Artificial kidney (AK), it self is not complate aparatus, so we developed many kinds of AK, such as multipurposes AK portable AK, belt type AK, peritoneal dialysis machine, new type adsorbents which are able to adsorb urea and also implantable AK, using hemofilter and colon. In animal experiment, it was proved that colon reabsorbed water and sodium but no waste materials from the filtrated fluid.

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As of October, 1912, private charges for chronic hemodialysis and peritoneal dialysis were covered by the government, therefore, number of patients under chronic dialysis therapy have significantly increased by year and year from that time. There were 30, 000 patients on chronic dialysis treated in 1, 130 dialysis centers in Japan at the end of June, 1979. In 1 year about 7, 300 patients suffered from terminal stage of chronic renal failure were newly treated with hemodialysis or peritoneal dialysis in Japan. The survival rate of chronic hemodiaysis patients was 85% in lyear, and 70% in 5 years after begining of the treatment at the end of 1978 in Japan.
These data suggest that the final total number of chronic dialysis patients in Japan will reach approximately 130, 000. In near future, at the end of 1989, 10 years after now, number of these patients will be more 2.46 times than number of patients at present. So that, we have to set up both well-trained staffs and kidney assist machines corresponding to an increase of the patients. However, it seems impossible to prepare such large requests in short period.
As a settlement of these problems, a short time dialysis (3 hours) should be introduced in the treatment, however, an usual dialyzer functioning with dialysis can not be able to perform maintenance dialysis in only 3 hours.
A new system combining direct hemoperfusion by microencapsulated, bead-shaped charcoal and hollow fiber kidney is available to perform 3 hours maintenace dialysis as results of our clinical applications in long period.
This system is not able to cut off the dialysis time, but also having a profit of removing middle molecular weight substances from the blood during the dialysis. As a result of removing unknown substances, an uremic pericarditis and uremic nueropathy are markedly improved with this treatment.
This newly devised kidney assist system is veru usuful for the settlement of increasing patients under treatment of chronic renal failure, for rehabilitation of them and for treatment for patients under some kinds of uremic conditions.

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Fundamental qualities necessary for the success of vascular substitutes were recognized and they are less reactivity, antithrombogenicity, high porosity, suitable flexibility and long standing durability.
There have appeared two innovations in the fabrication of synthetic prosthesis. One is the velour surface construction and the other is the expanded PTFE. These grafts showed rather excellent anti-thrombogenic properties, but neointimal fibrous hyperplasia was then found as a cause of late rethrombosis.
The effect of drugs which interfare with platelet function, on the formation of neointimal hyperplasia suggests that hyperplasia seems to be due to recurrent platelet aggregation to anastomoses. Clinical application of the drugs, particulary for small vassel reconstruction, is discussed.

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Based on the analysis of conventional vascular prosthesis, current trends in the development of vascular prosthesis were discussed in this paper to extend the clinical vascular reconstruction by vascular substitutes. It was demonstrated in the recent our experimental study that PTFE-methylmethacrylate graft copolymer prosthesis available for venous reconstruction were 80% patent about 8 years after the insertion into the superior vena cava of mongrel dogs, so new developments of vasculae prosthesis might be followed as that of new blood-compatible materials.

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With the aim of resolving the problem points of venous return in the total artificial heart replacement experiment, a new type of blood pump having a performance closely corresponding to that of a natural heart was developed with an accessory chamber with the blood contact surface in the pump exposed to the air. With the use of the mock circulation unit, experiments were conducted to test the performance of this new pump together morphological and anatomical fitting trials of the pump within the thorachc cavity of calves and chronic pump implantation tests. By the development of a new blood pump with an accessory chamber having a soft housing during dialtole and a hard housing during systole, performance approaching that of the natural heart could be attained.

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Though artificial heart study is progressing rapidly especially in these few years, there remains many problems to be solved.
In this paper, the problems which will be occured on the way to develope the ideal artificial heart, and the factors preventing to solve these problems were analized. These factors were classified into technical factors and social factors. The technical factor is generated in the case that the research is not attained to the level to solve the problems, or that manufacturing technique for making up a new appratus is lacked.
To exclude these technical factors, the establishment of cooperative research system between engineer and medical doctor is important. This society should have effort to ask for governor to construct such a research institute.

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In order to develop the designed materials for artificial organs, the interaction between materials and biological system should be clarified. In this report the problem about protein-adsorption on the surface of artificial organ was described from the view point of the functional change of adsorbed plasma proteins. The results of conformational analysis of serum albumin and γ-globulin adsorbed on polyion complex (PIC) corresponded to those of platelet adhesion behavior on PIC. The conformational change (denaturation) of adsorbed albumin contributed to enhance the adhesion and metamorphosis of attatched platelets. The orientation of adsorbed γ-globulin turned out to play an important role on the adhesion of such cells as platelet, leukocyle and lymphocyte.

