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Layer Microdissection of Tricuspid Valve Leaflets for Biaxial Mechanical Characterization and Microstructural Quantification
Published on: February 10, 2022
Comprehensive 4-stage categorization of bicuspid aortic valve leaflet morphology by cardiac MRI in 386 patients
I G Murphy1, J Collins1, A Powell1
1Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Ave, Suite 1600, Chicago, IL, 60611, USA.
Insights
A new classification system for bicuspid aortic valve (BAV) disease, assessed by cardiac MRI, reliably categorizes diverse valve phenotypes. This aids in understanding BAV
Area of Science:
- Cardiovascular Imaging
- Cardiac Morphology
- Medical Classification Systems
Background:
- Bicuspid aortic valve (BAV) disease presents significant heterogeneity, impacting valve function and associated aortopathy.
- Existing classification schemes for BAV lack comprehensive detail regarding commissure fusion, leaflet asymmetry, and orifice orientation.
- Accurate phenotypic categorization is crucial for appropriate patient follow-up and surveillance strategies.
Purpose of the Study:
- To develop and validate a novel BAV classification scheme utilizing cardiac Magnetic Resonance Imaging (MRI).
- To assess the frequency of different BAV phenotypes and the reliability of the proposed classification system.
- To integrate detailed morphological features including commissure fusion, leaflet asymmetry, and valve orifice orientation.
Main Methods:
- A new BAV classification system was developed, building upon the Sievers surgical classification with added details on orifice orientation, partial leaflet fusion, and leaflet asymmetry.
- The classification was applied to 398 cardiac MRI studies by a single observer.
- Repeatability was assessed using intraobserver and interobserver kappa scores, and MRI findings were compared with operative reports for sensitivity and specificity.
Main Results:
- The classification scheme was successfully applied to 386 of 398 (97%) cardiac MRI studies.
- Right-left leaflet fusion was the most common type, seen in over half of cases; partial leaflet fusion occurred in 46% of patients.
- High interobserver agreement was achieved for valve orientation (κ=0.90), type (κ=0.72), and partial fusion (κ=0.83). MRI demonstrated high sensitivity and specificity for orientation and Sievers type when compared to operative reports.
Conclusions:
- The proposed MRI-based BAV classification schema is reliable for categorizing diverse valve morphologies, including leaflet size, orifice orientation, and commissural fusion.
- The classification effectively captures the heterogeneity of BAV phenotypes.
- This detailed classification may enhance understanding of the relationships between BAV morphology, hemodynamic derangements, and the development of aortopathy.
Abstract:
Bicuspid aortic valve (BAV) disease is heterogeneous and related to valve dysfunction and aortopathy. Appropriate follow up and surveillance of patients with BAV may depend on correct phenotypic categorization. There are multiple classification schemes, however a need exists to comprehensively capture commissure fusion, leaflet asymmetry, and valve orifice orientation. Our aim was to develop a BAV classification scheme for use at MRI to ascertain the frequency of different phenotypes and the consistency of BAV classification. The BAV classification scheme builds on the Sievers surgical BAV classification, adding valve orifice orientation, partial leaflet fusion and leaflet asymmetry. A single observer successfully applied this classification to 386 of 398 Cardiac MRI studies. Repeatability of categorization was ascertained with intraobserver and interobserver kappa scores. Sensitivity and specificity of MRI findings was determined from operative reports, where available. Fusion of the right and left leaflets accounted for over half of all cases. Partial leaflet fusion was seen in 46% of patients. Good interobserver agreement was seen for orientation of the valve opening (κ = 0.90), type (κ = 0.72) and presence of partial fusion (κ = 0.83, p < 0.0001). Retrospective review of operative notes showed sensitivity and specificity for orientation (90, 93%) and for Sievers type (73, 87%). The proposed BAV classification schema was assessed by MRI for its reliability to classify valve morphology in addition to illustrating the wide heterogeneity of leaflet size, orifice orientation, and commissural fusion. The classification may be helpful in further understanding the relationship between valve morphology, flow derangement and aortopathy.
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