What does "atrial" mean?

Of or pertaining to an atrium, especially the atrium of the heart.

Atrial

/ˈeɪtɹi.əl/ adj

adj ·Rare ·Advanced level

Adjective

1
Of or pertaining to an atrium, especially the atrium of the heart. not-comparable
"The most common type of irregular heartbeat is atrial fibrillation or AFib. It is estimated that between three and six million people in the United States have AFib."

Adjective

1
of or relating to a cavity or chamber in the body (especially one of the upper chambers of the heart) wordnet

"Atrial fibrillation happens when electrical impulses in two of the four chambers of the heart go into an irregular or chaotic pattern."

From atrium + -al.