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Inflammatory response and tumorigenesis caused by polymeric materials are main topics among the problems concerning tissue compatibility. Our previous and recent results related to the topics are summarized and discussed. Combination of our in vitro repeated extraction test and cell culture test provides us useful information for understanding the intensity, pattern or duration of the acute or subacute inflammatory response. Plastic film tumorigenesis are compared after subcutaneous implantation in rats, hamsters and guinea pigs, and discussed on the basis of our hypothesis which stresses the importance of the thickness of the fibrous tissue capsule formed around the implants.

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In 1978 the Agency of Industrial Science and Technology of the Ministry of International Trade and Industry began a five-year project with the objective of developing an implantable hearing aid, or “artificial middle ear”. The function of the middle ear is to conduct sound to the inner ear, and impairment of this function results in a hearing loss of about 50 dB. The artificial middle ear would replace or even improve upon defective middle ear structures. Signals from a microphone would be amplified and transmitted to the stapes by a vibrator. The criteria for this device are that it be totally implantable including the energy source, and that it be essentially maintanence-free. The incidence of failure must be minimal and irreparable damage to the inner ear is to be avoided. Implantation should not require esoteric technical skills, and repair and reimplantation should be readily accomplished when necessary. Close cooperation among technology, medicine and rehabilitation will be imperative.

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A plasma perfusion device, comprising a packed bed of adsorbent and narrow straight porouswalled channels set in the bed, was designed to perform, in a single container, all the procedures of plasma perfusion, i. e. separation, perfusion, dust removal and returning. It was expected that, in the upper reaches, the plasma in the blood stream would permeate into the bed through the channel walls and, in the lower reaches, the plasma in the bed would gradually return into the channels. The velocity and pressure distributions, the contact efficiencies and the pressure drops in in vitro systems were analytically obtained. They depend on the module geometry, the wall resistance to filtration, and the shape and size of adsorbent. Experiments of creatinine adsorption were carried out with flat-plate modules of 180mm length and 40mm width utilizing Nuclepore membrane of 1μm pores as channel walls and Kureha BAC MU-LL activated charcoal as adsorbent. As thoretically predicted, the creatinine removal efficiency was dependent mainly on the thickness of the channel in vitro. It decreased from about 70% to 4% with the increase of the thickness which ranged from 0.2mm to 0.4mm. In vivo experiments on canine bodies with modules of 0.15mm channel thickness suggested that this device has good blood compatibility and effectiveness sufficient for practice.

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We have developed a controler system of sequential Hi/LO sodium concentration (144-134 mEq/1) in dialyzate for single pass method.
It was possible that in fact dialyzate sodium concentrations wave removed little by little and serum sodium slowly.
During benodialysis using this system, no trouble, such as dialysis disequilibrium syndrome was occured.
The merit of this system were the following:
(1) We don't need the I. V. infusion solution.
(2) The ultrafiltration rate was maintained above its desired level.
(3) No side-effect was found after dialysis such as hypertension.
(4) It is easy for us to treat this system in dialysate single pass method.

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Filters (membrane: ethylene vinylalcohol copolymer hollow fiber, surface area: 0.11m²) were implanted subcutaneously (inguinal) into 13 nonnephrectomized mongrel dogs. Three of them served for hemodynamic study. In the remaining 10, function of the filters, and a microscopic change of the membrane were followed up to 192 hours. Heparin was administered continuously using infusion pump. Two stage operation was selected to prevent hemorrage.
Just after implantation, ultrafiltrate obtained was 25.2±6.4ml/hour in the average. It decreased, however, to 17.0±7.9ml/hour at 24 hours, and 4ml/hour at 192 hours. The decrease of ultrafiltrate was explainable from clotting of peripheral hollow fibers. Fibers at the central part of the filters were free of thrombus. These results suggest a possibility of implanting a filter for blood purification.

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We have developed the bicarbonate dialysate central supply machine and had clinical experiences with the system for 10 months.
As the result, the concentration, PH and the temperature of dialysate was stabe and disequi librium syndrome during hemodialysis was much creased. The amounts of trace metals in dialysate were shown to be negligible.

