Outlet strut fracture of Björk-Shiley convexo-concave valves: Can valve-manufacturing characteristics explain the risk?

Abstract

It is our view that a combination of factors related to valve design, manufacturing process, and patient characteristics are responsible for outlet strut fractures of Björk-Shiley convexo-concave valves. Multiple hook deflection tests have emerged as a potential new risk factor for outlet strut fracture in both The Netherlands and the United Kingdom. This factor appears to be correlated with the presence of other abnormalities. A further study is needed to investigate the factors correlated with multiple hook deflection tests. On confirmation of risk, the presence of multiple hook deflection tests may be added to equations, quantifying the risk of outlet strut fracture for comparison against risk of mortality and serious morbidity from explant operations.

Fatigue-life assessment and validation techniques for metallic vascular implants

“…Given that the US Food and Drug Administration (FDA), which has regulatory authority over such devices, recommends durability testing to the equivalent of 10-15 years of pulsatile loading [1] (400-to 600-million cycles at 72 heartbeats per minute), implant fatigue performance is of prime importance. The Bjork-Shiley ConvexoConcave heart valve failure issues experienced in the 1980s and '90s [2][3][4] underscore the importance of vascular implant fatigue performance and design validation. It has been estimated that fatigue fracture of various Bjork-Shiley design iterations resulted in approximately 600 fractures [3,4].…”

Leaflet Escape in a New Bileaflet Mechanical Valve

“…1,3 At present, several studies are evaluating various risk factors associated with the use of these prostheses, determining the propensity of structural rupture with leaflet escape, and calculating the individual clinical risk for these patients connected with the prophylactic replacement. 7,8 In the absence of recognized guidelines, certain physicians 9 -11 concluded that the benefit of replacing the prostheses outweighs the risk of prosthesis failure, whereas other physicians 12 claim that elective replacement of the valves involves a similar mortality rate. A combination of host and prosthesis factors was postulated.…”

“…Disk escape continues to be the Damocles' sword for Ϸ35 000 recipients of the Björk-Shiley convexo-concave 6,7 and for many patients who received one of 3 other mechanical prostheses that presented the same mode of failure (Omnicarbon, Tekna, and Duromedics). 1,3 At present, several studies are evaluating various risk factors associated with the use of these prostheses, determining the propensity of structural rupture with leaflet escape, and calculating the individual clinical risk for these patients connected with the prophylactic replacement.…”

“…A combination of host and prosthesis factors was postulated. 7,13 Now, therefore, the identification of predictors of pivot fracture becomes crucial for the TRI Technologies recipients worldwide. In light of these regrettable incidents, we followed up all the patients by blood samples, 2D echocardiogram, and fluoroscopy to evaluate leaflet movements.…”

Twenty-Five–Year Experience With the Björk-Shiley Convexoconcave Heart Valve

“…Recent analyses of manufacturing records describing the production of individual valves suggest that some additional characteristics of the manufacturing process may predict the risk of OSF. 15,25,26 The most prominent among such variables was having Ͼ1 hook deflection test (a quality-control process to test for flexibility of the valve's outlet strut) performed. Having Ͼ1 of these tests tends to be highly correlated with the rework status of the valves (an indicator of whether the valve was known to have received additional manipulation, such as smoothing of cracks or rewelds), a modest but significant predictor of OSF.…”