A development of the automatic control algorithm for the total artificial heart system using pneumatic driving unit. The difficulty in the hardwere to control air pressure has almost solved. Therefore, establishment of a control algolism has become the most important issue in the automatic control of TAH system using a pneumatic driving unit. This study attempts to develope an automatic control algorithm which deals with 1) a change of the set point, 2) disturbances given to the body, 3) troubles concerning machine or pumps. Manipulating parameters are positive and negative pressure, systolic %_of each pump and pulse rate. Input information to decide manipulated driving parameters are the status of the stroke of each pump and right pump flow (controlled variable).

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Two hemodynamic parameters (total flow (cardiac output+bypass flow (BF)), LAP) can be controlled through automatic variation of BF. The change in BF was achieved by electronically Varying %-systole (Fs). An external microcomputer can be interfaced to allow realization of more precise circulatory control for LVAD by altering range and step change of Fs. This system-exhibited satisfactory, stable and safe performance in chronic experiments and clinical cases with profound LV failure, whereas patients successfully recovered.

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Evaluation of inflow valves of total artificial heart: New system for evaluating the valves has been developed and 3 kinds of inflow valves were tested. Results were as follows; 1) leaflet valve is the best in r-heart. 2) ball valve (in modified duct) is better in 1-heart, if it is possible to make the diastole shorter. 3) usual disc valve is not recommended, because some amount of blood to close the valve is lost by regurgitation and the stroke volume concequently decreased.

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Feasibility of compliance car with Dacron velourr covered Hexsyn diaphragm was studied. The tissue capsule on the flexing diaphragm was very thin (200μ) and stable. The static compliance decreased to 50% during the first p. o. year, but no further decrease was observed thereafter and kept within the satisfactory range. The energy loss due to the chamber was supposed to be less than 0.2 Watts-sec, which was negligibly small value. Approx. 1.2ml/day of gas had permeated through the Hexsyn diaphragm.

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We had three calves of this research. Two out of three died of thrombus formation at 23 days and bleeding from the gastrointestinal tract at 8 days after surgery. Second surgery was achieved on the 28th day after initial replacement for one calf which showed raised both atrial pressures around 25th day. We lost it on the surgical table because of bleeding.
Though we could not make this project, we could put the artificial heart to the baby calf without problems and it would be Possible to exchange both ventricles through right thoracotomy.

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In this study, pump flows computed from the Hall effect stroke signals of the pusher-plate type pumps were compared with actual flows in a simulated circulatory system that comprised of a pulsatile atrium and ventricle. The main purpose was to evaluate effects of right atrial to pulmonary artery flow during ventricular diastole and those of valvular regurgitation on the left-right flow differences. As a result, when the ventricle was operated in the variable rate or atrial synchronous mode, errors based on the Hall sensor method were less than 5%. Wherefore, reported left-right flow differences may be due to shunt flows such as bronchial flow instead of measurement errors or valve regurgitation.

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Feasibility of prolonged circulatory maintenance with a SAH was studied in eight goats. Provided that pulmonary vascular resistance was less than 15, 000 dynes. sec. cm^-5. Kg, and also that right atrial pressure was kept at 10-16mmHg, circulation was maintained well. The goats behaved quite normally, however, several thoracentesis were required to remove pleural effusion. The longest surviving duration was seventeen days. Non-beating myocardium was atrophied.

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Twelve surgeries were performed to replace the goat heart with TAH. Our TAH is implantable, air driven diaphragm type-The longest survival is 8 days. The main causes of the death were bleeding and respiratory restriction following the hematomas in the thoracic cavity. Great care should be paid to prevent abdominal distention avoiding restriction of the respiration. During our experiment, TAHs were driven uneventfully except for the stucking of the mitral valve in case 7.

