The heart has four chambers – two at the top (the atria) and two at the bottom (the ventricles). The normal trigger for the heart to contract arises from the heart’s natural pacemaker, the SA node, which is in the top chamber the Right Atrium
The Sino Atrial Node (SA) node is a section of nodal tissue located in the upper wall of the right atrium. The SA node is also referred to as the pacemaker of the heart coordinates the contraction of the heart sends out regular electrical impulses causing the atrium to contract and to pump blood into the bottom chamber (the ventricle). [A node is a specialized type of tissue that behaves as muscle and nerve tissue. When nodal tissue contracts (like muscle tissue) it generates nerve impulses (like nervous tissue) that travel throughout the heart wall.] The electrical impulse then passes to the ventricles through a form of ‘junction box’ called the AV node (atrio-ventricular node). This electrical impulse spreads into the ventricles, causing the muscle to contract and to pump blood to the lungs and the body.
What is Sinus Syndrome?
Sick sinus syndrome is the name for a group of heart rhythm problems i.e. a condition in which the heart beats with an irregular or abnormal rhythm-(arrhythmias) in which the sinus node — the heart’s natural pacemaker — doesn’t work properly.
Normally, the sinus node produces a steady pace of regular electrical impulses. In sick sinus syndrome, these signals are abnormally paced. A person with sick sinus syndrome may have heart rhythms that are too fast, too slow, punctuated by long pauses — or an alternating combination of all of these rhythm problems.
This syndrome is a very rare one, but chances of getting this increases with age. Many people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm.