Cardiovascular applications

Hydrophobic or Hydrophilic Polymers with Excellent Mechanical Properties and Flexibility, Tunable Surface Energy for Cardiovascular Applications. Blood Compatibility ... 

Evaluation of the fatigue properties of elastomers suitable for cardiovascular application is currently a long, and therefore, costly proposition. This is especially true if the fatigue tests are to be conducted in contact with blood. 

After extensively characterizing and fatigue testing the five candidate materials, we have some opinions on their usefulness in cardiovascular applications ... 

Butyl rubber - This material generally had the least endurance in fatigue tests, but it may be adequate for some cardiovascular applications. Advantages include less sensitivity to stress concentrators than Pellethane, a very low permeability to fluids, a moderate creep resistance and widespread availability at low cost. Disadvantages include a relatively low fatigue resistance compared to the elastomers specifically designed for these applications. The rubber tested was not designed for medical applications and had standard rubber additives and modifiers that were cytotoxic unless the material was extracted after manufacture. 

Clinical Cardiovascular Applications of NO Donor Therapy - Past and Present... 

Some polymers have a specific set of bulk properties that make them ideal for a certain application, but cannot be used because the surface properties are inappropriate. For example, a material may have excellent elasticity but cannot be used in cardiovascular devices because the polymer surface triggers blood clotting. Alternatively, another polymer may have excellent surface biological compatibility but is too brittle for a cardiovascular application. An answer to this problem, like many others, is to select a polymer for its advantageous bulk properties and then carry out property modification reactions on the polymer surface without affecting the bulk material. 

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. 

Logic would dictate that increasing brain levels of DA should ameliorate symptoms permanently (a cure ), or at least temporarily. Direct parenteral DA administration is useless since the compound does not penetrate the blood-brain barrier (BBB) (however, see Chapter 10 for cardiovascular applications). It was shown that oral dosing with L-DOPA (levodopa, Dopar) could successfully act as a pro-drug to the extent it entered the brain (on a specific carrier) and was then decarboxylated to DA there. The clinical results in terms of decreased tremors and rigidity were dramatic. However, there were complications... 

Piezoelectric sensors are used in cardiovascular applications for external (body surface) and internal (intracardiac) phonocardiography. They are also used in the detection of Korotkoff sounds for indirect blood pressure... 

In contrast, drugs that release endogenous nitric oxide and donors of the molecule were in use long before nitric oxide was discovered and continue to be very important in clinical medicine. The cardiovascular applications of nitroprusside (Chapter 11) and the nitrates and nitrites (Chapter 12) have been discussed. The treatments of preeclampsia and of pulmonary hypertension and acute respiratory distress syndrome are currently under clinical investigation. Early results from the pulmonary disease studies appear promising, and one preparation of nitric oxide gas (INOmax) has been approved for use in neonates with hypoxic respiratory failure. 

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