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Abstract
Murmurs were described first by Laennec in 1819, after which the significance of a
murmur became a matter of debate. By the late 19th century, many physicians regarded
systolic murmurs as "organic," whereas others believed that they were often "functional."
Samuel Levine became a central figure in separating functional from organic systolic
murmurs. Freeman and Levine's 1933 study of 1,000 "noncardiac" subjects determined
the frequency, cause, and significance of systolic murmurs. Murmurs were rated on
a scale of 1 to 6 grades of intensity. Approximately 20% of their patients had grade
1 or 2 systolic murmurs. Hypertension, fever, tachycardia, and anemia were common
factors, and the murmurs were considered functional because they would often disappear
when these causes were controlled. Of 19 subjects with grade 3 or 4 murmurs, all were
determined to have organic heart disease or anemia. Thus, louder systolic murmurs
were found to be a significant finding, as were the cause, location, and effects of
posture. They concluded that systolic murmurs often have an explanation and that their
grade can be useful in the diagnosis and prognosis. They cautioned that a loud systolic
murmur did not necessarily indicate a bad prognosis or even serious heart disease.
Levine's system of grading a systolic murmur is valuable and persists into the 21st
century.