Concentric activation

Acknowledgement

Antonio Rapacciuolo

Head of EP

What will you learn?

Normally, the only pathway available for action potentials to enter the ventricles is through a specialized region of cells (atrioventricular node, or AV node) located in the inferior-posterior region of the interatrial septum.
The A-V node slows the impulse conduction. When the A-V node is the only electrical connection between atria and ventricles, increasing heart rate will result in a prolonged A-V delay. This feature protects the ventricles from very high rate atrial activity.
The A-V node is also able to conduct electrical stimuli from the ventricles to the atria. Since in the normal heart it is the only electrical connection between atria and ventricles, the first atrial activity is demonstrated close to the region of the A-V node. This can be demonstrated by stimulating the right ventricle and positioning a decapolr catheter into the coronary sinus: the first atrial electrogram will be recorded by the proximal dipole while the most delayed one by the distal dipole