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The high bleeding risk patients should be strictly restricted the prolongation clotting time during and after homodialysis.
We investigated the precise heparin neutralization rate with the monitoring of WBAPTT in vivo examination.
Minimal heparinization (M·H) and Regional heparinization (R·H) were also evaluated clinically in the high bleeding risk patients during hemodialysis.
1) One mg of protamine could be neutralized 95.4 u. of heparin in vivo examination, and 1.1mg of protamine neutralized 99.4 u. of heparin, There were significant differences of heparine neutralization rates between 1mg and 1.1mg of protamine.
2) In the one shot of protamine at the end of dialysis, average heparine neutralization was 106.7% by the theoretical doseges of protamine caluculate from WBAPTT (average doses: 5.6mg) and 109.0% by the conventional doses of 30mg of protamine.
3) We could reducted the total heparin doses. to 46% by the usage of M·H compared with optimal heparinization.
4) The heparin rebound phenomenon were not noticed definitely in 8 patients by the R·H (protamine heparine rate: 1.36).
We concluded that M·H and R·H are safe in the dialysis for high bleeding risk patients than the conventional method and the clotting time in the extra coporeal circulation can be controlled easier by the M·H than R·H.

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To prevent adverse effects of heparin, new heparin free anticoagulant method for hemodialysis using ticlopidine was studied. Ticlopidine is a strong anti-platelet drug and suppresses platelet functions more powerfully than aspirin or dipyridamol.
In dog experiments, 150-200mg/kg of ticlopidine were given orally. Platelet aggregation rate reduced gradually and reached below 10% (1st phase of aggregation) or 35% (2nd phase) of pre-treated values after 10-12 hours. Thereafter, hemodialysis was performed for 2 hours. During hemodialysis, pressure differences between pre- and post-dialyser showed no elevation. Appearances of blood coagulation in dialyser after hemodialysis were as same as treated with heparin.
Thrombocytopenia during hemodialysis was more severe in heparin than ticlopidine. These results indicate that ticlopidine can be used as an anti-coagulant drug for hemodialysis. However, ticlopidine has shortages to act for longer time and to cause gastrointestinal symptomes such as anorexia or nausea in high dosage. So, for clinical usage, it is more preferrable to expect to reduce dosage of heparin.

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We developed a new type of bead activated charcoal (PAC). In the previous report, we demonstrated that PAC can be used for direct hemoperfusion without encapsulation. This time, the clearances of creatinine, uric acid and vitamin B₁₂, carbon powder relaese and compatibility fo blood cells were studied, comparing with four kinds of encapsulated charcoals (CAC).
The clearances of three substances of PAC were superior to the cellulose coated AC, and same to the poly-MAMA coated AC. The degree of carbon powder release was less and damages of blood cells were same compared with CACS.
In conclusion, PAC can be used in noncoated state safely for direct hemoperfusion and has advantages to release minimal carbor powders and to save the procedure of encapsulation.

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Shunt failure is one of the most troublesome problems in chronic haemodialysis. Various operations such as the use of autogenous vein grafts, heterogenous artery grafts and artificial grafts are used for the patients who had multiple vascular operations caused shunt complications. A retrograde arteriovenous forearm fistula reported by Graben in 1973 is one of these operations. We have modified Graben's technique as shown in Fig. 1-2. and used for 39 patients who had previous multiple shunt failures. Long term patency rate more than 6 months was 87.2% and four fistulas now have been successfully in use for more than 5 years. Initial edema of forearm occurred in all patients but it regressed spontaneously. Other complications were not observed except two patients experienced aneurysma in fistula.

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These few years, many investigators have been studying hemofiltration (HF) and hemodiafiltration (HDF) as one of methods for treating chronic uremia. It is said that HF and HDF have high efficiency in eliminating middle molecular substances from blood. However, the appropriate method for evaluating the characteristic curve in cut-off molecular weight of a membrane and the definite value of the cut-off MW have not been presented.
We measured the cut-off MW in a different kind of HF and HDF membranes with using blood and normal saline solution, and obtained the following favorable results.
1) When the cut-off MW of HF and HDF membranes was measured in blood and normal saline solution, the cut-off MW in blood was lower than that in the normal saline solution for each of the membranes.
2) It seems that the major factors in decreasing the cut-off MW in blood are concentration polarization and the clogging on the surface of membrane, and not the protein-binding of the indicated substances.
3) The cut-off MW was not affected by a change in share rate, transmembrane pressure and circulation time.
4) The adsorption of the indicated substances on the membrane was observed in some kind of membranes. Therefore, it is absolutely important to collect the samples after circulating blood effectively and sufficiently in order to measure the cut-off MW value accurately.
5) Our method using blood is applicable to the evaluation of HF and HDF membrane, and our gel chromatography method may be recommended as an effective method for measuring the indicated substances in plasma and blood.

