ECG Flashcards
Explain hexaxial leads
-Limb leads that look in frontal plane
What leads are hexaxial view?
- Leads I, aVL (lateral)
- leads II, III, aVF (inferior)
- aVR: superiomedial
What leads are bipolar?
Leads I, II, III
What leads are unipolar?
- aVR (augmented voltage) right arm
- aVL (left arm)
- aVF (foot)
Wha is the view of precordial leads?
- look in transverse plane
- v1 through v6
__________ of __________ reflects how __________ or force is to axis.
Magnitude…..deflection……parallel
_________ to axis results in _______ line.
Perpendicular…….flat
What leads show inferior wall infarct?
II, III, aVF
What leads show lateral wall infarct?
I, aVL, v5, v6
What leads show anteroseptal wall infarct?
v1 through v4
Define the mean QRS axis.
the average direction of ventricular depolarization in frontal plane based on leads I and II
What is the normal QRS axis range?
+90 to -30
How to determine QRS axis? (3 steps)
- Look at hexaxial leads (I, II, III, aVR, aVL, aVF),Find most isoelectric
- which lead is perpendicular to isoelectric lead?
- Fine tune
(down deflection moves left away hexaxial lead)
(up deflection move right toward hexaxial lead)
The more perpendicular the axis is to a lead, the more ________ the QRS complex will be.
isoelectric
What determines a left axis deviation?
< -30 degrees
What determines a right axis deviation?
> +90 degrees
What can cause left axis deviation?
- inferior wall myocardial infarct
- left anterior fascicular block
- left ventricular hypertrophy (sometimes)
What can cause right axis deviation?
- right ventricular hypertrophy
- acute right heart strain
- left posterior fascicular block
What causes P wave abnormalities?
-atrial enlargement
What leads are best to detect atrial enlargement in what planes?
II (frontal)
v1 (transverse)
What ECG changes would you detect with RIGHT atrial enlargement?
Lead v1 would show upward deflection
What ECG changes would you detect with LEFT atrial enlargement?
lead v1 would show downward deflection
What leads best detect QRS abnormalities?
v1 and v6
What causes QRS abnormalities?
ventricular hypertrophy
What EKG changes detected with right ventricular hypertrophy?
- Wide R in v1
- Deep S in v6
- right axis deviation
What EKG changes detected with left ventricular hypertrophy?
- Deep S in v1
- Tall R in v6
- left axis deviation
BBB are best seen in which leads?
v1 and v6
Ventricle must rely on what type of signaling?
cell to cell
What prolongs depolarization and widens QRS?
Bundle branch block
What EKG changes are present with RBBB?
- v1 shows RSR “rabbit ears”
- v6 prominent S
What EKG changes are present with LBBB?
- v1 prominent S
- v6 notched R
What is a fascicular block and what leads best detect on EKG?
- left ventricle (anterior and posterior branch one to each papillary muscle)
- aVL and aVF
ST elevation vs. Non-ST elevation MI
- Ionic leak shifts EKG baseline
- shifts down if damage on surface (ST elevation)
- shifts up if damage at subendocardium (depressed ST)
What causes pathological Q waves?
- Develop in leads overlying infarcted tissue
- no electrical activity, “window” for lead to see opposite side of heart depolarizing away from lead
