bluuebunny/crossref_metadata_2025 huggingface dataset:
Hemodialysis with Cellulose Membranes Primes the Neutrophil Oxidative Burst
Authors: Ward Richard A. , McLeish Kenneth R.
Published: November 2008

Abstract: Hemodialysis with cellulose membranes causes a complement‐mediated neutropenia. Changes in neutrophil function have also been reported; however, it is unclear if these changes indicate a direct effect of the membrane on neutrophils or if they are a consequence of the neutropenia. We tested the hypothesis that neutrophil oxidative burst activity is enhanced during dialysis with cellulose membranes. Resting and Staphylococcus aureus‐stimulated H2O2 production were determined predialysis and in blood entering and leaving the dialyzer during the first 30 min of dialysis and in blood leaving the membrane module in a single‐pass on‐line model of hemodialysis. Resting H2O2 production increased slightly but significantly during the first 30 min of dialysis. Transit of neutrophils through the dialyzer caused a marked increase in stimulated H2O2 production, indicating priming of the oxidative burst. However, priming was limited to the first 5 min of dialysis before the onset of neutropenia. In contrast, stimulation and priming of H2O2 production persisted throughout 30 min of single‐pass on‐line perfusion. These results indicate that cellulose membranes both stimulate and prime neutrophil oxidative burst activity but that these effects are partially obscured by neutropenia.
Hantaan Virus Infection with Acute Renal Failure
Authors: Polenaković Momir , Grĉevska Ladislava , Gerasimovska‐Tanevska Vesna , Onĉevski Angel , Džikova Sonja , Ĉakalaroski Koĉo , Masin Georgi
Published: November 2008

Abstract: We report on 10 patients with acute renal involvement in Hantaan virus infection observed at the Department of Nephrology, Faculty of Medicine, Skopje, Republic of Macedonia, during a period of 3 years (October 1987‐July 1990). Eight patients were male and 2 were female, aged 37.5 ± 4.8 years. The diagnosis of Hantaan virus infection was proven by an indirect immu‐nofluorescent and ELISA test with a significant increase of the titer after a week to ranges from 1:512 to 1:2,048. Percutaneous renal biopsy was performed in 3 cases using standard procedures for optical and immuno‐fluorescent microscopy. Fever, weakness, headache, conjunctival injection, hematuria, and lumbar pain were clinical features all patients had in common. Complete anuria was noted in 7 out of 10 and oliguria in the other 3 of the 10 cases with serum levels of creatinine 967 ± 152.6 u.mol/L. Other following laboratory findings were leukocytosis in 10 out of 10 patients, with neutrophylia, and reduction of serum sodium and potassium in 8 out of 10, and a decrease in serum complement C3 in 3 out of 10 patients. Percutaneous renal biopsy confirmed interstitio‐nephritis in 2 out of 3 biopsied patients and acute diffuse proliferative glomerulonephritis in the third. Interstitial mononuclear infiltration with dominant T cells proven with monoclonal antisera (direct immunoperoxidase method) was present in all 3 cases. The outcome of the disease was good in 8 of the 10 patients with a development of polyuric phase and complete recovery of renal function later. One patient with interstitial lesions on biopsy developed chronic renal failure, and the other with a concomitant brucellosis died during the polyuric phase of the disease.
In Vitro and In Vivo Evaluation of a Small Caliber Vascular Prosthesis Fixed with a Polyepoxy Compound
Authors: Mazzucotelli Jean Philippe , Bertrand Patrick , Benhaiem–Sigaux Nicole , Leandri Jacqueline , Loisance Daniel Y.
Published: November 2008