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The generation rate of urea for 3F patients (0.28±0.06g/hr) were compared with that for HD patients (0.38±0.05g/hr). Considering the removal of accumulated amount of urea for the term of treatments (14g), the suitability of HF treatment of 20L. substitution was established. On the standpoint mentioned above, the new plate-type hemofiltration filter with high performance, DAICEL “HemoFresh” was developed. From the clinical test results for it, very high and stable performance, good biocompatibility were confirmed. All treatments were completed within 5 hrs with comfortable feeling of patients.

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Anion exchange type and reversed-phase type high performance liquid chromatography (HLC) were used for medical application, including the evaluation of artificial organs. The pattern of chromatogram of such physiological fluids as serum and urine was found out to give us lots of qualitative and quantitative informations available for diagnosis of cancer and liver cirrhosis. Correlation matrix method, newly developed by us, was very useful for analyzing the metabolic change induced by cancer growth. HLC was applied for the estimation of kidney function, especially glomeruli filtration rate. Moreover HLC was available for the evaluation of artificial kidney and artificial liver.

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Although large number of research studies to develop the present system of hemodialysis have been done mainly on dogs, only a few reports are found as far as the successful long survival of uremic dogs is concerned.
In the present paper, it was clarified that consideration of suitable priming volume (PV) based upon the physiologic characteristics of dogs is essential to maintain the nephrectomized dog for long period.
The hemodinamic studies, by changing PV from 6.8 to 13.8/Kg B. W. have indicated that these two parameters should be less than 11ml/Kg B. W..
In the studies to estimate the protein metabolites in nephrectomized dogs, it was shown that the daily increases of BUN and serum creatinine (Cre) to be removed as maintenance metabolites were 294±25.4mg/Kg B. W.·day and 25.0±1.41mg/Kg B. W.·day respectively.
In conclusion, it should be essential for long survival to select or develop the hemodialyzer based upon these figures relating to PV, surface area and metabolic rate on the body weight basis of laboratory dogs.

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The newly developed hollow fiber oxygenator (H. F. O.) was tested in animal experiments and applied to 40 cases in open heart surgery.
5 dogs were used as test animals for H. F. O. using right heart bypass method. The 1.8M² F. H. O. was perfused 4hrs continuously with an average of 1.3 1/min of venous blood at 37°C and pure oxygen at a rate of 1.8 1/min. Average PaO₂ was 239±91mmHg and PvO₂ 41±8, PaCO₂ 30±6, PvCO₂ 39±10mmHg respectively. Free hemoglobin after 4hr perfusion was 38.0±14.5mg/dl. 40 cases including 34 congenital and 6 acquired heart diseases were operated using 1.8 or 3.3M² H. F. O. Perfusion time was 56±32min and free hemoglobin was 46.7±59.2mg/dl at the end of cardiopulmonary bypass. Average blood perfusion rate was 2300±900ml/min and oxygen flow rate was 1200±500ml/min. PaO₂ was 474±44mmHg and PaCO₂ 28±8mmHg when average Ht was 25±4%. Pressure across the 3.3M² H. F. O. was about 70mmHg at a blood flow rate of 1.0 1/min.
This H. F. O. was observed to have excellant capability of oxygen and carbon dioxide gas transfer with small amount of hemolysis in 40 patients undergoing open heart surgery.

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Gas transfer performance of Kolobow membrane oxygenator was evaluated at 20°C and 25°C using a testing and evaluation method which was previously reported from our laboratory. Gas transfer characteristics were summerized as follows.
1. Both oxygen and carbon dioxide transfer rate were decreased as blood flow rate was increased.
2. Both oxygen and carbon dioxide transfer rate were increased as gas blood flow ratio (V/Q) was increased. The oxygen transfer rate was slightly low when V/Q was below 0.5 and approached to the constant value when V/Q was above 0.5. The carbon dioxide transfer rate was increased linealy below the V/Q of 2.0 and approached to the constant value above the V/Q of 2.0.
3. During hypothermia the oxygen transfer rate was improved but the carbon dioxide transfer rate was lowered compared with those during normothermia. And the optimum V/Q at 20°C was also discussed.

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Well controlled man-machine interaction is one of the most mandatory factors in circulatory assist. We designed a long-term extracorporeal circulation system possessing a servomatic flow controlling mechanism with closed circuit.
The bypass circuit is illustrated in Fig. 1. Venous blood is allowed to drain by gravity flow into a reservoir bag with a capacity of 1000ml or 600ml (Fig. 2). Blood is drawn from the reservoir to the roller pump and then pumped through the membrane, through the heat exchanger, to the arterial cannula.
The mechanism of the servomatic regulation of the pump flow is shown in Fig. 5. The system is designed to determine the pump flow to the appointed speed, in accordance with the change in the blood level of the reservoir which is detected by four sensors (Efector; ifm-Japan Co., Ltd.).
Dog experiments have shown us that this system is quite safe, easy to operate and has a very desirable regulating effects from the viewpoint of stabilizing the preload of the natural heart.

