P6vices for hydrodynamic simulation are required in a variety of studies such as device evaluation, cardiovascular modeling and for student training. Most studies today use different, incompatible circuits, which must be redesigned for every new application. To obtain a universal apparatus, a unitized system with standard connectors was developed. Three types of connectors were selected: 1" flange connectors, 1/2" tubing connectors and Luer-connectors with a 2 mm lumen. The complete system consists of reservoirs, throttles, valve holders, adapters for Doppler ultrasound probes, and converters to link these basic diameters. The apparatus can be driven by membrane, centrifugal and geared pumps. The system has successfully been used in echocardiographic studies of stenosis and valvular insufficiency, for pulse propagation in vascular grafts, and to test the hydraulic performance of cardiac assist devices. Flow rates between 0.1 and 30 l/min and pressure gradients up to 250 mmHg were achieved. In practical use, the system can be adapted to suit various investigations, with minimal expense. Standardization of the parts and connectors results in simple documentation and good reproducibility.
To improve the filling characteristics of pneumatically driven membrane artificial hearts (AHs), a vacuum is applied during diastole. This paper describes an ejector system for AH-drivers based on the Venturi effect, which was designed for this purpose. It provides vacuums of more than -40 mmHg at flow rates up to 50 l/min requiring a supplying primary gas pressure of less than 150 kPa (1140 mmHg). Under normal working conditions, the necessary supply flow was less than 5l/min. The device is small, cheap, quiet and fail-safe, and has been evaluated successfully in experimental and clinical use.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.