Abstract: A small caliber vascular prosthesis obtained from an ovine internal thoracic artery (3. 8–4. 5 mm ID) fixed with a polyepoxy compound and treated with heparin has been evaluated. Cytocompatibility was evaluated in vitro using human endothelial cells (HEC). HEC were obtained from human saphenous vein and cultivated in culture medium supplemented with 25% human serum. Graft segments were rinsed using a standard protocol proposed by the manufacturer. Tissue reaction was tested on a rabbit model of subcutaneous implantation. The patency rate and healing patterns were evaluated comparatively with polytetrafluorethylene (PTFE) 4 mm ID prosthesis in a canine model of carotid interposition. Cytocompatibility assay showed that there was low adhesion on vascular grafts (20 ± 2% of endothelial cells seeded) and no growth of HEC on the graft surface. The graft patency rate was 55% in both groups, and actuarial freedom from occlusion was not different at 3 months (37. 7 ± 15% in Denacol–fixed grafts versus 38. 1 ± 14% in PTFE). Histological studies on the biological grafts shows a frequent neointimal hyperplasia at the anastomosis (5/12), a lack of endothelial cells lining the graft surface, a good preservation of the media, and a moderate inflammatory response in the adventicia. The Denacolfixed graft has presented excellent surgical properties and preservation of the histological structure. Nevertheless, the patency rate was not improved when compared with the PTFE control graft.
Monitoring of TPMT in Heart Transplant Recipients under Immunosuppressive Therapy with Azathioprine
Authors: Gummert J. F. , Schutz E. , Oellerich M. , Mohr F. W. , Dalichau H.
Published: November 2008

Abstract:Azathioprine (AZA) is routinely used in double and triple immunosuppressive therapy after cardiac transplantation. In some cases it causes severe myelosuppres–sion. The interindividual differences in AZA toxicity is probably due to differences in the drug metabolism. Thi–opurine methyltransferase (TPMT) is thought to be the most important enzyme in the catabolism of AZA. A deficiency in this enzyme will presumably increase the availability of 6–mercaptopurine for the anabolic pathway thereby leading to increased cytotoxicity. A 65–year–old male underwent heart transplantation at our institution with an uncomplicated course. Immunosuppression consisted of cyclosporine, prednisolone, and AZA. Several weeks after the administration of AZA, the patient developed severe leukopenia. TPMT activity was then measured in this patient and found to be below the detection limit. Subsequently the patient died from multiorgan failure due to septicaemia. As a result of this experience, we started to screen all patients for TPMT deficiency. In 58 healthy controls, the mean activity was found to be 11. 8 nmol/h/ml of red blood cells (RBC) while in 13 patients on our waiting list, the mean activity was found to be 11. 97 nmol/h/ml of RBC. In 15 patients after heart transplantation and azathioprine treatment, the mean activity was found to be 17. 2 nmol/h/ml of RBC. We suggest screening for TPMT activity in transplant patients with leukopenia under AZA therapy. If TPMT deficiency is present, the AZA dosage should be adjusted or alternative immunosuppressive regimens should be considered.
Hemolysis and Heat Generation in Six Different Types of Centrifugal Blood Pumps
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: What the most causative factor affecting hemolysis is still controversial. To resolve this problem, we investigated the relationship between hemolysis and heat generation in six types of centrifugal blood pumps (Bio–Pump, Delphin, Capiox, Nikkiso, Isoflow, and Toyobo). The analyzed parameters were index of hemolysis in fresh goat blood, pumping performance, and heat generation in a thermally isolated mock circuit. These parameters were analyzed at a flow rate of 5 L/min by changing the pressure head (100 mm Hg and 500 mm Hg). At 500 mm Hg of pressure head, the Bio–Pump needed the highest rotation number and showed the highest hemolytic rate and heat generation. The index of hemolysis is well correlated to heat generation (r2= 0. 721). Heat may originate from the motor by conduction, hydraulic energy loss, and mechanical friction between the shaft and seal. We strongly suspect that hemolysis was caused by a factor such as mechanical friction which generates heat locally.
Reconstruction of Liver Tissue In Vitro: Geometry of Characteristic Flat Bed, Hollow Fiber, and Spouted Bed Bioreactors with Reference to the In Vivo Liver
Authors: Bader Augustinus , Knop Erich , Frühauf Nils , Crome Olaf , Böker Klaus , Christians Uwe , Oldhafer Karl , Ringe Burkhard , Pichlmayr Rudolf , Sewing Karl–Friedrich
Published: November 2008

