Mitral valve prolapse produces two signature sounds heard through a stethoscope: a sharp mid-systolic click, followed by a late systolic murmur. The click is a brief, high-pitched snapping sound that occurs partway through each heartbeat, and the murmur is a whooshing noise that trails after it. Not everyone with mitral valve prolapse has both sounds. Some people have only the click, some have only the murmur, and some have both together.
The Mid-Systolic Click
The most distinctive sound of mitral valve prolapse is the mid-systolic click. It’s a short, crisp, high-pitched pop that happens in the middle of the heart’s contraction phase. To understand why it happens, picture the mitral valve as two small flaps held in place by tiny tendon-like cords called chordae tendineae. In a normal heart, those cords keep the flaps sealed shut while the heart squeezes blood out. In mitral valve prolapse, the flaps are enlarged or stretched, and the cords may be longer than usual.
As the heart contracts, the floppy flaps billow backward into the upper chamber. The click occurs at the exact moment the stretchy cords snap taut, like a parachute catching air and jerking its lines tight. Ultrasound studies have confirmed the timing: the click coincides precisely with the instant the valve leaflet reaches its point of maximum prolapse and the tension on those cords peaks. It’s essentially the sound of the valve’s support structure being yanked to its limit.
This click is best heard at the apex of the heart, which sits near the left side of the chest just below the nipple. It’s different from an aortic ejection click (another type of heart sound) because it occurs later in the contraction cycle, well after the pulse begins.
The Late Systolic Murmur
After the click, many people with mitral valve prolapse also have a murmur. This is a whooshing or blowing sound caused by blood leaking backward through the valve (regurgitation) once the flaps have prolapsed. The murmur starts at the moment of the click and continues through the rest of the contraction. It’s typically described as a crescendo murmur, meaning it gets louder as it goes.
In some cases, the murmur takes on an unusual quality. Rather than a soft whoosh, it can sound like a honk or a whoop. This honking character comes from the valve leaflets themselves vibrating as blood flows past them, almost like a reed in a musical instrument. It can be surprisingly loud and has occasionally alarmed patients who can hear it without a stethoscope.
How Body Position Changes the Sound
One of the most telling features of mitral valve prolapse is that its sounds shift depending on what the person is doing. This happens because the timing of the click and murmur depends on how full the heart is with blood. When the heart holds less blood, it reaches the critical volume where the valve flaps can no longer stay closed sooner in the contraction. That means the click happens earlier, and the murmur lasts longer.
Standing up or bearing down (the Valsalva maneuver, like straining on the toilet) reduces blood return to the heart. Both of these make the click move earlier in the heartbeat and the murmur grow louder and longer. Squatting does the opposite: it pushes more blood back to the heart, delays the click, and shortens the murmur. Gripping something tightly with both hands (a handgrip maneuver) also changes the sound by increasing resistance in the blood vessels, which makes the murmur louder but actually delays the click.
Doctors use these positional changes as a diagnostic tool. If a heart sound shifts predictably with standing, squatting, or straining, that pattern is a strong indicator of mitral valve prolapse rather than other conditions that can produce similar murmurs.
How It Differs From Other Heart Sounds
The murmur of mitral valve prolapse can sound similar to the murmur caused by hypertrophic cardiomyopathy, a condition where the heart muscle is abnormally thick. Both get louder with standing and the Valsalva maneuver. The key difference is what happens during a handgrip: gripping increases the mitral valve prolapse murmur but decreases the hypertrophic cardiomyopathy murmur. This distinction matters because the two conditions require very different management.
Pure mitral regurgitation from other causes (a torn cord, a damaged valve from infection) typically produces a murmur that lasts through the entire contraction, from start to finish. Mitral valve prolapse is different because there’s usually a silent gap at the beginning of the contraction before the click and murmur kick in. That silent gap, followed by the click, is what makes mitral valve prolapse sound unique.
What You Might Notice Yourself
Most people with mitral valve prolapse never hear anything unusual. The click and murmur are typically only detectable with a stethoscope. But in cases with a loud honking murmur, the sound can occasionally be audible to the person or even to someone sitting nearby. Some people with MVP also feel a sensation that matches the click, described as a brief flutter or skip in the chest. This isn’t the same as a dangerous arrhythmia, though it can feel unsettling.
Many people with mitral valve prolapse have no audible findings at all, especially when lying down or when the prolapse is mild. The condition is often picked up incidentally during an echocardiogram (heart ultrasound) rather than by stethoscope alone. An echocardiogram remains the definitive way to confirm the diagnosis and assess whether any significant blood is leaking backward through the valve.