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This paper concerns with building an adaptive control system of the left heart assist by a mini-computer. This system is designed to pump out adaptively a desired mean volume flow of the blood with the maximum transmission power to the change in the mechanical characteristics of the systemic circulation.
To check the system for canine experiments aiming at human application, experiments by a mock circulation was made. The results indicate that the system can finish one cycle of adaptation within 30s, and can pump out the maximum mean volume flow of the blood 2.5l/min for physiological variation of mechanical impedance of the canine systemic arteries.

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Pulsatile cardiopulmonary bypass system for clinical use was developed. To improve the flow characteristics of the pump and to determine its optimal drive conditions, a mechanical simulator was used. Findings were as follows:
1) Incorporation of a flexible reservoir of 60ml at the pump inlet produced the maximum outflow and increased it by 30% compared with the non-reservoir case.
2) Water hammer phenomenon at the pump inlet disappeared when the systolic time of the pump was reduced by 10% from the full stroke condition. Under this optimal drive condition, mechanical hemolysis was negligible.

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Improvement of the prototype of bilateralpulsatile closed-circuit cardiopulmonary bypass system was achieved. In animal experiments of goat by prototype, it was thought that it would be neccessary to achieve much perfusion flow, less priming volume and smaller machine size. In order to find out the factor which reduced perfusion flow, we analysed the hidrodynamical caracteristics of our system and it was revealed the main factors were venous and arterial cannulae. in order to use bigger and shorter connectiot tube, putting all part but membrane oxygenator and heat exchanger in the sterized area, we could priming volume less than 1300ml and get perfusion flow of 5L/min. with one of 6mm arterial cannula and two of 6mm cannulae.

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A new blood pump consists of three parts: a latex tube with a diameter of 19mm which has been used for standard roller pump, a housing which is made of acryl resins and two poviting disc valves at the inflow and outflow orificies. The pump is driven by a pneumatic power. Blood filling into the latex tube depends only upon the restorative power of the latex tube itself. Maximal flow rate of 5.6 1/min was obtained against the resistance of 100cm H₂O. Without valves, the pump can be used as a assist device for pulse making. This is connected to the arterial line of the standard roller pump.

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Many open heart surgery by extracorporeal circulation can be done sefely, especially during operation lasting less than 60 minutes. The advantages of delivering pulsatile rather than nonpulsatile flow during long-time extracorporeal circulation have not been completely established. This study was designed to compare the physiologic and morphological effects of pulsatile and nonpulsatile extracorporeal perfusion on the peripheral vascular circulation for 4 hours in mongrel dogs.
The disporsable pulsatile blood pump for extracorporeal circulation, NIKKISO PP-11, Type has two soft leaflet valves and U-shaped silastic blood chamber.
These experiments suggest that long-time pulsatile pumping extracorporeal circulation offers significant advantages in terms of better physiolosic, morphological effects: higher renal flow, higher renal tissue flow, higher duodenal tissue flow, lower renal vascular resistance, and lesser ultrastructual degeneration of kidney and pancreas.

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A new device of pneumatic driven pulsatile pump was applied for cardiopulmonary bypass in 50 cases of adult valvular disease. In order to obtain good hemodynamics, optimal driving conditions and cannula resistance were measured by mock test.
Pressure gradient across aortic cannula was measured in 4 different sizes of cannula. It was found that the pressure gradient was much higher in smaller size of cannula (5.5, 6.5mm), therefore, aortic pressure did not reach over 100mmHg even though driving pressure increased up to 0.5Kg/cm².
Aortic cannula for adult patient in pulsatile perfusion should be selected larger than 8.0mm in diameter in order to maintain adequate blood pressure of higher than 100mmHg. (Fig. 2)
The direction of tip of aortic cannula gave much influence to aortic pressure wave form. When tip of cannula was twisted in certain degree against aortic wall, resistance increased in cannula tip, and pressure wave form became distorted. (Fig. 4)
Fig. 5 shows the clinical cases of pulsatile perfusion in different types of aortic cannula.
The optimal driving conditions and the optimal size of aortic cannula were decided by the mock test. (Fig. 6).
The administration of vasodilator markedly influenced to the hemodynamics. Peripheral circulation was well corrected in a few minutes after the administration of this agent. (Fig. 7)
In order to obtain good hemodynamics during pulsatile perfusion, both mechanical control of optimal pump drive and physical control in peripheral circulation were most important.