Abstract: Bioreactors currently being developed for hybrid artificial livers vary greatly with respect to their microenvironment. The specific architecture modifies the relationship parenchymal and nonparenchymal cells have with the exchange surfaces of the bioreactor. Most designs are either based on hollow fiber, spouted bed, or flat bed devices. This diversity is contrasted by the uniform and unique organization of the in vivo liver. The liver cells are arranged as plates and both sinusoidal surfaces of the hepatocytes are enclosed within the matrix of the space of Disse. In this study we intended to define the in vivo liver tissue characteristics in a manner useful for an organotypical approach to hepatic tissue engineering. Transmission electron microscopy of an in vivo liver was utilized to describe these ratios. The ratios defined in this study are based on the constant hepatocellular expression of two sinusoidal surfaces. A relationship is established between the expression of the sinusoidal surfaces and their use as attachment and exchange surfaces inside a bioreactor. The presence of biliary surfaces and nonparenchymal cell surfaces is compared. The functional relevance of an in vivo like extracellular matrix geometry for oxidative biotransformation of primary hepatocytes in vitro was studied using the two model drugs cyclosporin and rapamycin. The generation of the hydroxylated cyclosporin metabolites AM 9 and AM 1 and four rapamycin metabolites was analyzed by high performance liquid chromatography (HPLC). It is shown that the cell–specific biotransformation rates at 1 week in culture in matrix overlayed hepatocytes was 5–10 times that of hepatocytes without matrix overlay. Bilaminar membrane (BLM) bioreactors were used to reconstruct extracellular matrix geometry, three–dimensional cell plates, and sinusoidal analogs in between cell plates.
A Proposal for a Theory and Detection Method of Cavitation Potential of Mitral Bileaflet Heart Valve
Authors: Zhang Zuren , Ye Chun–Xiu , Wang Yi–Shan
Published: November 2008

Abstract: We believe that cavitation damage to mitral bileaflet heart valve (MBHV) is caused by microcracks of hydrophobic pyrolite carbon. Our proposal is to detect cavitation potential of MBHV with an acoustic technique under various conditions of transvalvular pressures, ventricular dp/dt, leakage flow, and gas concentration in fluid. This modality, different from recent research in theory and technique, will lead to a standardized noninvasive and sufficiently sensitive technique for the detection of MBHV, to reject those valves believed to cause cavitation damage, and to develop cavitation–resistant MBHV.
In Vitro Testing of Artificial Heart Valves: Comparison Between Newtonian and Non‐Newtonian Fluids
Authors: Pohl Manfred , Wendt Max Otto , Werner Sabine , Koch Brigitte , Lerche Dietmar
Published: November 2008

Abstract: The in vitro testing of artificial heart valves is often performed with simple fluids like glycerol solutions. Blood, however, is a non‐Newtonian fluid with a complex viscoelastic behavior, and different flow fields in comparable geometries may result. Therefore, we used different polymer solutions (Polyacrylamid, Xanthan gum) with blood‐like rheological properties as well as various Newtonian fluids (water, glycerol solutions) in our heart valve test device. Hydrodynamic parameters of Björk‐Shiley heart valves with a tissue annulus diameter (TAD) of 21–29 mm were investigated under aortic flow conditions. Major results can be summarized as follows. The mean systolic pressure differences depend on the model fluids tested. Closing time and closing volume are not influenced by the rheological behavior of fluids. These parameters depend on TAD and the pressure differences across the valve. In contrast, rheological behavior has a pronounced influence upon leakage flow and leakage volume, respectively. Results show furthermore that the apparent viscosity data as a function of shear rate are not sufficient to characterize the rheological fluid behavior relevant to hydrodynamic parameters of the heart valves investigated. Therefore, similarity in the yield curves of non‐Newtonian test fluids mimicing blood is only a prerequisite for a suitable test fluid. More information about the viscous and elastic component of the fluid viscosity is required, especially in geometries where a complex flow field exists as in the case of leakage flow.
Changes of Intraaortic Balloon Volume During Pumping in a Mock Circulation System
Authors: Sakamoto Tohru , Akamatsu Hideki , Swartz Marc T. , Shoji Yasushi , Kazama Shigeru , Fujiyoshi Kohji , Hashiguchi Yasuhiro , Suzuki Akira , Miyashita Mitsuyoshi , Arai Hirokuni , Suzuki Akio
Published: November 2008

