Acoustic assessment of the physical integrity of Björk-Shiley convexo-concave heart valves.
BACKGROUND
Several lines of evidence indicate a two-stage failure mode for the Björk-Shiley convexo-concave (C/C) heart valve, in which one of the two outlet strut legs separates from the flange before the other, potentially providing an opportunity to identify and prophylactically replace failure-prone valves. Radiographic single leg separation (SLS) detection, although successful, is subjective and skill intensive, implying a need for both an objective preliminary screen and subsequent corroboration of the radiographic findings.


RESULTS
We developed a time-windowed, power density analysis of C/C valve closing sounds to detect the vibrational resonance that characterizes the presence of an intact outlet strut in clinically functioning, 29-mm-flange size C/C valves. Recordings from more than 800 patients enrolled in radiographic SLS detection studies were analyzed, and the assessment algorithm was evaluated through a blinded test of 32 study valves for which the true status became known consequent to an autopsy or surgical explantation. Valves were objectively scored on a 0-to- 1 scale, with 1 being assuredly intact and scores of < 0.50 indicating a probable SLS. All except five valves (incorrectly designated probable SLS) were classified correctly, for a sensitivity of 1.00 (95% confidence interval, 0.79 to 1.00) and a specificity of 0.69 (0.41 to 0.89).


CONCLUSIONS
This level of accuracy is sufficient to serve as an effective preliminary screen, potentially allowing a threefold concentration of SLS prevalence among the C/C valves of patients undergoing radiographic assessment. The value of acoustic classification in avoiding unnecessary operations prompted by false-positive radiographs is less certain.
Dow
J J
JJ
Tracor Applied Sciences, Inc, Austin, Tex, USA.
Plemons
T D
TD
Scarbrough
K
K
Reeder
H
H
Hovenga
M
M
Wieting
D W
DW
Chandler
J G
JG
D000162:Acoustics; D000465:Algorithms; D016001:Confidence Intervals; D006350:Heart Valve Prosthesis; D006801:Humans; D011336:Probability; D011475:Prosthesis Failure; D011859:Radiography; D012680:Sensitivity and Specificity; D014732:Vibration