ECG Flashcards
Normal magnitude
10mm/mV
Normal speed
25mm/s
Calculate rate
Count QRS, x 6
Determining SR
-Each p wave followed by QRS
- Each QRS preceeded by p
- QRS regular
- PRi consistent
Normal PR
120ms-200ms
PR <120ms
Wolf Parkinson White - can cause re-entry tachycardias
A/w delta waves
PR >200ms (5 small sq)
1st degree heart block
QRS follows some, but not all, Pw
2nd degree heart block
Types of 2nd degree heart block
Mobitz Type 1 - gradual increase in PRi, finally missed QRS
Mobitz Type 2 - fixed PRi, regular droppings of QRS in a set ratio, e.g. 2:1 block
Which type of 2nd deg HB more likely requires pacing?
Mobitz Type 2
Pw and QRSc in no way linked
3rd deg HB, urgent pacing required
Best leads to determine axis
Lead 1 and aVF
Causes of L. axis deviation
LBBB
LVH
Old inf.MI
Pacing
LAFB
WPWs
Causes of R. axis deviation
RVH
PE
COPD
Old lat.MI
LPFB
NA channel blocker toxicity (e.g TCA OD)
WPWs
Causes of negative L1 & aVF
Hyperkalaemia
VT
Limb lead misplacement