Abstract: The effects of hemodynamic changes on intraaortic balloon (IAB) volumes were studied experimentally using a helium tachometer in a mock circulatory system. The IAB volume decreased with increases in the heart rate and mean aortic pressure, but the degree of reduction in the IAB volume was different among 4 commercially available IAB drivers. Improvements in IAB consoles are needed to compliment the progress made in percutaneous techniques for IAB insertion resulting in smaller balloons.
Evaluation of Double Filtration Plasmapheresis, Thermofiltration, and Low–Density Lipoprotein Adsorptive Methods by Crossover Test in the Treatment of Familial Hypercholesterolemia Patients
Authors: Suzuki Mitsuru , Yamane Shingo , Matsugane Takao , Nobuto Takuo , Azuma Nakanobu , Nishideu Toshio , Shinomiyat Masaki , Saito Kou , Sasakind Norihiro , Nose Yukihiko
Published: November 2008

Abstract: A comparative assessment has been made regarding efficacy and safety of the double filtration plasmapheresis (DFPP), thermofiltration (TFPP), and low–density lipoprotein (LDL) adsorptive (PA) methods by making a crossover test on heterozygous familial hypercholesterolemia patients. Treatments by DFPP, TFPP (secondary membrane Evalux 5A), and PA (Liposorber LA–40) were carried out 5 times each, with a 2–week interval, in 5 patients with heterozygous familial hypercholesterolemia. The same plasma separator (Plasmacure PS–60, polysulfone) was used in all cases, and the volume of plasma processed was set at 4 L. High removal rates were obtained of total cholesterol, LDL cholesterol, triglycerides TG, and apolipoprotein B (apoB) by all three methods, and no differences were observed. Lipoprotein (a), apoA–2, apoC–3, fibrinogen, and immunoglobulin M (IgM) showed significantly high removal rates by the DFPP and TFPP methods compared with the PA method.

The sieving coefficient of albumin and high–density lipoprotein (HDL) cholesterol at 2 and 4 L of plasma processed exhibited high permeabilities using all three methods. Supplementing albumin was not necessary. An increase of the transmembrane pressure was observed in 1 case treated by DFPP but was not observed when using the TFPP or PA method. No changes were observed in serum interleukin 1β (IL–lβ) or tumor necrosis factor–a (TNF–α) before and after treatment by any of the three methods. No remarkable side effects were observed using either the DFPP or TFPP method. The DFPP and TFPP methods showed efficacy and safety that was not inferior to the PA method in conventional LDL apheresis, and the dead–end method of the filter operation without the discarding of plasma was shown to be possible.
Extracorporeal Removal of Lipids by Dextran Sulfate Cellulose Adsorption
Authors: Olbricht Christoph J.
Published: November 2008

Abstract: Extracorporeal removal of low–density lipoprotein (LDL) cholesterol by dextran sulfate adsorption is indicated in patients with diet and drug resistant hypercholesterolemia to prevent or to regress coronary heart disease. Plasma separation is the first step in the process, followed by adsorption of LDL cholesterol and lipoprotein (a) (Lp[aJ) to negatively charged dextran sulfate co–valently bound to cellulose beads. The reduction per treatment in LDL cholesterol is 65–75% and in Lp(a) 40–60%. In most patients one treatment per week is sufficient to reduce mean LDL to 100–150 mg/dl. Minor side effects occur in 2–6% of treatments. Major side effects are rare. In uncontrolled studies long–term treatment was associated with inhibition of progression and induction of regression of coronary artery disease. LDL apheresis by dextran sulfate may increase blood perfusion of some tissues, and preliminary results indicate a beneficial effect on therapy resistant nephrotic syndrome with hypercholesterolemia.
Findlay Implantable Two‐Stage Centrifugal Pump
Authors: Moulder Peter V. , Findlay Iain S. , Zone Robert M. , Thompson Arnold J. , Silber Harry A. , Rank William R. , Charbonnet Michael D. , Webb Watts R. , Harrison Lynn H.
Published: November 2008

