How do you rate intensity of heart murmurs?
By tradition, murmurs are graded on a scale of 1 to 6 which was initially a research tool used for the study of systolic murmurs (Freeman & Levine, 1993) and is known as the Levine system.
|Grade 1||Faint; heard only with special effort|
|Grade 2||Soft but readily detected|
|Grade 3||Prominent but not loud|
|Grade 4||Loud, accompanied by a thrill|
|Grade 5||Very loud|
|Grade 6||Loud enough to be heard with the stethoscope just removed from contact with the chest wall|
Levine system was initially developed for classifying benign vs. pathological (grade 3 or more) murmurs. However, there are limitations in terms of reproducibility and inter-rater reliability. More recently, it has been shown using heart sounds as an internal reference improved the reproducibility (Keren et al.)
|Grade 1||Clearly softer than the heart sounds|
|Grade 2||Approximately equal in intensity to the heart sounds|
|Grade 3||Clearly louder than the heart sounds, but no thrill|
|Grade 4||Associated with a thrill by palpation|
|Grade 5||Heard with one edge of the stethoscope lifted|
|Grade 6||Heard with both edges of the stethoscope lifted|
Freeman AR, Levine SA: Clinical significance of systolic murmurs: Study of 1000 consecutive “noncardiac” cases. Ann Intern Med 6: 1371-1379. 1933.
Keren R, Tereschuk M, Luan X. Evaluation of a novel method for grading heart murmur intensity. Arch Pediatr Adolesc Med. 2005 Apr; 159(4):329-34.