ECGs are frequently presented to candidates sitting the OSCE element of the exam, a systematic approach is essential.
- Name, date, calibration (1mv=1cm, 0.2s=1cm [small square 40 msec])
- Rate = 300/number of big squares between Q-Q
- Rhythm AF, tachy (>100), brady (<60), sinus, heart block
- Axis normal = -30° to +110°
P peaked, tall Dright atrial hypertrophy
notched, broad Dleft atrial hypertrophy
P-R >5 small squares
I degree block: prolonged PR interval
II degree block:
Wekeneback: sequential of PR interval
Mobitz typ II: fixed PR, dropped QRS (2:1, 3:1…)
III degree block: disassociation of P and QRS
QRS wide (<2.5 small squares)
MarroW Dright bundle branch block
WilliM Dleft bundle branch block
Q 1mm wide, 2mm/25% of R-wave
D old MI
Normal in lead I, aVL V6
ST raised: 1mm 2xconsangious limb-leads, 2mm chest-leads
Depression: myocardial ischemia
Reverse tick: digoxin effect
Saddle shaped elevation: acute constrictive pericarditis
T peaked hyperkalaemia
Flat, prolonged, hypokalaemia
Normal in III, V1-2 (and V3 in Negroes)
MI: Hyperacute T-waves, ST-elevation T-wave inversion, Q-waves. Inf. (II, III, aVF) Ant. (V1-4), Lat. (I, aVL,V5-6) Post. look at V1-2. New LBBB.
PE: S-I (deep S-waves in I), Q-III (Q-waves in III), T-III (inverted T-waves in III). More generally a sign of R-heart strain.
Hyperkalaemia: tall tented T, wide QRS
Hypokalaemia: flattened T, prominent U, (muscle weakness, cramps, tetany)
ECG Wave-Maven – is a resource with many “barn-door” ECGs, presented in a quiz format; large database, expert explanations.