Abstract The Findlay centrifugal pump is unique in its two‐stage pumping mechanisms and in its complementary interrelationship of the stages to each other and to the exit system, and it forms an extremely efficient unit. The first stage is a lift force pump as an inlet. The second and major stage is a shear force pump. Twenty‐six prototypes, many multiply modified, have been hand fabricated, and most have had classic pump function analyses. Six pumps have demonstrated minimal hemolysis (3.5‐5 h). At modest rotation speeds, it pumps water up to 10 L/min. Forty‐four acute studies in normal dogs have been performed with the Findlay pump in a ventricular assist system. Blood flows through the pump ranged from 1.2 to 4.5 L/min. The conclusion is that the Findlay pump has the ability to operate with low blood damage, performs at acceptable rotational speed with reasonable hydraulic and mechanical efficiency, and is small and implantable.
Wear‐Resistant, Hemocompatible Ti‐Nb‐Zr and Zr‐Nb Alloys to Improve Blood Pump Design and Performance
Authors: Davidson James A. , Daigle Kenneth P. , Kovacs Paul
Published: November 2008

Abstract Over the past several years, we have developed novel titanium‐niobium‐zirconium (Ti‐Nb‐Zr) alloys to address the long‐term performance needs of orthopedic implants. The unique properties of these alloys also render them promising candidates for blood pumps. These properties include excellent biocompatibility in combination with high strength and toughness, and low elastic modulus (low stiffness). Additionally, these metal alloys are readily hot or cold worked into complex shapes including wire, foil, tubing, and bar. They are readily machined and polished, and they can be surface oxidized to form a hard, wear‐resistant, low‐friction ceramic surface layer. In this diffusion‐hardened condition, oxygen also hardens the underlying metal to optimize the bone between the ceramic oxide surface and the tough metal substrate. Unlike metal surfaces, oxidative wear, which can alter surface energy, friction, and hemocompatibility, does not occur. Consequently, the combined benefits of a stable, wear‐resistant, low‐friction ceramic surface layer with the toughness, strength, formability, and thermal conductivity of metal may provide improvements in the design and performance of blood pumps and peripheral graft and percutaneous (power) components of the pump.
Evaluation of the Wear of the Pivot Bearing in the Gyro C1E3 Pump
Authors: Makinouchi K. , Nakazawa T. , Takami Y. , Takatani S. , Nose Y.
Published: November 2008

Abstract To estimate the lifetime of the pivot bearing system of the sealless centrifugal Gyro C1E3 pump, pivot bearing wear phenomena of the C1E3 were studied. The pivot bearing system consisted of a male and female pivot made of ceramics and ultrahigh molecular weight polyethylene (UHMWPE), respectively. First, many pumping tests were performed with the C1E3 under various pumping conditions, and the effects of impeller position and fluid on wear were analyzed. Through these preliminary tests, it was found that the wear progress of the pivot bearing consisted of initial wear and stationary wear. Most of this initial wear is caused by the plastic deformation of the polyethylene female pivot. It also was observed that bovine blood was almost comparable to water in its effect on the stationary wear rate at the same rotational speed. Based on these results, a long‐term pumping test was performed with the C1E3, and initial and stationary wear rates were determined. At the same time, the maximal loosening distance (LDmax) (permissible total wear) of the C1E3 was determined experimentally from hemolytic and hydraulic performance perspectives. By using experimentally determined parameters the lifetime of the pivot bearing system of the C1E3 pump was estimated for various pumping conditions. The lifetime of the pivot bearing system of the C1E3 was typically 10 years for right ventricular assist, 8 years for left ventricular assist, and 5 years for cardiopulmonary bypass.
High‐Resolution Fluorescent Particle‐Tracking Flow Visualization within an Intraventricular Axial Flow Left Ventricular Assist Device
Authors: Kerrigan John P. , Yamazaki Kenji , Meyer Rebecca K. , Mori Toshio , Otake Yasuo , Outa Eisuke , Umezu Mitsuo , Borovetz Harvey S. , Kormos Robert L. , Griffith Bartley P. , Koyanagi Hitoshi , Antaki James F.
Published: November 2008

