• A 12-lead ECG can be interpreted systematically by following a series of steps:
1- Rate -- fast or slow?
2- Rhythm -- sinus? regular or irregular?
3- Axis -- normal or deviated?
4- Intervals (PR, QRS, QT) -- shortened or prolonged?
5- P waves -- biphasic? inverted? uniform?
6- QRS complexes -- high voltage? bundle branch block? pathologic Q?
7- ST segments -- elevated or depressed?
8- T waves -- peaked? inverted?
• Depending on the patient’s clinical picture, steps might not be followed in exact order and certain components are looked at first to expedite diagnosis and management. For example, in:
Angina with suspecting STEMI: look for ST elevation and Q wave (step 6)
Palpitation with suspecting atrial fibrillation: look for irregular rhythm and absence of P wave (step 2)
Hyperkalemia: look for peaked T wave and presence of sine wave (step 8)
