ECG 2

Question 1

normal axis of QRS is down and to the left by how many degrees

Answer 1

60 degrees -from 0 at LA

Question 2

if there is a change in the mean axis of your QRS, what does that tell you

Answer 2

-there is something pathological going on

Question 3

what degrees correspond with leads:

1,2,3, Avr, avl, avf

Answer 3

1- 0
2-60
3- 120
Avr-210
AvL- -30
AvF- 90

Question 4

axis deviation

Answer 4

when the mean electrical axis is outside normal limits

Question 5

left axis deviation reasons

Answer 5

hypertrophy- systemic htn, valve disease, congenital
obesity
end of deep expiration
supine
left bundle branch block (wide QRS)

Question 6

right axis deviation reasons

Answer 6

• end of long inspiration
• tall stature
• hypertrophy- pulmonary valve stenosis, pulm htn, congenital
• right bundle branch block
• coming to standing position

Question 7

what causes an abnormal QRS

Answer 7

A) increased voltage:

• more muscle that’s depolarizing
• thin chest (like in a grandma)-thin and can detect the electrical signal better so it looks like increased voltage

b) Decreased voltage:
- previous MI (less muscle, also wide QRS)
- fluid in pericardium or pleural space (dampens signal that reaches outside the surface of the body)
- Large chest size from pulmonary emphysema, insulate charge and reduce what reaches the surface

Question 8

if a patient has a prolonged QRS, what can that indicate?

Answer 8

-previous MI because less efficient at contracting the ventricles

Question 9

If a patient has a pleural effusion, what can that do to the QRS voltage?

Answer 9

decrease the voltage as it impedes the electric signal

Question 10

what would you expect the QRS to look like on a thin, old lady?

Answer 10

-increased voltage because it picks up the voltage better

Question 11

if a patient has ventricular hypertrophy, what can it do to the QRS voltage?

Answer 11

-it can increase the voltage as there is more muscle to charge

Question 12

what causes ST depression

Answer 12

subendocardial injury

Question 13

what causes ST elevation

Answer 13

transmural (epicardial injury) -MI

Question 14

what ekg features do we see with hyperkalemia
rhythm 
rate
p
pr
qrs
QT
ST
T

Answer 14

-rhythm and rate are normal
-P wave- mild to low amplitude
-PR- normal or prolonged
-qrs- lengthened
-QT-shortened -the amt of time vent. contract is lessened
ST- may be elevated
T-peaked

Question 15

hypokalemia
rhythm 
rate
p
pr
qrs
QT
ST
T

Answer 15

rhythm -normal
rate- normal
p- normal
pr- may be prolonged
qrs- within normal limits or possibly widened
QT- not discernible as T wave flattens
ST- depressed
T-amp is decreased; inverted T wave (U) may appear

Question 16

hypercalcemia
rhythm 
rate
p
pr
qrs
QT
ST
T

Answer 16

rhythm-normal
rate-normal
p-normal
pr-may be prolonged
qrs-normal or prolonged
QT-prolonged
ST-normal
T-normal, maybe depressed

Question 17

hypocalcemia
rhythm 
rate
p
pr
qrs
QT
ST
T

Answer 17

rhythm -normal
rate-normal
p- normal
pr-normal
qrs-normal
QT-prolonged
ST-prolonged
T-normal, maybe flattened