Just as musical instruments create sound by air moving through small openings, fluid moving briskly in containers or small spaces and going through small openings can create turbulence which can create a sound. Blood moving through heart valves that are working properly can sometimes create a murmur which is “innocent” and not due to any serious cardiac problem. This can also occur if the heart is working vigorously in non-cardiac conditions such as pregnancy, anemia or an overactive thyroid. However, significant heart valve abnormalities or structural heart defects (whether present at birth, known as congenital heart disease, or acquired due to disease) can cause a heart murmur.
Louder murmurs can be due to more serious valve problems, but some of the most significant structural heart problems can cause very soft or faint murmurs. Experienced cardiologists or physicians can often get an idea of how serious a valve problem or structural heart abnormality is by carefully listening to the heart with the stethoscope. Often, listening to a patient’s heart sounds over time allows the physician to determine the progression of the underlying problem, especially in conjuction with other signs on physican exam, changes in a patient’s symptoms and other findings from testing. Ultimately, echocardiography, or an ultrasound of the heart, is the test of choice to help confirm structural heart or heart valve disease and whether a heart abnormality is changing in conjunction with patient symptoms and physical exam. A cardiologist is often asked to evaluate a patient with a heart murmur.
When blood flow is turbulent within the heart, a heart murmur usually is present. When a valve is not opening adequately (valve stenosis), the area that blood flows through is restricted or smaller than usual which leads to turbulence of flow. If a valve is not closing properly and blood is leaking backwards (valve regurgitation), turbulence is usually present.
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Written by and/or reviewed by Mark K. Urman, M.D. and Jeffrey F. Caren, M.D.