Intraatrial and Interatrial Conduction Delays

This section will provide an overview on intraatrial conduction delays, which are slowdowns in conduction within the atria, and interatrial conduction delays, which are slowdowns in conduction between the right and left atria.

This section will cover:

• Normal atrial conduction pathways, such as: the internodal tracts, which connect the sinus node to the AV node; Bachmann's bundle, the main "highway" that conducts signals from the right atrium to the left atrium; and the coronary sinus, which offers an alternative pathway for activating the left atrium.

• The pathobiology behind atrial conduction disorders, such as toxic-metabolic effects (i.e. hyperkalemia, sodium channel blocking medication) and fibrosis (either from structural heart disease or cardiac surgery). 

• Intraatrial conduction delays, extending from a minor prolongation of atrial depolarization causing a flattened p wave, to atrial standstill.

• Interatrial conduction delays due to either partial or complete conduction delays in Bachmann's bundle, and its effect on the ECG.

• Atrial dissociation, which is a phenomenon whereby there the right and left atria are electrically isolated from each other, usually due to heart surgery (i.e. transplantation). This will also cover dissimilar atrial rhythms, where there is coexistence of atrial flutter or fibrillation in one atrium and a more regular rhythm in the other.