Original article: cardiovascular
Late results after mitral valve replacement with bileaflet mechanical prosthesis in children: evaluation of prosthesis-patient mismatch

https://doi.org/10.1016/j.athoracsur.2003.09.066Get rights and content

Abstract

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.

Section snippets

Patients and methods

Since 1982, 37 mitral valve replacements using a bileaflet mechanical prosthetic valve were performed in 32 children at Fukuoka Children's Hospital or Kyushu University Hospital. The age at implantation of the prosthesis ranged from 2 months to 16 years (mean, 5.6 years of age), and body weight ranged from 3 kg to 37.3 kg (mean, 15.9 kg). As a previous procedure, correction of atrioventricular septal defect was performed in 12 patients (partial type in 9 and complete type in 3), correction of

Results

Figure 1 shows the size of the prosthesis and body weight of the patients at the time of implantation. The sizes of St. Jude Medical valve hemodynamic plus series is considered to be 2 mm bigger than its original size, because the manufactured valve orifice area of the St. Jude Medical valve hemodynamic plus series is 2 mm bigger than the manufactured valve orifice area of the St. Jude Medical standard valve with the same valve diameter.

There was no operative death. There were 5 late deaths,

Comment

Although reparative techniques of the mitral valve abnormalities in children have made remarkable progress with acceptable midterm and long-term results 1, 2, 3, 4, 5, 6, a reparative procedure is not always feasible. Uva and colleagues [2] reported that one fourth of their patients who had undergone repair of congenitally malformed mitral valve needed subsequent replacement of the valve. Their result was comparable with the data of our previous report [5] of 20% incident rate of mitral valve

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