QUANTITATIVE DETECTION OF OUTLET STRUT SEPARATIONS IN BJORK-SHILEY CONVEXO-CONCAVE MITRAL-VALVES

Background As of January 31, 1995, 564 outlet strut fractures (OSFs) o f Bjork-Shiley convexo-concave (BSCC) heart valves had been reported t o the Shiley Heart Valve Research Center, of which approximately two t hirds resulted in the death of the patient. Previous studies indicate that one leg of the outlet strut separates (single-leg separation, SLS ) from the valve before the second leg breaks, which results in comple te OSF. To identify those valves at risk of complete OSF, an in vivo r adiographic imaging technique is being developed to evaluate the strut leg integrity. The goal of the present study was to develop an object ive postprocessing technique to evaluate outlet strut leg integrity qu antitatively in these cineradiographic images. Methods and Results Twe nty-two sets (12 intact valves, 10 SLS valves) of cineangiographic ima ges were obtained from individuals whose valve status was subsequently verified ex vivo. Several quantitative measures of SLS were evaluated to identify possible loss of metal or gaps in the SLS legs. Two of th ese measures, decrease in pixel intensity (DIPI) ratio and gap halfwid th, are diagnostic metrics of SLS: ie, the maximum likelihood estimate of the area under the receiver operating characteristic curve was 0.8 92 (SD, 0.066) for a model based on DIPI ratio and 0.802 (SD, 0.093) f or gap half-width. Conclusions We have developed a postprocessing tech nique that can be used to objectively evaluate outlet strut integrity in cineradiographic images of BSCC heart valves. At an estimated speci ficity of 1.0, the estimated sensitivity of the objective review was c omparable to that of a subjective expert review panel.