The aortic regurgitation murmur is a high-pitched, blowing sound heard best in early diastole, the brief pause after each heartbeat when the aortic valve should be sealed shut. Its presence is one of the strongest bedside clues that blood is leaking backward from the aorta into the left ventricle. A large review of the evidence found that hearing this early diastolic murmur makes the diagnosis of at least mild aortic regurgitation 9 to 32 times more likely, and its absence largely rules moderate or worse disease out.1JAMA. Does This Patient Have Aortic Regurgitation? But the murmur has quirks that trip up even experienced clinicians, including a systolic companion sound that can send the workup in the wrong direction and a set of whole-body vascular signs that belong more to the 19th century than to a modern echo lab.
What the Murmur Actually Sounds Like
The classic aortic regurgitation murmur starts immediately after the second heart sound and fades away as diastole progresses. Clinicians describe it as “decrescendo,” meaning it begins at its loudest and gradually trails off, like a gust of wind dying down. It is high-pitched, soft, and blowing in quality, which is precisely why it is easy to miss in a noisy room or during a rushed exam. You hear it best with the diaphragm of the stethoscope pressed firmly along the left sternal border, roughly at the third or fourth intercostal space, while the patient sits up and leans forward after a full exhale. That posture brings the aortic root closer to the chest wall and quiets the lungs.
The pitch reflects the physics of the leak. Blood rushes backward through a narrow gap between the aortic valve leaflets under a steep pressure gradient, and that high-velocity jet vibrates surrounding tissue at higher frequencies. As the pressure difference between the aorta and the left ventricle shrinks through diastole, velocity drops, the vibrations get quieter, and the murmur fades. In severe disease, the pressure equalizes so fast that the murmur can become surprisingly short, which is counterintuitive: a louder, longer murmur does not always mean worse disease. Echocardiographic measures like the rate at which the pressure difference falls over time help sort out severity when the stethoscope alone sends mixed signals.2PubMed Central. Echocardiographic assessment of aortic regurgitation: a practical guideline from the British Society of Echocardiography
What Causes the Leak
Aortic regurgitation can arise from problems with the valve itself or from stretching of the aorta around a structurally normal valve. On the valve side, a bicuspid aortic valve is one of the most common congenital culprits. People born with two cusps instead of three sometimes live for decades before the valve begins leaking, and the first sign may be severe left ventricular failure that seems to appear out of nowhere.3PubMed Central. An undiagnosed bicuspid aortic valve can result in severe left ventricular failure Rheumatic heart disease, once the leading cause worldwide, remains important in low- and middle-income countries. It scars and retracts the valve cusps over years, eventually preventing them from closing completely.
Infective endocarditis is a more abrupt cause. Bacteria colonize the valve, forming vegetations that erode the leaflets or create perforations. In some cases the infection spreads beyond the valve into surrounding tissue, producing abscesses, aneurysms of the mitral-aortic junction, or even perforation into the pericardial sac.4Journal of the American Society of Echocardiography. Transesophageal echocardiographic recognition of an unusual complication of aortic valve endocarditis These complications can turn a manageable valve problem into a surgical emergency.
On the aorta side, dilation of the aortic root is a major and sometimes underappreciated mechanism. When the root enlarges, it pulls the valve leaflets apart even if the leaflets themselves are perfectly normal. Conditions like Marfan syndrome, other connective tissue disorders, and age-related degeneration all enlarge the root progressively. Surgical guidelines call for replacing the root and ascending aorta once dilation reaches a threshold, because the secondary regurgitation will only worsen as the aorta continues to stretch.5PubMed Central. Dilation of the thoracic aorta: medical and surgical management
The Systolic Murmur That Often Tags Along
Here is something that surprises people who learn about aortic regurgitation from a textbook: most patients with moderate disease also have a systolic murmur, not just a diastolic one. In one study, a systolic murmur was present in 86 percent of patients with moderate aortic regurgitation and half of those with mild disease.6Clinical Cardiology. A systolic murmur is a common presentation of aortic regurgitation detected by echocardiography The majority of those systolic murmurs were classified as benign-sounding, meaning they could easily be mistaken for an innocent flow murmur or ignored as unrelated to the aortic valve.
The explanation is straightforward. When blood leaks back into the left ventricle during diastole, the ventricle has to pump a larger-than-normal volume forward on the next beat. That extra flow through the aortic valve during systole creates turbulence, producing a systolic ejection murmur even though the valve’s opening is not actually narrowed. The danger for the patient is that a doctor hears the systolic sound, dismisses it, and never listens carefully enough for the softer diastolic murmur hiding behind it. In clinical practice, the diastolic component is the diagnostically important one, but the systolic component is often the louder of the two.
