Risk of strut fracture of Björk-Shiley valves

doi:10.1016/0140-6736(92)91328-6

The Lancet

Volume 339, Issue 8788, 1 February 1992, Pages 257-261

https://doi.org/10.1016/0140-6736(92)91328-6 Get rights and content

Abstract

The incidence of and factors that predispose to outlet strut fracture of Björk-Shiley heart valves are still not known. To obtain such information a retrospective cohort study was conducted on all 2303 patients in the Netherlands with a 60° convexo-concave (60°CC) or a 70° convexo-concave (70°CC) Björk-Shiley heart valve. Patients have been followed-up for a mean of 6·6 years (range 1-4271 days). 42 cases of mechanical failure due to outlet strut fracture have been recorded—6 of the 7 patients with fracture of the aortic valve died, as did 18 of the 35 patients with fracture of the mitral valve. Multivariate analysis identified wide opening angle (70°), large valve size (≥29 mm diameter), and young age (<50 years) as risk factors for outlet strut fracture. For large 70°CC mitral valves the cumulative risk of outlet strut fracture after 8 years was 17·4% (95% Cl 9·1-31·6). Unlike previous findings, this excessive risk applied to late as well as to early batches of valves. In patients with a large 60°CC mitral valve the cumulative risk after 8 years was 4·2% (95% Cl 2·7-6·5). The incidence rate of outlet strut fracture in 60°CC and 70°CC valves (aortic and mitral) was constant over time. Overall survival since implantation was better for patients with 60°CC prostheses than for those with 70°CC prostheses; the adjusted hazard ratio for mortality for patients receiving a 70°CC prosthesis was 1·5 (95% Cl 1·1-2·0). Together with the low (24%) necropsy rate, this ratio suggests that the reported incidence of strut fracture for the 70°CC valves is an underestimate. The data indicate that prophylactic replacement of 60°CC and 70°CC valves is advisable for selected groups of patients. Since the case-fatality rate is 50% for emergency replacement of faulty valves, patients suspected of Björk-Shiley heart-valve failure should be referred without delay to a cardiothoracic centre.

References (18)

D. Lindblom et al.
Mechanical failure of the Björk-Shiley valve
J Thorac Cardiovasc Surg
(1989)
D. Lindblom et al.
Mechanical failure of the Björk-Shiley valve. Incidence, clinical presentation, and management.
J Thoroc Cardiovasc Surg
(1986)
Wg Marshall et al.
Early results of valve replacement with the Björk-Shiley convexo-concave prosthesis
Ann Thorac Surg
(1984)
Lf Hiratzka et al.
Outlet strut fracture of the Björk-Shiley 60°CC convexo-concave valve: current information and recommendations for patient care
JACC
(1988)
Dg Husebye et al.
Reoperation on prosthetic heart valves. Analysis of risk factors in 552 patients
J Thorac Cardiovasc Surg
(1983)
Shiley
Dear Doctor letter
(1988)
Committee on Energy and Commerce, US House of Representatives
The Bjork-Shiley heart valve: "Earn as you learn"
(1990)
Advising patients with artificial heart valves
Lancet
(1990)

There are more references available in the full text version of this article.

Cited by (90)

