Flashcards in 12 Lead ECG interpretation Deck (26):
What leads lie in the frontal plane?
• aVl, aVr, aVf
• I, II, III
What leads will show septal infarct?
• V1, V2
What leads will show anterolateral infarct?
• V5, V6
Which leads will most likely show left ventricle hypertrophy?
• V5, V6
Which leads will most likely show right ventricle hypertrophy?
• V1, V2
What leads lie in the horizontal plane?
• V1 - V6
Where does normal depolarization of the left ventricle go?
• Right to left and downward from right arm towards left leg
What is the predominant vector in leads V1 and V2?
• Negative. Forces moving away from right ventricle
What is the normal vector in leads I and II?
• Positive, as forces are going towards positive electrodes
• (left arm, left leg)
Because of the way the heart depolarizes, what is the vector direction in aVR?
• Negative, as current is moving away left and down
By convention, what is the normal QRS axis?
• -30 degrees to positive 90 degrees
• Remember degrees are clockwise, goes negative at 180
A normal QRS axis is predominantly positive in which leads?
• I and II
• These lie within the -30 to +90 degree window
A right axis deviation is predominantly negative where?
• Lead I
A left axis deviation is predominantly negative where?
• Lead II
What leads will show what in a right bundle branch block?
• Widened QRS in all
• Terminal QRS positive in right sided leades
• V1 and V2 are right sided so they have a late positive deflection
• Late forces are moving right
What lead will show the largest late positive deflection in a left bundle branch block?
• V1 will be negative
What causes not a QRS widening but a QRS axis shift?
• Distal left bundle blocks
• Anterior fascicle = left axis deviation
• Posterior fascicle = right axis deviation
ST depression during exercise likely indicates what?
• Transient ischemia
Inverted T waves likely indicates what?
• Acute coronary syndrome and the ischemia that is a result
ST elevation is likely indicative of what pathology?
• Transmural injury in acute coronary syndrome
• Usuall with a clot due to platelet aggregation occluding coronary artery
• Can avoid MI if caught early
Q waves likely indicate what if found in 2 or more adjacent leads?
• Transmural infarcts and dead myocytes
ST depression can mean what two different things?
• Transient ischemia due to coronary syndrome
• OR if it is persistent, it more likely indicates subendocardial infarct
If you see Q waves in leads I, aVL and V5/6, what does that likely indicate?
• Lateral wall infarcts
When Q waves are seen in V1 - V4, what is likely causing that?
• Anterior wall infarcts
What might indicate a P wave abnormality?
• Over 2.5mm in an inferior lead likely indicates atrial enlargement
• Wide, notched P wave with late negativity in V1 might indicate left atrial enlargement
What can a QRS axis shift tell you?
• Right axis shift, RVH or posterior hemiblock
• Left axis shift - LVH or anterior hemiblock