bluuebunny/crossref_metadata_2025 huggingface dataset:
A Flow Visualization Study of the NCVC Centrifugal Blood Pump
Authors: Araki Kenji , Taenaka Yoshiyuki , Masuzawa Toru , Tatsumi Eisuke , Wakisaka Yoshinari , Watari Masanobu , Nakatani Takeshi , Akagi Haruhiko , Baba Yuzo , Anai Hirofumi , Park Young Hwan , Eya Kazuhiro , Toda Koichi , Takano Hisateru
Published: November 2008

Abstract: A compact centrifugal pump, NCVC–1, has an open–type impeller with 6 curved vanes, and it is characterized by no shaft and no seal. A tunnel is placed in the center of the impeller–rotor assembly to irrigate the back space behind the rotor. To evaluate the flow, we performed 3 visualization methods: tracer, oil film, and injection streak line method. The flow, observed by the tracer method in NCVC–1, indicated little turbulence along vanes. A volute chamber proved effective to reduce vortex formation in the outlet. Oil film pattern revealed no flow separation on vanes at 5 L/min. Washout flow behind the rotor is essential to prevent thrombus formation and was shown as inward spiral flow without any stagnation. These data suggested that a combination of visualization techniques was useful to analyze various flow conditions, and the NCVC–1 has excellent flow characteristics with little turbulence and little flow stagnation, which must be beneficial to low hemolysis and high antithrombogenicity.
The Margin of Safety in the Use of a Straight Path Centrifugal Blood Pump
Authors: Kijima Toshihiko , Nojiri Chisato , Oshiyama Hiroaki , Horiuchi Kunio , Nogawa Atuhiko , Hamasaki Hiroaki , Ogihara Mitsuaki , Katsuda Helio Shun , Amano Nobuhiko , Fukasawa Hiromichi , Akutsu Tetuzo
Published: November 2008

Abstract: A new centrifugal blood pump with a rotor that arranges 6 straight paths radially was developed for open heart surgery and temporary circulatory support. We describe comparative studies of the margin of safety in the practical use of the new pump. This pump was evaluated for temperature increase, cavitation, and pressure sensitivity. Two commercially available centrifugal pumps, the Biomedicus cone type and the Sarns 3M impeller type, were used as control pumps. The temperature increase in the new pump was four times slower than in the impeller pump when the outlet and the inlet of the pump was clamped. No sign of cavitation was observed when 0. 1 ml air was introduced to the pump inlet under a negative pressure of 200 mm Hg in fresh bovine blood. As for pressure sensitivity of centrifugal pumps in practical applications, circuit resistance was a more essential factor than flow–pressure curves of the pump.
Emergency Cardiopulmonary Bypass Support in Patients with Cardiac Arrest Caused by Myocardial Infarction
Authors: Mori Yoshio , Ueno Katsumi , Hattori Arihiro , Kim Toshiya , Aoyama Takuma , Segawa Tomonori , Mimoto Hiromichi , Tomita Ryosho , Tanaka Tsutomu , Mori Noriyoshi
Published: November 2008

Abstract: Emergency percutaneous cardiopulmonary bypass support (PCPS) was instituted in 3 patients with acute myocardial infarction in cardiac arrest refractory to conventional resuscitation measures. All had severe double or triple vessel disease. Percutaneous transluminal coronary angioplasty (PTCA) was performed in 1 patient, and PTCA and directional coronary atherectomy (DCA) were performed in the other 2 patients on combined intraaortic balloon pumping (IABP) and PCPS. Flow rates of 2 to 5 L/min were achieved, with restoration of mean arterial pressure to more than 60 mm Hg during PCPS. The status of all patients was improved hemodynamically with PCPS. One patient died of hemorrhage during PCPS.

DCA was successfully performed in the other 2 patients, and PCPS and IABP was discontinued. Time on PCPS ranged from 10 h to 8 days. Time on IABP ranged from 10 days to 2 weeks. These 2 patients died of pneumonia or multiorgan failure after 1. 5 months. In conclusion, emergency PCPS is a powerful resuscitative tool that may stabilize the condition of patients in cardiac arrest to allow for definitive intervention.
Fuzzy Logic and Control: Principal Approach and Potential Applications in Medicine
Authors: Rau Günter , Becker Kurt , Kaufmann Ralf , Zimmermann Hans‐Jürgen
Published: November 2008

Abstract: During the last few years intelligent machines appeared in nearly all technical areas, such as consumer electronics, robotics, and industrial control systems. There are for example washing machines that work very effectively, need comparably less power than in the past, and have short execution times because they adjust their washing cycles to each set of clothes and change their washing strategies as the clothes become clean. These intelligent systems are based on fuzzy control strategies, i.e., common sense rules are used to describe a system's behavior instead of complex mathematical models. We have applied this new technology to control problems as well as to reasoning problems in biomedical engineering where appropriate mathematical models could not be built due to the complexity of the problem. After a short introduction to the concepts of fuzzy logic two approaches in the field are described: a fuzzy control strategy for the pump rate adjustment of a novel total artificial heart and an intelligent alarm system based on fuzzy inference which supports the anesthetist in monitoring and evaluating the hemodynamic state of a patient undergoing cardiac surgery. These examples indicate the inherent reliability and stability of this technique in the field of complex dynamic systems. Such properties are highly significant especially in medical applications.
Hemodialyzer Performance: A Review of the Trends over the Past Two Decades
Authors: Woffindin Celia , Hoenich Nicholas Andrew
Published: November 2008

