Does the Mitral Annulus Grow in Children Following Early Mechanical Valve Replacement?

  • Dr Lucian Durham, The Mayo Clinic, Rochester, Minnesota, USA, United States
  • Dr Harold Burkhart, The Mayo Clinic, Rochester, Minnesota, USA, United States
  • Dr Joseph Dearani, The Mayo Clinic, United States
  • Prof Francisco Puga, The Mayo Clinic, Rochester, Minnesota, USA, United States
  • Dr Patrick O'Leary, The Mayo Clinic, Rochester, Minnesota, USA, United States
  • Prof Hartzell Schaff, The Mayo Clinic, Rochester, Minnesota, USA, United States

    • Introduction: Irreparable mitral pathology may lead to early mitral valve replacement (MVR) in children. Often, a small mechanical prosthesis (<23mm) is required raising concerns for annular growth in patients who may require mitral valve re-replacement (MVRR). The aim of this study was to evaluate interval annular growth in this cohort.

    Methods: Between 1972 and 2006, 164 children underwent MVR; 102 of these children (median age: 4 yrs., range: 7 days – 11 yrs.) required a small mechanical prosthesis (<23mm). The most common diagnoses were congenital mitral stenosis/regurgitation (48%), AVSD (46%), and other (6%). This cohort was analyzed for age, body surface area (BSA), prosthesis size, annular size and Z-score at time of MVR and MVRR.

    Results: At the time of MVR, 78 patients had a BSA of 0.77+0.06m2, annular size 24+0.62mm (Z-score 2.91+0.23) and ultimately did not require MVRR. The cohort requiring MVRR (n=24) had BSA 0.62+0.05m2 (p=NS vs. MVR only), annular size 20+0.49mm (Z-score 1.85+0.22) (p=0.008 vs. MVR only) at time of initial implant. In the interval between MVR and MVRR (7.8+1.1 yrs), BSA increased to 1.12+0.07m2 and annulus size increased to 24+0.47mm (Z-score 1.80+0.28).

    Conclusions: The data support somatic growth of the mitral annulus following MVR with small mechanical prosthesis as evidenced by normal interval increase in BSA with unchanged Z-score. Additionally, there was a statistically significant difference in Z-scores between the cohorts requiring MVRR and those not needing re-replacement suggesting that placement of a slightly larger prosthesis may decrease the need for MVRR.