Aortic stenosis produces a harsh, rough murmur that rises and then falls in intensity during each heartbeat. Doctors often describe this crescendo-decrescendo pattern as diamond-shaped on a sound recording, meaning the murmur starts soft, builds to a peak, and fades before the next beat. It’s one of the most recognizable heart sounds in clinical medicine, and its specific qualities reveal a lot about how severe the narrowing has become.
The Core Sound: A Harsh, Rising-Falling Murmur
The classic aortic stenosis murmur is low to medium pitched and has a quality variously described as harsh, rasping, grunting, or rough. If you’ve ever heard audio recordings, the sound is often compared to a “whooshing” or “blowing” noise with a gritty texture layered over it. It occurs during systole, the phase when the heart is actively pumping blood out through the narrowed aortic valve. That’s what gives it the crescendo-decrescendo shape: blood accelerates through the tight opening, reaches peak turbulence mid-squeeze, then slows as the contraction ends.
This diamond-shaped envelope is one of the key features that distinguishes aortic stenosis from other systolic murmurs. A leaking mitral valve, for example, produces a more constant, plateau-like sound throughout systole rather than one that builds and fades. That difference in shape is often the first clue a clinician picks up on.
Where It’s Loudest
The murmur is heard best at the right upper edge of the breastbone, roughly at the second rib space. This makes anatomical sense because the aortic valve sits just beneath that spot. From there, the sound commonly travels upward into the neck. A doctor can often hear it clearly over the carotid arteries on both sides, and in some patients the vibration is strong enough to feel with a hand placed on the neck.
That transmission into the neck corresponds to an important physical finding called pulsus parvus et tardus, a slow-rising, late-peaking pulse. In rare cases, the murmur’s vibrations traveling through the neck vessels are even visible to the naked eye as a delayed pulsation in the suprasternal notch (the small dip at the base of the throat).
The Gallavardin Phenomenon
Sometimes the murmur sounds different depending on where you listen. At its usual spot near the right collarbone, it has that classic harsh, rough quality. But when a clinician moves the stethoscope down to the apex of the heart (near the left nipple), the same murmur can take on a higher-pitched, almost musical tone. This shift is called the Gallavardin phenomenon, and it can trick even experienced listeners into thinking two separate problems are present. It’s actually the same murmur being filtered differently by the chest wall and surrounding structures.
Extra Sounds That Accompany the Murmur
Beyond the main murmur, aortic stenosis can produce additional sounds that help paint the full picture.
An ejection click is a brief, high-pitched “snap” heard just after the first heart sound. It occurs at the moment the stiffened valve leaflets reach their maximum opening. Ejection clicks are especially common in younger patients whose valves are still somewhat flexible, particularly those born with a bicuspid aortic valve (two leaflets instead of the usual three). When a bicuspid valve isn’t yet significantly narrowed, the click tends to be loud and clearly separated from the first heart sound. As stenosis worsens and the valve becomes more rigid, the click often disappears because the leaflets can no longer snap open with any force.
The second heart sound also changes. Normally, this “dub” in the “lub-dub” has two components: the aortic valve closing followed almost immediately by the pulmonary valve closing. In aortic stenosis, the aortic component becomes quieter because the thickened, calcified valve leaflets don’t slam shut with their usual force. In severe cases, the aortic closure sound may be nearly inaudible.
How the Sound Changes With Severity
One of the most clinically useful features of the aortic stenosis murmur is that its timing shifts as the valve gets tighter. In mild stenosis, the murmur peaks early in systole, relatively close to the first heart sound. As the obstruction worsens, the peak moves progressively later, occurring closer to mid or even late systole. This happens because the left ventricle has to work harder and longer to force blood through the narrowing, so peak turbulence shifts later in the ejection phase.
Severe aortic stenosis is typically defined by a peak blood velocity across the valve of 4 meters per second or higher, or a mean pressure difference of at least 40 mmHg. At this level of obstruction, aortic valve closure can be delayed so much that it actually occurs after the pulmonary valve closes, reversing the normal order. This is called paradoxical splitting of the second heart sound, and hearing it is a strong indicator of severe disease.
There’s one important caveat: in very advanced disease, when the heart muscle itself starts to fail and can no longer generate strong contractions, the murmur can actually become quieter. A softer murmur doesn’t always mean milder disease. It can mean the heart has weakened to the point where it can’t push enough blood through the valve to create loud turbulence. This is one reason the murmur alone isn’t enough for diagnosis, and echocardiography (ultrasound of the heart) is used to measure the actual valve opening and blood flow velocities.
What It Sounds Like Compared to Other Murmurs
Several heart conditions produce murmurs during systole, so distinguishing them matters. The crescendo-decrescendo shape is the single most helpful feature separating aortic stenosis from mitral regurgitation, which produces a more uniform, “blowing” murmur that stays at roughly the same intensity throughout systole. Mitral regurgitation is also loudest at the apex of the heart rather than the upper right chest, and it tends to radiate toward the left armpit rather than the neck.
Hypertrophic cardiomyopathy, a condition where the heart muscle is abnormally thick, can produce a similar-sounding crescendo-decrescendo murmur. One way clinicians differentiate it at the bedside is through physical maneuvers. Straining down (the Valsalva maneuver) tends to make hypertrophic cardiomyopathy louder while making true aortic stenosis softer, because reducing the amount of blood in the heart shrinks the turbulence across a fixed valve narrowing but worsens the dynamic obstruction in a thickened heart.
What You Might Experience
If you have aortic stenosis, you won’t hear the murmur yourself. It requires a stethoscope to detect, and even then, it takes a trained ear to characterize the timing, pitch, and radiation accurately. What you might notice are the downstream effects of the narrowed valve: shortness of breath during exertion, chest tightness, dizziness or fainting spells, and fatigue that worsens over months or years. These symptoms tend to emerge once stenosis reaches the severe range, and their onset typically signals that the condition will progress meaningfully within two to five years.
If a doctor tells you they heard a murmur during a routine exam, the next step is usually an echocardiogram, which gives precise measurements of how open the valve is and how fast blood is moving through it. The murmur itself provides the first clue, but those measurements determine what happens next.