A fatigue-resistant microcable for small diameter leads of active implantable medical devices.

Reliability is a key-but-challenging requirement of active implantable medical devices. Implanted medical devices, such as leads, are exposed to tough environments in terms of corrosion and movement. Alongside good reliability, there is also a need for the size of medical implants to be reduced, both to minimize trauma and to enable sites that have hitherto been inaccessible to be reached, such as the tortuous venous collateral network of the left ventricle. Finally, specific electrical properties are required to adequately stimulate or sense specific regions within the human body. In this work, we present a composite microcable that combines small size with high electrical performance and long-term lead robustness. Combining multiple individually insulated electrical conductors in a microcable structure is perfectly suited for leads with multiple selectively contacted electrodes. The use of fine wires of 19 µm diameter enables the manufacture of a 7 × 7 microcable with an extremely small total diameter of less than 0.3 mm. In addition, the fine wires are composed of a core-shell metal-to-metal composite, which allows multiple advantages in one microcable: good X-ray visibility, high electrical conductivity, and very high fatigue resistance. The new MP35N®-Pt composite wire exhibits very strong lead robustness with good electrical conductivity. The fatigue test results presented were obtained by applying 90° bending under tensile load and show that the microcable has a 35-fold increase in high cycle fatigue robustness compared to standard PtIr20 leads. The resulting fracture surfaces were analyzed with scanning electron microscopy. Complementary results from conductivity measurements, X-ray visibility tests and mechanical testing have also been presented to illustrate the benefits of this newly developed composite microcable compared to state-of-the-art electrical conductors for medical implant applications.

Longitudinal relations among perceived autonomy support from health care practitioners, motivation, coping strategies and dietary compliance in a sample of adults with type 2 diabetes.

The purpose of this study was to test the causal ordering among perceived autonomy support from health care practitioners, motivation, coping strategies and compliance to dietary self-care activities. Using a cross-lagged panel model, we investigate how these variables relate to one another over a one-year period. A total of 365 adults with Type 2 diabetes participated in the study. Results suggest that autonomous motivation and active planning are reciprocally related over time, and that prior autonomous motivation is related to the extent participants subsequently comply with their diet. Results are discussed in light of Self-determination Theory and the coping perspective.