11.29 A Flashcards
The P wave of an EKG is generated by what event?
atrial contraction
The QRS complex is generated by what event?
ventricular depolarization
The T wave is generated by what event?
ventricular repolarization
Which ventricle contributes more to the magnitude of the QRS complex?
the left because it has a greater mass
The ST interval is representative of what?
phase II of the ventricular action potential
Where on an EKG would AV node depolarization fall if it was strong enough to show up?
in the PR interval
An EKG has leads in what two planes?
frontal and horizontal
The horizontal leads of an EKG are which ones?
V1 - V6
The frontal leads of an EKG are which ones?
I, II, III, aVR, aVL, aVF
Which frontal lead measures the vector directly downward?
the aVF lead
ST segment elevation seen on an EKG is indicative of what?
infarcted tissue
ST segment depression on an EKG is indicative of what?
ischemia
What six things should you look for on an EKG?
- rate
- rhythm
- axis
- intervals
- hypertrophy
- ischemia/infarction
Which leads will shows an axis deviation if one is present?
I and aVF
What does it mean to check for sinus on an EKG?
confirm that each p wave have an associated QRS complex and vice versa
How can one determine heart rate from a standard EKG?
divide 300 by the number of large boxes between beats
Should the EKG be positive or negative in leads I and aVF?
they should both be positive
How will afib show up on an EKG?
- irregular beat
- tachycardia
- lots of microdepolarizations in the p wave
How should one treat atrial fibrillation?
with anticoagulants to reduce the risk of stoke
Atrial fibrillation most commonly arises due to what?
chronic hypertension causes stretching of the heart which creates electrical disturbances
What are the four possible characterizations for EKG axis?
- left deviation
- normal
- right deviation
- extreme right deviation
When would one expect to see an extreme right axis deviation on an EKG?
in someone with situs inversus
What are some possible causes of left ventricular hypertrophy?
- chronic hypertension is most common
- aortic stenosis, HOCM are also possible
How does hypertension show up on an EKG?
as a larger QRS complex in the aVL and V3 leads
Describe the EKG of a 1st degree AV block.
prolonged PR interval
Describe the EKG of a 2nd degree AV block, Mobitz I.
sequential prolonging of the PR interval followed by a dropped beat and then the pattern restarts
Describe the EKG of a 2nd degree AV block, Mobitz II.
- normal PR interval and then a non-conducted P wave
- so beats are occassionally skipped
Describe the EKG of a 3rd degree AV block.
complete dissociation between atrial depolarization and ventricular depolarization
How would one treat a 2nd degree AV block, Mobitz I?
avoid other AV nodal blocking agents or maneuvers
How would one treat a 1st degree AV block?
by avoiding other blocking agents or maneuvers
How would one treat a 2nd degree AV block, Mobitz II?
with a pacemaker
Which AV blocks are benign?
1st degree and 2nd degree Mobitz I