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Total artificial heart (TAH) was implanted in the goat, that survived 344 days.The prominent autopsy findings were generalized thrombosis and thromboembolism and centri-lobular necrosis of liver with fibrosis and hemorrhage. These various legions were considered to be due to multiple causes of artificial heart devices and physiology. Such as thrombogenicity of devices, congested venous circulation, abnormal distribution of blood flow and so on.

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A goat replaced with total artificial heart under the extracorporeal circulation with hypothermia could survive for 344 days in our laboratory. At the 226 days, lung emboli was occurred due to the thrombus from the right pump and two blood pumps were exchanged with new ones. Thereafter, hypoxia, circulatory insufficiency and chronic anaemia were shown in the goat and the animal experiment was terminated. In the autopsy, diffusive edema, clotting in the lungs and the kidneys etc. and liver damage were detected.

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Relationships between hydrodynamic perfprmances of the tri-leaflet polyurethane valves, and valve stent flexibility, coaptation zone and leaflet thickness were studied using mock circulator. As a result, in the aortic position, higher stent flexibility, smalier coaptation zone and thinner leaflet each improved the calculated effective orifice area (EOA) by 29, 12 and 72%. While in the mitral position, EOA increased by 25 and 73% with smaller coaptation zone and thinner leaflet, respectively. Our valves fabricated by incorporating improvement in these design parameters demonstrated. far better hydrodynamic performances when compared to the Bjork-Shiley tilting disk valve.

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The authors have developed a trileaflet prosthetic valve that is fabricated of segmented polyurethane reinforced with nylon mesh. Each leaflet of the valve is obliquely conical in shape, so that it is prone to buckling. This valve is hydraulically efficient when tested in a pulse duplicator. The accelerated fatigur test revealed that no leaflet rupture occurred after 20×10⁶ cycles. In vivo testing of our polyurethane trileaf let valve has shown it to have sufficient antithrombogenicity.

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Newly designed artificial heart valves for ventricular assist device were presented. New valves were constructed with three conic membranes and supporting stems. The flow in the new valves is eccentric, so that blood must flow afro and the deformed membrane. Then, hydrodynamic property of two types of new valve was evaluated and compaired with Bjork-Shiley valve. The evaluation was made by measurement of pressure-flow relationships in a steady and pulsatile flow, and leakage under constant pressure. The results of these experiments proved that new valves showed nearly the same hydrodynamic performance as Bjork-Shiley valve. In addition, the new valves were very easy to form, becanse of their simple shape and structure.

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Factors affecting antithrombogenecity of a commercial available heart valve. XPS analysis disclosed oxidised layer of more than 100 Å on a Ti valve ring. Oxidised layer consisted of O^2- and OH^- or H₂O combined to Ti. In vitro “kinetic test” disclosed that an the Ti valve ring blood clotted in a shorter time than on sputtered Ti. Worse blood compatibility of Ti valve ring is due to oxidised layer, which was produced during maching process.

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Hydrodynemic data of newly-developed val ves (four mechanical, one porcine aortic and two bovine pericardial valves) were obtained in the in-vitro valve testing system. Among them, Ca rpentier pericardial valve gave the largest effective orifice area (EOA) both in the inlet and outlet position. Duromedics bileaflet and Bjork-Shiiey mono-strut valves belonged to the largest EOA group in the pump inlet and outlet, respectively. Improved Bicerval disc, Kanton porcine and Shanghai bovine valves exhibited similar characteristics to those of the BS, Standard Hancock and Ionescu-Shiley, respectively. EOA in polyurethane Coraflex valve remained large even at high pulse rate.

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Five kind of prosthetic heart valves were tested in mitral position using our original sinniation system. These prosthetic valves were Hancock pericardial, low profile lonescu-Shiley pericardial, St Jude Medical, conveao-concave Björk-Shiley and Carpentier-Eowads supra annular valve, the effective orifice areas (EOA) of Hancock pericardial valve were compared with EOA of other valves under the simulation of atrial fibrillation and low cardiac output. Hancock pericardial valve obtained the largest EOA among these valves under both conditions.

