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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?

• V6
• 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


What might be indicated by wide QRS segments?

• Over 0.12 seconds usually means a bundle branch block
• RBBB large late R in V1 with a late S wave in V6
• LBBB wide QS wave in V1 and wide R wave in V6