Sick sinus syndrome (also known as sinus node dysfunction) is a group of related heart conditions that can affect how the heart beats. "Sick sinus" refers to the sino-atrial (SA) node, which is an area of specialized cells in the heart that functions as a natural pacemaker. The SA node generates electrical impulses that start each heartbeat. These signals travel from the SA node to the rest of the heart, signaling the heart (cardiac) muscle to contract and pump blood. In people with sick sinus syndrome, the SA node does not function normally. In some cases, it does not produce the right signals to trigger a regular heartbeat. In others, abnormalities disrupt the electrical impulses and prevent them from reaching the rest of the heart.
Sick sinus syndrome can result from genetic or environmental factors. In many cases, the cause of the condition is unknown.
Sick sinus syndrome accounts for 1 in 600 patients with heart disease who are over age 65. The incidence of this condition increases with age.
Most cases of sick sinus syndrome are not inherited. They are described as sporadic, which means they occur in people with no history of the disorder in their family.
Published Date: August 01, 2013Published By: National Institutes of Health