Late results after mitral valve replacement with bileaflet mechanical prosthesis in children: evaluation of prosthesis-patient mismatch.
BACKGROUND
Mechanical prosthesis is the choice of valve at the mitral position in children, although re-replacement of prostheses because of prosthesis-patient mismatch is almost inevitable when prostheses were implanted in small children. The methods to predict prosthesis-patient mismatch as a result of patients' somatic growth or pannus formation in children by noninvasive methods have not been well established.


METHODS
Thirty-two children underwent mitral valve replacement with 37 bileaflet mechanical prostheses (26 St. Jude Medical prosthetic valves, and 11 CarboMedics prosthetic valves) and were followed up a mean of 6.8 years (maximum 18.3 years) with a complete follow-up rate of 94%.


RESULTS
There were no operative deaths and 5 late deaths. Re-replacement of mitral valve because of prosthesis-patient mismatch was required in 5 patients. Freedom from valve-related events and re-replacement of mitral valve at 15 years were 32% +/- 23% and 54% +/- 18%, respectively. Actuarial survival rate was 63% +/- 19% at 15 years. Prosthetic valve orifice area index (manufactured geometric prosthetic valve area divided by patient's body surface area) was well correlated with maximum transprosthesis flow velocity estimated by Doppler echocardiography during follow-up, whereas valve orifice area index had no significant correlation with pulmonary artery wedge pressure assessed by cardiac catheterization. Maximum transprosthesis flow velocity had a significant correlation with pulmonary artery wedge pressure.


CONCLUSIONS
Valve orifice area index itself was not a reliable index to predict prosthesis-patient mismatch. Maximum transprosthesis flow velocity was a useful index to predict pulmonary artery wedge. Invasive cardiac catheterization to determine re-replacement of the prosthesis should be considered when maximum transprosthesis flow velocity exceeds 270 cm/s.
Department of Cardiovascular Surgery, Kyushu University Hospital, Fukuoka, Japan. masudam@heart.med.kyushu-u.ac.jp
Munetaka
M
Masuda
Hideaki
H
Kado
Hideki
H
Tatewaki
Yuichiro
Y
Shiokawa
Hisataka
H
Yasui
D000293:Adolescent; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization; D002648:Child; D002675:Child, Preschool; D015150:Echocardiography, Doppler; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D006801:Humans; D007223:Infant; D008943:Mitral Valve; D011474:Prosthesis Design; D012086:Reoperation; D015996:Survival Rate