cardiac murmur, an abnormal sound heard during auscultation of the heart, caused by altered blood flow into a chamber or through a valve. A murmur is classified by the quality of the sound, its time of occurrence during the cardiac cycle, its duration, and its intensity on a scale of I to VI. Also noted are the part of the heart over which the murmur is heard and any parts to which it radiates. In certain age groups, many systolic murmurs are benign and of no significance, whereas others signal a cardiac disorder. Diastolic murmurs are always pathological. Also called heart murmur.
