Why is the Lub-Dub Louder Than the Tricuspid and Mitral Sounds?

Table of Contents Hide
  1. lub-dub
  2. tricuspid
  3. mitral
  4. pulmonary
  5. aortic

The lub-dub is one of the three major types of heart sounds. The other two are the tricuspid and mitral sounds. Let’s take a look at the normal sounds that these three types make. In addition, we’ll talk about how they are different.

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DUPP and lub sound are similar to each other, but there are some differences between them. The lub sound comes from the heart beating. During pregnancy, the heart produces the lub sound. During late diastole, the lub sound is louder than DUPP. Unlike the DUPP sound, which is the result of the heart fluttering, the lub sound is the result of the heart beating with more force.

The first sound of the heart is called the lub. It is produced when the mitral and tricuspid valves close. The second sound is called the dup and it is the same sound but has a slightly different pitch. At rest, the interval between the two heart sounds is longer.


The tricuspid sound is a characteristic of the heart. It is produced when a prolapsed leaflet from the tricuspid valve opens and closes, followed by a closure of the mitral valve. During a normal heart beat, the tricuspid sound is usually soft and low-pitched, while in the presence of a tricuspid prolapse, the noise is higher-pitched and loud.

In a normal heart, the mitral and tricuspid valves close almost simultaneously. In some patients, however, the tricuspid valve closes significantly before the mitral valve, creating two distinct audible sounds. This is known as a split-S1 sound, and can be clearly heard in up to 40% of normal patients.


A murmur, or sound, generated from the mitral valve is characteristic of various heart conditions. It may be a benign or dangerous symptom of heart disease. Whether the murmur is harmless or asymptomatic, a professional echocardiogram is an indispensable tool for the accurate diagnosis of heart problems.

The mitral valve produces two sounds: the first is called the aortic valve and is heard across the chest. The second, the pulmonic valve, is heard only in the pulmonic area and is much louder than the first. This second sound can also be heard in certain types of heart conditions, such as mitral stenosis, severe mitral regurgitation, and prolapsed mitral valve.


The pulmonary lub sound is louder than the aortic lub sound. It’s the result of the closure of the semilunar valves of the aortic and pulmonary arteries. The aortic valve closes first, followed by the pulmonary valve. The pulmonary valve closes last, because it sends more blood to the right side of the heart during inspiration. The amount of time between the two sounds varies depending on the respiratory rate.

In young people, the second heart tone is divided into its two components: the pulmonary area and the 2nd ICS, located on the left side of the sternum. During inspiration, the interval between the two components shortens and merges with the S1 sound.


A murmur is a sound produced by turbulent blood flowing through an incompetent valve. This condition causes blood to backflow against the valve, resulting in a noise reminiscent of someone sticking his thumb in a water hose. The first sound is often called the lub or lu-ub sound. A murmur chart indicates the location and level of the murmur, and can identify the cause of this symptom.

The Aortic lub sound is louder than the tricuspid lub sound. This is due to the high pressure in the systemic circulation slamming shut the aortic valve, while low pressure in the pulmonary circulation gently closes the pulmonary valve. This delay allows for a wider split of the sound. This delay can be exacerbated by increased right ventricular filling. As a result, more blood stays in the RV, delaying closure of the pulmonary valve.