Artificial arteries

Last but not least requirement, artificial arterial substitutes must be able to be connected to the host s vessels using sutures, the only reliable mean surgeons trust (Fig. 2). The connections performed must be stable and blood tight for as long as the prosthesis will remain patent. This last condition has supported the interest of surgeons for vascular prostheses made of woven or non-woven and knitted synthetic fabrics. The following sections give an outline of the different steps that line the evolution of materials for the cardiovascular system, and present some prospective solutions that have been proposed and supposed to improve the performances of these materials. 

Elastomer technology is useful in medicine. Muscles and arteries contain giant molecules, called elastin, that make muscles and arteries contract. Doctors can give artificial arteries to people with severe heart problems or other diseases. Unfortunately these artificial arteries do not last long enough. Can they be replaced by a new type of elastomer ... 

Dr. Judit Puskas holds Canada s first Industrial Research Chair in Elastomer Technology at the University of Western Ontario in London, Ontario. She thinks that an elastomer called polyisobutylene, along with some of its derivatives, looks promising. In the future, it may be used to make better artificial arteries. It may also be useful for other implants, since it can imitate the rubber-like properties of elastin. 

Zip-lock bags, carrier bags, microwave-safe shrinkwrap food film, Tupperware containers, food chopping boards, food packaging films, milk, bread and beer crates, water pipes, electrical cable insulation, geo-textiles, replacement body parts (e.g. heart valves, artificial arteries, hip Joints). ... 

Westerhof, N., Elzinga, G., and Sipkema, P. 1971. An artificial arterial system for pumping hearts. /. Appl. Physiol. 31 776-781. 

Isenberg BC, Williams C, Tranquillo RT, Small-diameter artificial arteries engineered in vitro. Circ Res, 2006, 98, 25-35. 

As explained earlier, the segmented structure of poly(ether-urethanes) leads to high swelling and partial solution when the polymers are immersed in liquids of widely varying polarity. Table 1 lists the effects of a number of liquids on non-halogenated Biomer including some hydrophilic vinyl monomers. Note that all results were obtained with artificial arterial... 

This is the first type of artificial artery which shows the presence of an elastomechanical layer surrounding the healed man-made artery. 

Coronary artery disease remains the main killer. The mortality from coronary artery disease has decreased by 28% in the last 20 years. A first acute myocardial infarction had mortality of 28% in 1963 and today it is about 7%. The price of life has become more and more valuable. We are only on the threshold of understanding the pathogenic and biological principles of the generation of atheroma, but once established, obstructive lesions need coronary artery dilatation, coronary artery bypass or arterial replacement. The saphenous vein is an excellent bypass conduit but its life expectancy is 3 to 10 years only until it thromboses, or becomes atheromatous and is blocked or obliterated by cholesterol filled intima or clot. The internal mammary artery is ideal but flow is too small to sustain adequate flow to the entire heart. Here too, there is the need for new non-thrombogenic materials to reconstruct artificial arteries, substances which are durable, non-thrombotic and do not promote atherogenesis. There is also the need for simple, non-invasive techniques to measure coronary blood flow and the anatomy of the coronary arteries to plan subsequent surgical procedures. 

Organics (artificial arteries, parachutes, pen tips, telephones) 2.63... 

One of the characteristics of the woven arterial prosthesis is the tissue ingrowth that occurs within the interstices of the fabric. It is possible that this tissue can effectively reconstitute a new artery, thereby obviating the adverse effects of degradation. This possibility is utilized in at least one design of artificial artery in which the material is designed to be degradable to some extent. The material utilized here is a blend of poly(ether urethane) and poly(lactic acid). 

An important development towards the artificial kidney was achieved by Dr. Belding Scribner in 1960, who devised a U -shaped shunt implanted through the skin between an artery and vein to access the blood stream to perform routine dialysis (Ratner, 2004). Dr. Scribner made use of Teflon tubes to access the vessels and provides a nonstick surface for the transport of blood. The Scribner shunt has allowed more than one million patients to survive from kidney failure. 

In the isolated perfused kidney model, the artery of the kidney is perfused and urinary samples as well as venous blood samples can be collected to determine the drug concentration. A serious drawback of the model is that isolation and artificial perfusion greatly affect the function of the organ as shown by a dramatic drop in the glomerular filtration rate. Another in-vitro model is the isolated tubule in which samples can be taken from both the luminal and basolateral sites of the tubule [140,141]. The disadvantage of this technique as well as of the isolated kidney model, is that they require specific equipment and expertise and therefore can only be performed in rather specialized laboratories. Experiments using freshly isolated or cultured cells are more simple to carry out [142,143]. Tubular cells can be grown in a po-... 

Another field of application of fluorinated biomaterials is connected to lesions or evolving disease pathology of blood vessels. In particular, arteries may become unable to insure an adequate transport of the blood to organs and tissues. Polytetrafluoroethylene (PTFE) and expanded e-PTFE are the preferred materials for vascular prostheses. The interactions of blood cells and blood plasma macromolecules with both natural and artificial vessel walls are discussed in terms of the mechanical properties of the vascular conduit, the morphology, and the physical and chemical characteristics of the blood contacting surface. 

In many species, the entire gland is located such that it may be readily excised intact and undamaged. An artificial blood supply may be connected to cannulated veins and arteries (Figure 1.6) if desired, the blood supply may be passed through an artificial kidney. The entire mammary gland may... 

The blood of the patient, withdrawn from an artery near the wrist, is allowed to flow through the blood circuit, which includes the dialyzer, usually a blood pump plus monitoring instruments, and is returned to a nearby vein. The connections to the blood vessels are made via the so-called subcutaneous arteriovenous shunt this involves an artificial tube that connects the artery and vein underneath the wrist skin. 

Cellulose, an important constituent of wood, has long chains of glucose molecules linked by glycoside bonds. These chains are cross-linked by hydrogen bonds. Many biological polymers have unusual mechanical properties, not at present matched by the properties of artificial macromolecules. For instance, arteries are... 

J.H. Gibbon, Jr, Artificial Maintenance of Circulation During Experimental Occlusions of Pulmonary Artery, Arch. Surg. Chicago 34, 1105 (1937). 

---