Regular Buzzing (Musical) Murmur in Pediatric Patients
A regular buzzing or musical murmur in a pediatric patient is most commonly Still's murmur, an innocent vibratory murmur that requires no intervention when properly identified by an experienced examiner. 1
Most Likely Cause: Still's Murmur
Still's murmur is the classic "buzzing" or vibratory innocent murmur in children and has these distinctive characteristics: 1, 2
- Medium-pitched, vibratory quality that sounds like a "buzzing" or "twanging string" 1, 2
- Heard at multiple locations: apex, left lower sternal border, left middle sternal border, and right upper sternal border 1, 2
- Disappears or becomes quieter and localizes to the left lower sternal border when the child stands up 1, 2
- Not associated with any structural cardiac defects 1, 2
Other Innocent Causes of Musical/Buzzing Sounds
While Still's murmur is most common, other innocent murmurs can occasionally have musical qualities: 1
- Venous hum: Medium-pitched, blowing character with diastolic accentuation at the upper sternal border; disappears with jugular compression or supine position 1, 3
- Innocent pulmonary systolic murmur: Medium-pitched, harsh character at left middle and upper sternal border; disappears when upright 1
When to Suspect Pathology
Red flags that indicate the buzzing sound may be pathologic rather than innocent include: 4, 5, 6
- Grade 3 or louder intensity 4, 6
- Harsh quality rather than vibratory 4
- Diastolic component (diastolic murmurs virtually always indicate pathology) 1, 7
- Holosystolic duration 7, 5
- Abnormal second heart sound 4
- Increases in intensity when standing (opposite of Still's murmur) 4, 6
- Radiation to the back or neck 5
Clinical Approach Algorithm
For an asymptomatic child with a buzzing murmur: 1
Perform positional maneuvers: Have the child stand up. If the murmur disappears or becomes quieter and localizes to the left lower sternal border, this strongly suggests Still's murmur 1, 2
Assess the quality: A true vibratory/buzzing quality with medium pitch is characteristic of Still's murmur 1, 2
Check for red flags: Absence of symptoms, normal S2, grade 2 or less intensity, and no other abnormal findings support an innocent murmur 1, 4
If you can confidently identify Still's murmur with these characteristics, no further workup is needed 1
When to Refer or Obtain Echocardiography
Immediate referral to pediatric cardiology is indicated for: 1, 5
- All neonates with murmurs (neonatal murmurs have higher rates of pathology and are harder to characterize) 1, 5
- Any murmur you cannot confidently identify as innocent 1
- Presence of any red flags listed above 4, 5, 6
- Symptoms suggesting cardiac disease: failure to thrive, cyanosis, respiratory distress, exercise intolerance 1, 4
- Family history of sudden cardiac death or congenital heart disease 4
Critical Pitfalls to Avoid
- Do not assume all "musical" murmurs are innocent: Musical murmurs can result from uniform periodic vibration of abnormal cardiac structures, including degenerated valves 8
- Do not rely on ECG or chest X-ray to differentiate innocent from pathologic murmurs: These tests are not cost-effective and can misclassify murmurs 5
- Do not dismiss louder innocent murmurs: Still's murmur can occasionally be grade 3 and still be innocent, though this warrants closer evaluation 3, 7
- In older children, cardiac murmurs are more commonly functional than pathologic, but history and physical examination by a skilled observer are essential to distinguish them 1