Heart Assist Device

Poly(tetramethylene oxide) polyols (PTMEG) are high performance polyethers that are crystalline waxes at molecular weights above 650 and liquids at lower molecular weights. They are only available as diols, but they produce adhesives with good hydrolysis resistance and moisture resistance, which is why these adhesives are even used in medical devices, blood bags, catheters, and heart-assist devices [25]. Certain thermoplastic polyurethane adhesives and solvent-borne adhesives are also based on PTMEG s. 

As an integral member of THI s animal research team, Brano designed and preformed studies involving myocardial protection during cardiac operations, as well as temporary and permanent mechanical circulatory assist devices, heart valve prostheses, and synthetic vascular grafts. In addition he authored, and co- authored approximately 300 publications, and oversaw the writing of numerous heart failure and transplant protocols. 

Heart Assist Devices. Heart attacks that require hospitalization occur in more than 500,000 people each year. In some cases, a mechanical device is needed to relieve the damaged heart of part of its pumping burden. Several such devices have been developed, and all involve polymers. 

The simplest heart assist device is the intraaortic balloon pump (lABP) which consists of two small PEUU balloons mounted on a hollow catheter that is about 30 cm long. The distal occluding balloon is 18 mm in diameter, and the proximal pumping balloon is 14 mm in diameter. The device is inserted into the aorta via the femoral artery and connected to a pump that then expands and contracts the balloons in rhythm with the heart beat. This prosthesis is considered to be the best heart assist device because it is simple in design and easy to insert. Improved circulation does occur in about three-fourths of the patients, but the mortality rate still remains high (65-90%) in cases of refractory cardiogenic shock. The lABP is used over 15,000 times annually (51. 52). 

The most widely used heart assist device, other than the heart-lung machine routinely used in surgery, is the intraaortic balloon pump (lABP) which consists of a PEUU balloon mounted on a hollow catheter. The lABP is Inserted into the aorta via the femoral artery and is then expanded and contracted by an external pumping system to match the heart beat. While this device does provide significant Improvement in circulation and also allows the heart to rest partially after a myocardial infarction, the mortality rate is still 65-90 ( 8). 

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. 

Type of end use — this may deal with transmission of information (biopotentials, temperature, pressure, blood flow rate), energy (electrical stimulation, power for heart-assist devices), transfer of matter (cannula for blood), and load (attachment of a prosthesis) ... 

M. Szycher, Polyurethane elastomer for heart assist devices, Google Patents, 1978. 

Segmented polyurethane elastomers, prepared from diisocyanates, macrodiols and chain extenders, are frequently used in the construction of implantable medical devices, such as cardiac pacemakers, heart valves, catheters, and heart assist devices, because of their excellent mechanical properties and haemocompatibility. Polyether macrodiols, such as poly(tetramethylene oxide) (PTMO), are used to prepare polyurethanes for implant, since they offer an increased resistance to enzymatic hydrolysis compared with polyester-based polyurethanes. 

DDI has low toxicity and high resistance to moisture it reacts with diamines to form polyurea coatings that are internally plasticized and have excellent resistance to moisture and to yellowing by ultraviolet light. Besides coatings, important application fields for dimer diisocyanates, are polyurethane implants like stents or heart-assist devices and PUR rocket propellant liners or sealants. 

Bezuidenhout, D., WiUiams, D.F., ZiUa, R, 2015. Polymeric heart valves for surgical implantation, catheter-based technologies and heart assist devices. Biomaterials 36, 6-25. 

Implantable Heart-Assist and Compression Devices Employing an Active Network of Electrically-Controllable Ionic Polymer-Metal Nanocomposites... 

Boston, J, M. Simaan, J. Antaki, and Y. Yu, Control Issues in Rotary Heart Assist Devices, Proc. American Control Conference, 3473 (2000). 

Letsou, G. V., Shah, N., Gregoric, 1. D., Myers, T. J., Delgado, R., and Frazier, O. H. 2005. Gastrointestinal bleeding from arteriovenous malformations in patients supported by the Jarvik 2000 axial-flow left ventricular assist device. / Heart Lung Transplant 24 105-109. 

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