Between January 1977 and August 1988, twenty-four patients (Congenital heart disease: CHD 12 and acquired valular disease: AHD 12) were treated by tricuspid valve replacement. There were no operative and late death in CHD, bud were one operative and one late deathswi th congestive heart failure in AHD, Fifteen bilogical cardiac valves and 10 mechanical valves were used in TVR and one patient had primary tissue failure at 9.8 years and two patient with Duromedics valve had thrombosed valve at 30 and 33 months postoperafively.

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35 patients receiving mechanical (17 St. jude, 3 Bjork-Shiley) or bioprosthetic valve (6 pericardial valve, 9 porcine valve) for tricuspid position were analyzed, There were one valve thrombosis (0.1%/patient-month (p-m)) and 2 endocarditis(0.2%/p-m) in mechanical valve. One primary valve failure occurred in hospital-made bioprosthesis (0.8%/p-m). Long term reslts of tricuspid valve replacement with both valves were satisfactory. Long-term durability of tricuspid bioprosthesis could be expected.

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Between 1976 and 1987, 613 bioprosthetic valves in the mitral position, with a follow up of 2535 patient-years, and 96 bioprosthetic valves in the tricuspid position, with a follow up of 334 patient-years, were implanted at Mitsui Memorial Hospital. Freedom from primary tissue failure (PTF) for mitral position is 96.8±1.0% at 5 years and 69.7±5.1% at 10 years, though for tricuspid position it figures 100% at 5 and 10 years. In adult patients there is no significant difference of freedom from PTF between older and younger generations.

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Primary tissue failure (PTF) after mitral valve replacement was comparatively evaluated between in patients with the Hancock valve and with the Liotta valve. PTF occurred earlier and more frequently in the Liotta group than in the Hancock group because of disruption of leaflet without severe calcification and stenotic lesion, resulting in significant decrease of the calculated probability of freedom from PTF in the Liotta group. It was suspected that low profiling of stent height was the major cause of disruption. In addition to disruption and calcification, stent creeping was a cause of valve failure especially in the Hancock valve. Hemodynamic function of the Hancock valve in PTF assessed by Doppler ultrasound was significantly inferior to the Liotta valve in relation to the passing of time. In addition, it was suggested that peak MVG was related to valvular regurgitation and MVA was related to valvular stenosis. In conclusion, we should furthermore be careful concerning the durability of the Liotta valve.

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The Duromedics (DM) prosthetic valves were implanted in the mitral position in 20 cases. Neither an early nor a late death was encountered. There was no valverelated complication, so far, during the mean follow-up of 12 months. The early clinical and hemodynamic results were evaluated comparing with those of the St. Jude Medical (SJM) and the Bjork-Shiley (B·S) prostheses. An order of SJM. DM and BS with serum LDH and bilirubin values from higher to lower was seen. Hemodynamic study was assessed with a continuous wave Doppler. Mitral pressure gradients were same in all three mechanical valves. However, effective prosthetic valve orf ice area was significantly larger in DM group than SJM and BS group.

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In the period from May, 1980, to June, 1988, 624 St. Jude Medical valve prostheses have been implanted in our hospital. During this period we have experienced 12 cases of hemolytic anemia immediately after operation. Then we have studied about hemolysis after SJM prosthtic valve implantation and compared with Bjork-Shiley and Carpentier-Edwards valve. In acute period LDH values after SJM valve implantation was higher than that of BS and CE valve. There were no clinical hemolysis in chronic period. LDH values after double valve replacement was higher than that after single valve replacement. Massive blood transfusion, residual aortic regurgitation, valve orientation and preoperative liver dysfunction were thought to be risk factors of hemolytic anemia.

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Thrombosed valve prosthesis which leads to a serious complication of artificial valve malfunction is said to be of exceedingly rare occurrence under anticoagulant therapy insofar as the prosthesis is inserted in place of the aortic valve. Unfortunately, however, we have had 4 cases of thrombosed valve prosthesis in the past 15 years during which time a total of 246 Björk-Shiley spherical type aortic prostheses were used by us for aortic valve replacement. These 4 cases were all female and a reduction in dosage of anticoagulant therapy during menstruation was considered a primary causative factor for thrombosis of prostheses. In all 4 cases, reoperation consisted of a thrombectomy, excision of pannus and turning of the prosthesis to such a degree as changes its opening direction by 180° from the original. Although one patient died of mediastinitis 3 months postoperatively, the other three have had an uneventful course over respective postoperative periods of 62, 39 and 7 months. Experiences gained in these cases tell us that female patients who are in a postoperative condition following cardiac valve replacement should most advisably be given ample gynecological treatment measures as needed, with a strict avoidance of imprudently reducing the dosage of anticoagulant therapy.

