What is sick sinus syndrome? Sick sinus syndrome is the name for
several conditions in which the sinus node does not work the
right way. The sinus node (also called the sinoatrial node) is a
natural pacemaker in your heart that helps your heart beat
steadily. An electric current starts in one of the upper
chambers (called the atria) of the heart and goes through the
heart to the bottom chambers (called the ventricles). The sinus
node can increase your heart rate during times of high demand,
such as during exercise. If you have sick sinus syndrome, your
heart rate may be too slow or too fast to meet the needs of your
body. About 1 in 600 people with heart problems have sick sinus
syndrome. It usually affects people who are at least 70 years
old. Women are affected about as often as men. Written by
familydoctor.org editorial staff