Retrieval analysis of mechanical heart valves: impact on design and clinical practice.

Explanted mechanical heart valves were examined nondestructively, and the findings were related to guidelines, technical reports, and other information to judge the risk of failure and its possible impact on valve design and clinical practice. Diagnoses for single valves could be made, but risks and rates of failure for patient populations could not be predicted due to insufficient information concerning the manufacturing process and valve and patient numbers. Based on the results of this study and the principle that decisions on recalls and patient counseling must be based on scientific knowledge rather than on wait and see policies, the following is recommended: registration of all implanted valves, follow-up of a large cohort of valve carriers, comparison of wear test results of preimplant and postretrieval valves, maintenance of a reference stock of valves and materials, and submission of failure scenarios to certifying bodies.

Single-institution effectiveness assessment of open-heart surgery in octogenarians.

OBJECTIVE: To determine short- and long-term outcome of open-heart surgery in octogenarians. METHODS: We reviewed the medical charts of 130 consecutive octogenarians undergoing open-heart surgery. Patients with significant comorbidity were excluded from the study. The effect of cardiac and operative risk factors on mortality and morbidity was evaluated. General practitioners and cardiologists were contacted in order to obtain information on the patients' current medical and functional status. RESULTS: Operative mortality for valve replacement (VR) and coronary artery bypass grafting (CABG) was 11.5%. Four-year survival was 73.5% with 75.9% still living independently. The relative risk for operative mortality was 4.3 in case of extracorporeal bypass time exceeding 95 min and 3.6 in case of significant left main stem disease. The risk of late death increased 2.5 times at a left ventricular ejection fraction lower than 50%. CONCLUSIONS: Our data match the results of similar studies involving large numbers of patients. When a multicenter data bank is missing, the evaluation of a relatively small patient group can yield information that may be as useful to patient and physician as information obtained by large studies. Open-heart surgery in octogenarians carries an acceptable mortality risk and its effectiveness in terms of improved quality of life is good.

Non-destructive assessment of 62 Dutch Björk-Shiley convexo-concave heart valves.

OBJECTIVE: Non-destructive assessment of 62 Björk-Shiley convexo-concave heart valves in view of the risk of fracture and possible detection of defects by means of X-ray or acoustics. METHODS: Scanning electron microscopy and stereomicroscopy of an unselected sample of valves, representing approximately 70% of the valves explanted between 1991 and 1996. Mean duration of implantation was 10.7 +/- 1.9 years. RESULTS: Six of the 62 valves had a fracture with disk escape. Of the remaining 56 valves, 11 (19.6%) had a single-leg fracture and seven (12.5%) showed a crack. Valves, 24 (42.8%), revealed no significant defect. After 4600 days of implantation, large valves (i.e. > or = 29 mm) showed a 6.7 time increase in the risk of crack or single-leg fracture compared with smaller valves (OR 6.7, 95% CI 1.8-24.6, P = 0.04). In a small in-vitro experiment with single-leg fracture, rapid smearing occurred, resulting in strut leg separation upon some movement. CONCLUSIONS: After approximately 400 x 10(6) cycles, 42.5% of the retrieved intact valves was without significant defect, while 32% had a serious prefracture defect. Time evolution from defect to fracture remains unpredictable. Also, detection of prefracture defects, including single-leg fracture, remains difficult, because a "well-detectable' fracture with dislocation is just a brief condition. However, technical knowledge can enhance the epidemiological and manufacturing information used for clinical decision making.

A risk assessment and control model for the failing Björk-Shiley convexo-concave heart valve.

For risk assessment and control of the failing Björk-Shiley convexo-concave heart valve, we present a life cycle-based complex system model and a risk intensity assessment model, allowing consistent analysis of this complex medical problem and identification of all pertinent aspects of product-related risks to patients.

What can be done to improve the safety of heart valves?

In the Netherlands, the incidence of fractured Björk-Shiley convexo-concave heart valves led to investigations regarding the extent, impact, and management possibilities of this public health problem. Apart from an epidemiological study, we performed a safety management study. This study led us to conclude that: (1) the Björk-Shiley convexo-concave heart valve is perceived as a safety risk by patients, doctors, and health care administrators alike; (2) doctors and health care administrators rely heavily on the technical information regarding artificial heart valves that is provided by the manufacturer; (3) the professionals best qualified to assess and control the risks of heart valve replacement are cardiac surgeons. Based on these conclusions, this report provides recommendations regarding safety risk assessment and the participation of doctors in preimplantation and clinical research programmes in order to improve the safety of newly designed heart valves.