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During a 3-year period from January 1985 to March 1988, 72 Duromedics bileaflet valves were used for valve replacement. Of these 72, 36 were used in mitral position. Complications of Duromedics bileaflet valves in mitral position encountered by us so far are reported. Complications of prosthetic valve replacement that occurred in our series included (1) incompetence of prosthetic valve, (2) endocarditis, (3) paravalvular leakage and (4) hemolysis. All cases had a favorable course during early postoperative periods, but the long-term result of these prosthetic valves remains to be evaluated by future studies.

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Five out of 18 cases of cardiac valve replacement due to infective endocarditis needed second operations because of prosthetic valve endocarditis. All cases had perivalvular leakage and rapidly progressing heart failure, We treated three cases with mitral prosthetic valve endocarditis by replacement of infected prosthetic valve. One of these three cases died of new infection due to HD and other two cases survived and was doing well with no sign of infection. We treated two cases with aortic prosthetic valve endocarditis by translocation of the aortic valve. In one of these cases, the prosthetic valve was sutured to the ascending aorta and two saphenous vein grafts were placed on the proximal coronary arteries. In other case, the composite valve graft was used to replace the ascending aorta and two saphenous vein grafts was used to replace the ascending aorta and two saphenous vein grafts were placed on the proximal coronary arteries. One case died 1 year postoperatively because of rapidly progressing proximal coronary grafts ostial stenosis due to inflamation. The other case survived and was doing well with no sign of infection. Translocation of the aortic valve for infective aortic valve endocarditis is a useful operative technique when conventional valve replacement technique cannot be utilized.

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Fifteen patients of active infective endocarditis (IE) (group A) and 22 patients of inactive IE (group I) were surgically treated in Kyushu University Hospital. Early mortality was 6.7% (1/14) in group A and 0% in group I. Actuarial survival rate was 72.4±11.7%, 21.1±24.8% in group A and 100±0% (p<0.01), 100±0% (p<0.001) in group I at 1 and 5 years after operation, respectively. Five patients required reoperation in group A because of periprosthetic leak (3), prosthetic valve IE (1) and thrombosed valve (1). At 5 years the freedom from reoperation was 64.3±12.8% in group A and 94.7±5.1% (p<0.02) in group I. Thus, in comparison with inactive cases, late results of surgical treatment for active IE were less satisfactory.

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Aspirin (ASA) has been used for antiplatelet therapy following prosthetic valve replacement, but highdose conventional ASA treatment may reduce the effects of antiplatelet therapy because of aspirin dilemma phenomenone. In this study, the effect of ASA 81mg/day was evaluated with bleeding time, platelet aggregation, TXB₂ and 6KP values between prosthetic valve group (group-A) and other open heart surgery group (group-B). Bleeding time and ADP-induced platelet aggregation had no significant change. But in both groups, collagen and arachidonic asidinduced platelet aggregation was significantly suppressed by ASA 81mg/day without aspirin dilemma phenomenon.

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Assessment of platelet function presents a challenge to cardiac surgeons. An instrument, Sonoclot; is described with measures change in platelet function (clot impedance on a vibrating probe). Normal platelet function and dysfunction show distinct and characteristic Sonoclot signatures. This instrument was utilized to assess the platelet function impatients after valve replacement. Shoulder peak interval appeared to be specific for platelet function. The shoulder to peak interval was easily measured on the chart recorder and my be the more convenient parameter to define platelet function. The study was relatively easy to performed and the results were generally available within 20 minutes. Sonoclot studies are quick and easy to perform, and appear to be a valuable and reliable adjunct in the diagnosis of platelet function after valve replacement patients with antiplatelet therapy.

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Surgical problems and treatment in patients requiring reoperation for malfunctioning prosthetic valves are reviewed in our institute. 382 valve replacement operations were performed, implanting 469 valves for recently 25 years. 26 valves of 21 procedures were reoperation (5.6%): 4.7% in aortic, 5% in mitral, 6.7% in tricuspid valve. In those patients 3 cases had two reoperation. Most common causes of reoperation were primary tissue failure of porcine xenograft (Carpentier-Edwards valve) and cloth wear of Starr-Edwards ball valve and thrombosis of the St. Jude Medical mechanical valve. St. Jude Medical valve were almost used for the alternative prosthetic valve in reoperation. Overall mortality in reoperation was 28.6%. Most of postoperative complication were low cardiac output syndrome with IABP support. It concluded that St. Jude Medical valve is a most reliable artificial valve and recommended now for second operation.