Abstract Flow visualization is typically applied in blood pump development to both confirm the design expectations and identify regions that may be predisposed to blood element deposition and trauma. Rotary pumps, in particular, place high demands on the technique chosen to visualize the flow given the limited visual accessibility of the flow path and the high impeller speeds. Fluorescent image‐tracking velocimetry currently is used at the University of Pittsburgh Medical Center to visualize flow accurately inside of these pumps both qualitatively and quantitatively. Flow patterns under steady conditions within an intraventricular axial flow, left ventricular assist pump (prototype No. 7, SUN Medical Technology Research Corporation, Nagano, Japan) were investigated using this technique. The flow fields at the impeller‐stator interface and at the pump outlet were given specific attention. This allowed the assessment of the fluid dynamics throughout the hydrodynamic design limits of the pump.
Tandem Operation of a Turbo Blood Pump (BP‐80‐Type Centrifugal Pump) to Reduce Hemolysis
Authors: Wakisaka Y. , Taenaka Y. , Nakatani T. , Anai H. , Araki K. , Nishimura T. , Tatsumi E. , Masuzawa T. , Baba Y. , Toda K. , Eya K. , Miyazaki K. , Takewa Y. , Takano H.
Published: November 2008

Abstract When operating turbo blood pumps in tandem, the strength of shear stress is reduced, but the exposure duration of the stress is increased. The purpose of this experiment was to compare the degree of contribution of these two factors on hemolysis as well as to evaluate the effectiveness of the tandem operation of turbo blood pumps. Tandem operation of two Bio‐pumps (BP‐80; Medtronics Bio‐medicus, Inc., Eden Prairie, Minnesota, U.S.A.) were compared with single operation of a BP‐80 in in vitro hemolysis tests in three different driving conditions, that is, pumping heads of 200, 350, and 500 mm Hg under a pump flow rate of 5 L/min. The Allen's hemolytic indexes of the tandem operation at pumping heads of 200, 350, and 500 mm Hg were 0.014, 0.020, and 0.080 mg/dl, respectively. The hemolytic indexes of the single operation at pumping heads of 200, 350, and 500 mm Hg were 0.014, 0.056, and 0.12 mg/dl, respectively. These results indicate that tandem operation is a useful method of reducing hemolysis with the BP‐80 under high pumping heads and that the effect on hemolysis of exposure to higher shear stresses may be more serious than that of longer durations of exposure to shear stress in turbo blood pumps.
A Magnetically Suspended and Hydrostatically Stabilized Centrifugal Blood Pump
Authors: Hart Robert M. , Filipenco Victor G. , Kung Robert T.V.
Published: November 2008

Abstract A magnetically suspended centrifugal blood pump intended for application as a long‐term implantable ventricular assist device has been built and tested. The rotor is freely suspended in the blood by magnetic and hydrostatic restoring forces. This design obviates the need for bearings and shaft seals, and eliminates the problems of reliability and thrombogenicity associated with them. The positional stability and hydrodynamic performance of the pump has been characterized in vitro at flows of up to 10 L/min at physiologic pressures. Radial position control is realized by an analog electronic feedback control system. The pressure distribution in the fluid surrounding the rotor provides dynamic control in the axial direction with no active feedback. Rotor excursion is less than 50 microns (μ) when the housing receives an impulse peaking at an acceleration of 40 g or upon sudden blockage of the flow. In vitro blood measurements indicate an acceptable level of hemolysis compared with that of a standard centrifugal pump.
Clinical Application of a Newly Developed Autoflow Control System for the Terumo Centrifugal Pump: From External Control to Built‐in Direct Control
Authors: Nishida Hiroshi , Nishinaka Tomohiro , Endo Masahiro , Koyanagi Hitoshi , Oshiyama Hiroaki , Nogawa Atsuhiko , Akutsu Tetsuzo
Published: November 2008

