Experimental evaluation of mechanical heart support system based on viscous friction disc pump

Aim. Experimental evaluation of the viscous friction disk pump efficiency, studying the relationship between inter-disk clearance and sizes of input and output ports and pump performance parameters.Materials and methods. To assess the characteristics and to optimize the disk friction pump design the pump model and experimental stand were created. Pump dimensions were set on the basis of medical and biological requirements for mechanical heart support systems and with due consideration of the experimental studies of our colleagues from Pennsylvania. Flow volume of the working fluid was measured by float rotameter Krohne VA-40 with measurement error of not more than 1%. The pressure values in the hydrodynamic circuit were measured using a monitor manufactured by Biosoft-M. Expansion device allowed changing the flow resistance of the system simulating the total peripheral resistance of the circulatory system.Results. Linear direct correlation between the pump performance and the pressure drop of liquid being created at the inlet and outlet of the pump was obtained. The required flow rate (5–7 l/min) and pressure (90–100 mmHg) were reached when the rotor speed was in the range of 2500–3000 rev/min. It has been shown that the increase of the inlet diameter to 15 mm has not resulted in a significant increase in the pump performance, and that the highest efficiency values can be obtained for the magnitude of inter-disk gap of 0.4–0.5 mm.Conclusion. Designed and manufactured experimental disc pump model for pumping fluid has showed the fundamental possibility to use this model as a system for mechanical support of the heart.

THE EXPERIMENTAL MODEL OF DISC-PUMP FOR MECHANICAL CIRCULATORY SUPPORT

The relevance of the use of circulatory support systems for the treatment of chronic heart failure (CHF) has increased over the recent years. Up to 20% of the patients from the waiting list for a donor heart die each year before they could get one. In our country, there is a huge need for mechanical heart support systems. However, the acquisition of foreign systems is associated with the excessive fi nancial costs. In addition, nowadays, there is no system that would meet all medical and technical requirements in full, and at the same time, would be of high safety for the patient. Therefore, research on the development of the systems of auxiliary circulation is highly relevant and is in demand in our country. One of the promising directions in this fi eld is disk pumps of viscous friction, which are based on the operation principle of Tesla disk pump. This article describes the creation and operation of the current model of the disk pump. The results of the bench tests confirmed that the expendable pressure characteristics of our disk pump are capable of providing the necessary parameters of blood circulation. The findings confi rm the perspective of the selected research area and provide the basis for further development and testing of this model of pump.

PROSPECTS OF DISK PUMP FOR MECHANICAL CIRCULATORY SUPPORT IN CARDIAC SURGERY (REVIEW)

The need of circulatory support systems in the treatment of chronic heart failure is increasing constantly, as 20% of the patients on the waiting list die every year. Despite the great need for mechanical heart support systems, the use of available systems is limited by its expensiveness. In addition, there is no one system that is 100% responsible to all medical and technical requirements and that would be completely safe for patient. Therefore, further research in the field of circulatory support systems considering health and technical requirements is relevant. One of the new directions in the study are disc pumps of viscous friction for liquid transporting, based on the Tesla pump principle. The operation principle of such pumps is based on the phenomenon of the boundary layer which is formed on the disk rotating in a fluid. There are experimental studies of models with different variants of the rotor suspension, various forms and numbers of the disks, forms of the pump housing. However, none of the above samples was brought to clinical trials. Furthermore, despite the potential of that model there have been no pumps of similar type used so far in circulatory support systems. Published data provide a basis for further development and testing of the pump model and allow hoping for leveling a number of significant shortcomings of modern left ventricular bypass systems.