Prosthetic Aortic Valve Regurgitation: The Story of a Missing Piece in the Puzzle
2022, JACC: Case Reports
Citation Excerpt :
Structural valve degeneration is fairly uncommon within the first decade after surgical aortic valve replacement (≤15%), but the incidence has been reported to increase thereafter.6 Fracture of prosthetic valves has been reported with mechanical aortic valve prostheses and after transcatheter pulmonary valve replacement.7,8 However, to our knowledge, our case represents the first report of fracture of a bioprosthetic surgical valve in the aortic position with strut embolization to the systemic circulation.
The Björk-Shiley convexo-concave heart valve experience from the perspective of the supervisory panel
2013, American Journal of Cardiology
Citation Excerpt :
The number of fractures increased to a peak in the mid-1980s and began a steady decrease thereafter. The factors affecting risk of OSF were originally examined in a retrospective cohort study on all 2,303 Dutch patients implanted with 60° or 70° valves.13 After an average follow-up period of 6.6 years, the investigators identified 42 cases of OSF.
The 20-year activities of a medical supervisory panel appointed under the terms of a settlement agreement of the Bowling v. Pfizer class action suit involving the Björk-Shiley convexo-concave (BSCC) heart valve are detailed. Of approximately 86,000 valves implanted, catastrophic failure of the valve was reported in 663 patients from 1978 to 2012. In 1994, a 7-member medical panel consisting of cardiologists, cardiovascular surgeons, epidemiologists, and a nontechnical chairman was appointed by the federal court. The panel collected clinical and manufacturing data, supported epidemiologic studies assessing risk factors for valve fracture, and developed guidelines for payment for explanting potentially defective valves in patients. Three sets of guidelines, based on comparisons of estimated risks of valve fracture versus risks of valve replacement surgery, were issued by the panel to help guide patients and their physicians in decisions about explanting valves. In addition, the panel supported research directed at identifying valves at risk for outlet strut fracture. The primary techniques evaluated included analyzing acoustic signals from the valves, imaging valves for potential cracks in the struts, and structural analyses of Björk-Shiley convexo-concave valves, but none proved applicable for large-scale surveillance of the patient population. The panel also became a patient advocate and acted as an intermediary between the manufacturer and the attorneys initiating the legal settlement. The panel's experiences may help inform future strategies for guideline development for other medical devices or procedures involving risk-benefit comparisons.
Fatigue fracture of the Björk-Shiley heart valve strut and failure diagnosis from acoustic signatures
2010, Theoretical and Applied Fracture Mechanics
Citation Excerpt :
In 1979, the Björk–Shiley 70° convexo-concave valve was introduced with remilling of the inlet strut of the 60° valve or with a solid design. By January 1990, 389 outlet-strut fractures of the convexo-concave valve were reported to the company [3]. Such failures can lead to catastrophic events.
Repeated loading of the outer strut leg of the Björk–Shiley 60° convexo-concave (BSCC) valve results in fatigue crack propagation, with a duration from a few months to a few years. Sound and vibration analysis emitted from the strut of the BSCC valve due to impact is used to monitor the propagation of the fatigue crack before it would lead to the failure of one or both legs of the outlet strut. Analytical and experimental results established that the range of the fundamental natural frequency is 4000–8000 Hz. Analysis of sound emitted from the strut of the valve due to impact may be used to monitor the propagation of the fatigue crack before it would lead to the failure of the one or both legs of the outlet strut.
Noninvasive evaluation of Bjork-Shiley convexo-concave prosthetic heart valves
2009, NDT and E International
Prosthetic heart valves of the Bjork-Shiley convexo-concave (BSCC) type have been used extensively in implants; however, there have been reports of cases where one component of the valves failed, leading to the demise of the patient. This paper presents a new method for noninvasive electromagnetic evaluation for this type of valve, using an eddy current transducer with orthogonal coils. In vitro experiments on BSCC prosthetic heart valve replicas have shown that discontinuities of outlet strut with depths equal or larger than 0.4 mm can be detected with a probability of detection (POD) of 86.4%, and in the case of discontinuities with depth equal or larger than 0.6 mm with POD of 97%. Blind tests effectuated on 32 BSCC prosthetic heart valves have shown that, using the proposed method, the tested valves have been correctly classified.
Clinical prediction rule for 30-day mortality in Björk-Shiley convexo-concave valve replacement
2003, Journal of Clinical Epidemiology
We aimed to develop a clinical prediction rule for 30-day mortality in patients undergoing Björk-Shiley convexo-concave (BScc) valve replacement, based on primary valve implantation procedures.
We studied 30-day mortality in 2,263 patients who received a BScc valve between 1979 and 1985 in The Netherlands. A logistic regression model was constructed and internally validated with bootstrapping techniques.
Predictors for mortality were emergency operation, coronary artery disease, mitral or double-valve replacement, BScc implant being a reoperation, endocarditis, poor left ventricular function, age, concomitant tricuspid valve plasty, and aortic root replacement. The area under the receiver operating characteristic curve (AUC) for the predicted probability of death was 0.76 (95% CI 0.72–0.80). The model calibrated well, and had adequate discriminative ability in 195 BScc valve patients who underwent explantation, including 53 prophylactic explantations (AUC 0.81, 95% CI 0.73–0.89).
A prediction rule derived from BScc valve implantation data performed well in patients undergoing explantation. Because the model provides accurate individualized estimates of the risk of mortality after reoperation, it may be helpful for decision making in patients with BScc valves.
Use of flexibility tests in the manufacturing process of 60° Björk-Shiley convexo-concave valves and the risk of outlet strut fracture
2003, Journal of Thoracic and Cardiovascular Surgery
Outlet strut fracture remains a concern for 30,000 patients living with a Björk-Shiley convexo-concave heart valve (Shiley, Inc, Irvine, Calif, a subsidiary of Pfizer, Inc). Previous studies (Netherlands and United Kingdom) investigating valve manufacturing aspects identified multiple performance of the hook deflection test as a risk factor for 60° valves. The present study validated this finding using new data with a greater number of valves implanted worldwide. Risks of outlet strut fracture associated with other manufacturing aspects were also investigated.
A matched case-control study design was used including 416 outlet strut fracture cases and 803 controls.
Analyses similar to that of the Dutch and United Kingdom studies produced odds ratios of 3.4 (95% confidence interval [CI]: 1.1-10.3) and 2.8 (95% CI: 1.1-7.3), respectively, for multiple hook deflection tests. Load deflection test, which replaced the hook deflection test, showed a statistically significant association with outlet strut fracture: odds ratio of 5.0 (95% CI: 2.1-11.8) and 6.2 (95% CI: 2.2-18.0) for single and multiple load deflection tests, respectively. An analysis where hook deflection tests were separated from load deflection tests showed significantly elevated odds ratios with performance of any type of flexibility test, and the highest odds ratio was observed with a combined performance of load and hook deflection tests.
Multiple hook deflection tests can now be considered for inclusion in the risk model used for guidelines on explant surgery to improve prediction of outlet strut fracture and provide patient reassurance. Load deflection tests and combined performance of hook and load deflection tests were found to be significant risk factors. No outlet strut fractures were reported for valves manufactured after March 1984 when the load deflection test was still in place. Examining manufacturing documents for these valves may identify new risk factors that could be responsible for the outlet strut fractures risk that remains unexplained to date.

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ORIGINAL ARTICLESRisk of strut fracture of Björk-Shiley valves

Abstract

J Thorac Cardiovasc Surg

J Thoroc Cardiovasc Surg

Ann Thorac Surg

JACC

J Thorac Cardiovasc Surg

Dear Doctor letter

The Bjork-Shiley heart valve: "Earn as you learn"

Advising patients with artificial heart valves

Lancet

ORIGINAL ARTICLES
Risk of strut fracture of Björk-Shiley valves