Korean Circ J.  2009 Apr;39(4):157-162. 10.4070/kcj.2009.39.4.157.

The Measurement of Opening Angle and Orifice Area of a Bileaflet Mechanical Valve Using Multidetector Computed Tomography

• Lee DH
• Youn HJ
• Shim SB
• Lee SH
• Jung JI
• Jung SE
• Choi YS
• Park CS
• Oh YS
• Chung WS
• Kim JH

• KMID: 2225691
• DOI: http://doi.org/10.4070/kcj.2009.39.4.157

Abstract

BACKGROUND AND OBJECTIVES
The aim of this study was to assess mechanical valve function using 64-slice multidetector computed tomography (MDCT). SUBJECTS AND METHODS: In 20 patients (mean age, 50+/-12 years; male-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 protractor. 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+/-0.6degrees and 131.1+/-3.2degrees for the mitral valves and 11.1+/-0.9degrees and 120.6+/-1.7degrees for the aortic valves, respectively. CONCLUSION: MDCT is an accurate modality with which to assess the function and morphology of bileaflet mechanical valves.

Keyword

Valve; Heart; Computed tomography

MeSH Terms

Aortic Valve
Heart
Humans
Mitral Valve
Multidetector Computed Tomography

Figure

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  Fig. 1 The GOAs, lengths, and opening/closing angles of SJM valves determined by 64-slice MDCT. The images are analyzed using an Image-Pro Plus Image module (Media Cybernetics) and were compared with the manufacturer's values for the GOAs, lengths (A), opening angles (B), and closing angles (C) of the SJM valves as determined by 64-slice MDCT. GOAs and lengths were measured on the vertical image of the mechanical valve. The opening and closing angles were measured on parallel images of the mechanical valve. GOA: geometric orifice area, SJM: St. Jude Medical, MDCT: multidetector computed tomography.

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  Fig. 2 A 39-year-old woman who presented for assessment of function after undergoing SJM mitral valve replacement (valve size, 29 mm) for infective endocarditis. In the mitral valve, the GOA determined by MDCT was 3.35 cm2 and the manufacturer's value was 3.5 cm2. The valve length determined by MDCT was 28.6 mm and the manufacturer's value was 29 mm. The opening angle determined by MDCT was 11.2° and the manufacturer's value was 10°, and the closing angle determined by MDCT was 132.1° and the manufacturer's value was 130°. A: a vertical reformatted image of the valve shows the SJM mitral valve (#29) with symmetric opening of mechanical components. The valve is intact, based on measurement of the GOA and the length. B: a parallel reformatted image of valve shows the SJM mitral valve (#29). The valve is intact based on measurement of the opening and closing (not shown) angles. SJM: St. Jude Medical, GOA: geometric orifice area, MDCT: multidetector computed tomography.

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  Fig. 3 A 54-year-old woman who presented for assessment of function after undergoing SJM aortic valve replacement (valve size, 19 mm) for severe aortic stenosis. In the aortic valve, the GOA determined by MDCT was 1.68 cm2 and the manufacturer's value was 1.7 cm2. The valve length determined by MDCT was 18.6 mm and the manufacturer's value was 19 mm. The opening angle determined by 64-slice MDCT was 11.7° and the manufacturer's value was 10°, and the closing angle determined by MDCT was 119.6° and the manufacturer's value was 120°. A: a vertical reformatted image of valve shows the SJM aortic valve (#29) with symmetric opening of the mechanical components. The valve is intact based on measurement of the GOA and the length. B: a parallel reformatted image of valve shows the SJM aortic valve (#29) with symmetric opening of the mechanical components. The valve is intact based on measurement of the opening (not shown) and closing angles. SJM: St. Jude Medical, GOA: geometric orifice area, MDCT: multidetector computed tomography.

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  Fig. 4 The correlation coefficients and Bland-Altman analysis for the GOA based on the manufacturer's value and determined by 64-slice MDCT. A: the correlation coefficients for the GOA based on the manufacturer's value compared with those determined by MDCT were 0.433 for the mitral valve and 0.874 for the aortic valve (p<0.001). B: the Bland-Altman analysis of bias revealed that there were no significant bias between the GOA based on the manufacturer's value and MDCT for the mitral valve (observed bias, 1.121; 95% confidence interval, 0.823-1.1418). C: the Bland-Altman analysis of bias revealed that there were no significant bias between the GOA based on the manufacturer's value and MDCT for the aortic valve (observed bias, 0.938; 95% confidence interval, 0.642-1.223; p<0.001). The solid line is the mean difference; the dotted lines mark the standard deviations of the differences. Mean GOA=(manufacturer's value+MDCT)/2. GOA: geometric orifice area, MDCT: multidetector computed tomography.

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  Fig. 5 The correlation coefficients and Bland-Altman analysis for the valve length based on the manufacturer's value and determined by 64-slice MDCT. A: the correlation coefficients for the valve lengths based on the manufacturer's values compared with those determined by MDCT were 1.145 for the mitral valve and 0.790 for the aortic valve (p<0.001). B: the Bland-Altman analysis of bias revealed that there was no significant bias between the GOA based on the manufacturer's value and MDCT for the mitral valve (observed bias, 1.121; 95% confidence interval, 0.823-1.1418). C: the Bland-Altman analysis of bias revealed that there was no significant bias between the GOA based on the manufacturer's value and MDCT for the aortic valve (observed bias, 0.938; 95% confidence interval, 0.642-1.223; p<0.001). The solid line is the mean difference; the dotted lines mark the standard deviations of the differences. Mean length GOA=(manufacturer's value+MDCT)/2. GOA: geometric orifice area, MDCT: multidetector computed tomography.

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