Abstract: We have developed an autoflow control system for the Terumo Capiox centrifugal pump, the SP‐101. First, we made an external control system regulated by a personal computer through a serial communications line. Although an in vivo experiment using a goat showed excellent performance in regulating the flow, a communication error that caused an abrupt and instantaneous flow fluctuation was noted occasionally. Therefore, we incorporated a check‐sum function to solve this problem. After this improvement, 5 patients safely underwent cardiopulmonary bypass using a pump having this autoflow control. As the next step for more practical usage, we developed a built‐in autoflow control system in which the control device is entirely incorporated into the console without a communications line. This system demonstrated better response and reliability than the external control system and was applied successfully in 3 patients. In conclusion, this autoflow mode will expand the usage of centrifugal pumps through improved handling.
Numerical Simulation of Nonpulsatile Left Ventricular Bypass
Authors: Mitsui Norimasa , Fukunaga Shintaro , Koura Yoshihiko , Morita Satoru , Hotei Hiroshi , Sueshiro Masafumi , Sueda Taijiro , Matsuura Yuichiro
Published: November 2008

Abstract: A computer simulation was carried out to investigate the influence of nonpulsatile left ventricular assistance on hemodynamics. A simulation circuit was constructed to represent the circulatory system. A source of current was added to denote the nonpulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. We introduced a pulsatility indicator (PI) to clarify the pulsatility characteristics in the hemodynamics; this PI was defined as the ratio of the pulse pressure (PP) to the mean aortic pressure (AoP). When nonpulsatile bypass flow increased, the mean AoP, tension time index (TTI), and diastolic pressure time index (DPTI) increased, and cardiac output, PP, and PI decreased. When assisted flow increased with the constant total flow rate, the mean AoP and DPTI changed little; the PP, TTI, and PI decreased, and the endocardial viability rate increased. The PI would be helpful in evaluating the effect of pulsatility.
The Heart‐Hemopump Interaction: A Study of Hemopump Flow as a Function of Cardiac Activity
Authors: Meyns Bart , Siess Thorsten , Laycock Sarra , Reul Helmut , Rau Günter , Flameng Willem
Published: November 2008

Abstract: The Hemopump is a useful left ventricular assist device. Because it is a rotary blood pump, the pump performance is not constant and is dependent on the cardiac cycle. We measured the static flow delivered by the pump at varying pressure heads (ΔP) in a mock circulation. These data are compared to the pump performance in vivo. On the basis of these results, 5 sheep were instrumented for continuous Hemopump flow measurement as well as left ventricular and aortic pressure measurements. The Hemopump flow was relayed instantaneously to the pressure head. Low filling and ventricular failing (through intravenous administration of a beta‐blocker) conditions were applied. The in vivo measured flows also are pressure head dependent, but the flow curve shows hysteresis resulting in a loop during each cardiac cycle. The in vivo peak flows (AP = 0) are similar to the in vitro data. The in vivo means flows (A 50 mm Hg) are similar to the in vitro data for the lower pump speeds but are less than that at the higher pump speeds (3.74 ± 0.55 L/min in vivo at Speed 7 versus 4.6 L/min in vitro). Low filling interrupts the AP‐flow loop and reduces flow. In the failing ventricle, AP increases and flow is reduced. The cannula leaks and results in aortic insufficiency (0.36 ± 0.05 L/min) when the pump is turned off. Several conclusions have been drawn from these tests: Cardiac activity is beneficial for the pump performance as well as when the aortic pressure curve is nonpulsatile; the longer the systolic phase, the higher the pump flow; the pump should never be turned off in clinical use; and filling is important for the pump's performance.
A Calf Model for Left Ventricular Centrifugal Mechanical Assist
Authors: Mann Fred A. , Wagner‐Mann Colette C. , Curtis Jack J. , Demmy Todd L. , Turk James R.
Published: November 2008

