A fast, pounding heartbeat could be due to AFib, a type of heart rhythm problem. Know the warning signs and when treatment is needed.
Disease
Atrial flutter
Learn more about this condition in which the heart's upper chambers beat too quickly, causing a rapid, but usually regular, heart rhythm.
Disease
Atrial septal defect (ASD)
This heart problem that is present at birth causes a hole between the heart's upper chambers. It can be treated.
Disease
Atrial tachycardia
This type of fast heartbeat may occur after heart surgery or during pregnancy. But infections may trigger it too. Learn how it's diagnosed and treated.
Disease
Atrioventricular canal defect
This congenital heart defect involves a hole in the heart. It affects blood flow through the heart valves. Learn the symptoms and how it's treated.
This most common type of supraventricular tachycardia, a type of irregular heartbeat, tends to occur in young women. Know the symptoms and treatment.
Disease
Attention-deficit/hyperactivity disorder (ADHD) in children
This condition affects children and may continue into adulthood. It can include having a hard time paying attention, being hyperactive and being impulsive.
Disease
Atypical genitalia
In this rare condition, a baby's genitals are not clearly male or female. Genitals may not be fully developed or the baby may have features of more than one sex.
Disease
Atypical hyperplasia of the breast
Learn how a diagnosis of atypical lobular hyperplasia or atypical ductal hyperplasia affects your risk of breast cancer and what you can do.
Disease
Auditory processing disorder (APD)
This type of hearing loss involves the brain. Learn about ways that can help people with the condition hear better.
Disease
Autism spectrum disorder
This condition related to brain development causes problems in getting along with others socially and communicating. Symptoms and severity can vary widely.
Disease
Autoimmune encephalitis
Learn how the immune system mistakenly attacks brain cells to cause swelling in the brain related to this group of conditions.