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A paste-type electrode made from a fibrin glue and a carbon black was used for the stimulation of phrenic nerves by a diaphragm pacemaker. The electrodes were implanted at both phrenic nerves in dogs. Interelectrode impedance, threshold current for stimulation and tidal volumes were measured at various times after implantation. There is a good indication that the electrode can be used over a long period of time for stimulating the phrenic nerves.

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An intramuscular diaphragm pacemaker which can be controlled by the body temperature was developed. A couple of unipolar electrodes were attached into dog's diaphragm. Applying the cathodal, anodal or bidirectional wave form to the electrodes, the characteristics of the each stimulation wave form was tested. When the cathodal wave form was used, the smooth control of the tidal volume could be obtained. The animal's metabolism was elevated and the pacing rate was controlled by the right atrial blood temperature. It was confirmed that controlling by the body temperature was useful in a range of relatively moderate to extreme metabolic elevation for intramuscular stimulation.

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Six kinds of programmers and 8 kinds of multiprogrammable pacemakers were used for the evaluation of cross-programming phenomenon. Cross-programming phenomenon occurred in Pacesetter Programalith III using Siemens programmer 600, 600AV, 700. Output parameter changed from 7.5, 5, 2.5V to 1.3V. Cross-programming phenomenon can occur due to the transmission of the programmer satisfying the security code of the pacemaker or the programmer transmission causing on instability in the pacemaker's circuit. Physicians must be aware of the importance of utilizing only compatible programmer and pacemaker systems.

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There has been no quantative way to determine the optimal time setting of rate responsive (RR)mode after implantation of rate responsive pacemakers (RRPM). Recent progress of real time telemetry system applied to RRPM seems to make it possible to determine. By means of sequential measurement of initial voltage thresholds after pacemaker implants, it was evidenced that i) in uses of new endocardial leads, a week after implant is advisable for the setting of the RR mode, ii) in in cases of replacement of generators alone, a few days after implants is enough for the setting, iii) in cases of new myocardial leads, on the otber hand, more than two weeks seems to be necessary before setting of the RR mode. In conclusion, real time telemetry is an useful andnecessary system for decision of time setting of the RR mode.

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Pacemaker replacement from VVI to DDD type was evaluated in 18 patients (5 male, 13 female). Average was 56.7 years (range 39 to 70 years). The causes of pacemaker replacement were battery cell depletion in 16 cases, pacemaker syndrome in 1 cese, and lead fracture 1 case. After change of pacing mode by replacement, cardiac function represented by NYHA classification and CTR were significantly improved. In three cases, with combined cardiac disease (ASR, Sarcoidosis, DCM), however, it was not improved. It is considered that pacemaker replacement from VVI to DDD type may be needed in the patients with A-V block or Sick sinus syndrome unless they have combined cardiac disease.

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To clarify the incidence of venous abnormalities associated with transvenous DDD-pacing leads, 21 venograms were obtained in the patients paced 1-31 (mean 12) months. Six venograms demonstrated severe obstruction with collateral circulation; 2 of these showed total venous obstruction. Seven venograms showed venous stenosis without collaterals. The remaining 8 venograms revealed neither obstruction nor collaterals. It is suggested that venous abnormalities associated with double transvenous pacing leads occur commonly. Physicians should pay attention to the complication of venous thrombosis, while managing with DDD-paced patients.

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This is a report of three cases in which chronically infected transvenous pacemaker leads caused Staphylococcus epitermidis bacteremia. Multiple atempts at removing these leads were unsuccessful. Treatment was successful in two cases. We concluded that removal of the infected pacemaker lead with cardioplumonary bypass should be performed as soon as possible when it caused bacteremia.

