Other Blood-Contacting Devices

Poly(ether-urethanes) (PU) BIOSPAN Polymer Technology Croup, Inc. Heart valves, vascular grafts, and other blood-contacting devices... 

For biomedical applications, inhibition of protein adsorption, as well as platelet activation and adhesion on the polymer surface, is critical to the efficiency of the material. For example, use of PHAs as artificial blood contacting devices such as arteries and anticoagulant films was limited by surface-induced thrombosis. The adsorption of plasma proteins and adherence of activated platelets onto the polymer surface resulted in their transformation to pseudopods and subsequent release of platelet biochemical content, which in turn activated other platelets leading to the... 

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. 

The goal was to prepare an anchorable (polystyrene) product that, when exposed to an aqueous, saline environment, would result in exposure and swelling or other freedom of the hydrophilic spacer that would, in turn, allow the biologically active compound, heparin, to inhibit clotting and/or that could be used for fabrication of blood-contacting devices for the same purpose. These potential end uses were to be tested at a later date. 

Other cardiovascular uses have included coatings on pacemakers and pacemaker lead-wires for purposes of insulation and for achieving biocompatibility. Medical grade silicone elastomer has been widely used as a material of construction in experimental artificial hearts and heart assist devices. Silicone tubing is often preferred for use in roller-type blood pumps during cardiopulmonary bypass. Medical grade silicone elastomer contains no leachable or organic plasticizers and thus contributes minimal contamination in blood contact applications. 

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. 

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