Can Mixed Reality Improve Decision-Making for ASD Closure in Dogs? A Five-Case CTA Study

Application of an Interactive, Stereoscopic Three-Dimensional Viewer to Evaluate Atrial Septal Defects in Five Dogs

C.H. Stoner; S. Wesselowski; S.G. Gordon; A.B. Saunders

Background

Atrial septal defects (ASDs) are uncommon congenital cardiac anomalies in dogs and frequently occur alongside other congenital heart diseases. Definitive closure, particularly via device occlusion, requires careful assessment of defect size, rim tissue adequacy, and proximity to adjacent cardiac structures. Traditional echocardiography may be insufficient for comprehensive anatomic characterization, motivating the use of advanced three-dimensional (3D) imaging techniques. This case series evaluates whether computed tomography angiography (CTA) combined with an interactive, stereoscopic mixed-reality viewer can improve assessment of candidacy for ASD device occlusion in dogs.

Methods

Five client-owned dogs with confirmed secundum ASDs underwent standard transthoracic echocardiography followed by retrospective ECG-gated CTA under conscious sedation. CTA datasets were reconstructed into 3D models using commercially available software and reviewed in a stereoscopic mixed-reality environment with interactive manipulation. The ASDs were visualized en face, measured in orthogonal planes, and evaluated for rim tissue adequacy and spatial relationships to surrounding structures, particularly pulmonary veins. These findings were used to guide recommendations regarding device occlusion versus conservative or alternative management.

Results

All five dogs had secundum ASDs with mild to moderate right-sided cardiac enlargement. Concurrent congenital heart disease was present in four dogs, most commonly pulmonary valve stenosis and atrioventricular valve dysplasia. Three-dimensional stereoscopic evaluation demonstrated inadequate or absent rim tissue in four dogs, precluding device occlusion. One dog had sufficient rim tissue and successfully underwent hybrid device occlusion, followed later by balloon pulmonary valvuloplasty, with long-term favorable outcome. The remaining four dogs were managed conservatively or medically and remained clinically stable or mildly symptomatic at follow-up.

Limitations

This report describes a small case series without a control group, limiting generalizability. Outcomes were descriptive rather than comparative, and the incremental benefit of stereoscopic mixed-reality visualization over conventional 3D CTA review alone was not quantitatively assessed.

Conclusions

Interactive stereoscopic mixed-reality visualization of CTA-derived 3D cardiac models provided detailed anatomic assessment of ASDs and surrounding structures in dogs. This approach was particularly valuable for evaluating rim tissue adequacy and procedural feasibility, directly influencing clinical decision-making for device occlusion. The findings support the utility of advanced 3D visualization tools as adjuncts in the assessment and procedural planning of congenital heart disease in veterinary cardiology.

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