Development of the Cardiac Conduction System

Question 1

The fibrous annulus of the mitral and tricuspid valves are derived from what structure? Disturbances of epicardial outgrown result in what clinical EP phenomenon

Answer 1

The pro-epicardial organ (PEO). Mechanical inhibition of proper out growth ofthe epicardium results in broad accessory AV connections and pre-excitation

Question 2

What is a Monckeberg sling and with what congenital heart disease conditions is it associated?

Answer 2

The Monckeberg sling is the eponym for “twin-av nodes”. This congenital conduction system anomaly is due to the development and persistence of 2 AVN with separate penetrating His bundles. It can cause reentry. The sling is specialized conduction tissue that connects the nodes. It is most often seen in unbalanced AV canal, AV discordance. There is typically an anterior AV node such as that seen in LTGA and a posterior AV node such as is seen in AV canal.