Atrioventricular nodal delay is due to
Cause of the Slow Conduction. The slow conduction in the transitional, nodal, and penetrating A-V bundle fibers is caused mainly by diminished numbers of gap junctions between successive cells in the conducting pathways, so there is great resistance to conduction of excitatory ions from one conducting fiber to the next. Therefore, it is easy to see why each succeeding cell is slow to be excited.Ref: Guyton and Hall textbook of medical physiology 13th edition. Page:125
Less gap junctions
More tight junctions
Intercalated discs
Prolonged refractory period
Cardiovascular system