The heart tone “lub,” or S1, is caused by the closure of the mitral and tricuspid atrioventricular (AV) valves at the beginning of ventricular systole. The heart tone “dub,” or S2 ( a combination of A2 and P2), is caused by the closure of the aortic valve and pulmonary valve at the end of ventricular systole.

In a healthy adult, the heart makes two sounds, commonly described as ‘lub’ and ‘dub.’. The third and fourth sounds may be heard in some healthy people, but can indicate impairment of the heart function. S1 and S2 are high-pitched and S3 and S4 are low-pitched sounds.

The lub dub sounds are produced primarily by the closing of these heart valves during each cardiac cycle. The first sound (S1), or “lub,” occurs when the atrioventricular (AV) valves—the tricuspid and mitral valves—close at the beginning of ventricular contraction (systole).

This shutting of the atrioventricular valves creates the first sound of your heartbeat -- "Lub!" By this time, the heart's electrical signal has passed from the atria into the ventricles, so while the atria relax, the ventricles contract.

The lub dub sound is primarily created by the closing of heart valves during the cardiac cycle. The first sound, “lub,” occurs when the atrioventricular valves close at the beginning of ventricular contraction.

2021年1月26日 · There are 2 main heart sounds that can be heard during auscultation: S 1 and S 2, also affectionately known as ‘lub’ and ‘dub’ respectively. The S 1 and S 2 heart sounds are part of the normal heart sounds.

2025年3月20日 · The meaning of LUBB-DUPP is the characteristic sounds of a normal heartbeat as heard in auscultation.

The second “lub-dub” is the sound of the aortic and pulmonary valves closing soon after. But if there is a problem, a murmur may be added to this normal “lub-dub.” By using a stethoscope to listen to your heart, your doctor’s trained ear can tell if the abnormal sound indicates turbulence.

If you put a stethoscope over the chest, you’ll usually hear something that sounds like lub dub, lub dub, lub dub, which repeats over and over again, with each cardiac cycle, or heartbeat.

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