Lub-dub Sounds May 2026

That longer rest is crucial. It’s the moment when the heart fills up with blood again, preparing for the next "lub." Sometimes, a doctor doesn't hear a clean "lub-dub." Instead, they hear a "lub- shhh -dub" or a "lub-dub- whoosh ." This is called a heart murmur .

A slightly lower-pitched, longer "lub."

The powerful lower chambers of your heart (the ventricles) begin to contract. This sudden spike in pressure slams shut the two top valves: the Mitral and Tricuspid valves. These valves separate the upper chambers (atria) from the lower chambers. When they close, they vibrate, creating that thudding "lub" sound. lub-dub sounds

Spoiler alert: It’s not the heart muscle contracting, and it’s not the blood whooshing around.

"The squeeze is over. We are locking the exit doors to keep blood moving forward." The Silence in Between Have you noticed the pause between the "lub" and the "dub"? That silence is the systolic pause (the squeeze). The longer pause after the "dub" is the diastolic pause (the rest/fill). That longer rest is crucial

Thump-thump. Thump-thump.

After the heart squeezes blood out to the lungs and body, the ventricles relax. The blood in the major arteries (the Aorta and Pulmonary Artery) wants to rush back into the heart, but two different valves—the Aortic and Pulmonary valves—snap shut to stop it. Their closure creates the "dub." This sudden spike in pressure slams shut the

Think of your heart as a house with four rooms (chambers) and four doors (valves). To get blood moving in the right direction, those doors must open to let blood through and then slam shut to prevent it from leaking backward. The "lub" and "dub" are the sonic booms of those doors closing. The first sound, "Lub" (clinically known as S1 ), marks the beginning of systole —the moment your heart squeezes blood out to the body.