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Large sized heart-lung machine with built-in typed dual cooler/heater unit and cardioplegia pump had been developed in Japan. New machine's design objectives are small overall size to occupy less space in OR, and easy transportation from OR to ICU or cath, 1ab, in case of emergency surgery. Dual cooler/heater unit is located in the pump base. Arterial blood pump with 150mm roller, and three 120mm roller pumps are located on the base that are vent, suction and cardioplegia perfusion uses. ECUM pump is attached on the left side pole mast. Thus, the machine is consisted of 4 major integrated components which are blood pumps, dual cooler/heater unit, cardioplegia pump with cooling unit, and ECUM unit. The size dimensions are W. 855mm, H. 800mm D. 680mm. This integration into small sized one unit is contributed to the improvement of machine handling and operations, and is provided better visibility of all blood tubings for perfusionest. Therefore, the safety level of ECC has been improved.

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Surgeons face a special challenge in treating Jehovah's Witnesses. Seventeen of such followers were operated with CPB. Ages ranged 6-51 years old, and male-female ratio was 3:14. Body weights were 21.5-51.0kg, and the longest perfusion time was 222min. except one fatal case. The minimum Ht during CPB ranged 18-31%. Although one case was lost because of severe LOS. The others were all alive. Two cases were reopened for hemostasis. Applications of the membrane oxygenator, Cell-Saver and Auto-Blood Return System, together with prompt decision of reopen at the time of excessive bleeding are suggested to be important for the successful open-heart surgery without blood transfusion.

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We have measured the plasma osmotic pressure (POP) and the colloid osmotic pressure (COP) before, during, and after extracorporial ciculation (ECC). The POP mesurments showed correlation to manitol loading and the blood glucose levels. The COP mesurments showed good correlation up to 30min during ECC, to the COP of the priming fluid and blood fraction in it. Albumin and globulin were the main components of the COP during the whole observastion period.

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Polypropylene (PP, 1.0m²) and cellulose acetate (CA, 0.6m²) hemoconcentrator were used as a double filtration for cardiopulmonary bypass (CPB) and post bypass hemoconcentration. PP+CA (0.6) showed lower proteinemia during CPB compared with pp (1.0m²) or CA (1.3m²) single used filtration group. However, PP+CA decrease the added priming volume and increased the protein content of filtrate. Double filtration might be useful and effective method for CPB instead of its cost performance.

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Twenty-four patients were studied. First group was with UF during CPB and second group was without UF (priming volume=2440ml, discarding the oxygenator blood). In the next 2 groups, the diluted oxygenator blood was reinfused without UF (priming volume=2440, 1920ml). The function of the heart, lung, kidney after CPB was equally good among the 4 groups. The amount of the blood using in the operations was significantly decreased by reinfusing the diluted oxgenator blood. Indication of the OF was decided as follow: l; urine volume during CPB below 2ml/kg/hr, 2; hematocrit during CPB below 20%, 3; anuria was suspected after CPB.

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We have applied two type oxygenators, MAXIMA (extracapillary blood flow fiber oxgenator) and Shiley M-2000 (bi-level crossf low membrane oxygenator). The purpose of this study is to examine the ability these two type membrane oxygenators to preserve a pulsatile flow wave forme. The inlet peak pressure was changed from 240mmHg to 558mmHg accompanied by the pulsatile blood flow 2.0 to 4.0L/min in both lungs. The loss of energy across the membrane oxygenator was about 50 to 90mmHg, but the ideai pressure gradient was obtained in periferal arterial pressure. It was considered that the effective pulsatile extracorporeal circulation could be achieved by using pulsatile roller pump with these tow type oxygenators.

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We clinically evaluated SARNS membrane oxygenator comparing with MAXIMA. With low priming volume of 320ml, non-hemic extracorporeal circulation was more easily performed with SARNS than with MAXIMA. Both oxygenator showed good blood gas exchange. Plateret preservation was tended to be better in SARNS group than in MAXIMA group, but the grade of hemolysis was vice versa. Complement activation evaluated with C3a was less in SARNS group than in MAXIMA group. We conclude that both oxygenators have no special problem in clinical use, but SARNS has the advantages in non-hemic extracorporeal circulation and shows less complement activation.

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The clinical study of the coiled silicon rubber membrane type oxygenator was performed in 15 patients. This oxygenator provided adequate O₂ and CO₂ transfer capability without time dependent deterioration. No deleterious hematologic consequences was observed despite of relatively high pressure drop between inlet and outlet of oxygenator. Platelet index (platelet counts/hematocrit) was not significantly decreased during bypass, and plasma free hemoglobin increasing rate was 0.45±0.25mg/dl/min, which was low enough to maintain the stable serum haptoglobin value. Because of low priming volume (470ml), this oxygenator can be used to non-hematic primed extracorporeal circulation. The present study indicates that this oxygenator would be suitable for clinical application.

