Visualization and Quantification of the Unrepaired Complete Atrioventricular Canal Valve Using Open-Source Software

Abstract

Background: Repair of complete atrioventricular canal (CAVC) is often complicated by residual left atrioventricular valve regurgitation. The structure of the mitral and tricuspid valves in biventricular hearts has previously been shown to be associated with valve dysfunction. However, the three-dimensional (3D) structure of the entire unrepaired CAVC valve has not been quantified. Understanding the 3D structure of the CAVC may inform optimized repair.

Methods: Novel open-source work flows were created in SlicerHeart for the modeling and quantification of CAVC valves on the basis of 3D echocardiographic images. These methods were applied to model the annulus, leaflets, and papillary muscle (PM) structure of 35 patients (29 with trisomy 21) with CAVC using transthoracic 3D echocardiography. The mean leaflet and annular shapes were calculated and visualized using shape analysis. Metrics of the complete native CAVC valve structure were compared with those of normal mitral valves using the Mann-Whitney U test. Associations between CAVC structure and atrioventricular valve regurgitation were analyzed.

Results: CAVC leaflet metrics varied throughout systole. Compared with normal mitral valves, the left CAVC PMs were more acutely angled in relation to the annular plane (P < .001). In addition, the anterolateral PM was laterally and inferiorly rotated in CAVC, while the posteromedial PM was more superiorly and laterally rotated, relative to normal mitral valves (P < .001). Lower native CAVC atrioventricular valve annular height and annular height-to-valve width ratio before repair were both associated with moderate or greater left atrioventricular valve regurgitation after repair (P < .01).

Conclusions: It is feasible to model and quantify 3D CAVC structure using 3D echocardiographic images. The results demonstrate significant variation in CAVC structure across the cohort and differences in annular, leaflet, and PM structure compared with the mitral valve. These tools may be used in future studies to catalyze future research intended to identify structural associations of valve dysfunction and to optimize repair in this vulnerable and complex population.

Keywords: Congenital heart disease; Echocardiography; Valvular heart disease.

Figure 1.. Overview of Normal Anatomy and Complete Atrioventricular Canal Anatomy.

A. Cutaway diagrams of a normal heart and complete atrioventricular canal. B. Schematic diagrams from a ventricular view.

Figure 2.. Visualization and Modeling of CAVC Annuli and Leaflets in Mid-Systole.

A. Schematic of CAVC annular modeling; B. Creation of CAVC Annular Curve; C. Smoothed CAVC annulus curve visualized in SlicerHeart; D. Schematic of CAVC leaflet modeling from ventricular view; E. 2D ventricular view of CAVC valve segmentation in SlicerHeart from ventricular view; F. CAVC leaflet model visualized from atrial view in with 2D slice intersections in SlicerHeart. (Red = superior bridging leaflet, Blue = right mural leaflet, Green = inferior bridging leaflet, Orange = left mural leaflet).

Figure 3.. CAVC Leaflet Quantification.

A. Visualization of Segmented CAVC valve from atrial (left), inferior (middle) and ventricular view (right) in SlicerHeart; B. Visualization of CAVC coaptation surface areas from atrial (left), inferior (middle) and ventricular view (right) in SlicerHeart; C. Visualization of leaflet billow (red) and tenting (blue) from atrial (left), inferior (middle) and ventricular view (right) in SlicerHeart.

Figure 4.. Papillary Muscle Angle Quantification in CAVC and Normal Mitral Valves.

A. Papillary muscle angle relative to annulus plane in CAVC and normal mitral; B. “Septal Point” based rotation angle measurement in CAVC and normal mitral valves. Reference vector is perpendicular to the septal plane, and papillary muscle base points are projected to the common CAVC and common normal mitral/tricuspid valve plane; C. “Center point” based rotation angle measurement in CAVC and normal mitral valves. Reference vector is perpendicular to the center plane, and papillary muscle base points are projected to the left CAVC and mitral valve plane. CAVC = Complete atrioventricular canal, NM = Normal Mitral.