At the junction of the superior vena cava and high lateral right atrium is a cluster of cells that generates the initial electrical impulse of each normal heart beat, called the sinoatrial (SA) or sinus node. Electrical discharge of these pacemaker cells stimulates adjacent cells, leading to stimulation of successive regions of the heart in an orderly sequence. Impulses are transmitted through the atria to the atrioventricular (AV) node via preferentially conducting internodal tracts and unspecialized atrial myocytes. The AV node is located on the right side of the interatrial septum. It has a slow conduction velocity and thus delays impulse transmission. AV nodal transmission time is heart-rate–dependent and is modulated by autonomic tone and circulating catecholamines to maximize cardiac output at any given atrial rate.
Almost all of us have felt very fast heart beats some times in. . . .
Treatment may not always be needed if you have an arrhythmia. In. . . .
The Electrical System in Your Heart An average heart beats. . . .
To diagnose a heart arrhythmia, your doctor will ask questions. . . .
Types of Arrhythmias There are two basic kinds of arrhythmias. . . .
Your heart works as a pump that takes blood to the lungs and then. . . .