Abstract: Using data generated in the course of an evaluation program for hemodialyzers and associated devices, which was supported by the Medical Devices Agency of the Department of Health, we have compared the performance characteristics of 23 hemodialyzers evaluated 20 years ago with those of 18 hemodialyzers evaluated during 1993–1994. Surface areas of the two groups ranged from 0.6–2.5 m2 (mean 1.13 m2) and 0.6–1.8 m2(mean 1.18 m2), respectively. The device performance has been compared both in vivo (small molecular clearance) and in vitro (middle molecular clearance and ultrafiltration coefficient) at blood and dialysate flows of 200 and 500 ml/min, respectively. Our comparison shows that over the past 2 decades there has been a marked improvement in functional performance. For clearance of small molecules, current dialyzers using cellulose–based membranes offer a 47% improvement for urea clearance, within the surface area range < 1.2 m2, while for dialyzers whose surface area is > 1.2 m2 the improvement is less marked (12%). The improvements noted in the clearance of creatinine were similar. Associated with the improved clearance of small molecules was an improved middle molecular clearance (74% for surface areas < 1.2 m2 and 63% for surface areas > 1.2 m2) and an increased ultrafiltration coefficient, higher by 154 and 133%, respectively, for the two surface area groups. Due to the smaller number of devices in the modified cellulose and synthetic membrane categories, it has not been possible to make such a detailed comparison. However, the experimental data demonstrate that devices currently produced incorporating modified cellulose and synthetic membranes overlap in performance and that in those devices that were in clinical use 20 years ago using synthetic membranes, current equivalents have also improved. These improvements are reflected in the concomitant reduction of treatment times from 30 h/week in 1970 to 12 h or less currently.
Application of a Standard Method to Characterize Clearance Blood Flow Relationships in Hemodialysis
Authors: Hoenich Nicholas Andrew , Appleton David , Cox Penelope Jayne , Woffindin Celia
Published: November 2008

Abstract: The effectiveness of solute removal of a hemodialyzer may be judged by the ability of the device to remove solutes over the clinical range of blood flow rates. The expression of solute removal characteristics of hemodialyzers at standard or specific blood flow rates is important for clinical use and comparison. The solute removal at a specific blood flow rate is derived mathematically, usually by the fitting of a curve to the blood flow solute removal characteristics established experimentally over a range of blood flow rates. The commonly used methods of obtaining such a relationship are discussed and a new method of curve fitting is described. This method is derived from the mathematical theory defining the overall dialyzer mass transport relationship which governs the clearance blood flow relationship in any dialyzer. The derived relationship between the blood flow rate and the clearance has been validated using data generated for a commercially produced hemodialyzer.
Long‐Term Clinical Evaluation of an Adsorbent Column (BM–01) of Direct Hemoperfusion Type for (β2–Microglobulin on the Treatment of Dialysis‐Related Amyloidosis
Authors: Gejyo F. , Teramura T. , Ei I. , Arakawa M. , Nakazawa R. , Azuma N. , Suzuki M. , Furuyoshi S. , Nankou T. , Takata S. , Yasuda A.
Published: November 2008

Abstract: The clinical efficacy and safety of a β2–microglobulin (β2M) adsorbent column, BM–01, on the treatment of dialysis‐related amyloidosis were investigated in 7 hemodialysis patients for more than 6 months. The percent reduction of serum β2M was more than 60–70%, and the level at the end of each session was less than 10 mg/L in almost all patients. The amount of β2M removed was calculated as more than 200–300 mg/session. The results demonstrated that BM–01 performed very well for removing β2M, was capable of maintaining less than 25 mg/L of time average concentration (TAC) for β2M, and improved the clinical symptoms. Clinically severe side effects were not observed. We recommend that BM–01 should undergo further evaluation for its usefulness in the long‐term treatment of dialysis‐related amyloidosis, though treatment with the column may not be successful in preventing the onset of the disease.
Clinical Trial of New Polyurethane Vascular Grafts for Hemodialysis: Compared with Expanded Polytetrafluoroethylene Grafts
Authors: Nakagawa Yoshihiko , Ota Kazuo , Sato Yuichi , Teraoka Satoshi , Agishi Tetsuzo
Published: November 2008

Abstract: We developed a new polyurethane vascular access graft coated with gelatin and reinforced with knitted polyester fibers (PE‐PEUG). Advantages over expanded‐polytetrafluoroethylene graft (E‐PTFEG) were previously reported in experimental studies. Between May 1990 and August 1992, 39 PE‐PEUGs including 34 loop and 5 straight and 18 E‐PTFEGs including 18 loop were implanted to create arteriovenous (AV) fistulas in a total of 52 adult patients on maintenance hemodialysis (HD). They were followed up until October 1994. Hemostasis on the suture line was achieved within 3 min in all patients implanted with PE‐PEUGs. Bleeding from the needle holes of PE‐PEUG stopped within 10 min with gentle finger pressure. Minimal local edema developed in only a few patients implanted with PE‐PEUG while most patients implanted with E‐PTFEG developed moderate lo cal edema. One seroma formation was found in an E‐PTFE case. Aneurysmal dilatations were observed twice in a PE‐PEUG patient 9 and 17 months after the implantation and once in a E‐PTFEG patient 2 years after the implantation. The cumulative patency rate at 1 year in the PE‐PEUG and E‐PTFEG groups were 53.2 and 70.8%, respectively. Our clinical study showed that the PE‐PEUG had several advantages over E‐PTFEG: prompt hemostasis, no persistent edema and no formation of seroma, no change in elasticity, and sufficient mechanical strength. However, the cumulative patency rate was inferior to that with E‐PTFEG implanted in our series. Further modifications are therefore necessary to improve the patency rate.
Laparoscopic Mesenterioadhesiotomy and Tenckhoff Catheter Placement in Patients with Predisposing Abdominal Surgery
Authors: Kurihara Satoshi , Akiba Takashi , Takeuchi Masashi , Nakajima Kazumi , Inoue Haruhisa , Yoneshima Hideo
Published: November 2008