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Serial measurements of the urinary NAG excretion were done in 16 patients who underwent open heart surgery, in order to detect the renal damage prior to the deterioration of the renal function. The excretion of NAG was measured before, during, and after the cardiac surgery with cardio-pulmonary bypass (CPB), and was found to have its peak about 3 hours after the end of CPB. The NAG excretion increased as CPB time prolonged, and returned to normal range on the first postoperative day. There was a good correlation between the total CPB time and the total amount of NAG excretion. The excretion pattern of β₂-microglobulin, a sensitive indicator of the reabsorptive function of the kidney, was similar to that of NAG, but its peak was delayed several hours. The study of the urinary excretion of NAG may be of value in predicting postperfusion renal failure.

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A flow through system with ion selective electrodes for the measurement of the blood potassium ion and hydrogen exponent (pH) continuously during cardiopulmonary bypass in human open heart surgery is described. Potassium concentrations obtained with this method agree well with the ones determined by flame photometry and pH values correspond well with those made by blood gas analyzer (AVL). The time delay in measurement with this system is relatively long (1min. 45sec.) but will be shortened in the future. Continuous monitoring of these important parameters can help reduce metabolic derangements during cardiopulmonary bypass and make post bypass management easier.

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Avcothane coated PVC paste (Av-PVC) pump have made prolong the survival days of goats replaced totally with artificial heart and made improve the animal's surviving condition in our institute. In this study, the Av-PVC pump antithrombogenecity was compared with that of PVC pastepump and segmented polyurethane by SEM analysis. The effect of anticoagulant, anti-platelet aggregate drug and the influence of blood flow rate on these material antithrombogenecity were also investigated. The Avcothane surface was almost free from platelet or fibrin deposition after use in animal for few months under the use of anticoagulant. In the case without use of heparine, a small amount of micro-fibrin deposition was observed on the Avcothane surface. Platelet deposition on the PVC paste surface was comparatively little, in spite of thick protein layer deposition. Polyurethane used inthis study revealed almost the same antithrombogenecity with Avcothane.

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Blood pumps, control, haemodynamics and blood chemical analysis on 174 days survival of TAH goat was reported in this paper.
Cardiac output and blood pressures were maintained within normal ranges by regulating driving-pressures of both AH pumps during the whole course except postoperative and terminating stage.
Ht decreased frequently and blood transfusions were performed.
Serum proteins decreased transiently and blood enzymes increased transiently, however these values recovered after 1 week postoperatively. Electrolytes were shown within normal range except before death.
Total bilirubin increased after blood transfusions and BUN increases after 5 months. Leukocytosis was detected after 3 months.
Ringshaped clottings were detected around the B-S valves in the Avcothane coated PVC blood pumps.
Subcutaneous edema, liver enlargement with central necrosis or liver cirrhosis, kidney infarctions, ascites, mesentheliar haemotomas were recognized in the autopsy.

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Our institute has started to develop our own heart assist system, which is composed of heart assist device and control-driving unit. The former is air-driven, diaphragm type, and its assist mode is bypass type from left atrium to descending aorta. The latter is computerized and markedly synchronous with electrocardiogram by a use of T-wave trigger mode. This heart assist system proved excellent pump function on the pressure-load test apparatus.
Acute hemodynamic study using goats showed as follows; (1) Left heart bypass for normal heart increased total output while arterial and left atrial pressure remained unchanged. (2) Left heart bypass for severe heart failure lowered left atrial pressure and left ventricular work while total output and arterial pressure were maintained at reasonable level.
Further improvement of our heart assist system was discussed.

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Pacemaker or electrode implantation for permanent pacing was performed on 4 cases with congenital heart disease during or after cardiac surgery. The first case with VSD+PH who suddenly developed complete A-V block approximately 9 months after VSD patch closure was treated with implantation of permanent pacemaker after 5 years observation.
The second case who originally had incomplete ECD developed into complete A-V block immediately after intracardiac repair. Permanent pacemeker was successfully implanted in this patient one month after the onset of complete A-V block.
In the third case who had Ebstein's anomaly with S-A block, intracardiac repair and pacemaker implantation were done simultaneously.
The fourth case who had Corrected TGA+VSD+ASD+PH with congenital complete A-V block was implanted with myocardial electrode for permanent pacing during open heart surgery. This electrode, however, has not been utilized yet, as he had remained asymptomatic without pacemaker implantation since then.

