AH interval on ECG is for conduction ?

Ans. is 'b' i.e., From AV node to bundle of His Ceain intervals are measured to provide information regarding AV block. i) PA interval : It is time taken from onset of P-wave to onset of deflection in atrial catheter. It is an index of intra-atrial conduction. Normal vlaue is less than 55 mS. ii) AH interval : it represents conduction through AV node, i.e., conduction from AV node to bundle of His. Normal vlaue is less than 130 mS. iii) HV interval : It represents conduction through His-Purkinje system, i.e., conduction from His-Purkinje system to ventricular muscle fibers. Normal value is less than 50 mS.