Abstract: Peritoneoscopic surgery has been performed widely for a variety of abdominal surgical diseases. We describe here a safe and reliable technique of laparoscopic‐assisted mesenterioadhesiotomy and peritoneal Tenckhoff catheter placement in patients who have previously undergone abdominal surgery. Five patients suffering from end‐stage renal failure previously underwent single and/or polyabdominal surgery. The surgical procedures included hysterectomy, ovarian resection, appendectomy, and transabdominal right nephrectomy. Under general endotrachial anesthesia, a laparoscope was placed down through a direct cut made using a trocar. After CO2 gas insufflation, another one or two trocars were put in place for surgical procedures. To avoid intestinal injury, mesenterioadhesiotomy was performed carefully using a high‐frequency hook electrode, forceps, and scissors forceps, and the Tenckhoff catheter was subsequently inserted with forceps directly into Douglas' fossa. Peritoneal equilibration tests performed 30–70 days after the initiation of continuous ambulatory peritoneal dialysis (CAPD) treatment revealed moderate to good peritoneal effectiveness. This procedure permits the surgeon to perform safe and exact catheter placement into Douglas' fossa even when there is a possibility that peritoneal and mesenterial adhesion are present. We believe that this technique of catheter placement may extend the indication for CAPD treatment in patients with predisposing lower abdominal surgery.
Normalization of Hematocrit with Recombinant Human Erythropoietin in Chronic Hemodialysis Patients Does Not Fully Improve Their Exercise Tolerance Abilities
Authors: Suzuki Masashi , Tsutsui Makiko , Yokoyama Akihiro , Hirasawa Yosihei
Published: November 2008

Abstract: In the recombinant human erythropoietin (rHuEPO) treatment of renal anemia, the target level has widely been accepted as approximately 30% of hematocrit (Hct) which means only partial improvement of the anemia. We tried to maintain 1 female and 9 male patients within a normal Hct and to estimate their exercise tolerance abilities. During the study, no serious complications were experienced. Their maximal oxygen uptake (Vo2max), evaluated for 1–6 months after reaching the desired Hct of 35–40% with rHuEPO, was 30.7 ± 2.4 ml of O2/kg/min. These results were significantly higher than those of the control groups whose Hct levels were maintained at around 30%. Although 1 female and 2 male patients were considered to be within the normal exercise tolerance abilities, the others showed lower values in comparison with the Japanese age– and sex‐matched values. Thus, it is not always possible to regain full exercise tolerance abilities even after restoring a normal Hct. Unknown factors besides anemia impairing their exercise tolerance abilities might exist in chronic dialysis patients.
Effect of Nafamostat Mesilate on Bradykinin Generation and Hemodynamics During LDL Apheresis
Authors: Kojima Shunichi , Shiba Mariko , Kuramochi Morio , Yamamoto Akira
Published: November 2008

Abstract: Dextran‐sulfate (DS) cellulose used for low‐density lipoprotein (LDL) apheresis seems to be a weak activator of the contact phase of the intrinsic coagulation pathway because the surface of this substance has negative charges. Heparin, a commonly used anticoagulant, has no effect on this process whereas the process is inhibited by a newly developed anticoagulant, nafamostat mesilate (NM). The effects on bradykinin generation were compared between heparin and NM. Five patients with severe hypercholesterolemia were treated with LDL apheresis using either heparin or NM on a different day. During apheresis with heparin, factor XII, high molecular weight kininogen, and prekallikrein were markedly decreased by passing through the DS column. A distinct generation of bradykinin was observed by passing plasma through the DS column, and this led to the rise of bradykinin levels from 12 ± 5 (mean ± SE) to 72 ± 14 pg/ml after treatment of 1,000 ml of plasma. NM suppressed almost completely the rise of bradykinin levels. Although blood pressure was apt to decrease during apheresis with heparin, there was no significant difference in blood pressure between heparin and NM. Since an angiotensin‐converting enzyme inhibitor may lead to a marked rise in blood levels of bradykinin by suppressing its degradation, the use of NM is recommended for apheresis in patients taking this drug.
Adhesion and Stability of Fibronectin on PTFE Before and After Seeding with Normal and Synchronized Endothelial Cells: In Vitro Study
Authors: Honduvilla N.G. , Buján J. , Lizarbe M.A. , Bellón J.M. , Olmo N. , Hernando A.
Published: November 2008

Abstract: The possible influence of the cell cycle on the efficacy of endothelial cell (EC) seeding onto the surface of polytetrafluoroethylene (PTFE) prostheses was studied. Likewise the ideal fibronectin concentration and optimal incubation time to guarantee the binding of this protein to the prosthetic surface have been calculated. Synchronized ECs, previously labeled with 3H‐thymi‐dine, were used, and the loss of radioactivity was determined at several times throughout the study. The results showed a progressive loss of cells on the prosthetic surface similar to that occurring with the seeding of un‐synchronized ECs. The optimal concentration of fibronectin was 20 μg/ml, and the optimal incubation time was 1 h.
Effects of Muscle Length, Frequency of Stimulation, and Fatigue on the Isometric Tension in Canine Latissimus Dorsi
Authors: Cestari Idagene A. , Marques Euclydes , Leirner Adolfo A.
Published: November 2008

