Samuel A. Levine and the history of grading systolic murmurs.

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.