Skeletal Model-Based Analysis of the Tricuspid Valve in Hypoplastic Left Heart Syndrome

Abstract

Hypoplastic left heart syndrome is a congenital heart disease characterized by incomplete development of the left heart. Affected children undergo a series of operations which result in the tricuspid valve becoming the only functional atrioventricular valve. Many of these patients go on to develop complications associated with heart failure and death such as tricuspid valve regurgitation. Predicting which patients will develop regurgitation as well as planning for corrective procedures could be greatly enhanced through better understanding of the relationship between geometry and function of the tricuspid valve. Traditional analysis has relied on simple, global anatomical measures which often can not capture localized structural changes. Recently, statistical shape modeling has proven to be useful for analyzing the geometry of the tricuspid valve. We propose to use skeletal representations (s-reps) for modeling the leaflets of the tricuspid valve in these patients. S-reps are a more feature-rich representation than traditional boundary-based models and have been shown to have advantages for statistical analysis. Unfortunately, it is more difficult to fit s-reps to many geometries which limits the application of their powerful analysis techniques. We propose an extension to previous s-rep fitting approaches which yields improved models for difficult to fit objects such as the leaflets of the tricuspid valve. We incorporate application-specific anatomical landmarks and population information to improve correspondence. We use several traditional shape analysis techniques to compare the efficiency of s-reps with boundary representations created using SPHARM-PDM. We observe that principal component analysis produces a more compact shape space using s-reps, needing fewer modes to represent 90% of the population variation, while distance-weighted discrimination shows that s-reps provide more significant classification results between valves with less regurgitation and those with more. These results demonstrate the power of using s-reps for relating structure and function of the tricuspid valve.