Abstract: An experimental protocol was designed to study the mechanical response of the canine latissimus dorsi muscle stimulated to contract isometrically. Active and passive tensions were measured with the muscle's initial length varying within 10% of its physiologic length in situ. The force‐frequency relationship was obtained at frequencies of stimulation of 1, 10, 15, 30, and 60 Hz. Muscle fatigability was assessed during 3 min of successive contractions. Tests were performed in pedicled muscles of anesthetized mongrel dogs (n = 10). Force‐length characteristics were found to affect evoked tension markedly. Maximal active tension was generated near the muscle length in situ. Specific isometric tension measured with unit pulse stimulation was 2 ± 0.4 N/cm2, and the time to peak twitch was 92.8 ± 2.67 ms. With 60 Hz of stimulation frequency, the tension was 9.31 ± 0.32 N/cm2, and the time to peak tension was 216.05 ± 16.28 ms. After the fatigue test, the tension generated decreased to 62.5% of its initial value, and this decline was paralleled by the rate of tension development and tension relaxation.
Effects of Electronic Autodefense Devices on Cardiac Pacemakers
Authors: Moraes José Carlos Teixeira de Barros
Published: November 2008

Abstract: The problem of interference on pacemakers as a result of extraneous electric current and electromagnetic fields is important since more than 1.5 million people worldwide have pacemakers implanted. Each year at least 100,000 people have cardiac pacemakers implanted. This article reports several effects of two electronic autodefense devices on some cardiac pacemakers. The results show that the interference affects severely the behavior of the cardiac pacemakers, but if the duration is no more than 5 s, the effects are not permanent, and the pacemakers return to the correct action as soon as the interference ceases.
A Paradigm for Design of Closed Loop Neuromuscular Electrical Stimulator Control Systems
Authors: Quevedo Antonio Augusto Fasolo , Cliquet Alberto
Published: November 2008

Abstract: The use of neuromuscular electrical stimulation (NMES) for rehabilitation of gait in spinal patients is widely known. The best results can be obtained with the use of biomechanical sensors and a closed loop NMES system. One of the biggest problems faced in the design of control systems for closed‐loop operation, in gait rehabilitation, is the variation of the mechanical conditions during the phases of gait. This work presents a new approach to ease the design of rule‐based closed loop systems for operation in conditions such as gait rehabilitation.
Electron Microscopic Study of Driving Diaphragms in Long‐Term Survival with a Total Artificial Heart
Authors: Vašku̇ Jaromír , Urbánek Petr
Published: November 2008

Abstract: A driving diaphragm in the long‐term working total artificial heart (TAH) is under serious mechanical stress, and the long steady contact with blood causes changes to the diaphragm's surface. These changes can be influenced either by local or systemic interventions. In our study, we tried to follow the development of changes to the diaphragm's surface comparing the samples of diaphragms of long (over 30 days) and short (under 30 days) surviving calves and the effect of some preventive measures as well. We could confirm the presence of two types of calcification: a dystrophic calcification affecting primarily formed thrombi and necrotic tissue, and a primary type of calcification that begins in the form of calcifying nuclei on the protein layer of the polyurethane surface that is later on extensively covered with a fibrin network and blood cells. The calcified deposits caused mechanical damage or were the source of microembolization to the vital organs. A clotting mechanism occurs at the same time as the calcifying process from the beginning, often forming a fibrin network in and over the calcified deposits. An attempt at prevention was made by systemic administration of colloidal iron solution, Ferrum Lek (fern saccharate in a stable colloidal form), based on the concept of the so‐called reversed calciphylaxis.
A Novel Bioreactor Design for In Vitro Reconstruction of In Vivo Liver Characteristics
Authors: Bader Augustinus , Knop Erich , Böker Klaus , Frühauf Nils , Schüttler Wolfgang , Oldhafer Karl , Burkhard Ringe , Pichlmayr Rudolf , Sewing Karl‐Friedrich
Published: November 2008

Abstract: We have constructed a bioreactor aimed at imitating the three‐dimensional micro‐ and macroenviron‐ment of the liver. In vivo hepatocytes are arranged in plates of cell monolayers and are specifically attached with both sinusoidal surfaces to the space of Disse which contains extracellular matrix. Nonparenchymal cells are located on the other side of the space of Disse toward the sinusoid. For supporting monolayer hepatocytes with bipolar attachment to the extracellular matrix, we used a double gel culture technique that sandwiches hepatocytes between two layers of collagen. In double gel cultures, albumin production increases during an adaptive period to the in vitro environment. In contrast to conventional trol (4). We have studied a variety of cellular parameters such as cytochrome P450 3A expression (27), drug metabolism (27, 28), protein secretion, and morphology. In situ‐like morphology and stable function was obtained in DG culture.
Influence of Hydration State on Plasma Volume Changes During Ultrafiltration
Authors: Wizemann V. , Leibinger A. , Mueller K. , Nilson A.
Published: November 2008

