Heart Sounds Lub Dub Jun 2026

The colloquial term "lub-dub" refers to the two primary heart sounds, designated $S_1$ and $S_2$. While deceptively simple in nomenclature, the precise timing and quality of these sounds offer a window into the hemodynamic status of the patient. This paper aims to demystify the genesis of these sounds and highlight their clinical relevance.

When "lub-dub" is interrupted or obscured by a "whooshing" noise, a cardiac murmur is present. Murmurs result from turbulent blood flow and are graded on a scale of I (barely audible) to VI (audible with stethoscope off the chest). heart sounds lub dub