Editing Cardiac pacemaker (section)

==Clinical significance==
===Damage to the SA node===
If the SA node does not function, or the impulse generated in the [[Sinoatrial block|SA node is blocked]] before it travels down the electrical conduction system, a group of cells further down the heart will become its pacemaker.<ref>{{EMedicine|article|155146|Junctional Rhythm}}</ref> This center is typically represented by cells inside the [[atrioventricular node]] (AV node), which is an area between the [[Atrium (heart)|atria]] and [[Ventricle (heart)|ventricles]], within the [[atrial septum]].  If the AV node also fails, [[Purkinje fibers]] are occasionally capable of acting as the default or "escape" pacemaker.

===Ectopic pacemaker===
[[File:Ectopic focus.svg|thumb|Illustration depicting an [[ectopic focus]]]]
An [[ectopic pacemaker]] also known as an ectopic focus or ectopic foci, is a group of  [[excitable cells]] that causes a premature heart beat outside the normally functioning SA node of the heart. It is thus a cardiac pacemaker that is ectopic, producing an ectopic beat. If chronic this can result in [[arhythmia]]s such as [[tachycardia]], [[bradycardia]], or [[ventricular fibrillation]]. An [[artificial pacemaker]] may be used to counter this.

====Artificial pacemakers====
{{Main|Pacemaker}}
A [[pacemaker]] is an artificial cardiac pacemaker, that is an [[Implant (medicine)|implanted medical device]] that generates electrical impulses delivered by electrodes to the chambers of the heart either the upper atria, or lower ventricles to cause the targeted chambers to contract and pump blood. By doing so, the artificial pacemaker takes over from the primary SA node pacemaker to regulate the function of the heart's electrical conduction system.