Lub | Dub Heart Sounds

Auscultation (listening to the internal sounds of the body) is a cornerstone of the physical examination. The human heart produces two primary sounds per cardiac cycle, often phonetically described as "lub-dub." These sounds are usually the only ones audible in a healthy individual. Understanding the mechanics behind these sounds provides critical insight into cardiac function and structural integrity.

As the ventricles relax, pressure within them drops. When ventricular pressure falls below the pressure in the aorta and pulmonary artery, blood attempts to flow backward. This backflow snaps the semilunar valves shut, creating the S2 sound. lub dub heart sounds