ECG Flashcards
what does the ECG record
the electrical activity of the heart
at rest what is the intracellular voltage of the myocardium compared to that of the extracellular space
-90mV
when does depolarisation of cardiac cells occur
when there is a sudden increase in permeability to the membrane of sodium
sodium rushes into the cell
what are the leads at the inferior wall of the left ventricle
II, III, aVF
what leads give a septal view
V1
V2
what leads give and anterior view
V3
V4
what leads give a lateral view
Lead I V5 V6 aVR aVL
what leads give an inferior view
Lead I
Lead II
aVF
what are the leads at the posterior left ventricle
V7,V8,V9
what is the interval of p wave duration
<0.12 sec
what is the time of the PR interval
0.12-0.2 sec
what is the time interval of the QRS
<0.1 sec
what are the normal, left axis deviated and right axis deviated cardiac vectors
- normal = between -30 and +90
- left axis deviation = between -30 and - 90
- right axis deviation = between +90 and +150
what can cause ST segment depression on an exercise ECG
myocardial ischaemia provoked by exertion
what can cause ST segment elevation on an exercise ECG
transmural ischaemia
