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Long-term Tricuspid Valve Function Following Norwood Operation
M. Elmi, E. Hickey, W. G. Williams*, G. S. Van Arsdell, C. A. Caldarone, B. W. McCrindle. The Hospital for Sick Children, Toronto, ON, Canada,
BACKGROUND:
Long-term functional outcomes following Norwood palliation are likely to depend partly on tricuspid valve (TV) performance in the systemic role. We therefore aimed to characterize features associated with TV intervention.
METHODS:
All 219 children (N=219, 1990-2007) who underwent Norwood stage 1 palliation resulting in a systemic right ventricle were investigated. In parametric competing risks analyses, primary endpoints included surgical tricuspid valve intervention (repair=27, replacement=3), and death (N=105). All 2705 echocardiogram reports were included in time-related analyses of outcome adjusted for repeated measures. Variable selection used bagging.
RESULTS:
The risk for TV intervention was mainly early, but a late risk is observed beyond 10-15 years after Norwood (figure). At the time of diagnosis, incremental risk factors for TV intervention included an absence of coarctation (P=.02, 70% reliability), aortic atresia (P=.05, 61%) and smaller indexed branch pulmonary arteries (P=.01, 50%). The hazard for TV intervention within a year of Norwood is tripled by absence of coarctation and doubled in the presence of aortic atresia.
At the time of Norwood operation, myocardial ischemic time (P=.01, 71%) and mitral atresia (P=.03, 50%) were additional risks for subsequent risk of TV intervention (figure). Echocardiographic indices immediately post-Norwood were not reliable predictors.
Competing risk factors for death included smaller birth weight, earlier era, smaller branch pulmonary arteries, and longer duration of DHCA.
TV intervention was successful in restoring functional natural history to parallel the remainder of the cohort. TV intervention did not compromise survival (82±2% 5 years after TV intervention). Repeat TV interventions were undertaken in 6 (3 repairs, 3 replacements). At latest follow-up, degree of TV regurgitation was not different between those who received intervention and those who did not.
CONCLUSIONS:
Long-term TV function in the systemic role is compromised by lengthy myocardial ischemic times, smaller branch pulmonary arteries and atretic left-sided morphology. Peri-Norwood echocardiographic assessment does not reliably predict subsequent risk of TV intervention. The emerging late hazard for TV intervention may have implications for long-term functional outcome and should be explored further. 
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