Atrial systole

Atrial systole is a critical phase in the cardiac cycle where the atria of the heart contract to pump blood into the ventricles. This process is initiated by the sinoatrial node, often referred to as the heart's natural pacemaker.

Overview

During atrial systole, the atria contract following an electrical signal from the sinoatrial node. This contraction forces blood into the ventricles, filling them and preparing them for the next phase of the cardiac cycle, the ventricular systole. The atrial systole accounts for about 20% of ventricular filling.

Physiology

The sinoatrial node generates an electrical impulse that travels through the walls of the atria, causing them to contract. This contraction pushes blood through the open atrioventricular valves into the ventricles. The atrioventricular valves then close to prevent backflow of blood into the atria when the ventricles contract.

Clinical significance

Disruptions in the atrial systole can lead to various cardiac arrhythmias, such as atrial fibrillation and atrial flutter. These conditions can result in inefficient blood flow and are associated with an increased risk of stroke and heart failure.

See also

• Cardiac cycle
• Sinoatrial node
• Atrial fibrillation
• Atrial flutter