Master the 8-step systematic approach, recognise life-threatening patterns in seconds, and never miss a STEMI, Wellens, or complete heart block again. The new ECG Atlas has 27 canvas-rendered waveforms with diagnostic criteria and management.
The Golden Rule of ECG Reading
Always interpret ECG in clinical context. A "normal ECG" does NOT exclude ACS. Always compare with previous ECGs. Treat the patient, not the ECG.
Calculate ventricular rate. Normal 60–100. <60 = bradycardia. >100 = tachycardia.
Regular or irregular? Is it regularly irregular (e.g. AF + fixed block) or irregularly irregular (AF)? Compare R–R intervals.
Present? Morphology (upright in I, II)? P before every QRS? QRS after every P? 1:1 relationship?
Normal 120–200ms? Constant? Lengthening? Non-conducted beats? Short (<120ms = WPW or junctional)?
Duration <120ms? Morphology (RBBB vs LBBB). R-wave progression V1–V6. Q waves (pathological if >40ms or >25% R height)?
Elevation or depression? Which leads? Reciprocal changes? J-point elevation? Convex vs concave morphology?
Upright or inverted? Symmetric or asymmetric inversion? Peaked (hyperkalaemia)? Biphasic (Wellens)?
Calculate QTc (Bazett: QT ÷ √RR). Normal <440ms male, <460ms female. Prolonged = risk of Torsades.
Small square
1mm = 0.04 sec = 40 ms
Large square
5mm = 0.20 sec = 200 ms
Vertical (amplitude)
1mm = 0.1 mV
Standard speed
25 mm/sec (most ECGs)
Emergency
ACLS & cardiac protocols
Hypertension
BP management module
Algorithms
Chest pain decision trees
Drug Database
Antiarrhythmic dosing
Based on ACC/AHA, ESC, and BTS guidelines. ECG interpretation always requires clinical context. When in doubt — senior review.