R Waves Flashcards
(12 cards)
What is R wave progression?
The stepwise progression of R waves from negative to positive across the chest leads v1 - v6
What is the direction of depolarisation?
From the SA node in the RIGHT atrium, depolarisation travels DOWN and TO THE LEFT
Why does R waves progression get more positive?
The direction of depolarisation is to the left; therefore right sided leads will be negative (v1) and the furthest left will be positive
What is the transition point?
When R is equal to (or greater than) S
Usually occurs around lead V3 - V4
What can abnormal R wave progression indicate?
Anterior MI
LVH
RVH
Conduction disease
What does the ST segment signify?
No electrical activity
Ventricles are still depolarised - not yet repolarised
What changes in the ST segment indicate ischaemia?
Elevation OR depression
What is the difference in shape between concave up and concave down?
Concave up is normal
Concave down (or horizontal) is more likely ischaemia
What does the T wave represent?
Ventricular repolarisation
How can you tell if there is a primary change in the ST segment/ T wave?
Narrow QRS
anything that affects depolarisation subsequently affects repol - therefore a broad QRS will always result in ST /T wave changes
What might cause an abnormal T wave?
Ischaemia
Bundle branch block
Ventricular hyper trophy
Any prolonged QRS
In which leads are T waves normally inverted?
V1 and aVR