Classic Signs You Can See and Feel
Chronic severe aortic regurgitation produces a striking collection of physical signs involving arteries throughout the body. These occur because the wide pulse pressure, a high systolic pressure paired with a very low diastolic pressure, sends exaggerated pulsations to every large vessel. Historically, these signs carried the names of the physicians who described them, and while modern imaging has made them less essential for diagnosis, they remain part of bedside teaching and still show up in clinical exams.
- Water hammer pulse: A forceful, rapidly rising and rapidly collapsing radial pulse, best felt by lifting the patient’s arm above their head. It reflects the steep rise in systolic pressure followed by the runoff of blood back through the leaking valve.
- Corrigan’s pulse: A visibly pulsatile carotid artery with the same rapid upstroke and sharp descent. In one case report of severe aortic regurgitation, the carotid pulsation was dramatic enough to be captured on video.7PubMed Central. Water hammer and Corrigan’s pulses
- Quincke’s pulse: Alternating flushing and blanching at the nail beds, visible when light pressure is applied to the fingernail tip.
- De Musset’s sign: A rhythmic bobbing of the head in time with the heartbeat, driven by the exaggerated arterial pulsations in the neck.
Duroziez’s sign deserves its own mention because it tests for something subtler. When you press a stethoscope gently over the femoral artery, you normally hear a single systolic sound. In significant aortic regurgitation, pressing a bit harder produces a second murmur during diastole. That diastolic murmur is created by retrograde blood flow in the femoral artery, confirmed by pulsed-wave Doppler ultrasound showing blood reversing direction in the artery during diastole. The sign has been reported to be close to 100 percent specific and about 90 percent sensitive for pure aortic regurgitation.8PubMed Central. Duroziez’s Sign A study using graphic tracings in the 1940s debated whether the second murmur truly reflected backward flow or was an artifact of arterial compression, and the question was eventually settled by Doppler imaging decades later confirming genuine retrograde flow.9American Heart Journal. On the pathogenesis of the signs of Traube and Duroziez in aortic insufficiency
Wide pulse pressure itself is an important clue. In that same case showing the water hammer pulse, blood pressure was 150 over 50, giving a pulse pressure of 100 mmHg, far beyond the normal range.10PubMed Central. Water hammer and Corrigan’s pulses All of these peripheral signs share a single cause: too much blood slamming forward in systole and then draining back through the faulty valve in diastole. If you see them in combination, especially the collapsing pulse and a low diastolic pressure, the stethoscope is almost certain to reveal the early diastolic murmur at the left sternal border.
How Reliably Can a Doctor Hear It
The honest answer is that auscultation is good but not great, and it depends heavily on who is listening. In a direct comparison of detection methods, auscultation had a sensitivity of 73 percent and a specificity of 92 percent for diagnosing aortic regurgitation. That means about one in four patients with the condition had no audible murmur. Pulsed Doppler echocardiography, by contrast, reached 96 percent sensitivity and 96 percent specificity, and it was positive in 19 patients in whom no murmur was found at all.11PubMed. Detection of aortic insufficiency by standard echocardiography, pulsed Doppler echocardiography, and auscultation. A comparison of accuracies
A broader systematic review looking at heart auscultation for valve disease in general found sensitivity ranging anywhere from 30 to 100 percent depending on the type of valve disease, the setting, and the examiner’s specialty. Most of the included studies relied on cardiologists or internal medicine specialists; when general practitioners did the listening, accuracy was lower.12BMJ Open. Diagnostic accuracy of heart auscultation for detecting valve disease: a systematic review This matters practically because many patients with early aortic regurgitation are first evaluated in a primary care office, not a cardiology suite. The diastolic murmur of aortic regurgitation is faint, high-pitched, and easy to confuse with ambient noise, a breath sound, or the murmur of pulmonic regurgitation.
Even among cardiologists, agreement on whether a diastolic murmur is present is only moderate when listening to recordings. In a clinical setting with a live patient, agreement improves substantially, likely because clinicians combine what they hear with what they see and feel, including the pulse character and blood pressure readings.13JAMA. Does This Patient Have Aortic Regurgitation? That integrated approach is how the bedside exam was always meant to work: the stethoscope alone is just one input.
