Characterization of ion release from a novel biomaterial, Molybdenum-47.5Rhenium, in physiologic environments

BACKGROUND CONTEXT

Metals from spinal implants are released into surrounding tissues by various mechanisms. Metal ion release has been associated with clinical implant failure, osteolysis, and remote site accumulation with adverse events. Significant corrosion and associated metal ion release has been described with currently used spinal implant alloys. A novel metal alloy, Molybdenum-47.5Rhenium alloy (MoRe®), was approved for use in medical implants in 2019 by the FDA.

PURPOSE

To evaluate the metal ion release profile of MoRe alloy after immersion in both a stable physiologic, as well as in an inflammatory environment.

STUDY DESIGN

In vitro study.

METHODS

The ion release profile of the MoRe alloy was comprehensively evaluated in-vitro after prolonged immersion in physiologic and inflammatory environments. Ion concentration analyses were then conducted using inductively coupled plasma-mass spectrometry (ICP-MS) methods. Comparative testing of titanium (Ti-6Al-4V) and cobalt chromium (Co-28Cr-6Mo) was also performed.

RESULTS

Under baseline physiologic conditions, the MoRe alloy demonstrates very low molybdenum and rhenium ion release rates throughout the 30-day test period. During the first time interval (day 0-1), low levels of molybdenum and rhenium ions are detected (<0.3 μg/cm² day) followed by a rapid reduction in the ion release rates to <0.05 μg/cm² day during the second time interval (days 1-3) followed by a further reduction to very low steady-state rates <0.01 μg/cm² day during the third time interval (days 3-7), which were maintained through 30 days. In the inflammatory condition (H₂O₂ solution), there was a transient increase in the release of molybdenum and rhenium ions, followed by a return to baseline ion release rates (days 2-4), with a further reduction to low steady-state rates of ∼0.01 μg/cm² day (days 4-8). The measured molybdenum and rhenium ion release rates in both steady state (<0.01 μg/cm² day), and inflammatory environments (0.01 μg/cm² day) were far below the established FDA-permitted daily exposure (PDE) of 1,900 μg/cm² day for molybdenum and 4,400 μg/cm² day for rhenium. In contrast, titanium and cobalt chromium approached or exceeded their established PDE values in an inflammatory environment.

CONCLUSIONS

The novel biomaterial MoRe demonstrated a lower metal ion release profile in both a physiologic and inflammatory environment and was well below the established PDE.  Comparative testing of the cobalt-chromium and titanium alloys found higher levels of ion release in the inflammatory environment that exceeded the PDE for cobalt and vanadium.

Wireless pulmonary artery pressure monitoring guides management to reduce decompensation in heart failure with preserved ejection fraction

BACKGROUND

No treatment strategies have been demonstrated to be beneficial for the population for patients with heart failure (HF) and preserved ejection fraction (EF).

METHODS AND RESULTS

The CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients (CHAMPION) trial was a prospective, single-blinded, randomized controlled clinical trial testing the hypothesis that hemodynamically guided HF management decreases decompensation leading to hospitalization. Of the 550 patients enrolled in the study, 119 had left ventricular EF ≥40% (average, 50.6%), 430 patients had low left ventricular EF (<40%; average, 23.3%), and 1 patient had no documented left ventricular EF. A microelectromechanical system pressure sensor was permanently implanted in all participants during right heart catheterization. After implant, subjects were randomly assigned in single-blind fashion to a treatment group in whom daily uploaded pressures were used in a treatment strategy for HF management or to a control group in whom standard HF management included weight-monitoring, and pressures were uploaded but not available for investigator use. The primary efficacy end point of HF hospitalization rate >6 months for preserved EF patients was 46% lower in the treatment group compared with control (incidence rate ratio, 0.54; 95% confidence interval, 0.38-0.70; P<0.0001). After an average of 17.6 months of blinded follow-up, the hospitalization rate was 50% lower (incidence rate ratio, 0.50; 95% confidence interval, 0.35-0.70; P<0.0001). In response to pulmonary artery pressure information, more changes in diuretic and vasodilator therapies were made in the treatment group.

CONCLUSIONS

Hemodynamically guided management of patients with HF with preserved EF reduced decompensation leading to hospitalization compared with standard HF management strategies.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00531661.

An innovative professional nursing practice model

Nursing, as with health care delivery, is changing to meet the greater challenges brought about by managed care and the accompanying external forces in the marketplace. Nurses, with their vast resources of knowledge and experience, are crucial in achieving optimal quality care. Given the opportunity to redefine and strengthen the impact of nursing practice at Piedmont Medical Center in Atlanta, Georgia, a group of advanced practice nurses began developing a unique practice model. The resulting Professional Nursing Practice Model--a theoretical framework created for nurses by nurses--presents a common vision of human beings, health, and nursing in accordance with the values and beliefs of nursing. This model demonstrates the importance of a person-centered, value-driven nursing practice across the continuum of health from birth to death.