heart murmur
A heart murmur is an extra whooshing, blowing, or swishing sound heard between the normal heartbeats, made by turbulent blood flow inside the heart or its great vessels. Smooth, fast flow through a wide channel is silent, like water gliding down a deep river; force that same flow through a narrowing, or backward through a leaky gate, and it tumbles into turbulence that the stethoscope picks up as a murmur.
Clinicians characterize a murmur by its timing in the cardiac cycle (systolic, between the first and second heart sounds, or diastolic, after the second), its loudness, where on the chest it is loudest, where it radiates, and its pitch and quality. These features point toward the source: a tight aortic valve gives a harsh systolic murmur, a leaky mitral valve a blowing systolic murmur carrying toward the armpit, and so on. The pattern is a map back to the underlying valve or flow problem.
Crucially, not every murmur means disease. Innocent or flow murmurs are common in children, pregnancy, fever, or anemia, where extra-fast but otherwise normal flow makes a soft sound through healthy valves. Distinguishing innocent from pathological murmurs rests on the sound's features, the rest of the examination, and, when needed, an echocardiogram to look at the valves directly.
On auscultation, a harsh systolic murmur loudest over the upper right chest and radiating to the neck suggests narrowing of the aortic valve, confirmed by Doppler echocardiography.
Where a murmur is loudest and where it radiates help localize which valve is involved.
A murmur's timing is the single most useful clue: systolic murmurs have many innocent causes, whereas a diastolic murmur is almost always abnormal and warrants imaging.