Abstract: To assess the influence of hydration state on plasma volume (PV) changes during ultrafiltration, 11 clinically normhydrated patients on maintenance hemo‐dialysis were studied intraindividually during 2 hydration states differing by 2–15% of lean body mass (LBM). Plasma volume was measured continually during a 15‐min ultrafiltration test including an ultrafiltration of 1% of target weight and during a 45‐min follow‐up period of blood recirculation through the dialyzer without ultrafiltration. In all patients a maximal decrease in relative PV was more pronounced when there was less hydration and when the grade of hydration correlated inversely with the maximal response of PV decrease (r = ‐0.68, p < 0.001). The same was observed between the hydration state and the slope of the PV decrease (r =—0.69, p<0.001). Plasma refilling was estimated in the period following ultrafiltration. The slope of the plasma volume increase correlated with the grade of hydration (r = 0.31, p<0.05) as did the asymtote of PV (r = 0.4, p<0.01). It is concluded that the less hydrated a dialysis patient is, the more pronounced will be the fall of the ultrafiltration‐induced plasma volume and the less distinct will be the recovery of the plasma volume after the discontinuation of ultrafiltration.
Effects of Lactate‐Based and Bicarbonate‐Based Peritoneal Dialysis Solutions on Neutrophilic Oxygen Consumption
Authors: Ing T.S. , Huie D.A. , Johnson V. , Ryu J. , Yu A.W. , Wong F.K.M. , Zhou F.Q.
Published: November 2008

Abstract: Acidic lactate‐based peritoneal dialysis solutions were found to impair neutrophil oxygen consumption markedly in sharp contrast to their pH 7.4 lactate‐based or bicarbonate‐based counterparts.
Comparative Hemolysis Tests of Rotary Blood Pumps
Authors: Itkin George P. , Matveev Yuri G. , Romanov Oleg
Published: November 2008

Abstract: At present, hemolysis is one of the most important characteristics used to evaluate rotary blood pumps. However, the conditions of testing procedures in various research centers differ considerably. We proposed to conduct the experiments under conditions similar to those from clinical applications of arterial pumps in ex‐tracorporeal perfusion. Proceeding from these considerations, the following parameters of Hemolysis (H) testing were adopted: output, 6 L/min; difference of pressure, 300 mm Hg; initial hematocrit, 30 mg%; and initial hemolysis (PHbo) <5 mg%. The channel pump IBP80 designed on the basis of the BP80 was tested using fresh human blood. The experimental results indicate that the H level due to the use of the IBP80 is 2–3 times less than H for the BP80. H dependence on the difference of pressure in the range between 200 and 300 mm Hg was noted for the BP80, which can be accounted for by the transition of the laminar conditions of flow to turbulence. According to the results of the hydrodynamic efficiency evaluation, the IBP80 is twice as efficient as the BP80.
An Implantable Seal‐less Centrifugal Pump with Integrated Double‐Disk Motor
Authors: Schima Heinrich , Schmallegger Helmut , Huber Leopold , Birgmann Irene , Reindl Christian , Schmidt Christian , Roschal Karin , Wieselthaler Georg , Trubel Wolfgang , Losert Udo , Wolner Ernst
Published: November 2008

Abstract: Thrombus formation and sealing problems at the shaft as well as the compact and efficient design of the driving unit have been major difficulties in the construction of a long‐term implantable centrifugal pump. To eliminate the problems of the seal, motor size, and efficiency, two major steps were taken by modifying the Vienna implantable centrifugal pump. First, a special driving unit was developed, in which the permanent magnets of the motor themselves are used for coupling the force into the rotor. Second, the rotor shaft in the pumping chamber was eliminated by adopting a concept recently presented by Ohara. The rotor is supported by 3 pins, which run on a carbon disk, whose concave shape leads to stabilization. The device has the following specifications: size: 65 mm (diameter) by 35 mm (height), 101 cm3; priming volume 30 cm3, 240 g; and a 6‐pole brushless double disk DC motor. The required input power of the described prototype is 15 W at 150 mm Hg, 5 L/min (overall η= 11%), and has an in vitro index of hemolysis (IH) of 0.0046 g/100 L. The test for in vitro thrombus growth exhibited far less thrombus formation in the new design than in designs with axles. In conclusion, the design of a special driving unit and the elimination of the axle led to the construction of a small pump with very low blood traumatization.
Considerations and Problems in the Development of the Mini‐Spindle Pump
Authors: Hager J. , Koller J. , Gschnitzer F. , Fitz A. , Klima G. , Brandstaetter F.
Published: November 2008

Abstract: The premise for the development of the mini‐spindle pump, planned as an implantable device for assisted circulation, was to transport 4 L of water/min in mock circulation with a speed of 12–15,000 rpm against an afterload of 90 mm Hg. After calculations, the resulting first prototype had a spindle rotor with 3 threads (outer diameter, 18 mm; inner diameter, 6.2 mm; length, 45 mm) in a U‐shaped housing, driven by an electric motor with a cooling system. In mock circulation, this pump moved 7.8 L of water/min at 18,000 rpm. To avoid animal experiments, its influence on the blood was tested in a Maxima oxygenator. The device circulated 4.2 L of blood/min with the same speed. Because of its high traumatic he‐molysis rate (>250 mg% of free hemoglobin after 7 h of pumping), the rotor was modified, first without effect at 2.5 threads and then at 4 threads. In addition, in this third prototype, the flow direction was reversed. This prototype was more effective (4.3 L of blood/min at 12,000 rpm in the oxygenator) and the hemolysis rate, after a pumping duration of 8 h, could only be reduced to 180 mg% of free hemoglobin. As a result, a fourth prototype was developed (i.e., the U‐shape of the housing was abandoned). This device functioned better than the third prototype (4.5 L of blood/min at 12,000 rpm in the oxygenator), but the blood trauma increased (220 mg% of free hemoglobin after 7 h of pumping). To find out if the oxygenator may be responsible for the hemolysis problem, the 16th prototype of the large spindle pump was tested in the oxygenator. The result was expected, the level of free plasma hemoglobin was high again (190 mg%). To verify the function of the third and the fourth prototype of the mini‐spindle pump, 4 animal experiments were performed. Under normal cardiac conditions, the devices emptied the left ventricle up to 70% with a speed between 10,500 and 11,200 rpm, moving about 6 L of blood/min (afterload between 65 and 90 mm Hg). The hemolysis rates were between 32 and 90 mg% of free hemoglobin in the plasma.
Basic Study to Develop the Undulation Pump for Practical Use: Antithrombogenicity, Hemolysis, and Flow Patterns Inside the Pump
Authors: Abe Yusuke , Chinzei Tsuneo , Isoyama Takashi , Ono Toshiya , Mabuchi Kunihiko , Imanishi Kaoru , Kouno Akimasa , Atsumi Kazuhiko , Fujimasa Iwao , Imachi Kou
Published: November 2008

