The measurement of opening angle and orifice area of a bileaflet mechanical valve using multidetector computed tomography

Background and Objectives: The aim of this study was to assess mechanical valve function using 64-slice multi-detector computed tomography (MDCT). Subjects and Methods: In 20 patients (mean age, 50 ± 12 years; mate-to-female ratio, 10 : 10), 30 St. Jude bileaflet mechanical valves (15 aortic and 15 mitral valves) were evaluated using MDCT. We selected images vertical and parallel to the mechanical valve. The valve orifice area (OA) and valve length were determined by manual tracing and the opening and closing angles were measured using a pro-tractor. The OA and length of the mechanical valves were compared with the manufacturer's values. Results: The geometric orifice areas (GOAs) based on the manufacturer's values and the OAs determined by MDCT were 3.4 ±0.2 cm² and 3.4 ± 0.3 cm² for the mitral valves and 2.1 ± 0.3 cm² and 2.1 ± 0.4 cm² for the aortic valves, respectively. The correlation coefficients between the OA measures were 0.433 for the mitral valves and 0.874 for the aortic valves (both p <0.001). The lengths based on the manufacturer's values and determined by MDCT were 29.3 ± 1.99 mm and 29.6 ± 1.65 mm for the mitral valves and 21.5 ± 2.1 mm and 20.7 ± 2.3 mm for the aortic valves, respectively. The Correlation coefficients between the measures were 0.651 for the mitral valve and 0.846 for the aortic valve (both p <0.001). The opening and closing angles determined by MDCT were 10.9 ± 0.6° and 131.1 ± 3.2° for the mitral valves and 11.1 ± 0.9° and 120.6 ± 1.7° for the aortic valves, respectively. Conclusion: MDCT is an accurate modality with which to assess the function and morphology of bileaflet mechanical valves.