sinoatrial

adj.
Of or relating to the sinoatrial node: a sinoatrial heart block.

[SIN(US) + ATRIAL.]

(sī'nō-ā'trē-əl) or si·nu·a·tri·al (sī'nū-ā'trē-əl, -nyū-, sĭn'yū-)
adj. (Abbr. S-A)

Relating to the venous sinus and the right atrium of the heart.

Pertaining to the sinus venosus and the atrium of the heart or to the sinoatrial node; abbreviated S-A, SA.

• s. block — an absence of a discharge from the sinoatrial node. The heart is regular unless there is an underlying atrial arrhythmia. Considered to be within the limits of normality provided it disappears with exercise.
• s. node — a collection of atypical muscle fibers and nerve endings in the wall of the right atrium, adjacent to the sulcus terminalis, where the rhythm of cardiac contraction is usually established; therefore also referred to as the pacemaker of the heart. Called also sinoatrial bundle, Keith's node, Keith–Flack node.