Abstract: The undulation pump (formerly called the pre‐cessional displacement pump) is a continuous flow displacement‐type blood pump that is being developed as an implantable total artificial heart. A new undulation pump was developed for chronic use and was examined with animal experiment and flow visualization studies. In the animal experiment using a left ventricular bypass in goats, severe hemolysis occurred. After driving for 12 h, thrombus formation inside the pump was found. In the flow visualization studies, the flow pattern showed that the flow inside the pump was a very complicated turbulent flow. Improvement of hemolysis and thrombus formation is important to realize implantable total artificial hearts using undulation pumps.
Pulsatile Total Artificial Heart Using a Reversible Rotary Pump
Authors: Fukunaga Shintaro , Mitsui Norimasa , Hotei Hiroshi , Nagata Hideyuki , Watari Masanobu , Tahara Ko , Sueda Taijiro , Matsuura Yuichiro
Published: November 2008

Abstract: A pump circuit was assembled and examined for use as an implantable artificial heart. The circuit consisted of a gear pump and 4 artificial heart valves. Mitral and pulmonary arterial valves were placed at the inflow port of the pump, and aortic and tricuspid valves were placed at the outflow port. The mitral and the tricuspid valves were connected to each reservoir at 10 mm Hg, and the aortic and the pulmonary arterial valves were connected to the head tanks at 80 and 20 mm Hg, respectively. The pump discharged pulsatile flows into both systemic and pulmonary arteries alternately by switching the direction of rotation periodically. Because the rated discharge was 1.7 L/min for the gear pump used, the measured flow rate was 0.8‐0.75 L/min at a heart rate of 60–110 bpm.
Development of an Autoflow Cruise Control System for a Centrifugal Pump
Authors: Nishida Hiroshi , Beppu Toshiyuki , Nakajima Masato , Nishinaka Tomohiro , Nakatani Hayao , Ihashi Kenji , Katsumata Takahiro , Kitamura Masaya , Aomi Shigeyuki , Endo Masahiro , Koyanagi Hitoshi , Oshiyama Hiroaki , Nogawa Atsuhiko , Amano Nobuhiko , Nojiri Chisato , Akutsu Tetsuzo
Published: November 2008

Abstract: To improve the ease of driving a centrifugal pump that is afterload dependent, we have developed an automatic flow control system for the Terumo Capiox centrifugal pump system. This system consists of an autoflow cruise control system with a safety cutoff. The Capiox Pump Console 3000 was controlled by a personal computer through a serial communication line. In the usual manual mode, the motor speed knob works as a pump speed control, and in the autoflow mode, the same knob works as a blood flow rate control. After selecting and obtaining the desired flow rate, the mode was changed from manual to autoflow mode. In the autoflow mode, the computer compares the desired flow rate with the actual flow measured by an ultrasonic Doppler flow‐meter and adjusts the motor rotational speed accordingly. During both in vivo and in vitro testing, this autoflow mode was able to return the changed flow that was disrupted by either clamping and declamping of the tubing or by the bolus injection of a vasomotor drug to the selected flow rate within 10 s without any significant fluctuation. In conclusion, the newly developed computer controlled autoflow system was able to produce a reliable and effective flow regulation for a centrifugal pump.
Experimental Use of a Semipulsatile Rotary Blood Pump for Cardiopulmonary Bypass
Authors: Mesana T. , Morita S. , Trinkl J. , Demunck J.L. , Gauthier T. , Aucomte F. , Havlik P. , Montiès J.R.
Published: November 2008

Abstract: We tested our valveless pulsatile rotary blood pump (CORA) extensively in animals, but only as a temporary implantable left ventricular assist device. To expand the scope of future clinical applications, we recently undertook experiments to assess the feasibility of our pump for use in a standard cardiopulmonary bypass circuit. We conducted 4 experiments in adult sheep (body weight, 40 kg): 2 with CORA and 2 with the BioMedicus pump (BP) for comparison. In all experiments, a currently used extracorporeal circuit with reservoir, filter, and membrane oxygenator (Sorin monolith) was installed, and open chest extracorporeal circulation (ECC) was performed for 6 h. Hemodynamic performance and hemolysis were evaluated. CORA provided semipulsatile systemic flow at a level comparable to that of the BP. Free plasma hemoglobin levels were slightly higher with CORA, but the decrease in platelet count was the same for both devices. There was no significant difference in the extent of blood trauma. We conclude that CORA could be successfully used for ECC with an oxygenator. Negative pressure can be prevented by our specially designed control system.
Mechanical Unloading with a Miniaturized Axial Flow Pump (Hemopump): An Experimental Study
Authors: Waldenberger F.R. , Wouters P. , DeRuyter E. , Flameng W.
Published: November 2008

