Applications artificial heart valves

Due to their chemical inertness, high abrasion resistance, low friction and good biocompatibility DLC films are very promising candidates for biomedical applications. For example, femoral heads of hip protheses have been coated successfully with DLC to reduce the production of small wear particles, which can lead to reactions on a cellular level. Furthermore DLC was shown to be a potential material for artificial heart valves where the films must be non-thrombogenic and must have a long-time stabihty in contact with blood [93]. Mitura et al. [94] investigated DLC... 

Silicone elastomers have a long history of use in the medical field. They have been applied to cannulas, catheters, drainage tubes, balloon catheters, finger and toe joints, pacemaker lead wire insulation, components of artificial heart valves, breast implants, intraocular lenses, contraceptive devices, burn dressings and a variety of associated medical devices. A silicone reference material has been made available by the National Institutes of Health to equate the blood compatibility of different surfaces for vascular applications. This material is available as a silica-free sheet. Contact the Artificial Heart Program, NHBLI, NIH, Bethesda, Md. for further information. 

Biomedical applications relate to the impact of a material, device or procedure in a medical or clinical situation on the health care of humans. The expected outcome should be positive when properly utilized. The application can be a medical device as simple as a syringe or a piece of gauze for cleaning wounds, or as complex as pacemakers, orthopaedic implants and artificial heart valves. For the purpose of this review, we take a focused view by considering the biomedical applications that have been proposed for chitin and chitosan. 

PHB finds applications in the development of biomedical devices and related products, as scaffolds in tissue engineering, development of vascular grafts and artificial heart valves and as a packaging material. One of the major limitations of using PHB is due to... 

Materials used in biomedical applications (that is, in intimate contact with living organisms) are called biomateriats. We ll see that a biomaterial must meet many requirements to be suitable for such applications as heart valves, artificial tissue, or hip replacement components. 

Due to their biodegradability and biocompatibility, PHBV and other PHA exhibit great potential for application in packaging (Zribi-Maaloul et al. 2013), to produce bioabsorbable scaffolds (Ke et al. 2014), membranes for controlled drug delivery, sutures, wound dressings, artificial heart valves, etc. (Ruiz et al. 2011) and in the agricultural sector, such as reforestation tubes, toiletries, and other sectors as toy and automotive industries. 

Biomaterials have played a vital role in the treatment of cardiovascular diseases, examples of applications including heart valve prostheses, vascular grafts, stents, indwelling catheters, ventricular assist devices, total implantable artificial heart, pacemakers, automatic internal cardioverter defibrillator, intraaortic balloon pump, and more. A key requirement for materials in cardiovascular applications, particularly blood-contacting devices, is blood compatibility, that is, nonthrombogenic. Additional requirements include mechanical and surface properties that are application specific. Surveying the field of polymers used in cardiovascular applications reveals that PUs, polyethylene terephthalate (PET), and expanded PTFE (ePTFE) are the most commonly used. This section will review each of the three polymers followed by a brief introduction of other emerging polymers for use in the cardiovascular area. 

Biomedical Applications. In the area of biomedical polymers and materials, two types of appHcations have been envisioned and explored. The first is the use of polyphosphazenes as bioinert materials for implantation in the body either as housing for medical devices or as stmctural materials for heart valves, artificial blood vessels, and catheters. A number of fluoroalkoxy-, aryloxy-, and arylamino-substituted polyphosphazenes have been tested by actual implantation ia rats and found to generate Httle tissue response (18). 

Teflon was introduced to the public in 1960 when the first Teflon-coated muffin pans and frying pans were sold. Like many new materials, problems were encountered. Bonding to the surfaces was uncertain at first. Eventually the bonding problem was solved. Teflon is now used for many other applications including acting as a biomedical material in artificial corneas, substitute bones for nose, skull, hip, nose, and knees ear parts, heart valves, tendons, sutures, dentures, and artificial tracheas. It has also been used in the nose cones and heat shield for space vehicles and for their fuel tanks. 

There is a great need for strong materials such as alloys that can snap back into shape. Medical applications include prostheses— artificial limbs—and implanted devices such as heart valves. Most biological substances are smart, and the ability to replace lost or injured tissues and organs with smart materials would be a tremendous medical advance. 

The application of polymeric materials in medicine is a fairly specialized area with a wide range of specific applications and requirements. Although the total volume of polymers used in this application may be small compared to the annual production of polyethylene, for example, the total amount of money spent annually on prosthetic and biomedical devices exceeds 16 billion in the United States alone. These applications include over a million dentures, nearly a half billion dental fillings, about six million contact lenses, over a million replacement joints (hip, knee, finger, etc.), about a half million plastic surgery operations (breast prosthesis, facial reconstruction, etc.), over 25,000 heart valves, and 60,000 pacemaker implantations. In addition, over AO,000 patients are on hemodialysis units (artificial kidney) on a regular basis, and over 90,000 coronary bypass operations (often using synthetic polymers) are performed each year (]J. 

As we shall see in Chapter 15, polyurethane is a polymer of choice for a wide variety of biomedical applications. Polyurethane is used extensively in the construction of devices such as vascular prostheses, membranes, catheters, plastic surgery, heart valves, and artificial organs. Polyurethanes are also used in drug delivery systems such as the sustained and controlled delivery of pharmaceutical agents, for example, caffeine and prostaglandin. ... 

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