OBJECTIVE To determine the prevalence and characteristics of left sided valvar regurgitation in normal children and adolescents.

DESIGN Prospective observational study.

SETTING Tertiary paediatric referral centre.

PATIENTS 329 volunteers (194 male, 135 female, age range 3–18 years).

MAIN OUTCOME MEASURES Detection of regurgitation with colour flow mapping after valve closure. Measurement of jet area, maximal velocity, and duration.

RESULTS Mitral regurgitation was present in six subjects (1.82%, 95% confidence interval (CI) 0.38% to 3.3%) and was not seen before 7 years of age. The jets ranged from 1.1 to 1.9 cm² (mean 1.4 cm²) in area and were confined to the proximal half of the left atrium. All of the detectable jets were pansystolic and five of six arose from the posteriomedial aspect of the mitral valve. Aortic regurgitation was seen in one girl aged 11 years (0.3%, 95% CI 0% to 0.9%). The signal was pandiastolic and 0.44 cm² in area.

CONCLUSIONS True mitral regurgitation occurring after rather than during mitral valve closure was detected in < 2% of subjects. These data support previous work in adult patients suggesting that trivial degrees of mitral regurgitation may be related to the process of aging. Aortic regurgitation is very rare in normal children and adolescents and should not be considered as a normal finding.