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The hydrodynamic performances, energy loss (EL) and performance index (PI), of three mitral valves (Björk-Shiley Standard, St. Jude Medical and Carpentier-Edwards, anulus diameter of 29mm) have been assessed by using a cardiovascular mock system. BSS was tested in three orientations while SJM and CE were in two orientations. The best performance (the lowest EL and the highest PI) obtained was as follows; for BSS in the posterior orientation, for SJM in the orientation with the two halfdiscs opened toward the rectangular direction of A-P position, and for CE in the orientation with only one leaflet opened near the aortic valve respectively.

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For the purpose of clinical evaluations of the Mitroflowvalve, we have measured effective valvuler orifice area (EOA), cardiac output at the heart rate of 90-180bpm made by the atrial pacing, and cineangiographic studies of cusp motion. The results were as follows: EOA were 2.28 (21A), 2.77 (23A), 3.12 (27M), 3.24, 3.52, 3.60cm² (29M). The cardiac output increased up to 170bpm in 2 cases studied. Cineangiographic studies of the cusp movement showed synergic opening and closing of the 3 cusps and maximum opening of each cusp at mid diastole or systole.

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Study on blood flow through prosthetic mitral valves using real-time two-dimentional dopp ler echocardiography. Blood flow through prosthetic mitral valves were recorded in 31 patients, 18 SJM valves, 2. Starr-Edwards disc valves, 11. porcine valves, 5. normol heart. Each valves showed charcteristic inflow patterns. SJM and porcine valves showed central flow, but blood flow through the prosehetic valves directed towavd the interventricular septun compared with normal pattern.

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Three types of Björk-Shiley tilting disk valves (flat disk, convexo-concave disk, monostrut convexo-concave disk) were tested in vitro under pulsatile flow condition. Velocity profiles of axial flow on the cross-section distal to these valves were determined using laser-Doppler anemometer. Flow through the minor orifice was lowest and flow profile was least uniform in the flat disk valve among three valves. The highest turbulence intensity was observed behind the cc disk valve. Average velocity profiles were similar in the cc and monostrut cc disk valves regardless of their different disk opening angles.

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Early clinical results of central opening bioprosthesis. Central opening bioprosthesis manufactured by the open position fixation was implanted in 9 patients (7 mitral and 2 aortic). All of them showed satisfactory clinical improvements upto 1.5 years postoperatively. None developed thrmboembolism without anticoagulants. The results encouraged us to continue its appraisal to confirm the predictable better durability.

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Longterm Follow-up: Eighty-nine patients underwent valve replacement with porcine xenograft (31 Hancock, 60 Carpentier-Edwards, and 6 Ionescu-Shiley) from 1975 to 1983. Analysis of the series revealed the following informations; hospital mortality, 16.9%; late mortality 1.9% per patient-year; acturisl 5 and 9 year survival rates, 76%±4.5% and 62%±8.8%, respectively; incidence of thromboembolism, 2.3% per patient-year; incidence of valve failure, 2.3% per patient-year. These results support the discontinued use of porcine xenograft except such cases as over 60-year-old patients, pregnant women, and the patients who can't continue anticoagulant therapy.

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Cardiac xenografts and SJM valves have been implanted on 106 and 68 cases of acquired valvular disease from 1974. Our study provided no significant difference between the prosthses. PVE was the major etiology of the cardiac xenograft failure.

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The atrioventricular valve replacement with ISLM has been done 17 patients from January to October, 1984. The operative results, clinical data and postoperative hemodynamics were not different between ISLM and ISU. The most important difference was the pressure gradients across pericardial valves, for example the mean value of ISU No. 29 was 3.3mnHg, ISU-No. 31 was 2.9mmHg, ISLM No. 29 was 2.3mmHg, and ISLM No. 31 was 1.7mmHg, that is, ISLM showed smaller pressure gradients than ISU. This result was also confirmed by doppler ultrasound. The improvement of ISU, especially decreasing the valve height, were considered to success.

