"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).
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." lub-dub sounds
Let’s pull back the curtain on the human body’s most important soundtrack. In simple terms, the "lub-dub" is the sound of your heart valves snapping shut. "The squeeze is over