Biomedical subjects

P T Cahalan

Publications and source records attributed to P T Cahalan.

3 recordsLinked to original sources

PubMed1988

Long-term neurostimulation of skeletal muscle: its potential for a tether-free biologic cardiac assist device.

Skeletal muscle has a tremendous capacity to adapt. This adaptive phenomenon is seen perhaps to the greatest extent when skeletal muscle is subjected to chronic low frequency stimulation via the motor nerve. There is a decrease in glycolytic enzymes and an increase in oxidative enzymes, as well as a change in the contractile proteins and an increase in the mitochondrial volume fraction of the muscle fiber. These adaptive changes result in a muscle that is considerably more fatigue-resistant. Specifically herein, we report on a pneumatic aortic counterpulsator device powered by skeletal muscle. These muscle pumps functioned continuously and pumped blood effectively in tether-free animals for several weeks.

Adaptation, Physiological↗

PubMed1988

Factors and interactions affecting the performance of polyurethane elastomers in medical devices.

Polyurethanes offer the greatest versatility in compositions and properties of any family of polymers. For implantable medical devices, a few specific elastomeric polyurethane compositions have demonstrated a combination of toughness, durability, biocompatibility and biostability not achieved by any other available material. Because of the complex behavior of implantable polyurethanes in the body environment, designers and fabricators of polyurethane-containing devices must pay particular attention to the choice of composition and design of components. Subsequent treatment during qualification, fabrication, sterilization, storage, implantation, in vivo operation and explantation also determine the performance and provide the means for assessing the efficacy of the polyurethane in the implanted device.

Biocompatible Materials↗

PubMedDate not supplied

Biostability considerations for implantable polyurethanes.

Polyurethanes have become the most valuable implantable elastomers for uses requiring toughness, durability, biocompatibility and biostability. They are inherently stable in the body environment. However, physical and chemical changes may be effected by conditions of processing, fabrication, use or interactions with other device components. Most prominent modes of polyurethane degradation include mineralization, environmental stress-cracking and oxidation. While the mechanisms of these forms of degradation are not fully understood, an awareness of their causes and effects can lead to procedures that provide all of the long-term functionality required for the sophisticated polyurethane-based devices of today and tomorrow.

Animals↗