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12 dogs (12kg in average weight) were experimented by the right thoracotomy under general anesthesia. Special electrodes made of stainless steel with the tip of 0.5mm in diameter and 7mm in length were used. They have the surface area of 10mm² Four electrodes were inserted at intervals of 5mm, 10mm and 20mm into the right atrial and the right ventricular surface respectively. Stimulation current threshold was measured both in acute (immediately after insertion) and in chronic period (3 weeks after implant) using Medtronic 5880 A. No difference of stimulation current threshold between right atrium and right ventricle was observed either in acute or in chronic period. Bipolar and unipolar electrodes did not show any significant difference. Stimulation current threshold was almost equal even though the distance between two electrodes varried from 5 to 20mm in the atrium and in the ventricle.
Stimulation current threshold between stimulation electrode and indifferent electrode was almost equal even though the surface area of the latter ranged from 10mm² to 80mm². Intracardiac R wave both in acute and chronic period was not affected by the distance between two electrodes, changing from 5mm to 20mm.
Position of indifferent electrodes and area of indifferent electrodes did not induce the change of R wave height either as an average.

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A compound prosthetic graft, which was woven with alternate yarns of nonabsorbable (Tetron) and absorbable (Collagen) fibers, was made and we called it as CoT graft. Though the patency of CoT graft of 8mm in diameter was 100%, the one of 4mm was 0%.
The study was done in order to know the causes of the occlusion of small caliber CoT graft.
Five kinds of CoT draft, which were different respectively in points, tanning, heating and the size of caliber, were implanted in arteries of 9 dogs in periods of 1 to 21 days. Scanning electron microscopic study was done.
The results. (1) How to treat collagen for tanning; CoT treated by 0.95% gluteraldehyde solution got pseudointima for motion ealier than one treated by 0.35% gluteraldehyde solution.
(2) Patency of CoT graft heated was better than the one non-heated.
(3) The size of the caliber of CoT graft was not related very much with a cause of occlusion of CoT graft is early stage.

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We evaluated a new compound graft made of a non-woven polypropylene sheet enforced by a tetron mesh layer. In canine aortic replacement using our compound graft (6mm in I. D. and 6cm in length), the graft patency rate was 100%, but in canine carotid replacement (4mm in 1.0. and 6cm in length), patency rate was not satisfactory (42.9% of compound graft supported with 4-0 monofillament polypropylene ring were patent, while all of control graft were thrombosed.) In patent cases, we observed the compound graft showed good tissure healings and minimal graft shortening and stiffening after implantation as compared with conventional synthetic vascular prostheses. In conclusion, to provide better antithrombogenicity in early post implantation period, we continue to evaluate this vascular graft with applying modifications to inner surface of our graft.

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Non-hemic priming cardiopulmonary bypass (CPB) is available in the adult, but it is difficult in infants or children. The purpose of this investigation is to examine if it is possible to perform it in dogs by the aid of artificial blood i. e. perfluorochemical (PFC) emulsion.
Seventy-five % of autologous blood, which is to be transfused after CPB, was removed in 16 dogs weighing around 10Kg and artificial blood CPB was performed. Nine dogs were used to determine the appropriate PFC concentration (conc.), O₂/blood flow ratio, PO₂, PCO₂, and pH of blood, and to study CO₂ elimination. Survival and complications after 45 to 50 minutes artificial blood CPB were evaluated with previously withdrawn autologous blood transfusion after the end of CPB.
The hemoglobin conc. of blood during CPB was 1.3±0.3Gm/dl. The O₂ delivery was satisfactory when PFC conc. was 24Gm/dl, PaO₂ over 500mmHg (O₂/blood flow ratio 1 to 1.5), and perfusion rate over 120ml/Kg B. W./min. The CO₂ elimination was normal. The A-V pH difference was large aruund 0.3, due to a large A-V PCO₂ difference, which was around 20mmHg. The PCO₂ and pH therefore were regulated to maintain the normal values in venous blood rather than arterial blood in survival examination. Weaning from CPB was uneventful in all dogs. Two dogs died of bleeding at 1st P. O. D. Three were sacrificed for histological examinations. The remaining 2 were well and alive at 36th and 29th P. O. D. Serious complications were (1) bleeding tendency and (2) infection. The former is probably due to hydroxyethylstarch and pluronic F-68, while the latter may be based on the attenuated immunological reaction by PFC in the artificial blood.
In conclusion, non- hemic priming CPB in dogs weighing around 10Kg was possible but further improvements as to prevention of bleeding tendency and immunological suppression were regired.

