Innocent murmurs may be guilty of causing anxiety in patients, relatives, and doctors; they may also generate complacency when greater suspicion might have discerned pathology behind the mask of innocence. It is this ambivalence which makes it necessary to redefine innocent murmurs and reevaluate their diagnosis and management.
Diagnosis and management may present problems of a technical, perceptual, or conceptual nature. Stethoscopes, even those of the same model made by the same manufacturer, vary in amplification and in peaks of resonance. Auditory perception is neither constant in the individual auscultator nor uniform in a group. Interpretation depends to a large extent on the physician's familiarity with usual or unusual sound patterns of innocent murmurs. A recent study1 disclosed observer variation among experts 20% of the time, as well as 20% interobservation variability in the individual listener.
A second look at some murmurs hitherto considered innocent is also adding to diagnostic