Applications cardiovascular system

The development of cardiac assist devices and other instrumentation and components which come in contact with the cardiovascular system requires materials which will perform in a physiological environment. One particularly difficult application is the diaphragm for blood pumps, which requires an elastomer to undergo cyclic deformation and/or flexing while in contact with blood. 

Acetylcholine is involved in many aspects of the regulation of the cardiovascular system. Thus, it may also play a role in the control of intercellular communication. Very early in gap junction research the effect of acetylcholine as an important transmitter on gap junction conductance has been investigated. First, Petersen and Ueda [1976] demonstrated an increase in junctional resistance in pancreatic acinar cells following the application of acetylcholine. Concomitantly, the release of amylase was stimulated. A minimum concentration of 1 pmol/l acetycholine was required to evoke uncoupling. The next question was, how is the acetylcholine effect mediated Calcium has been considered to contribute to the mechanism of action [Iwatsuki and Pertersen,... 

This last-mentioned successful series of control experiments, involving addition of cavitation nuclei to the cardiovascular system, brings to mind at least one feasible medical application for injected (synthetic) surfactant-stabilized microbubbles (cf. Chapters 9 and 10) as concerns evaluation of cardiovascular function. Various types of size-controlled, nontoxic, synthetic micro-... 

K. Lagana et al Multiscale modeling of the cardiovascular system application to the study of pulmonary and coronary perfusions in the univentricular circulation. J. Biomech. 38, 1129-141 (2004)... 

A number of other processes are in continuous development. Clinical applications of these therapies in the urogenital and cardiovascular systems, in peripheral and central nervous systems, pancreas, joint cartilage restoration, etc., are being studied. However, almost all procedures suffer from a common limitation the availability of donor cells. Cell therapies have to begin with a relatively high number of cells, and stem cells, irrespective of their origin, are always a minor subpopulation in tissues. 

This chapter discusses specific organ systems that contact a variety of substances in the workplace environment (or due to drug abuse and addiction), leading to health hazards. Important organs discussed here include the skin, the respiratory system, the cardiovascular system, the renal system, and the central nervous system (CNS). In the United States and other countries of the world, the application of phenol is on the increase in the manufacture of aromatic compounds, explosives, fertilizers, paints, rubber products, wood preservatives, synthetic resins, drugs and pharmaceutical products, plastics, leather tanning and... 

Heme oxygenase-1 is inducible and a number of compounds have been identified which induce it so as to produce carbon monoxide, biliverdin/bilirubin and Fe2+/ferritin [12]. These include aspirin, statins, curcumin (a component of turmeric) and resveratrol (a component of red wine). The induction of heme oxygenase takes many hours so that such treatments are applicable to chronic conditions. Aspirin and statins are now prescribed for the cardiovascular system but the significance of the heme oxygenase is unproven. The compounds that are catabolised to give CO provide an alternative procedure. 

High blood levels after topical application or injection of anesthetics may potentially cause systemic reactions. Toxic effects may appear in the central nervous system (CNS), cardiovascular system, or respiratory system. CNS toxicity appears initially as stimulation and may manifest itself clinically as nervousness, tremors, or convulsions. CNS depression, observed clinically as loss of consciousness and depression of respiration, usually follows. The earliest signs of cardiovascular involvement are hypertension, tachycardia, and, occasionally, cardiac arrhythmias. Late cardiovascular signs are hypotension, absent pulse, and weak or absent heartbeat. The effects on the cardiovascular system can develop either simultaneously with CNS depression or alone. If allowed to continue, such cardiac depression and resultant peripheral vasodilation are followed by secondary respiratory failure. 

Hemolysis is determined by placing powder, rods, or extracts of a material in contact with human or animal plasma for about 90 minutes at 37°C (31). The amount of hemoglobin released into solution after lysis of the red cells in contact with the device is measured. When red cells undergo lysis, hemoglobin is released from the cells, and the absorbance from released hemoglobin is proportional to the amount of cell lysis. Extensive red-cell lysis is not desirable for devices that are to be implanted in the cardiovascular system. The measurement of hemolysis and its relevance is a question that should be addressed it each device application. 

The application of antibodies in cardiovascular targeting in vivo originated with the experimental demonstration of the feasibility of using radiolabeled antimyosin antibody for diagnosis of acute myocardial infarction in 1976. Since then, the use of antibodies in the cardiovascular system has encompassed imaging of myocarditis,heart transplant rejection, dilated cardiomyopathy, alcohol induced cardiomyopathy,adriamycin cardiotoxicity, various other cardiomyopathies, vascular clots, atherosclerotic lesions,and even certain cancers such as soft tissue sarcomas.f Yet the best characterized and studied antibody for cardiovascular diagnostic targeting is monoclonal antimyosin Fab for its exquisite specificity... 

A newer application of pure perfluorocarbons with relatively low boiling points is as contrast agents for medical ultrasound examination of the circulatory system [112]. Making the ultrasound imaging technique available for examination of, in particular, the cardiovascular system and other soft tissues is highly important, because ultrasound technology is far more widespread and less expensive than other imaging equipment. 

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