Blood Pumps

Cardiac nuclear imaging using Tc -red blood cells can measure the fraction of blood pumped by the heart during each beat. Tc -DTPA and sodium (9-iodohippurate, C H INNaO, are used to measure renal function of the kidney. The enhanced or diminished uptake of... 

One successful total artificial heart is ABIOMED s electric TAH. This artificial heart consists of two seamless blood pumps which assume the roles of the natural heart s two ventricles (Fig. 7). The pumps and valves are fabricated from a polyurethane, Angioflex. Small enough to fit the majority of the adult population, the heart s principal components are implanted in the cavity left by the removal of the diseased natural heart. A modest sized battery pack carried by the patient suppHes power to the drive system. Miniaturized electronics control the artificial heart which mns as smoothly and quietly as the natural heart. Once implanted, the total artificial heart performs the critical function of pumping blood to the entire body (6). 

Siloxane-urethane segmented copolymers, which have very good mechanical, fatigue and surface properties 370,377 or their blends with conventional polyurethane-(ureas) have been successfully used in the production of blood pumps, intra-aortic balloons and artificial hearts 200,332,370,376,377). 

The primary function of the heart is to deliver a sufficient volume of blood (oxygen and nutrients, etc.) to the tissues so that they may carry out their functions effectively. As the metabolic activity of a tissue varies, so will its need for blood. An important factor involved in meeting this demand is cardiac output (CO) or the volume of blood pumped into the aorta per minute. Cardiac output is determined by heart rate multiplied by stroke volume ... 

These functions are carried out most effectively and efficiently when the involved tissues receive an abundant blood flow. Under normal resting conditions, the kidneys, which account for only 1% of the body s weight, receive 20% of the cardiac output (CO) the gastrointestinal tract receives approximately 27% of the CO and the skin receives 6 to 15% of the blood pumped by the heart per minute. Because these tissues receive more blood than they need to support metabolic activity, they can easily tolerate a... 

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. 

Biocompatibility (See Table 1), which is a phenomenological concept, is the essential property of biomaterials. For instance, the inner surface of an implanted vascular graft or blood pump (artificial heart) must be blood-compatible, while its outer surface must be tissue-compatible. In other words, the material surfaces must not exert any adverse elfects upon blood or tissue, or upon other biological elements at the interfaces. 

Intracorporeal oxygenators are an entirely different type of blood oxygenator that can be used within the body to temporarily and partially assist the lung functions of patients with serious pulmonary diseases. No blood pump is necessary. 

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. 

The use of synthetic polymers in medicine and biotechnology is a subject of wide interest. Polymers are used in replacement blood vessels, heart valves, blood pumps, dialysis membranes, intraocular lenses, tissue regeneration platforms, surgical sutures, and in a variety of targeted, controlled drug delivery devices. Poly(organosiloxanes) have been used for many years as inert prostheses and heart valves. Biomedical materials based on polyphosphazenes are being considered for nearly all the uses mentioned above. 

Cardiac output The volume of blood pumped by the heart in one cycle. 

I thought my eyelids had been burned open, but all I could see was the domed shape of my skull and the blood pumping across the vessels of my inner eye. I smelled the excited chemical scent of combustion. 

Park CH, Nishimura K, Akamatsu T, Tsukiya T, Matsuda K, Ban T. A new magnetically suspended centrifugal blood pump in vitro and preliminary in vivo assessment. Artif Organs 1996 20(2) 128-131. 

Hearing aids, blood pumps, catheters contact tens, electrodes 510(k)... 

Watanabe N, Sakota D. Deformability of red blood cells and its relationship to blood trauma in rotary blood pumps. Artif. Organs. 2001 31 352-358. 

BLSS The bioartificial hver support system is made up of a blood pump, a heat exchanger to control the blood temperature, as well as an oxygenator and a bioreactor. The hollow-fibre bioreactor generally contains 70—100 g of porcine hver cells. Initial experience with BLSS is encouraging. (92)... 

Although CFD has been widely used to model blood pumps and other membrane processes, its application in membrane BOs is very limited. Development of a CFD model requires simplifying assumptions. In their model. Baker et al. assumed that blood was statistically homogeneous the reaction between oxygen and hemoglobin was fast axial diffusion of gas was neglected ... 

Hemolysis procedures are described in ASTM F756-93 Standard Practice for Assessment of Hemolytic Properties of Materials and ASTM F1841-97 Standard Practice for Assessment of Hemolysis in Continuous Flow Blood Pumps . The presence of... 

Cardiac output—The volume of blood pumped by the heart per unit of time. Cardiac output is the product of heart rate and stroke volume. 

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