The Austin Flint Murmur
One of the more confusing sounds in cardiology is the Austin Flint murmur, a low-pitched rumbling sound heard at the apex of the heart during diastole. It occurs in significant aortic regurgitation and mimics the murmur of mitral stenosis, despite the mitral valve being structurally normal. The mechanism involves the regurgitant jet from the aortic valve striking the anterior leaflet of the mitral valve, partially closing it and creating turbulence in the incoming blood from the left atrium. The result is a diastolic rumble that can fool even experienced examiners into thinking there is mitral valve disease when the real problem is entirely at the aortic valve.14New England Journal of Medicine. Austin-Flint murmur versus the murmur of organic mitral stenosis
In case reports of severe aortic regurgitation, the Austin Flint murmur appears alongside the full constellation of peripheral signs: collapsing pulse, de Musset’s sign, Quincke’s pulse, and the early diastolic blowing murmur at the sternal border.15PubMed Central. Duroziez’s Sign Its presence generally indicates at least moderate regurgitation, because a small leak does not generate enough jet force to displace the mitral leaflet. In practice, echocardiography quickly settles the distinction between an Austin Flint murmur and true mitral stenosis, but on a physical exam, the two can sound nearly identical. The key differentiator at the bedside is that mitral stenosis typically has a loud first heart sound and an opening snap, whereas the Austin Flint murmur does not.
Acute Versus Chronic Aortic Regurgitation at the Bedside
Everything described so far applies primarily to chronic aortic regurgitation, where the left ventricle has had months or years to adapt by dilating and increasing its stroke volume. Acute aortic regurgitation is a different and more dangerous clinical picture, and the physical exam findings differ in ways that can be misleading.
When the valve fails suddenly, as with endocarditis eroding a leaflet or an aortic dissection tearing the root apart, the left ventricle has no time to enlarge. Blood pours back into a normal-sized, stiff chamber, and the diastolic pressure inside the ventricle shoots up rapidly. This means the pressure difference between the aorta and the ventricle equalizes quickly, so the diastolic murmur is short and soft rather than long and prominent. The wide pulse pressure and bounding peripheral signs also tend to be absent, because the ventricle cannot generate the exaggerated forward stroke volume that produces them. A patient in acute aortic regurgitation can look and sound deceptively normal on exam while deteriorating rapidly from pulmonary edema and low cardiac output. This is one scenario where relying on the classic murmur description from textbooks can be actively dangerous.
AI-Assisted Stethoscopes
Given the difficulty humans have with auscultation, there has been growing interest in letting algorithms listen to heart sounds. A recent study tested an artificial intelligence stethoscope system that used machine learning to classify left-sided valve diseases from recorded heart sounds. For aortic regurgitation specifically, the system achieved an area under the receiver operating characteristic curve of about 0.71, which represents moderate but far from excellent discrimination. It performed better for mitral regurgitation and for detecting any left-sided valve disease in general, where the area under the curve reached 0.85 with sensitivity of 83 percent and specificity of 78 percent.16PubMed Central. Automatic Diagnosis of Left Valvular Heart Disease Based on Artificial Intelligence Stethoscope
These numbers are a reality check for the enthusiasm surrounding AI in cardiology. An area under the curve of 0.71 for aortic regurgitation means the algorithm performs roughly on par with, or slightly worse than, an experienced human listener, which is itself not a particularly high bar. The hope is that future iterations trained on larger and more diverse datasets will improve, and that the technology will be most useful in settings where a cardiologist is not available, such as rural primary care clinics or community screening programs. For now, echocardiography remains far more reliable than either a human ear or an algorithm applied to heart sounds, and any clinical suspicion of aortic regurgitation should be confirmed with imaging regardless of what the stethoscope reveals.
When Severity Changes What You Hear
One of the more counterintuitive aspects of the aortic regurgitation murmur is that severity and loudness do not track in a straight line. Mild regurgitation often produces a faint, short diastolic murmur. Moderate regurgitation tends to produce the longest and most clearly audible murmur, because there is enough leak to generate continuous turbulence but the ventricle is still compensating well enough to maintain a significant pressure gradient throughout diastole. In severe disease, particularly in the acute setting, the murmur can actually shorten again as the ventricle fills rapidly and the driving pressure gradient collapses early.
This is why echocardiographic measures of severity have largely supplanted the stethoscope for grading. The rate at which the pressure difference between the aorta and the ventricle falls, measured as the pressure half-time on a Doppler tracing, directly reflects how fast equalization occurs. A shorter pressure half-time means more severe regurgitation, because a bigger leak equalizes pressure faster.17PubMed Central. Echocardiographic assessment of aortic regurgitation: a practical guideline from the British Society of Echocardiography Additional Doppler parameters like the width of the regurgitant jet, the volume of backflow, and the size of the opening through which blood leaks are combined into a grading scheme that is far more reproducible than what any stethoscope can provide. The murmur still serves as the first alert, the signal that something is wrong and that the echo machine should come out. But it was never meant to be the final word on how bad the leak is.