Echocardiographic assessment of prosthetic mitral valves in children.
OBJECTIVE
We studied how Doppler-derived hemodynamic parameters in children change as the relative prosthetic mitral valve (PMV) size decreases with somatic growth and evaluated the diagnostic utility of the parameters for detecting PMV obstruction in children.


RESULTS
We reviewed 26 echocardiographic examination results of 15 mechanical bileaflet PMVs in 12 children. The median age at echocardiographic examination was 6.6 (0.6-18.1) years. The PMV functioned normally in 24 examinations but was obstructed due to thrombosis in two cases. PMV sizes ranged between 16 and 25 mm, which were standardized to body surface area (BSA) at the examination with z-score calculations. We assessed the peak E velocity, mean pressure gradient (PG), and pressure half time (PHT) of the transprosthetic flow, the velocity-time integral (VTI) ratio of the PMV inflow to the left ventricular outflow, and the BSA-indexed effective orifice area (iEOA) of the PMV calculated with the continuity equation. Linear regression analysis revealed statistically significant correlations between all parameters of normally functioning PMVs and the PMV size z-scores (Pearson correlation coefficients: peak E velocity, -0.68; mean PG, -0.71; PHT, -0.82; VTI ratio, -0.76; iEOA, 0.79). Compared with the predictive values derived from the regression equations, the VTI ratio and iEOA exceeded ± 2 standard errors in both patients with obstructive PMVs.


CONCLUSIONS
To assess PMV function in children, Doppler-derived hemodynamic parameters should be compared with their predictive values based on relative PMV sizes. The deviation of the VTI ratio and iEOA from their predictive values may indicate prosthetic obstruction.
Division of Cardiology, National Center for Child Health and Development, Tokyo, Japan.
Taiyu
T
Hayashi
Department of Pediatrics, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Ryo
R
Inuzuka
Division of Cardiology, National Center for Child Health and Development, Tokyo, Japan.
Hiroshi
H
Ono
Division of Cardiology, National Center for Child Health and Development, Tokyo, Japan.
Hitoshi
H
Kato
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D015150:Echocardiography, Doppler / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007223:Infant; D008297:Male; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D008945:Mitral Valve Prolapse / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012189:Retrospective Studies
Doppler echocardiography; mitral valve prosthesis; thrombus