Korean J Radiol.  2015 Oct;16(5):1012-1023. 10.3348/kjr.2015.16.5.1012.

Measurement of Opening and Closing Angles of Aortic Valve Prostheses In Vivo Using Dual-Source Computed Tomography: Comparison with Those of Manufacturers' in 10 Different Types

• Suh YJ
• Kim YJ
• Hong YJ
• Lee HJ
• Hur J
• Im DJ
• Kim YJ
• Choi BW

• KMID: 2160768
• DOI: http://doi.org/10.3348/kjr.2015.16.5.1012

Abstract

OBJECTIVE
The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers' values and to compare CT-measured opening angles according to valve function.
MATERIALS AND METHODS
A total of 140 patients with 10 different types of mechanical aortic valves, who underwent dual-source cardiac CT, were included. Opening and closing angles were measured on CT images. Agreement between angles in normally functioning valves and the manufacturer values was assessed using the interclass coefficient and the Bland-Altman method. CT-measured opening angles were compared between normal functioning valves and suspected dysfunctioning valves.
RESULTS
The CT-measured opening angles of normally functioning valves and manufacturers' values showed excellent agreement for seven valve types (intraclass coefficient [ICC], 0.977; 95% confidence interval [CI], 0.962-0.987). The mean differences in opening angles between the CT measurements and the manufacturers' values were 1.2degrees in seven types of valves, 11.0degrees in On-X valves, and 15.5degrees in ATS valves. The manufacturers' closing angles and those measured by CT showed excellent agreement for all valve types (ICC, 0.953; 95% CI, 0.920-0.972). Among valves with suspected dysfunction, those with limitation of motion (LOM) and an increased pressure gradient (PG) had smaller opening angles than those with LOM only (p < 0.05).
CONCLUSION
Dual-source cardiac CT accurately measures opening and closing angles in most types of mechanical aortic valves, compared with the manufacturers' values. Opening angles on CT differ according to the type of valve dysfunction and a decreased opening angle may suggest an elevated PG.

Keyword

Mechanical aortic valve; Opening and closing angles; Measurement; Dual-source computed tomography

MeSH Terms

Adult
Aortic Valve/*radiography
Female
Heart Valve Diseases/therapy
*Heart Valve Prosthesis
Heart Valve Prosthesis Implantation/*instrumentation
Humans
Male
Middle Aged
Retrospective Studies
Tomography, X-Ray Computed/methods

Figure

• 

  Fig. 1 Examples of dual-source CT images for measuring opening and closing angles in normally functioning mechanical aortic valves. CT images show measurement of opening and closing angles (A-C) of normal functioning mechanical aortic valves. C. Measurements of DM (opening angle) and BS valves (opening and closing angles) could not be performed due to severe artifacts. BS = Björk-Shiley, CT = computed tomography, DM = Duromedics, MH = Medtronic-Hall, SJM = St. Jude Medical, SJR = St. Jude Medical Regent

• 

  Fig. 2 Bland-Altman plots to compare CT opening angle measurements and those of manufacturer. Mean differences between opening angles on CT and manufacturers' values were 4.2° for all valve types (except Björk-Shiley valves) (A) and 1.0° for seven valve types other than Björk-Shiley, ATS, and On-X valves (B). CT = computed tomography

• 

  Fig. 3 Correlation between transvalvular PG and opening angles. Scatter plots show positive correlations between mean PG and opening angles in all valve types, except Björk-Shiley valves (n = 128, r = 0.176, p = 0.047) (A) and seven valve types, except Björk-Shiley, ATS, and On-X valves (n = 103, r = 0.453, p < 0.001) (B). PG = pressure gradient

• 

  Fig. 4 CT measurements and TTE parameters between valve function groups. Box and whisker plots of (A) differences between manufacturers' values and opening angles on CT for all valve types and (B) in seven valves, except Björk-Shiley, ATS and On-X valves show significant differences between groups with different valve function*. Box and whisker plot of (C) mean PG according to valve function shows significant difference in PG between groups†. Presence of pannus (D) and significant pannus (E) are significantly different between four groups on CT. *Except between normally functioning valves and PG elevation only group, †Except between normally functioning valves and LOM only group and between PG elevation group and both LOM and PG elevation group. CT = computed tomography, LOM = limitation of motion, PG = pressure gradient, TTE = transthoracic echocardiography

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  Fig. 5 CT measurements in Carbomedics valves based on valve function. Long axis view CT images (top and middle) show opening and closing angles of Carbomedics valves in aortic position, and short axis view images (bottom) show subprosthetic area in valves with normal function and suspected dysfunction (LOM only, PG elevation only, and both LOM and PG elevation). Valve with suspected dysfunction and both LOM and PG elevation shows greater decrease in opening angle than that of valve with LOM only. LOM = limitation of motion, PG = pressure gradient

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