An abnormal and irregular heart rhythm in which electrical signals are generated chaotically throughout the upper chambers (atria) of the heart. Many people with atrial fibrillation have no symptoms. Among those who do, the most common symptom is an uncomfortable awareness of the rapid and irregular heartbeat (palpitations). Atrial fibrillation can promote the formation of blood clots that travel from the heart to the brain, resulting in stroke. Treatment of atrial fibrillation involves risk-factor control, use of medications to slow the heart rate and/or convert the heart to
normal rhythm, and prevention of blood clots. Also known as auricular fibrillation.
- Atrial septal defect (ASD)
Atrial septal defect (ASD): A hole in the septum, the wall, between the atria, the upper chambers of the heart. Commonly called an ASD. ASDs constitute a major class of heart formation abnormalities present at birth (congenital cardiac malformations). Normally, when clots in veins break off, they travel first to the right side of the […]
- Atrioventricular (AV)
Atrioventricular (AV): Pertaining to the atria (the upper chambers of the heart) and the ventricles (the lower chambers of the heart). The AV node is an electrical relay station between the atria and the ventricles. Electrical signals from the atria must pass through the AV node to reach the ventricles. The AV node is a […]
- Atrioventricular node
Atrioventricular node: The electrical relay station between the upper and lower chambers of the heart. Abbreviated AV node. Electrical signals from the atria must pass through the AV node to reach the ventricles. The AV node, which controls the heart rate, is one of the major elements in the cardiac conduction system. The AV node […]
Atrium: An entry chamber. On both sides of the heart, the atrium is the chamber that leads to the ventricle.
- Atrophic vaginitis
Atrophic vaginitis: Thinning of the lining (endothelium) of the vagina due to decreased production of estrogen. Atrophic vaginitis may occur with menopause.