Mitral and Tricuspid Valve Repair and Growth in Unbalanced Atrioventricular Canal Defects
John E. Foker, James M. Berry, Brian A. Harvey, Lee A. Pyles.
BACKGROUND: Congenital mitral and tricuspid valve (MV, TV) abnormalities and ventricular hypoplasia in unbalanced atrioventricular canal (UAVC) defects usually lead to a single ventricle repair. Our approach, however, is to both repair and induce growth of the hypoplastic AV valves and ventricles, eventually allowing a 2VR. We now provide mid-term data on: (1) Reliability of catch-up growth of hypoplastic structures. (2) Late quality of AV valves. (3) Adequacy of 2VRs.
From 1990-2005, 24 consecutive infants (14F, 10M) with UAVC defects (N=21) or subsets (N=3) had significant hypoplasia of one AV valve (HAVV) and/or ventricle (HV) defined as an echo derived z value of < -3.0 (standard error of mean from expected). Approaches included: (1) Staged repair with (a) complete valve repair, partial ASD and VSD closure and (usually) pulmonary artery banding, to induce growth of the hypoplastic structures and (b) later completion. (2) Partitioning the common AV valve to increase the HAVV size. In three, only a vestigial MV (3-5mm) was present and the large TV was partitioned to create a second MV valve. (3) Complete repair leaving a snared ASD or VSD allowing necessary short term intracardiac shunting and time for growth.
Local follow-up (5-15 years) assessed ventricular size by biplane echo measurements. When only a single view was provided, the ventricle was judged to either be within normal limits (wnl) or not.
Results are shown (Table 1). Deaths included one CNS bleed just prior to weaning from ECMO and two late potassium overdose deaths giving a mid-term survival of 88%. All survivors are doing well with 2VRs and, by report, 15/19 are on no cardiac medications.
1) A staged approach, including repair of HAVV abnormalities, induced growth and avoided the risk of initial complete repair.
2) Reoperations were uncommon but done for MV regurgitation (3) and MV replacement (1). The remainder has good valve function.
3) Valve repair and growth of the hypoplastic structures eventually achieved a 2VR in all.
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