Cardiovascular biomedical materials

Meng J, Kong H, Xu HY, Song L, Wang CY, Xie SS (2005) Improving the blood compatibility of polyurethane using carbon nanotubes as fillers and its implications to cardiovascular surgery. Journal of Biomedical Materials Research Part A 74A 208-214. 

Microbial cellulose is an interesting material for biomedical applications. Materials intended as vascular grafts must satisfy many important features such as blood compatibility, cell interactions and mechanical properties. Microbial cellulose has xmique properties that make it an exciting candidate as a cardiovascular graft material strength. 

A wide variety of parameters can directly affect the chemical and physical characteristics of a plasma, which in turn affect the surface chemistry obtained by the plasma modification. Some of the more important parameters include electrode geometry, gas type, radio frequency (0-10 ° Hz), pressure, gas flow rate, power, substrate temperature, and treatment time. The materials and plasmas used for specific biomedical applications are beyond the scope of this text, but the applications include surface modification for cardiovascular, ophthalmological, orthopedic, pharmaceutical, tissue culturing, biosensor, bioseparation, and dental applications. 

Shape-memory alloys (e.g. Cu-Zn-Al, Fe-Ni-Al, Ti-Ni alloys) are already in use in biomedical applications such as cardiovascular stents, guidewires and orthodontic wires. The shape-memory effect of these materials is based on a martensitic phase transformation. Shape memory alloys, such as nickel-titanium, are used to provide increased protection against sources of (extreme) heat. A shape-memory alloy possesses different properties below and above the temperature at which it is activated. Below this temperature, the shape of the alloy is easily deformed due to its flexible structure. At the activation temperature, the alloy can be changed by applying a force, but the structure resists this deformation and returns back to its initial shape. The activation temperature is a function of the ratio of nickel to titanium in the alloy. In contrast with Ni-Ti, copper-zinc alloys are capable of a two-way activation, and therefore a reversible variation of the shape is possible, which is a necessary condition for protection purposes in textiles used to resist changeable weather conditions. 

Dr. Thomas Chandy is a research associate in the Division of Chemical Engineering Material Sciences, Biomedical Engineering Institute and Interventional Cardiology Laboratories at the University of Minnesota. He has over two decades research experience at Sri Chlia Tvunal Institute for Medical Sciences Technology, Trivandrum, India, in the area of biomaterial surface engineering and blood biomaterial interactions. More recently. Dr. Chandy and Dr. Rao have focused their research on platelet biomaterial interactiorrs and development of assist devices for cardiovascular applications. They continue to be active in this newly evolving area of research. 

Many biomedical devices work inside the human body. Pacemakers, artificial heart valves, stents, and even artihcial hearts are some of the bionic devices correcting problems with the cardiovascular system. Pacemakers generate electric signals that improve abnormal heart rates and abnormal heart rhythms. When pulse generators located in the pacemakers sense an abnormal heart rate or rhythm, they produce shocks to restore the normal rate. Stents are inserted into an artery to widen it and open clogged blood vessels. Stents and pacemakers are examples of specialized bionic devices made up of bionic materials compatible with human structure and function. 

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