Label the parts of the cardiac conduction system on the diagram
Describe the normal ECG trace
What does each waveform correlate with?
P wave = Atrial systole causing increase in ventricular volume
PR interval = Time taken for current to pass from SA node to AV node
QRS segment = Isovolumic ventricular contraction which initiates ventricular systole
T wave = ventricular repolarisation
What is the frontal QRS axis?
The direction of the vector sum (average direction of the electrical depolarisation as it spreads through the ventricles during a single cardiac cycle).
Defined graphically by the QRS deflections of the frontal leads
Where are the precordial leads placed?
V1: 4th intercostal space just to right of sternum
V2: 4th intercostal space just to the left of sternum
V3: In between V2 and V4
V4: 5th intercostal space in mid clavicular line
V5: In same horizontal plane as V4, in anterior axillary line
V6: In same horizontal plane as V4 and V5 in the mid axillary line
Which surfaces of the heart to V1-V6 view?
(V1-V4 extensive anterior)