A heart murmur is an abnormal heart sound that could be caused by congenital and acquired structural abnormalities, but may sometimes also be present in healthy hearts. Valvular causes are obstructed (stenotic) valves and leaky (regurgitant) valves. Both conditions result from distortions in the valve leaflets and turbulent blood flow. Other structural causes are stiff, hypertrophied ventricles, with walls that vibrate when jets of blood hit them, and abnormal inter-chamber communications such as atrial or ventricular septal defects.
Murmur quality, timing, location, radiation, and loudness lead the clinician to a diagnosis. Examples of quality include harsh, musical, mechanical, or grinding. Examples of timing include systolic or diastolic; crescendo-decrescendo or continuous (“holosystolic”, or “holodiastolic”); and early-peaking, mid-peaking, or late-peaking. Location is usually stated as “loudest at” a particular auscultation location, such as the right upper sternal border or the apex. Radiation details where else the murmur can be heard, such as the neck or axilla. Loudness is graded on the Levine scale of I (only audible on listening carefully for some time) through VI (audible with the stethoscope not touching the chest).