Sinus Arrhythmia

Sinus beats show a gradual cyclical change in R–R intervals.

Programmatically generated teaching example. Morphology and supporting values are simplified.

Typical rate: Varies with the cycle
Regularity: Cyclic variation
P waves: Upright; one per QRS
PR interval: Constant
QRS: Narrow, <120 ms

Sources and review status

This guide uses RhythmDock’s centralized educational definitions. See reference sources and limitations. Published September 13, 2026. Independent medical review is pending; this is not a clinical interpretation tool.