Second-degree atrioventricular block
（重定向自Wenckebach）
![](/Images/godic/202502/20/Second_degree_heart_block4825.png")
![Sinus rhythm with acute inferior infarction complicated by Type I A-V block manifest in the form of 5:4 Wenckebach periods; R-P/P-R reciprocity.](/Images/godic/202502/20/Type_I_A-V_block_5-to-4_Wenckebach_periods4825.png")
![Sinus rhythm (rate = 100/min) with 3:2 and 2:1 Type II A-V block; RBBB](/Images/godic/202502/20/Sinus_rhythm_with_3-to-2_and_2-to-1_Type_II_A-V_block4825.png")
Second-degree atrioventricular block (AV block) is a disease of the electrical conduction system of the heart. It is a conduction block between the atria and ventricles.
The presence of second-degree AV block is diagnosed when one or more (but not all) of the atrial impulses fail to conduct to the ventricles due to impaired conduction.