Patients & Family
The heart
- The heart at work
- The heart's electrical system
The heart's electrical system
The electrical signal and normal sinus rhythm
The beating of the heart is controlled by the heart’s electrical system. The electrical system controls the speed and rhythm of your heartbeat. The system includes a network of electrical pathways, connected together by control areas called nodes.
The electrical signal originates in the right atria in a place known as the sinus node. The electrical signal continuously travels a path through your heart. When the signal arrives into one of the chambers, it causes the chamber to contract. When the signal moves out of that chamber, the chamber relaxes. In a healthy heart, the chambers contract and relax in a coordinated manner, known as rhythm.
This cycle of electrical stimulation is known as normal sinus rhythm and produces the familiar (‘lubb-dubb’) heartbeat sound.
If a problem occurs in your heart's electrical system, it can disrupt your heart's normal sinus rhythm. Any kind of abnormal rhythm or heart rate is called an arrhythmia. It's normal and healthy for your heartbeat to speed up or slow down during the day as your activity level changes. But it's not normal for your heart to beat out of rhythm. When your heart beats out of rhythm, it may not deliver enough blood to your body.
Electrical Signals
Hearts have several electrical currents running throughout them. The sinus node, often called the heart’s natural pacemaker, contains the most active electrical cells and initiates heartbeats.
Other electrical nodes found in the heart are responsible for transmitting signals to different sections of the heart.
Problems in an electrical node or anywhere along the electrical pathway can disrupt the regular beating of the heart and cause different types of arrhythmia.
For example, the atrioventricular (AV) node transmits signals from the atria to the ventricles. Disruptions within this pathway causes a disorder known as AV nodal reentrant tachycardia, which causes the heart to beat too fast.
Another type of abnormal electrical pathway between the atrial and ventricles can lead to a congenital syndrome that causes the heart to beat too fast. This syndrome is known as Wolff-Parkinson-White Syndrome.