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It cannot be redused to contact the blood with gas and the biomaterial. And then, complement is activated and appears anaphylatoxin. We compared PHO to HF-4000, SILOX, CAPIOX II on peripheral blood leucocyte counts, immunoglobuln and complements. The coparison of the corrected values showed that SHO had less loss of those protein factories than any other membronous oxygenator. It dued to membronous biomaterial, silicone. There were no differences between extra and intra capillary corporeal circuration. PHO, which we developed was more less than SHO. But, it was not inferior to HF-4000, CAPIOX II.

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CAPIOX E membrane oxygenator (Group-C) consists of extracapillary blood flow and gravity drainage. We used CAPIOX E for open heart surgery in 30 adult patients, and the results were compared with bubble oxygenator DIDECO D700 (Group-D), used in 8 patients. The following results were obtained. (1) Plasma free hemoglobin was same in the two groups. (2) Group-C demonstrated higher platelet counts (p<0.05), and better preservation of aggregation mechanisms (p<0.01). (3) Factor VIII was also less reduced in Group-C, however, Fibrinogen, Factor X, and XII were much higher in Group-D. This study indicates that CAPIOX E is superior to DIDECO D700 as regards to hematocoagulation activities during bypass.

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Newly developed microporous polypropylene hollow fiber oxygenators (CX-III and CX-E), in which blood was perfused outside and oxygen gas was passed inside the fibers, were applied to thirty five cases in open heart surgery, and performances of the oxygenators were evaluated clinically. In case of using CX-III, PaO₂ and PaCO₂ were 386±73mmHg and 27±4mmHg respectively when V/Q and FiO₂ were 0.62±0.18 and 0.86±0.17 respectively. In case of using CX-E, PaO₂ and PaCO₂ were 373±79mmHg and 35±5mmHg respectively, when V/Q and FiO₂ were 0.53±0.12 and 0.63±0.07 respectively. Thus, excellent gas performance was obtained in using both CX-III and CX-E. Serum free hemoglobulin level was maintained low during cardiopulmonary bypass. Both the oxygenators were safely and in all cases.

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Fourteen adult patients undergoing open heart surgery were examined. The following parameters were determined; fibrinogen, ATIII, FPA, plasminogen, α2PI, and FPBβ15-42. In addition to these conventional parameters, TAT and α2PI-Pm complex were also measured using ELISA method. Although all patients were given heparin, progressive increase in FPA and TAT were recorded during CPB, indicating that heparinization was not able to inhibit completely the formation and function of thrombin. On the other hand, FPBβ15-42 and α2PI-Pm complex increased significantly during CPB. These findings indicate that the enhanced fibrinolytic activity, which has dissolved intravascular fibrin, is in turn rapidly inactivated by inhibitors such as α2PI.

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we analyzed the serial levels of plasma β TG and PE 4 and platelet aggregation to evaluate the preventive effect of proeperative small dose of ticlopidine on the postoperative thrombosis in 41 patients who underwent open heart surgery. The patients were divided into 3 groups: Group I; control (12 cases), Group II; 200mg/day of ticlopidine was started to be administered 2 to 3 days after operation (19 cases), Group III; the same dose of ticlopidine was administered for 7 days preoperatively and readmini stered 2 to 3 days afer operation (10 cases). In Group II, the release of PF 4 was not inhibited during the first 7 postoperative days probably because of the insufficient suppression of platelet aggregation immediately after operation. In Group III, platelet aggregation was consistently maintained in low level during perioperative periods and the incidence of the accentuarion of the release reaction of βTG and PF 4 was reduced as well.
It is concluded that the preoperative treatment by 200mg/day of ticlopidine is expected to be effective to prevent the thromboembol is complications immediately after operation without the increased risk of excessive blood loss.

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The changes of platelet count, plasma βTG and PF4 concentrations and other hematological parameters were analyzed in order to evaluate the effect of 2ng/ml/min of Iloprost infusion on platelet preservation during CPB. 13 patients were divided into 2 groups. Group I: control (5 cases). Group II: Iloprost (8 cases). Iloprost infusion did not inhibit the platelet activation due to heparin administration, however, 20μM ADP-induced aggregation was significantly suppressed and platelet loss was prevented during CPB in Group 2. The increase of plasma levels of βTG and PF4 during CPB was significantly suppressed in Group 2 as well. It is concluded that Iloprost infusion is effective to preserve platelet during CPB.