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There are some advantages to fix a porcine valve supra annuler site (TVSI: Tricusapid Valve Superimpose) for sever tricuspid regurgitation. This technique keep the tricuspid complex, never injure the conduction system and fix the prosthetic valve safe and quickly. We used this techique combined with MVR for sever MS+TR+AR case in emergency. Post operative state was almost good, and he discharged two month postoperative days. We examined this case by two-dimentional doppler echo cardiography. Blood flow from right atrium through the prosthetic valve and native valve as a laminal flow. There was no paravalvuler leakage and the porcine valve fulfilled its own function. This examination suggest that TVSI technique is usefull for sever tricuspid regurgitation.

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12 explanted pocine xenografts were examined for calcium by radiography and microscopy. Calcification was present 8 of 9 valves (89%) implanted for 4 years or longer. By the subcutaneous implantation model system, we observed T₆ treated Hancock valve and bovine pericardial valve were less calcified than standard processed Hancock valve.

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Jude Medical and the Ionescu-Shiley heart valve prosthesis. The short term results of the valve replacement with the St. Jude Medical (SJM) and/or Ionescu-Shiley (I-S) prosthetic valve were evaluated. The total patients (pts) of 115 were followed for an average of 15 (range 1 to 29) months. These included 14 pts of aortic, 45 pts of mitral, 6 pts of pulmonary, 3 pts of tricuspid, and 47 pts of multiple valve replacement. There were 8 perioperative (5.6%) and 6 late deaths (4.6% per patient-year). All early deaths were the pts of multiple valve replacement. Reoperation was necessary in 5 pts, because of paravalvular leaks in 3 pts and valve dysfunction due to tissue over-ingroth in 2 pts of SJM valve. The transient thromboembolism occured in a patient of aortic SJM valve, and a patient of mitral I-S valve. All discharged pts improved their clinical condition after valve replacement.

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Since September, 1980. eleven patients have received eight pulmonary and three tricuspid valve replacements (PVR, TVR) with St. Jude Medical (S. J. M.) prostheses. There was one open a tive death. One patient, 25 y. o. man with Ebstein's disease, showed thromboembolic complication, who was not on a regimen of anticoagulation after discharge. Two children, 4 y. o. and 2 y. o. girls, underwent in situ PVR with SJM21-A and right vevtriclar out flow enlargement with mesh-supported porcine pericardium patches. They showed intermittent dysfunction of S J M prosthesis since 24 days and 18 months after operation, respectively. These intermittent dysfunction continued with or without antithrombus and anticoagulant therapy. The intermittent nature of these dysfunctions is difficult to explain, but it is probably the result of the change of the obliquity and the axis of blood flow due to the morphological changeof right ventriclar outflow patches. We recommend, that using S J M prosthesis in pulmonary position with RV outflow patch enlargement, the size and sort of the patch should be carefully evaluated as well as the position and obliquity of the valve.

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Jude Medical Valve Prosthesis in Mitral Position and Study on the Possible Causes of Hemolysis in the Postoperative Periods. Between May 1980 and December 1983, 229 patients had mitral valve replacement (MVR) with the St. Jude Medical valve prosthesis (SJM). 9 patients required blood transfusion because of acute hemolytic anemia. The procedure in which the pivot axis of two leaflets oriented either parpendicular (parpendicular procedure) or parallel (parallel procedure) to the mitral commissure was applied for the MVR. In patients with mild residual aortic regurgetation, the degree of hemolysis by measuring serum lactate dehydrogenase was more severe with significance in patients with the parallel procedure than those with the parpendicular procedure in both early and late postoperative periods. And thus, we recommend that the pivot axis of the SJM valve should be implanted by parpendicular procedure.

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In 67 patients with prosthetic heart valve, platelets, haptoglobin, hemopexin, β-thrombogloburin, platelet aggregation, platelet shape, Faetor VIII and MDA recovery rate were determined.

