top of page

Pacemaker Tissues of the Heart



  • Pacemaker produces impulses to trigger heartbeats.

  • Cells of the pacemaker tissue depolarize spontaneously → fire action potential at regular intervals. This firing rate is different for different pacemaker tissues.

  • Following tissues have pacemaker activity:

    • SA Node (Sinoatrial Node): Firing rate 70-80 /min

    • AV Node (Atrioventricular Node): Firing rate 40 /min

    • Purkinje Fibers: Firing rate 20 impulses/min

The fastest pacemaker tissue dominates the others

↓

Sets the pace of the heart

↓

As SA node is the fastest among all

↓

Normally the pacemaker of heart is SA node

↓

SA node is called primary pacemaker of the heart

↓

If SA node does not function properly

↓

The next fastest tissue i.e. AV node becomes the pacemaker

↓

AV node is called secondary pacemaker of the heart

↓

If AV node also fails

↓

Purkinje fibers set the pace

↓

Purkinje fibers are called tertiary pacemaker

↓

However Purkinje fibers are very slow and not reliable as pacemaker

↓

Might need to implant artificial pacemaker

 

Next >>

Comments


bottom of page