1. Correlation between ECG and electrical cardiac activity
2. NORMAL
3. Sinus Bradycardia
   HR is about 46 with normal QRS complex shape and normal intervals
4. SVT
   HR is around 200, normal shape of QRS complex (narrow QRS complex tachycardia) with absent P waves
5. SVT
   HR is around 200, normal shape of QRS complex (narrow QRS complex tachycardia) with absent P waves
6. VT
   HR is around 200 with abnormally shaped QRS complexes (wide complex tachycardia)
7. VT
   HR is around 140 with abnormally shaped QRS complexes (wide complex tachycardia)
8. 2ND DEGREE HB
   No. of P waves is more than No. of QRS complexes, many P waves are not followed by QRS complexes.
9. VF
   Completely deformed ECG with no detectable QRS complexes
10. Delta wave
    WPW syndrome with slow upstroke of the QRS complex making the delta wave with short PR interval
11. Prolonged QT interval (Congenital long QT syndrome (Romano-Ward syndrome))
12. ECG changes with hyperkalemia