Definition
A soft blowing sound (similar to a breath sound) caused by movement of blood within the heart and adjacent large blood vessels.
Types
- Functional —does not indicate organic disease of the heart and may disappear upon return to health. (Example: hypertension)
- Innocent —vibrations in normal valves because of rapid blood flow. (Examples: following exercise or with fever).
NOTE: Approximately 30% of all children have functional or innocent murmurs. These murmurs are always systolic and may disappear with a change in position. They are grade I or II . - Organic —murmur caused by structural changes in heart or vessels.
Grading of Murmur
Grading indicates volume (loudness) or intensity and is usually based on a system with six values, as follows:
| Grade | Intensity |
|---|
| I/VI | Barely audible |
| II/VI | Faint, but easily heard |
| III/VI | Soft to moderately loud without thrill (palpable vibration) |
| IV/VI | Moderate to loud with thrill |
| V/VI | Loud: heard with stethoscope barely on chest with easily palpable thrill |
| VI/VI | Heard with stethoscope lifted from chest (Thrill is present.) |
Grading of cardiac murmurs may also be based on a system with four values:
| Grade | Intensity |
|---|
| I/IV | Faintest |
| II/IV | Soft |
| III/IV | Loud |
| IV/IV | Very loud |
Other noteworthy components of murmur classification are:
- Location: Aortic, pulmonic, tricuspid, mitral area
- Radiation: Of sound
- Timing: Early, mid, or late systole or diastole
- Character: Crescendo, that is, gradual increase in volume, or decrescendo, that is, gradual decrease in volume
- Quality: Blowing, harsh, rumbling
- Pitch: High, medium, low
- Variance: With respiration or position change