EKG Flashcards
Inferior MI leads
II, III, aVF
Lateral MI leads
I, aVL, V5, V6
Posterior MI leads
AVR
Septal MI leads
V1, V2
Anterior MI leads
V3, V4
Time of a small box
0.04
Time of a big box
0.2
Number of Boxes and Rate
1 box-300 bpm
2 boxes- 150 bpm
3 boxes- 100 bpm
4 boxes- 75 bpm
Best place to look for p waves
Inferior limb leads
Define first degree AV block
Delayed conduction through AV node
Longer PR interval >200ms
2nd degree AV block
Aka Mobitz 1
Aka Wenckebach
Progressively longer PR interval with a non conducted (dropped) beat
2nd degree AV block Mobitz II
PR interval is constant with intermittent dropped beat
3rd degree heart block
No association between QRS and P waves, often more p waves than QRS- higher atrial rate
Inverted p waves indicate:
Lower atrial or junctional rhythms with retrograde conduction…
Know the axis
Method for determining QRS axis
- Find isoelectric lead- direction of vector is perpendicular to this lead
- Choose lead that is 90 degrees away
- If QRS is +, this is the axis
- If QRS is -, axis is 180 degrees from this lead
Causes of right axis deviation
RV strain (PE)
COPD (pulmonary hypertension)
Lateral STEMI
Causes of Left axis deviation
LBBB
Inferior MI
Wave characteristics in left atrial enlargement
Lead II Bifid P wave- (two connected waves)
Lead V1- biphasic
Right atrial enlargement
Peaked p wave (p pulmonale) >2.5mm leads II, III
Sokolow- Lyon index
EKG criteria for ventricular hypertrophy
S in V1 + R in V5 >35mm….
Pattern of strain in EKG
Downsloping ST depression with rapid UPSLOPE
Pathological Q waves
> 2mm deep
25% of QRS complex
ST/T abnormalities with Qs suggest true infarct
Small Qs are normal
ISCHEMIA in ST depression
> 1mm of horizontal or downsloping ST depression 60-80 msec after J point