ECG Flashcards
Normal PR interval
120-200 ms (3-5 small squares)
First degree heart block
Fixed prolonged PR interval where QRS complex is always present
Second degree heart block mobitz type 1
Gradual prolonging of PR interval and hen a missed QRS
Second degree heart block mobitz type 2
PR interval is fixed but there are dropped beats, clarify if it is 2:1, 3:1 ect
Third degree heart block
No relation between QRS and P waves
What does a short PR interval mean
SA node is closer to the AV node or accessory pathway e.g WPW syndrome - Delta waves
Delta waves
early ventricular depolarisation e.g WPw syndrome - not diagnostic need tachy too
two causes of broad QRS
Ventricular etopic and bundle branch block
cause of tall QRS
Ventricular hypertrophy
where should the transition from S > R wave to R > S wave happen?
V3 or V4
What could S>R in V5 and V6 suggest?
Previous MI
What does r wave progression mean?
small R in V1 and big R in V6
ST elevation is significant when it is greater than 1 mm (1 small square) in
2 or more contiguous limb leads or >2mm in 2 or more chest leads.
ST depression ≥ 0.5 mm in ≥ 2 contiguous leads indicates
myocardial ischaemia.
T waves are tall if they are
> 5mm in the limb leads AND > 10mm in the chest leads (the same criteria as ‘small’ QRS complexes)
Tall T waves can be associated with
Hyperkalaemia (“Tall tented T waves”)
Hyperacute STEMI
T waves are normally inverted in
V1 and if in III normal variant
if you see abnormal T wave inversion
Describe anatomical distribution
Describe Biphasic T waves
Biphasic T waves have two peaks and can be indicative of ischaemia and hypokalaemia
describe Flattened T waves
Another non-specific sign, this may represent ischaemia or electrolyte imbalance
Describe U waves
The U wave is a > 0.5mm deflection after the T wave best seen in V2 or V3.
These become larger the slower the bradycardia – classically U waves are seen in various electrolyte imbalances or hypothermia, or antiarrhythmic therapy (such as digoxin, procainamide or amiodarone).
Inferior leads
II, III, aVF
Lateral leads
I, aVL, V5, V6
Anterior leads
V3, V4