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Blood coagulation and platelet function were studied in 25 cases having cardiac valve replacement especially in early postoperative days. Platelet counts, thrombotest, plasma fibrinogen, FDP and antithrombin-III were measured during the first day and 35th day postoperatively. Platelet count, plasma fibrinogen and FDP were increased significantly, however antithrombin-III showed no remarkable change. From the result, hypercoagulation was suspected in this period. The data suggests that the adequate antithromboembolic therapy is necessary for the patients iunnediately after valve replacement.

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The 20 patients with the O-S Aortic valve replacement have been studied. The data were compared with the results of patients with the Björk-Shiley valves. In tee both groups, subject and haemodynamic changes were excellent improvement and were no significant differences. Functional property of the O-S valve in the Aortic position was investigated by cineradiography. The maximum opening angle of the disc were 60.8±7.5° in sinus rhythm, 53.8±6.7° in atrial fibrillation. Thus, the opening angle of disc was decreased. The only 2 cases were showed the maximum opening angle 80. The functional valve property was found in limit of the disc opening angle.

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A series of eighty-eight hospital survivors who underwent aortic valve replacement from September 1966 to September 1984 was reviewed. Cardiac catheterization was performed on 32 survivors of them one year after operation. A 25mm and 27mm SJM, and 6-S prosthesis had a minimum pressure gradients and an wide effective orifice area. However, a 19mm and a 21mm SJM valve had a residual systolic gradient. Maximum opening angle of an Omniscience prosthesis decreased to less than 50 degrees in many patients at the late stage. These two are problems in the future.

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The late result and the hemodynamic function of Bicer-val (B-V) prosthesis in the aortic position was evaluated in 30 patients who had aortic valve replacement. The cardiac output and the simultaneous transvalvular gradient were recorded at rest (R) and during exercise (EX). Left ventriculography was performed at R. There was no thromboembolism or late death. The maximum opening angle of the prosthesis was 79±1 degrees. The average aortic mean systolic gradient was 9mmHg at R and 14mmHg during EX in 21mm B-V, 3mmHg at R, 9mmHg during EX in 23mm B-V, 2mmHg at R, 9mmHg during EX in 25mm B-V. The mean effective orifice area was 1.51cm² at R, 1.79cm² during EX in 21mm B-V, 4.53cm² at R and 3.29cm² during EX in 23mm B-V, 3.29cm² at R and 2.78cm² during EX in 25mm B-V. The B-V prosthesis in the aortic position has favorable systolic function when compared with other aortic valve prosthesis currently available. with aortography, aortic regurgitation was mild. However, in one of the 30 consecutive patients, open stuck valve was encountered during operation, successfully managed by 180° rotation of the disc occuluder only. This dangerous complication may occur when the open angle on the prosthesis become large.

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Clinical evaluation of aortic valve replacement with Omni-Science prosthetic valve was performed in 30 patients. The clinical results were good. There were one case of early death, two cases of late death (3.4%/p-y) and five cases of thromboembolism (8.5%/p-y). There were few which could reach the maximum opening angle of 80 degrees. Omni-Science prosthetic aortic valve showed high incidence of thromboembolism and incomplete opening of disc.

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The 22 Björk-Shiley valves were evaluated by cineradiographic examination. The opening angle was 58.6°±3.7° by Sohma's method and 59.3°±4.2° by Verdel's method. The ring motion was a 3°±1.5°. The 2 detached valves showed tilting motion of the ring and poor opening angle with fluttering phenomena of the disc.

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Fifty-two patients with isolated chronic aortic regurgitation were operated, 36 with Medtronic Hall valves, during the past 3.5 years. CTR, LVDs and LVDd improved into almost normal values three months after AVR, but LVEF, %FS and mVcf did not show a significant change within one and a half year. Seven patients, with LVDs more than 55mm and %FS less than 25%, received AVR. Four of them with administration of Prazosin prior to surgery showed satisfactory improvement in cardiac sizes and functions before and after AVR.

