 & V4 (LV)
Summarize the coronary artery supplies and their associated lead changes
LAD - anterior/septum
* V1-2 septum
* V3-4 ventricle
Circumflex - lateral (some posterior)
* V5-6
* Lead I
* aVL
RCA - inferior, posterior, RV
* inferior: lead II, III, aVF
* posterior: tall R waves & ST depression in V1 & V2
* RV: ST elevation in V4 (for STEMI only)
What is a pathological Q wave?
A Q wave that is more than 1/4 the size of the R wave
* indicates necrotic tissue
What does an ST elevation indicate?
STEMI - complete block of vessel
* requires immediate attention
* localized to anatomical groups on ECG
* full thickness damage to myocardium
What is R wave progression? Where is the largest?
The R wave becomes taller and the S wave becomes smaller through V1-V6 as the views wrap around the heart
* the largest should be at the apex V4/V5
* if its not, the electrical activity is early or late (thicker muscle or poor lead placement)
What is ventricular axis & what does it tell us?
The average direction of ventricles should be towards the + pole of lead II
* indicates heart disease if there are deviations from the normal direction
* extreme right or left deviation = no mans land in the RUQ of heart
How do you determine axis deviation?
What happens during a RBBB?
What does it look like on ECG?
Septum depol. left to right; Left ventricle depolarizes first, right follows slowly
* best seen in V1
* therefore QRS willl be wide
* rSR pattern, bunny ears
* ST/T waves will be abnormal, NOT MI
What happens during a LBBB?
What does it look like on ECG?
Septum depol. right to left; Right ventricle depolarizes first, left follows slowly
* best seen in V6
* therefore QRS willl be wide
* R wave is wide, sometimes bump
* ST/T waves will be abnormal, NOT MI
What does a down sloping ST depression indicate?
NSTEMI - partial block of vessel
* can also be horizontal ST depression
* only partial thickness damage to subendocardium
* widespread changes; does not localize on ECG
As MI evolves, what will you see in ECG? Why?
early, middle, late, or old detection
Hyperacute T waves
* early sign of oxygen deprivation
ST elevation
* within hours
* may be w/ tall or inverted T waves
* cell injury/damage is aparent but reversible
STEMI w/ pathological Q waves
* Q waves are more than 1/4 R wave
* 1-12 hours
* some cells dying
Old infarct
* takes up to 2 weeks
* ST segment returns to normal
* pathological Q wave remains as there is none reversible cell death
Which are the reciprocal leads? (mirror image)
Reciprocal lead is a different view of the heart which reverses the ECG info
PAILS
ST elevation in ____ will show as depression in ____
* Posterior … anterior
* Anterior … inferior
* Inferior … lateral
* Lateral … septal or inferior
What is the treatment for RV infarction? Why?
Increase preload via bolus +++ before inotrope/pressors
* need to stretch ventricle out as much as possible
How do you identify a posterior MI on ECG?
Use a 15 lead ECG; place leads 7,8,9 on the left back, 5th intercoastal space
* posterior MI = ST elevation in these leads
* if unable to do 15 lead, use reciprocal: ST depression in V1,2,3 and tall R waves
Why is AVR different?
Normal ECG - negative deflections only
What MI would include aVR ECG changes?
Left main or proximal left main artery occlusion
* wide spread ST depression with ST elevation in aVR greater than V1
How do you assess 12 lead ECG?
- Identify rate and rhythm
- Find Axis
- Is the QRS wide or not?
-
If yes check for BBB
* RBBB = V1 - rSR pattern
* LBBB = V6 - wide or notched
~5.If no, check for ischemia / MIs
* NSTEMI - ST depression / inverted T waves
* STEMI - ST elevation in at least two leads from same group and pathological Q waves