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For continuous monitoring of changes in plasma free hemoglobin (Hb) concentration during extracorporeal circulation, a prototype system of compact hemolysis sensor was developed. Blood-plasma was continuously separated from blood by a disk filter type plasma separator installed on a housing wall of a non-positive displacement type blood pump. Hb concentration change was detected as absorbance change of plasma by an optical monitor unit consisted of LED (λmax=560nm), interference filter (λ=540nm) and photodiode. The Hb concentration values measured by this system were compared with those by conventional colorimetric method, and close agreement between the simultaneous data from these two methods were observed.

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A new system for continuous monitoring of hematocrit during extracorporeal circulation was developed. The system utilizes the principle that the ratio of blood resistivity to plasma is a function of hematocrit. Blood-plasma was continuously separated from blood by a disk filter type plasma separator installed on a housing wall of a non-positive displacement type blood pump and its resistivity was simultaniously measured with blood by a resistivity meter. Hematocrit was calculated from the ratio using the Maxwell-Fricke expression. The hematocrit values measured by this system (Hct_c) were compared with those by the capillary method (Hct_m): the linear regression equation was Hct_c=1.00Hct_m-0.002 with a correlation coefficient r=0.996. Close agreement between the simultaleous data from these two methods were also observed in animal experiments using dogs.

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We measured red cell filtration rate as an index of red cell deformability that is essential for normal microcircuration. Red cell deformability was impaired oxygen bubbling and roller pump. This impairing was inhibited by metylpredonizolone. So I had rather using membrane oxygenator than bubble oxygenator.

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In 11 cases of cardiovascular surgery, intraoperative auto transfusion was performed using a Haemonetics Cell Saver IV R for saving intraoperative hemorrhage and remaining blood in the extracorporeal circulation system. An average of 1229.0±576.3 (mean±SD) of suspension, 45.5±12.8% of Hematocrit was obtained and the red cell deformability was measured by a modification of Reid's method. Red cell deformability was preserved well in intraoperative salvaged blood, especially in the PGE₁ group.

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Hemoglobinuria and hemolysis combine with the cases under longtime extracorporal circulation of cardiac surgery. For the treatment of hemoglobinuria, it is necessary that quantitative analysis of free hemoglobin is performed rapidly and simply. Column method is simplified quantitative analysis by means of sepharose immobilized haptoglobin. This method was evaluated in 20 cases (9-valve replacement, 2-valve plasty, 9-CABG) under longtime extracorporal circulation and compared with ordinary method. The blood sample was examined immediately after stopping of extracorporal cerculation. In results, free hemoglobin was 49.1 31.7mg/dl by column method and 42.6 29.2mg/dl by ordinary method respectively. The results suggest that column method is useful analysis of free hemoglobin for the patients with hemoglobinuria as well as ordinary method.

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Pumpless ECMO experiment for acute respiratory failure was carried out using extracapillaly blood flow type membrane oxygenator, which was developed by this department. The oxygenator has many advantage, compact, small priming volume and low pressure drop. Control group (n=5) without pumpless ECMO all died within 4 hours. 24-hours ECMO was carried out 4 in 9 dogs. Hypoxia and hypercapnea were improved and CO₂ transfer rate didn't decreased. The oxygenator seems to be available for long-term pumpless ECMO.

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Extrcorporeal respiratory support for a relatively long period of hours by AV bypass and pumpless ECMO was conducted using a newly developed polypropilen extracorporeal perfusion and membrane oxygenator. Vital lung before and after respiratory assistance and the model lung with acute respiratory insufficiency exhibiting hypoventilation were observed by permiable electron microscope and were then compared. Those results indicated that this type of extracorporeal respiratory support would prevent impairment of the ultramicro structure in pulmonary tissue due to respiratory insuff icnecy. Especially the method for a relatively long period of hours was considered to be effective in repairing type B epithelial cells associated with the production and secretion of surfactant.

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We have designed a new chronic experimental model to evaluate a long-term performance of artificial lungs. Right ventricular assist device (RVAD) was implanted in 3 goats. Artificial lungs were set on the outlet conduit of the RVAD 2 weeks postoperatively when the surgical influences were neglected. Six artificial lungs were evaluated for 11 to 191 hours without any major complications. Time courses of gas exchange charasteristics were easily estimated with continuous monitoring of exhausted gas analysis. We conclude that this method is quite useful for a long-term evaluation of artificial lungs.

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