The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node(SA node), situated in the walls of right atrium of the heart to be propagated to and stimulate the muscle of the atria and ventricles(myocardium). The myocardium contracts after stimulation. It is the ordered stimulation of the myocardium that allows efficient contraction of the heart, thereby allowing blood to be pumped throughout the body.
The parts of the heart beat in an orderly sequence: Contraction of the atria(atrial Systole) is followed by contraction of ventricles(ventricular Systole), and during Diastole(relaxation) all the four chambers are relaxed.
The structure that makes up the conduction system of the heart are:
- Sinoatrial node (SA node)– electrical impulses of heart arises form this structure which is situated in the wall of the right atrium.
- Internodal atrial pathways – there are three conduction pathways between SA node and AV node.
- Atrioventricular node (AV node)– the only conducting tissue between the atria and ventricles and situated at the lower part of septa dividing two atria.
- Bundle of His and its branches – takes over the impulses from the AV node and distributes to the ventricular musculature.
- Purkinje fibers – Purkinje fibers are the final conductive tissue leading the electrical impulses to the deeper tissues of ventricles.
The electrical conduction in the heart can be monitored by use of an electrocardiogram(ECG). ECG is a non invasive method of evaluating the electrical activity of heart. Abnormal patterns in conduction of impulses in the cardiac musculature are– arrhythmia, flutter, fibrillation etc. these can be life threatening conditions unless urgently attended to.