Accession Number : AD0666301

Title :   RESEARCH ON FLUID MECHANICS PROBLEMS ASSOCIATED WITH ARTIFICIAL HEARTS.

Descriptive Note : Final rept.,

Corporate Author : AVCO EVERETT RESEARCH LAB EVERETT MASS

Personal Author(s) : Zlotnick,M.

Report Date : APR 1967

Pagination or Media Count : 32

Abstract : Research was carried out in two areas: (1) in the analysis of pressure pulse wave propagation in the aorta, and (2) in problems associated with balloon-pumping (a technique providing emergency ventricular-assist by counterpulsation). A physical-mathematical model was devised to represent the aorta taking into account time delays associated with hydroelastic wave propagation not considered in the windkessel model. An effort was made to avoid the complexity, and the resulting tendency to obscure physical insights, associated with highly detailed 'delay-line' computer approaches. Based primarily on the one-dimensional wave equation, which is shown by an heuristic analysis to be a satisfactory approximation to the physical situation being considered, the calculations yield typical pressure time-histories and stroke volumes appropriate to the physiological input parameters used. The input parameters consist principally of impedance values at the major branches from the aorta, basic geometric parameters, and the (dimensionless) shape of the stroke velocity time history. In connection with the research in balloon-pumping, two types of instability were disclosed. One form of instability is associated with the inflated balloon and one is associated with the inflation process. For the inflated ballon, it has been found theoretically that as the blood flow velocity approaches the wave speed of the balloon-aorta system, the balloon occludes the aorta. The phenomena, which can have catastrophic effects on the efficacy of balloon pumping if not properly compensated, is somewhat reminiscent of the 'sonic barrier' in aerodynamics. Experimental indication of the onset of this process is reported. (Author)

Descriptors :   (*MECHANICAL ORGANS, *FLUID MECHANICS), HEART, AORTA, BLOOD PRESSURE, PULSE RATE, BLOOD CIRCULATION, HYDRODYNAMICS, PROPAGATION, ONE DIMENSIONAL FLOW, HYDRAULIC EQUIPMENT, MATHEMATICAL MODELS, STABILITY, BALLOONS, INFLATABLE STRUCTURES, OBSTRUCTION(PHYSIOLOGY)

Subject Categories : Medicine and Medical Research
      Medical Facilities, Equipment and Supplies
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE