Evaluation of hemolysis within a blood pump on a computer is useful for developing rotary blood pumps. The flow fields in the axial flow blood pump were analyzed using computational fluid dynamics (CFD). A blood damage index was calculated based on the changes in shear stress with time along 937 streamlines. Hemolysis of the pumps was measured using bovine blood. A good correlation between the computed and measured hemolysis results was observed. CFD analysis is useful for estimating hemolysis of rotary blood pumps on a computer.

A low rate of hemolysis is an important factor for the development of a rotary blood pump. It is, however, difficult to identify the areas where hemolysis occurs. Computational fluid dynamics (CFD) analysis enables the engineer to predict hemolysis on a computer. In this study, fluid dynamics throughout intracardiac axial flow pumps with different designs were analyzed three-dimensionally using CFD software. The computed pressure-flow characteristics of the pump were in good agreement with the measurements. The Reynolds shear stress was computed along particle trace lines. Hemolysis was estimated on the basis of shear stress (tau) and its exposure time (Deltat): dHb/Hb = 3.62 x 10(-7)(tau)(i)(2.416) x Delta(t)(i)(0.785). Particle damage increased with time along the particle trace lines. Hemolysis of each of the pumps was measured in vitro. The computed hemolysis values were in good agreement with the experimental results. CFD is a useful tool for developing a rotary blood pump.

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Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implanted. The objective of this study was to show the feasibility of using the Valvo pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo pump consists of an impeller and a motor. The motor is waterproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalized index of hemolysis (NIH) was 0.030 +/- 0.003 (n = 3) for a blood flow of 5 L/min at a pressure difference of 13.3 kPa. The pressure resistance of the ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,000 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The results showed that the Valvo pump can maintain systemic circulation with an acceptable level of hemolysis.

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The existence of rule-out diagnoses affects the results of statistics based on HIC data. Japanese statistics based on HIC data should be improved by utilizing the information on rule-out diagnoses.

Inadequate notification is a recognized problem of measles surveillance systems in many countries, and it should be monitored using multiple data sources. We compared data from three different surveillance sources in 2007: (1) the sentinel surveillance system mandated by the Act on Prevention of Infectious Diseases and Medical Care for Patients Suffering Infectious Diseases, (2) the mandatory notification system run by the Aichi prefectural government, and (3) health insurance claims (HICs) submitted to corporate health insurance societies. For each dataset, we examined the number of measles cases by month, within multiple age groups, and in two categories of diagnostic test groups. We found that the sentinel surveillance system underestimated the number of adult measles cases. We also found that HIC data, rather than mandatory notification data, were more likely to come from individuals who had undergone laboratory tests to confirm their measles diagnosis. Thus, HIC data may provide a supplementary and readily available measles surveillance data source.

Thrombus formation is a critical issue when designing a long-term implantable left ventricular assist system (LVAS). Fluid dynamic characteristics of blood flow are one of the main factors that cause thrombus formation. In this study, we optimized the fluid dynamics of a sac blood pump in our LVAS to ensure minimization of shear-related blood damage that could lead to thrombus formation. A pump housing and a sac chamber were designed with computer-aided design (CAD) software, and fluid dynamics were estimated by computational fluid dynamic (CFD) analysis. We adopted distribution of CFD results for qualitative evaluation, and we also tried to estimate normalized index of hemolysis (NIH) from the results of CFD analysis as a quantitative index of optimization for geometry of the blood pump chamber. A prototype model of the optimized blood pump was made using a three-axis computer machine tool by whittling pieces of nonfoamed polyurethane. Shear stress and theoretical NIH in the redesigned model were lower than those in the first model. Area of flow stagnation that was observed in the first model was not seen in the redesigned model. The results demonstrate that application of CAD/CAM technology to design an artificial heart contributes to optimizing a blood pump chamber for the purpose of reducing thrombus formation.