Abstract: A family of miniaturized axial flow pumps has been developed, including the Hemopump, the 14‐F, and the 21‐F HP, which were especially designed for cardio‐logical use. We designed an experimental set‐up to study the unloading properties of these devices in a model of regional stunning in an anesthetized, open thorax preparation in sheep. Stunning was caused by 15‐min occlusion of the diagonal branch of the left anterior descending coronary artery with subsequent 90 min of reperfusion. Regional myocardial function was assessed by sonomicrom‐etry. A control group was compared with 2 groups with either mechanical unloading during part of ischemia (Group 2) or the early phase of reperfusion (Group 3). In either unloading protocol, both Hemopumps were used. It was shown that recovery from asynchrony was significantly faster in Groups 2 and 3 if unloading was performed with the 21‐F HP compared with control Group 1 and the groups using the 14‐F HP (p > 0.05). Thus, mechanical unloading with the 21‐F Hemopump enhances recovery from stunning whereas unloading with the 14‐F HP has only minor effects on hemodynamics and no effects on recovery.
Gas Exchange Efficiency of a Membrane Oxygenator with Use of a Vibrating Flow Pump
Authors: Naganuma Shigeru , Nitta Shin‐ichi , Yambe Tomoyuki , Kobayashi Shin‐ichi , Tanaka Motonao , Hashimoto Hiroyuki
Published: November 2008

Abstract: We have developed a newly designed blood pump, named the vibrating flow pump (VFP), which can generate high frequency oscillated flow. The driving frequency is 10–50 Hz, and flow volume is linearly controlled electric power (current and voltage). The VFP was applied as the pump for extracorporeal circulation (ECC) in acute animal experiments. The gas exchange efficiency of the membrane oxygenator with the VFP and a roller pump (RP) was evaluated. Under general anesthesia with halothane, 7 adult goats underwent ECC; an inflow can‐nula was inserted into the right atrium, an outflow cannula was sutured to the descending thoratic aorta, and total ECC was performed with a flow of about 80 ml/min/ kg. The ECC system with the VFP showed excellent gas exchange efficiency compared with that of the RP. The hemodynamics of ECC using the VFP were easily maintained within normal limits. These results suggest that the VFP is very useful as a pump for ECC; thus, a compact‐sized ECC system may be achieved.
Improving Clinical Outcome with Centrifugal Mechanical Assist for Postcardiotomy Ventricular Failure
Authors: Curtis Jack J. , Walls Joseph T. , Schmaltz Richard A. , Demmy Todd L. , Wagner‐Mann Colette , McKenney Charlotte , Nawarawong Weerachai
Published: November 2008

Abstract: Between October 1986 and May 1994, 65 patients undergoing cardiac surgery required centrifugal mechanical assist devices to separate from cardiopulmo‐nary bypass. This experience was arbitrarily divided into early (n = 33) and recent (n = 32) groups for the purpose of comparing trends in morbidity and mortality. The incidence of mechanical assist application decreased from 2.19% in the early group to 0.96% in the recent group (p < 0.0001). Ability to wean patients from centrifugal assist increased from 33% in the early group to 53% in the more recent group, and hospital survival increased from 15 to 28%. The median chest tube drainage during the first 24 h decreased from 3,245 ml to 1,535 ml, and the incidence of renal failure decreased from 39.4% and 18.8% in the more recent group. Clinically relevant improvement in patient outcome following application of centrifugal mechanical assist for postcardiotomy ventricular failure is being observed.
Left Atrial‐Aortic/Femoral Bypass with a Centrifugal Pump without Systemic Heparin during Surgery on the Descending Aorta
Authors: Sander‐Jensen Kåre , Krogager Gert , Pettersson Gösta
Published: November 2008

Abstract: Active or passive bypass to support the distal circulation during cross‐clamping of the descending thoracic aorta has been reported to decrease the incidence of paraparesis, to reduce left ventricle afterload, and to preserve distal organ perfusion. The aim of this study was to describe and to evaluate a perfusion technique for surgery on the descending aorta in humans. Nine patients underwent surgery on the descending thoracic aorta. The left atrium was cannulated using a Carmeda bioactive surface cannula. Distal cannulation sites were the left common femoral artery or the aorta below the involved segment. The cannulae were connected to a BioMedicus centrifugal pump via Carmeda bioactive surface tubings and pump heads. No systemic heparin was used. Cross‐clamp time was 51 ± 6 min, and the pump flow was 2.3 ± 0.2 L/min. The mean arterial pressure in the upper body was 81 ± 4 mm Hg and 68 ± 5 mm Hg in the lower. Seven patients were discharged from hospital. Two patients with aortic rupture died; one died on the operating table, and the other, neurologically intact, died 4 days postop‐eratively due to multiorgan failure. No patients suffered spinal cord injury. It is concluded that active bypass without systemic heparin during cross‐clamping of the descending aorta is simple and safe.
Quantitative Reticulocyte Analysis May Be of Benefit in Monitoring Erythropoietin Treatment in Dialysis Patients
Authors: Jeffrey R.F. , Khan A.A. , Kendall R.G. , Norfolk D.R. , Will E.J. , Davison A.M.
Published: November 2008

