Question

Describe what would happen if instead of the AV bundle and bundle branches running down the septum and branching into Purkinje fibers that run up the lateral sides (outside walls) of the heart, the conducting pathway went from the AV node and branched out in a web throughout the ventricles towards the apex. How would this impact electrical activity and contraction of the ventricles? A complete answer should describe the function in the normal case, and how the new case would differ.

Answer 1

The conducting system of the heart conducts an impulse which is generated by pacemaker cells Sino-Atrial node (SA node), then the impulse is passed to the relay centre i.e., Atrio-Ventricular node (AV node) via three internodal pathways.

The impulses delay by 0.1 secs in AV node, which is called decremental conduction. Later from AV node, impulse gets conducted to the His Bundles, bundle branches (right and left), purkinje fibers, ventricular muscle or atrial muscle in an order.

So, when the conducting pathway went from AV node and branched out throughout the ventricles towards of apex, the duration of each impulse decreases and it may result in transmission of rapid impulses to ventricular muscles.

It may ultimately results in extreme ventricular tachycardia which interferes with ventricular function.