A heart murmur itself is not a symptom you feel. It’s a sound, specifically a whooshing or swishing noise that a doctor hears through a stethoscope when turbulent blood flows through your heart. Most heart murmurs cause no symptoms at all and are completely harmless. But when a murmur is caused by a structural heart problem, such as a damaged valve or a hole in the heart wall, the underlying condition can produce noticeable symptoms ranging from breathlessness to chest pain.
What a Heart Murmur Actually Is
Blood normally flows through your heart in a smooth, orderly way. A murmur happens when something disrupts that flow and creates turbulence, the same way water rushing through a narrow pipe sounds different from water flowing through a wide one. That turbulence produces a sound your doctor can hear and grade on a scale from 1 (barely detectable, requiring focused effort) to 6 (so loud a stethoscope doesn’t even need to touch the chest).
Several things can cause that turbulence. A valve may have stiffened from calcium buildup, narrowing the opening blood passes through. A valve might not close completely, allowing blood to leak backward. Or a hole in the wall between heart chambers, present from birth, can let blood flow where it shouldn’t. In some cases, a thickened heart muscle forces blood through a tighter space, producing a louder murmur. Even anemia, which thins the blood, can create enough turbulence for a detectable sound.
Innocent vs. Abnormal Murmurs
There are two broad categories, and the distinction matters. Innocent heart murmurs are harmless sounds made when blood moves normally through the heart’s chambers, valves, or nearby blood vessels. They don’t indicate any structural problem. These are especially common in children and often disappear on their own over time. Pregnancy, exercise, fever, and rapid growth can all produce innocent murmurs temporarily.
Abnormal heart murmurs signal something wrong with the heart’s structure or function. Doctors evaluate the murmur’s loudness, location on the chest, timing within the heartbeat, and quality of sound to figure out what’s going on. A murmur that occurs when the heart contracts (systolic) and one that occurs when the heart relaxes between beats (diastolic) point to different types of problems. Counterintuitively, louder isn’t always worse: a small hole in the heart wall can actually produce a louder, harsher murmur than a large one, because blood is forced through a tighter space.
Symptoms in Adults
An innocent murmur produces no symptoms beyond the sound itself. You’d never know it was there without a stethoscope. When an abnormal murmur is caused by a valve disorder or other structural issue, though, the heart may struggle to pump blood efficiently. That’s when symptoms appear, and they come from the underlying heart condition rather than the murmur itself.
The most common symptoms include:
- Shortness of breath, especially during physical activity or when lying flat
- Chest pain
- Dizziness or fainting
- Fatigue that seems disproportionate to your activity level
- Swelling in the legs, ankles, feet, or abdomen
- A bluish tint to the skin, particularly the lips and fingertips
- A chronic cough that doesn’t seem related to a cold or allergies
These symptoms tend to develop gradually. A valve that slowly stiffens over years may produce a murmur long before you notice anything wrong. Many people first learn about a murmur during a routine physical and feel perfectly fine. That’s normal, and it often means the murmur is innocent or the underlying issue is mild enough that the heart is compensating well.
Symptoms in Infants and Children
Heart murmurs are extremely common in kids, and most are innocent. But when a murmur in a child signals a congenital heart defect, the signs can look different than in adults. Babies can’t tell you they feel dizzy or short of breath, so the symptoms show up in other ways.
Poor feeding is one of the earliest red flags. A baby with a significant heart problem may tire quickly during feedings, eat small amounts, or fail to gain weight at a normal rate. You might notice excessive sweating, especially during feeding. Breathing that seems faster than normal or labored, even at rest, is another key sign. In more serious cases, the skin around a baby’s lips, fingertips, or feet may take on a bluish color, which indicates the blood isn’t carrying enough oxygen.
Older children with abnormal murmurs may complain of chest pain, feel faint during exercise, or tire much more easily than their peers. Swelling in the legs, feet, or belly can also develop. If your child has been told they have a murmur and later develops any of these signs, that’s worth a prompt call to their doctor.
How Murmurs Are Diagnosed
The murmur itself is detected with a stethoscope during a physical exam. From there, your doctor evaluates the volume (on that 1 to 6 scale), where on the chest it’s loudest, when it occurs during the heartbeat cycle, and what the sound quality is like. These clues point toward which valve or structure might be involved.
If the murmur seems potentially abnormal, an echocardiogram is the primary diagnostic tool. This is an ultrasound of the heart that creates real-time images of the chambers, valves, and blood flow. It can show whether a valve is narrowed or leaking, whether there’s a hole between chambers, and how well the heart is pumping overall. The test is painless and takes roughly 30 to 60 minutes.
A chest X-ray may be ordered to check whether the heart is enlarged, since an overworked heart can gradually increase in size. An electrocardiogram (ECG) measures the heart’s electrical activity through sensors placed on the chest, looking for irregular rhythms or other electrical patterns that suggest a structural issue. In less common cases where these tests don’t provide a clear answer, a cardiac catheterization may be done, where a thin flexible tube is guided through a blood vessel to the heart for more detailed measurements.
What Causes Abnormal Murmurs
The most common cause in adults is valve disease. Heart valves can stiffen and narrow over time as calcium deposits build up, a condition called stenosis. This forces blood through a smaller opening, creating turbulence. Valves can also fail to close properly, allowing blood to leak backward with each heartbeat. Both situations make the heart work harder than it should.
In children, the most frequent cause is a congenital heart defect, particularly holes in the walls separating heart chambers. A hole between the upper chambers (atrial septal defect) or lower chambers (ventricular septal defect) lets blood flow between sides of the heart that should remain separate. Small holes sometimes close on their own during childhood. Larger ones may need repair.
Other causes include a thickened heart muscle that partially blocks blood flow out of the heart, a condition where blood is forced through an abnormally narrow section of the aorta, and infections that damage the heart valves. Even conditions outside the heart, like severe anemia or an overactive thyroid, can increase blood flow enough to produce a murmur.
When a Murmur Needs Treatment
Innocent murmurs need no treatment at all. They’re a normal finding, not a disease. Your doctor may mention it during an exam and move on.
For abnormal murmurs, treatment targets whatever is causing the turbulent flow. A mildly leaky valve with no symptoms may simply be monitored with periodic echocardiograms to track any changes over time. If a valve has narrowed or is leaking badly enough to strain the heart, the options range from medications that reduce the heart’s workload to procedures that repair or replace the valve. How urgently treatment is needed depends on whether symptoms are present and how well the heart is compensating.
Holes in the heart that don’t close on their own can sometimes be sealed with a device threaded through a blood vessel, avoiding open surgery. The key point is that a murmur alone doesn’t determine whether you need treatment. The decision depends on what’s causing it, whether it’s affecting heart function, and whether you’re experiencing symptoms.