Murmur grading in humans and animals: past and present

Cardiac murmurs were first described approximately 200 years ago. Subsequently, various clinicians, starting with Samuel Levine, have proposed grading schemes, depicting intensity, or other murmur characteristics, in an attempt to differentiate pathological and physiological murmurs or different degrees of pathology. In the 1960s, these schemes were adapted by veterinary cardiologists and have been used over the last 50 years. However, the clinical utility of these schemes has only recently been examined in veterinary medicine (and never examined in humans), and these studies suggest that the current, commonly used murmur grading scheme is unnecessarily complex and contains redundant information. A simpler, more intuitive grading scheme might achieve the same desired outcome as the more complex scheme, potentially with less confusion. This review examines the history of murmur grading and proposes a reconsideration of the current grading scheme to improve clinical communication.