- Atropine is a parasympatholytics that blocks the M2 receptor of the SA node. Therefore, atropine increases the rate of SA node firing & thus => improving the conduction thru the AV node.
=> Therefore, Atropine can be used for sinus bradycardia because the SA node just needs some kicks.
=> Therefore, Atropine can be used for 2nd degree AV block Wenckebach bc the site of the cause of the AV node wenckeback is at the AV node.
=> Therefore, Atropine is not effective for 2nd degree AV block Mobitz type 2 because the site of the problem blockage is below the AV node.