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Multiple organ failure following prosthetic valve replacement. Since April 1981 to May 1984, 226 cases underwent prosthetic valve replacement at our hospital. Twenty three patients (10.2%) developed multiple organ failure (MOP) postoperatively with the results of 12 deaths (52.3%). The incidence of MOP after AVR, MVR and multiple valve replacement were 6.6%, 12.3% and 12.8% respectively. The mortality rate of the patients who had less than 3 organs failure was lower than the patients more than 4 organs failure (9.1%vs 91.7%). Twenty one patients revealed preoperative abnormal organ function besides cardiac failure. Among them eight cases developed MOP and the mortality rate of these patients group was higher than the other MOF patients (87.5%vs 33%). The preoperative intensive care in addition to peri-and postoperative management is essential to reduce the occurrence of MOP.

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Twelve patients of the 3rd op. were reviewed. The results were one surgical death and 4 of the late death. The most popular complications after re-MVR and re-AVR was the pen-prosthetic leakage. The prognosis of the leakage after multiple AVR revealed the progressive myocardial hypertrophy and fibrosis from the specimen of the LV biopsy and the necropsy. 3rd valve replacement, myocardium, hypertrophy, fibrosis, LV biopsy,

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This paper was examined the result of silicon ball valve replacement for over 16 years after surgery. Male to female ratio is 15 to 12. The mean age and mean follow up term were 23Y and 10M, 18Y and 8M respectively. Postoperative thromboembolism was occurred in 11 cases in which 10 cases were not under anticoagulant therapy. While two out of the 11 cases were remained speach disturbance and slight hand paralysis respectively, other 9 cases were completely recovered. At present, anticoagulant therapy is being done in 7 cases, anticoagulant and antiplatelet therapy in 6 cases, antiplatelet therapy in 9 cases, and other 5 cases are under no medication. LV function measured by UCG revealed almost satisfactory. In conclusion silicon ball valve will be expected much longerr term results if attention is paied to thromboembolism.

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Clinical late results of mitral valve replacement using Starr^Edwards disc prosthesis in sixteen cases were presented. There were three late sudden deaths, four cases with thromboembolic episode and three cases with other troubles relating to the prosthesis. Re-MVR was needed for six cases. There were only four cases (25%) without any trouble in late phase. Our experiences indicate that the cases of MVR using Starr-Edwards disc prosthesis need careful follow-up with consideration of re-MVR if any malfunction will be highly suspected.

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From January 1974 to November 1984 eleven children, nine with mitral, one with aortic and one with tricuspid valvular disease underwent prosthetic valve replacnment. As for mitral valve replacement, Björk-Shiley prosthesis was implanted in two, Starr-Edwards ball valve prosthesis (SEBV) in seven. One patient, in whom a Björk-Shiley prosthesis was implanted, experienced mechanical failure of the prosthesis due to thrombus formationn one yearr after the operation, A SEBV was used in the second operation. The another patient implanted with a Björk-Shiley prosthesis died suddenly one year. after the operation. As the cause of the death mechanical valve failure due tq thrombus formation was suspected. In one patient a 0M sized SEBV was replaced by a 2M SEBV ten years after the operation due to outgrowth of the patient. All the patients with SEBV have not experienced any mechanical valve failure. Disc type prosthesis such as Björk-Shiley prosthetic valve was thought to be vulnerable to thrombus formation. SEBV might be preferable for the mitral valve replacement in children in whom the volume in left ventricle is large enough and it does not cause outflow tract stenosis of left ventricle.

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In the Monostrut valve, the U shaped wire-form has been replaced by a thicker monolithic projection with no welds. The disc occluder opens to 70 degree instead of 60 degree. This new Björk-Shiley valve prosthesis was implanted in 41 patients between Oct., 1983 and Oct., 1984. There were 3 early deaths not related the prosthesis. There were no late deaths and no mechanical failure. A further study on this new prosthesis is warranted.

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