A heart murmur is an extra whooshing or swishing sound heard between or during normal heartbeats, caused by turbulent blood flow through the heart. Hearing the word "murmur" can be alarming, but most murmurs — especially in children and young, healthy adults — are completely harmless. The job of your doctor isn't just to detect a murmur, but to figure out which kind it is.
What Is a Heart Murmur?
Your heart normally makes two crisp sounds with each beat (often described as "lub-dub"), created by your heart valves closing. A murmur is an additional sound — heard with a stethoscope — caused by blood moving with more turbulence than usual as it flows through the heart's chambers or valves. Murmurs are graded by loudness on a standard scale (roughly 1 out of 6, barely audible, up to 6 out of 6, audible without even touching the stethoscope to the chest), but loudness alone doesn't determine how serious a murmur is.
Innocent vs. Pathologic Murmurs
This is the central distinction that determines everything else:
- Innocent (or "functional") murmurs happen in a structurally normal heart — they reflect normal blood flow that simply makes an audible sound, often because it's moving quickly (during fever, pregnancy, exercise, or in children and adolescents whose hearts and vessels are proportionally smaller). These require no treatment and no restrictions.
- Pathologic murmurs reflect an actual structural problem — most often a heart valve that's narrowed (stenotic) and doesn't open fully, or one that doesn't close tightly and leaks (regurgitant), or, less commonly, a hole or abnormal connection within the heart's structure.
A murmur's specific characteristics — where in the heartbeat cycle it occurs, where on the chest it's loudest, whether it radiates elsewhere, and how it changes with position or breathing — all give a trained examiner real information about which category it likely falls into before any imaging is even done.
What Causes Pathologic Murmurs
- Valve disease is the most common cause in adults — aortic stenosis, aortic regurgitation, mitral regurgitation, mitral stenosis, and tricuspid regurgitation each produce a somewhat distinct, recognizable murmur pattern. (See Valvular Heart Disease for the conditions themselves.)
- Hypertrophic cardiomyopathy can produce a murmur that changes distinctively with certain maneuvers, which is itself a diagnostic clue.
- Congenital heart defects — present from birth, sometimes not discovered until adulthood if mild — such as a hole between heart chambers (septal defect) or an abnormal connection between major vessels.
- High-flow states — anemia, fever, pregnancy, hyperthyroidism — can turn a normal heart's blood flow audibly turbulent without any structural problem at all, which is why a new murmur during pregnancy or an illness isn't automatically concerning on its own.
How It's Diagnosed
A murmur is usually first noticed during a routine physical exam with a stethoscope — it may be found incidentally, with no symptoms at all. From there:
- Your doctor's exam technique (timing, location, radiation, response to breathing or position changes) narrows down the likely cause before any test is ordered
- An echocardiogram is the key test — it directly visualizes the valves and heart structure, shows whether a murmur reflects a real abnormality, and if so, how significant it is
- Additional testing (ECG, chest X-ray, or more advanced imaging) is added selectively based on what the echo shows (see Cardiac Testing & Imaging)
When It's Usually Nothing to Worry About
- Found in a child or young adult with no other symptoms, normal growth, and normal activity tolerance
- Soft, brief, and doesn't radiate to the neck, back, or elsewhere
- Doesn't change with a family history of concerning heart conditions
- Confirmed as "innocent" by a normal echocardiogram
When to Call Your Doctor vs. Go to the ER
- A murmur is newly noticed at any age, especially in an adult, even without symptoms
- You have a known murmur and notice new shortness of breath, fatigue, or reduced exercise tolerance
- You have a known valve condition and are planning dental work or a procedure — some conditions warrant preventive antibiotics beforehand, which is worth confirming with your team
- A murmur is accompanied by chest pain, fainting, or severe shortness of breath
- Sudden, severe symptoms develop in someone with a known significant valve problem
Common Questions
I was told I have a murmur — does that mean I have heart disease?
Not necessarily at all — many murmurs, especially in children, are innocent and reflect a completely normal heart. An echocardiogram is what actually answers the question.
Will I need surgery?
Most murmurs never require any procedure — even many pathologic ones are simply monitored for years with periodic echocardiograms before (or instead of) any intervention is needed.
Can a murmur come and go?
Yes — innocent murmurs can appear and disappear with fever, pregnancy, or exertion, since they reflect flow conditions rather than a fixed structural problem.
I had a murmur as a child — do I need to worry about it as an adult?
Ask your doctor to confirm what type it was; a childhood innocent murmur usually resolves and needs no ongoing follow-up, but it's worth having that documented rather than assumed.
Can a murmur be heard through a stethoscope over clothing, or does it need to be a full exam?
A proper murmur evaluation needs direct auscultation through a thin layer or bare skin, in a quiet room, sometimes in more than one position (lying down, sitting, or after a brief position change) — this is part of why a rushed exam can miss or mischaracterize one.