Where is it loudest? When in systole? Intensity (Levine scale*) Other phenomena Typical age Likely murmur Incidence per 10,000 live births
Systolic murmurs            
LLSB and apex Midsytolic Mid to loud (2 to 4 out of 6) Enhanced by Valsalva maneuver and transition to standing; potentially associated with mitral regurgitation murmur Early adolescence, depends on extent of outflow obstruction Hypertrophic obstructive cardiomyopathy (audio file) 20
LUSB Midsystolic dependent on size Soft to loud (1 to 3 out of 6) Radiates to back, fixed split S2, less discrete respiratory variation Variable, dependent on size of defect Atrial septal defect (audio file) 5.4
Apex Holosystolic
or
Early blowing
Mid to loud (2 to 3 out of 6) Radiates to axilla, can have S3 Congenital or acquired, most common valve impacted in rheumatic heart disease Mitral regurgitation (audio file) 5
Apex Late systolic with a click Mid to loud (2 to 3 out of 6) Midsystolic click, enhanced by Valsalva maneuver School aged to adolescence Mitral valve prolapse (audio file) 5
LUSB left infraclavicular area Usually holosystolic (progresses to continuous) Mid to loud (2 to 4 out of 6) Machinery style; can have bounding pulses Typically, neonate; more common in prematurity Patent ductus arteriosus (audio file) 5
Left scapular region Variable systolic murmurs Soft to loud (1 to 3 out of 6) Louder murmurs commonly from coexistent aortic valve anomaly Neonate to adulthood Coarctation of the aorta 4
RUSB with radiation to the carotids Midsystolic Mid to loud (2 to 3 out of 6) 0.5% to 2% of children have a bicuspid aortic valve: many of these are missed neonatally
If left ventricular outflow tract obstruction is present, a diagnosis is more likely in the neonatal period
Can be associated with an ejection click
Neonate to adulthood Aortic stenosis (audio file) 3.8
LUSB Systolic (rarely continuous) Mixed (1 to 3 out of 6) Loud P2 (pulmonic component of S2) when pulmonary artery hypertension is present
Radiates to back and lungs
Frequently missed; would persist beyond peripheral pulmonary stenosis Supravalvular pulmonary stenosis (pulmonary artery stenosis) (audio file) < 1
LLSB Holosystolic or early Loud (2 to 3 out of 6) Associated with hepatosplenomegaly and a pulsatile liver Variable; Ebstein anomaly is the most common explanation Tricuspid regurgitation (audio file) < 1
Diastolic murmurs            
LLSB Mid-diastolic Soft (1 to 2) Uncommonly an anatomic stenosis, more likely functional from alternate pathology Variable Tricuspid stenosis 30
Apex Early Soft (1 to 2) More commonly associated with rheumatic heart disease Toddlers (> 12 months) and adolescents Mitral stenosis (audio file) < 1