Av block of ii &iii degree

In A-Vblock, electrical impulses which arise from atrium or sinus node they are partially or completely block and couldn`t reach to atrioventricular node and ventricle. in first degree A-Vblock A-V conduction time(P-R-interval) prolonged and in second degree A-V block some atrial impulses fail to reach the ventricles and thus atria and ventricle beat independently.