EKG intro Flashcards
what is the direction of electrical current flow?
from negative to positive
what axis is aVR?
-150 (or 10 o’clock)
what axis is aVL?
-30 (or 2 o’clock)
what axis is I?
0 (or 3 o’clock)
what axis is II?
60 (or 5 o’clock)
what axis is aVF?
90 (or 6 o’clock)
what axis is III?
120 (or 7 o’clock)
electrical force directed toward + pole of a lead generates what deflection?
positive deflection in that lead
what determines magnitude of deflection?
how parallel electrical force is to lead: more parallel = greater magnitude of deflection
what does perpendicular force look like?
flat line
what does 1 mm (one small box) represent?
.1 mV
how long is 1 mm?
.004 sec (5 small boxes/1 big box = 200 ms)
normal EKG findings include?
- every P followed by QRS
- upright P in I, II and III
- PR interval between 120 and 200 ms
- HR btwn 60-100 bpm
how to calculate HR?
1500/(# of small boxes between 2 QRS complexes)
alternate sequence to count with?
300 - 150 - 100 - 75 - 60 - 50
HR calc for irregular rhythm?
of QRS during 6 seconds, multiply by 10
normal QRS axis values?
-30 degrees to +90 degrees
which leads determine this most easily?
evaluate QRS in I and II (or I and aVF). if net QRS is + (and if II is most +) it’s normal
LVH findings?
ST segment depression, T wave inversion in leads with prominent R wave
RVH findings?
shifts QRS vector to R.
fascicular block findings?
?
RBBB findings?
V1: 2nd wide R wave (RSR) aka rabbits’ ears. also inverted T. but overall positive.
V6: late slurred S wave (overall broad QRS)
LBBB findings?
V1: deep wide S waves, looks like a W (negative)
V6: broad M. no Q waves.
criteria for RBBB?
unifascicular block.
- QRS complex greater than .12 sec
- RsR (M shaped/rabbits’ ears) QRS in lead V1
- widened/slurred S wave in I and V6
criteria for LBBB?
bifascicular block.
- QRS greater than .12 sec
- widened or slurred R wave of I and V6 (broad R, no Q)
- prominent QS or rS in V1 (broad S)
acute anterolateral MI on EKG?
STEMI. ST elevation in I, aVL, V2 thru V6