Abstract: Reticulocyte responses to low‐dose erythropoietin (EPO) were monitored using automated flow cyto‐metric analysis. Sixteen adult dialysis patients were treated with 1,000 U of recombinant human EPO (rHuEPO), subcutaneously, thrice weekly (mean dose 15.7, SD 3.7 U/kg). The reticulocyte count (baseline 31.1, SD 19.1 times 109/L) increased in 14 patients in the first week, with a peak response occurring at Week 2 (mean 57.3, SD 26.5 times 109/L, p < 0.01). There was a wide spectrum of response, the maximal absolute increment ranging from 6.8–69.7 times 109/L (maximal percentage increase 19–863%), Overall there was no relationship between the early increment in reticulocyte count and hemoglobin (Hb) response over the ensuing 4 months. Nine patients became transfusion independent (mean Hb increasing from 6.9, SD 0.8–9.2, SD 1.2 g/dl). Two patients had poor reticulocyte increments and no significant change in Hb.

The remaining 5 patients responded partially with a brisk reticulocyte response and a marked reduction in transfusion dependency, but without a sustained increase in Hb. On investigation, all had gastrointestinal bleeding (melena in 1, commencing after initiation of treatment, positive fecal occult bloods in 4), whereas none of the other patients showed evidence of blood loss. It is notable that the erythron was sensitive to this modest dose of rHuEPO in the majority of patients as evidenced by the reticulocyte response. The results provide useful information in the management of patients on rHuEPO. A small or inappar‐ent reticulocyte response suggests a confounding factor; a poor Hb response in the presence of active reticulocyte synthesis points to occult blood loss or hemolysis.
Influence of Hemodialysis Membranes on Gene Expression and Plasma Levels of Interleukin‐iβ
Authors: Qian Jiaqi , Yu Zhiyuan , Dai Huili , Zhang Qingyi , Chen Shishu
Published: November 2008

Abstract: Plasma levels of interleukin‐iβ (IL‐iβ) were measured in 10 normal subjects, in 11 nondialyzed end‐stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL‐iβ were 10.73 ± 5.24 pg/ml, 9.97 ± 3.61 pg/ml, 13.17 ± 4.04 pg/ml, 15.16 ± 6.16 pg/ml, and 13.96 ± 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p ≥ 0.05). In contrast, the gene expression of IL‐iβ for peripheral blood mononu‐clear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL‐iβ for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 ± 1.07, 3.34 ± 0.74, and 3.27 ± 0.64%, respectively. The levels of IL‐iβ gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p ≤ 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p ≥ 0.05). We suggest measuring the gene expression of cy‐tokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.
The Superiority of Hollow Fiber Membrane over Bubble Oxygenator in a Perfusion Circuit for the Evaluation of Small Caliber Endothelialized Arterial Prostheses
Authors: Mazzucotelli J.P. , Lecouls L. , Hamzaoui A. , Philippon C. , Bizouard E. , Moczar M. , Loisance D.Y.
Published: November 2008

Abstract: A perfusion circuit was constructed from a pneumatic ventricular assist device, 2 compliance chambers, 4 small‐diameter silicone tubes (ID 4 mm) simulating shear inducing vascular prostheses, and an oxygenator with a heat exchanger. A bubble oxygenator (in a BO circuit) and a hollow fiber membrane oxygenator (in an MO circuit) were studied. The circuits were perfused with 30% human serum containing culture medium for 7 days at 37oC. The pH, Po2, Pco2, Na+, K +, Ca2+, CI‐, glucose, and total protein concentrations remained the same in BO and MO circuits during the 7 days of perfusion. The differences between the values measured in the perfusion medium and in the medium maintained in the static conditions of cell culture were not significant. In the BO circuit, the amount of cholesterol and triglyceride concentrations decreased whereas the relative amounts of albumin, α1, α2, p, and γ globulins remained stable in the perfusion medium. The medium from the BO circuit did not promote the proliferation of cultured human saphenous vein endothelial cells. In the medium from the MO circuit, the cholesterol and triglyceride concentrations did not change with perfusion time; the proliferation rate and anticoagulant function of endothelial cells were maintained. The hollow fiber membrane oxygenator preserves the biological characteristics of the cell culture medium in a perfusion circuit. The MO circuit permits the performance of relevant studies on shear stress resistance and functional activity of human endothelial cells seeded onto vascular prostheses.
Inhaled Nitric Oxide During Extracorporeal Membrane Oxygenation for the Treatment of Severe Persistent Pulmonary Hypertension of the Newborn
Authors: Müller Werner , Kachel Walter , Lasch Peter , Varnholt Verena , König Stephan
Published: November 2008

Abstract: Inhaled nitric oxide (NO) as a complementary treatment was studied in 10 neonates during extracorporeal membrane oxygenation (ECMO) therapy of various persistent pulmonary hypertension of the newborn (PPHN)‐associated diseases. At individually different levels of inhaled NO (20–80 ppm), the mean Pao2 increased by 59.7% in 6 responders, but it remained unchanged in 4 nonresponders. Adverse side effects of the NO inhalation were tolerable. It was associated with a reversible decrease of the mean arterial blood pressure in 1 patient. During prolonged NO inhalation, the methemo‐globin (met‐Hb) level increased to 0.9‐4.6% in 6 patients. Based on these preliminary results, we conclude that inhaled NO during ECMO can improve oxygenation in some PPHN patients. Further studies with control groups are needed to determine whether inhaled NO can shorten ECMO treatment or improve the rate of survival among PPHN patients.