From the Guidelines
Innocent murmurs in pediatric patients are benign heart sounds that occur in children with structurally normal hearts, and the most common types include Still's murmur, innocent pulmonary systolic murmur, venous hum, carotid bruit, physiologic pulmonary artery stenosis, and mammary souffle, as defined by the American College of Cardiology/American Heart Association task force on clinical data standards 1.
Characteristics of Innocent Murmurs
These murmurs are typically characterized by their variability with position and respiration, absence of associated symptoms, and normal physical examination findings. They typically change or disappear with maneuvers like standing, squatting, or Valsalva.
- Still's murmur: a medium pitched, vibratory character heard at the apex, left lower sternal border, left middle sternal border, and right upper sternal border that disappears or becomes quieter and localizes to the left lower sternal border on upright position.
- Innocent pulmonary systolic murmur: a medium pitched, harsh character heard at the left middle and left upper sternal border that disappears with upright position.
- Venous hum: a medium pitched, blowing character with diastolic accentuation heard at the right or left upper sternal border that disappears with jugular venous compression or supine position.
- Carotid bruit: a medium pitched, harsh character heard at the right or left upper sternal border, supraclavicular region, or anterior portion of the lower neck that disappears with bilateral shoulder hyperextension.
- Physiologic pulmonary artery stenosis: a medium or high pitched, blowing character heard at the left middle sternal border that can also be heard at the same volume across the precordium and back that does not disappear with maneuvers but is only heard in infants <6 mo of age.
- Mammary souffle: a medium or high pitched, blowing character with continuous flow with systolic accentuation heard over or above the breasts that disappears with compression of the breast tissue.
Diagnosis and Management
According to the American College of Cardiology/American Heart Association guidelines, echocardiography is not recommended for patients who have a grade 2 or softer midsystolic murmur identified as innocent or functional by an experienced observer 2, 3.
- No treatment or activity restrictions are needed for innocent murmurs, though parents often need reassurance about their benign nature.
- Distinguishing features from pathologic murmurs include the absence of symptoms, normal growth and development, lack of other cardiac findings, and characteristic auscultatory features.
From the Research
Innocent Murmurs in Pediatric Patients
Innocent murmurs in pediatric patients are heart murmurs that are not associated with any structural heart disease. The following are key points about innocent murmurs:
- Nearly all pediatric murmurs are heard in normal hearts and are not due to cardiac disorders 4
- These murmurs usually can be classified by distinctive features and distinguished from organic murmurs by skillful clinical examination 4
- Innocent heart murmurs are quite common in children and adolescents, and are physiologic in nature 5
- A detailed history and thorough physical examination are critical to diagnose these innocent murmurs 5
Characteristics of Innocent Murmurs
The characteristics of innocent murmurs include:
- Asymptomatic 6
- Require no follow-up care 6
- Can be differentiated from pathologic murmurs by auscultation of heart sounds 6
- Require minimal follow-up care, and the expected outcome for a child with the diagnosis of such a murmur is excellent 6
Diagnosis and Referral
The diagnosis and referral of innocent murmurs involve:
- Obtaining a complete history and performing a complete physical examination to diagnose innocent cardiac murmurs 7
- Referral to a pediatric cardiologist for further evaluation is required when murmur assessment is not clear and diagnostic uncertainty is present 7
- Educating and reassuring parents remains an important aspect of this evaluation 7
- The pediatric nurse practitioner must be able to differentiate between the innocent and pathologic murmur 6