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Clinically used artificial organs is mostly related to transportation of mass, momentum and energy of living systems. Usually, some engineering technology has applied to the development of new artificial organs. But, the functions of the artificial organs only simulate the global input-output characteristics of a parts of living organ functions. Today, the development of many artificial organs is facing bottleneck due to the lack of technological new sheeds. In order to brake through the bottleneck, the new designing principle should be desireble. The designing principle should be the principle of transport phenomena in the living system. This report is recommending to build up the theoretical basis of artificial organs from the principle of transport phenomena in the living systems.

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Biomechanics is the mechanics applied to biology according to the definition proposed by Fung. Of the vast field included in the Biomechanics, quantitative and dynamic description of the mechanical properties of tissues is particularly important in the design of artificial organs and biomaterials. Optimal mechanical properties of an implant material can be specified only with adequate knowledge of the material properties of the tissues with which it comes in contact. Most of the currently available artificial organs are not designed optimally due to the lack of biomechanical data of living tissues as well as biomaterials which are incorporated in the artificial organs. The mechanical compatibility between the tissues and an implant should be studied more intensively.

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Nonwoven cloth has been considered to beasuitable material to be used as vascular substitutes, with its unique velour-like surface structure. Animal experiment showed that the thin and smooth layer of pseudointima on the luminal surface of the prosthesis has been always seen, whether the prosthesis has high porosity or not. So we have developed a 3-layered laminated vascular prosthesis made of a new nonwoven cloth which has no porosity.

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We analyzed the survival data on 76 patients undergoing cardiac surgery by the use of IABP. There were 46 patients with ischemic heart disease(IHD, G-I), 21 with valvular heart disease (VHD, C-II) and 9 with congenital heart disease(CHD, G-III). In G-I, the purposes of the use of IABP were (1) use at emergency operation for cardiogenic shock and mechanical complications of acute myocardial infarction (2) intraoperative use for the difficulty of weaning from extracorporeal circulation (ECC) or postoperative use for severe low output syndrome (LOS) (3) prophylactic and elective use for high risk patients (uncontrolled angina, poor left ventricular function, left main trunk disease). The survival rates for each use were 12.5, 50 and 86%, respectively. The use of IABP in G-II was mainly for intra and postoperative events equivalent to the purpose of (2) in G-I. The survival rate in this group was 43%. No appreciative difference in survival rates was present between the patients with mitral and aortic valve diseases. One patients with acute ischemic changes due to coronary air embolism responded dramatically well to IABP. The survival rate in G-III was low, 12.5%. No good response to IABP was observed in patients with LOS due to residual pulmonary stenosis. The only responder was a patient with right heart bypass surgery with circulation maintained only by the left ventricle.
The elective use of IABP is most controversial on its efficacy. There were certain advantages such as easy hemodynamic stability when weaning from ECC and during the postoperative course but disadvantages also existed in 14% of the patients, mostly ischemic legs. The efficacy of the elective use of IABP could not be determined by the comparison of survival rates between the groups of patients with and without IABP because of the difference in basic pathology. The elective use of IABP can be limited to only unstable hemodynamics or ongoing ischemia existing before operation.

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Recently, septic acute renal failure (ARF) patients show the tendency to increase. Since the mortality rate of this septic ARF remains high, the development of more effective treatment is urgent and important. The septic ARF frequently complicates other important organ failures such as pulmonary and hepatic one, and can be considered as a part of the multiple organ failure (MOF).
The impairment of reticuloendothelial system (RES) function seems to play a key role for the development of MOF. Therefore, the treatment for the depressed RES can be effective for septic ARF as well as for MOF. For this purpose, we have applied the direct hemoperfusion (DHP) with conventional hemodialysis expecting that DHP would work as an artificial RES and that DHP would improve RES function by detoxifying the toxic factors depressing the RES. We have also given some agents improving RES function.
Using these new regimen, we could get the significantly better survival rate of 77.8% (7/9) compared to that with the conventional treatment. This result indicates that DHP as an artificial RES is effective for the treatment of septic ARF.

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24 cases of acute hepatic failure and 6 cases of uremic neuropathy were treated with direct hemoperfusion.
only 4 cases of hepatic failure survived, but levels of conciousness and EEG finding were improved with DHP therapy. In majorty cases whose clinal symptomes improved with DHP, initial conciousness level were in stupor and background activities were in the range of θ-δ band, however fatal cases were in the δ band.
DHP accompany with hemodialysis showed obvious improvement in 4 cases of uremic neuropathy. In 2 cases neurological improvement appeared in eary month therapy with DHP, and nerve biopsy revealed no degenerative changes.
From these findings it is suggested that hepatic coma and uremic neuropathy with only functional change are indicated for DHP therapy.

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