Browsing by Author "Bruner, James Dennis"
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Item A blood pump for closed-chest left ventricular bypass(1969) Bruner, James Dennis; Dalton, Charles; Geddes, Leslie A.; White, Ardis H.; Flumerfelt, Raymond W.In the quest for more effective and less traumatic methods of treating heart failure the Baylor University College of Medicine, Department of Physiology, has developed a new method of left ventricular assistance. The method does not require thoracotomy and provides assistance to the failing myocardium. Inherent in this method, however, are some rather severe limitations on the pump and pumping system used in implementing the assist. Most notable among these is a long, small diameter tube (catheter) which is placed in the failing ventricle via a carotid artery in the neck. The catheter is used to withdraw blood from the ventricle for later infusion into the arterial tree. The dimensions of the catheter produce a significant pressure drop which is seen as a vacuum at the pump inlet. This vacuum, with normal pumps, decreases flow rates, increases hemolysis rates and results in other undesirable features of pump performance.Item Filtering characteristics of a long cylindrical steel bar with discontinuities in cross sectional area(1966) Bruner, James Dennis; Muster, Douglas F.; White, Ardis H.; Childs, S. Bart; Eichberger, Le Roy C.When a continuous longitudinal wave is propagated along the length of a finite cylindrical steel bar the frequency of maximum response of the propagated wave depends on the length of the bar. This is due to the reflections of acoustic energy which occur at the ends. Any other abrupt change in cross sectional area is also a point of energy reflection and if there are several area discontinuities spaced along the bar length the possibility of acoustic resonances exists. Typically, such a system is analyzed by means of mechanical-electrical analogies. A four-terminal electrical network is synthesized which has the characteristics of the mechanical system. The result is a Pi-section band pass filter composed of passive, non-dissipative components. These components are functions of the physical characteristics of the mechanical system and take into consideration such parameters as distance between discontinuities and area ratios at discontinuities. A computer program is given by means of which quantitative information is obtained and discussed. The attenuation is presented as a function of frequency for a typical physical model. The pass and stop bands for this system are discussed.