We developed a new transatrioseptal cannula for the left heart bypass which can be inserted safely and quickly by applicating modification of Seldinger technique. This cannula has a stylet in which 0.038 inch of guidewire is able to pass. In mongrel dogs weighing 15-20kg, 100-120ml/kg/min of flow volume could be obtained by using this 24 Fr. (ID=6mm) cannula in the left heart (left atrial-femoral artery) bypass. One day, three days and seven days after the insertion of this cannula in the left atrium, we pulled back this cannula to the right atrium. At that time, no meaningful interatrial shunt was detected. Moreover, the interatrial hole had been completely closed spontaneously one week after the decannulation in case of the three or less days' insertion. However, in case of the seven days' insertion, the hole had not been completely closed one week after the decannulation, but after two weeks it had been completely closed spontaneously.

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In the modern medical practice, it is essential to administer massive infusion such as total parenteral nutrition fluid and fresh frozen plasma even to anuric patients who do not respond to diuretics. However, such large water loading is hazardous in those patients causing many morbidities. The present study was undertaken to establish a safe and simple method of removing excess water with continuous hemofiltration (CHF) among those patients. In experimental study using overhydrated dogs, the CHF was confirmed to be a simple and safe method for the removal of excess water from the lung and muscle. The hemodynamic parameters were stable during the CHF. Taking these results into consideration, the CHF was applied on 16 critically ill overhydrated patients being unresponsive to diuretics. The CHF removed excess water very safely causing no adverse effects on cardiovascular system. The clinical effects of the CHF included improvement of pulmonary water infiltration and increase in caloric intake with total parenteral nutrition. These results indicate that the CHF is a safe, simple and effective method of excess water removal in the anuric critically ill patients.

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The pyridoxylated hemoglobin (PLP-Hb) was conjugated with polyethylene glycol (PEG) and tested for its biological half life (T_1/2) and safety by exchange-transfusion in rats. The T_1/2 of the PLP-Hbs conjugated with PEG 4, 000, 5, 000 or 6, 000 molecular weight was significantly increased as compared with that of stroma-free hemoglobin and PLP-Hb. However, there was no remarkable change in T_1/2 and P₅₀ value among them. Some of the hemoglobin preparations caused the elevation of GOT, GPT or cholesterol level in plasma one day after exchange-transfusion or the decline of alkaline phosphatase for 7 days. All of the test values were back to normal range after 14 days. The results suggest that the hemoglobin preparations do not cause serious side effects in vivo. However, it is indispensable to investigate the toxicity and infectivity of the contaminants in hemoglobin preparations before their application to human as artificial oxygen carrier.

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During the LVAD pumping, it is difficult to evaluate the degree of the cardiac function of the natural heart. To solve this problem, a mechanical circulatory model with which the cardiac function of the natural heart can be predicted without stopping of the LVAD pumping has been developed. This model was a closed circuit composed of three pulsatile pumps, five compliance tanks and three needle valves simulating the LVAD and the right and left heart, the capacitance elements of the blood vessels and the peripheral resistances. Two servo mechanisms simulating the autonomic control were designed and incorporated in the simulator. Twelve pairs of clinical hemodynamic data of on/off tests of LVAD pumping were analized with this simulation system. When hydrodynamic simulation data during the stop of LVAD pumping were compared with the corresponded human hemodynamics, the difference in the cardiac output between simulation and clinical data was kept within only ±0.1l/min. The differences between predicted and measured values in the left atrial pressure and the aortic pressure were within ±2.5mmHg and ±5.0mmHg, respectively. These data suggested that our simulation model has an adequate characteristics to predict the change in the hemodynamics of the clinical cases.

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The plasma non-corrected level of β₂-microglobulin (β₂-MG) increases during cuprophan membrane hemodialysis, but the mechanism other than hemoconcentration is controversial. To assess the possibility that, (1) β₂-MG would be increased during cuprophan membrane hemodialysis possibly due to bioincompatibility, (2) the inflammatory response would be involved in this process, we used 4h extracorporeal circulations (sham dialysis for 2h and dialysis for. 2h) under the condition of isovolemic in chronic hemodialysis patients without inflammatory disorders. The blood samples for estimating β₂-MG, C-reactive protein (CRP), α₁-antitrypsin, α₂-macroglobulin, α₁-acid glycoprotein, and haptoglobin were collected at 0, 15, 60, 120, 180, 240min and 10, 24, 48h. By this method, the results can be evaluated without any corrections. There was no change in plasma β₂-MG level and the acute phase reactant including CRP during the whole course of observations. These results may support the suggestion that β₂-MG is not increased during the cuprophan membrane dialysis and the inflammatory process is not associated with cuprophan dialyzer from the stand point of the response of acute phase reactant.

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