Abstract: The increased use of centrifugal mechanical assist (CMA) for treatment of refractory postcardiotomy cardiogenic shock highlights the need for experimental testing to improve clinical results. This report describes the preoperative conditioning, anesthetic and surgical technique, and postoperative management of a reliable calf model refined in this laboratory for in vivo sub‐chronic (96 h) testing of CMA. Holstein bull calves (2 to 3 months old; mean body weight, 78 kg; n = 35) were instrumented for left ventricular CMA; 4 of these calves were sham‐operated controls. Anesthetic recovery and postoperative restraint were accomplished in a specially designed crate to which each calf was preconditioned extensively. Younger calves were more readily conditioned and more tolerant of postoperative restraint than older calves. One calf died of ventricular fibrillation in‐traoperatively. One calf that had been heparinized developed uncontrollable hemothorax and died 12 h postoperatively. One calf prematurely dislodged his aortic cannula 15 h postoperatively and exsanguinated. Six calves developed pelvic limb paresis or paralysis because of lumbar spinal cord thromboembolism by 36 h postoperatively, and 3 of these calves were sacrificed by 42 h postoperatively. Fifteen calves required sedation in the first 12 h after the operation. Tachycardia associated with bottle feeding occurred in 15 calves. Second‐degree atrioventricular block was noted frequently during deep relaxation. Postmortem examination demonstrated the absence of surgical wound and distant infection, security of cannulae in all but the calf that prematurely dislodged the aortic cannula, absence of thrombus formation at cannu‐lation sites, and presence of thromboembolism in 51% of the calves. The incidence of thromboembolic lesions was not influenced by the need for chemical restraint, by the occurrence of feeding‐associated tachycardia, or by the presence of atrioventricular block. There were no thromboembolic lesions in any of the sham‐operated controls.
Less Blood Damage in the Impeller Centrifugal Pump: A Comparative Study with the Roller Pump in Open Heart Surgery
Authors: Nishinaka Tomohiro , Nishida Hiroshi , Endo Masahiro , Miyagishima Masayuki , Ohtsuka Goro , Koyanagi Hitoshi
Published: November 2008

Abstract: A centrifugal pump with an impeller (Nikkiso Centrifugal Pump, Model HPM15; Nikkiso Co. Ltd.) was applied to cardiopulmonary bypass (CPB) in 14 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin level, platelet count, and serum p‐thromboglobulin (pTG) level were measured during CPB. The results were compared with those obtained in a comparative roller pump (RP) group (n = 10). There was no difference in the time on CPB between the NP (109 min) and RP (121 min) groups. The serum pTG level (ng/ ml) was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB). The plasma‐free hemoglobin level also was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB, 120 min after the initiation of CPB, immediately after the termination of CPB, 3 h after termination of CPB; p < 0.01). There was no significant difference in platelet depletion. The HPM15 pump showed excellent hemodynamic performance with less blood trauma compared with the roller pump in its clinical application to open heart surgery.
Biventricular Bypass with Oxygenation for Postcardiotomy Ventricular Failure
Authors: Kodera Kohjiro , Kitamura Masaya , Hachida Mitsuhiro , Endo Masahiro , Hashimoto Akimasa , Koyanagi Hitoshi
Published: November 2008

Abstract: Between January 1984 and March 1995, biventricular bypass (BVB) with oxygenation was used in 17 patients for postcardiotomy ventricular failure at the Heart Institute of Japan, Tokyo Women's Medical College. Of the 17 patients, 12 (70.6%) were weaned from the circulatory support, and 8 (47.1%) were discharged from the hospital. The time interval from the end of cardiopulmonary bypass to the start of BVB was significantly shorter in weaned patients than in unweaned patients. The duration on support also has been shortened significantly in the last 6 years, compared with the earlier 6 years. Causes of death were severe heart failure or ventricular arrhythmia in 6 patients and multiple organ failure in 3 patients. These results suggest that early application and timely weaning from biventricular bypass with oxygenation might be the effective circulatory support of choice for treatment of postcardiotomy ventricular failure.
Characterization of Molecular Transport in Artificial Kidneys
Authors: Leypoldt John K. , Cheung Alfred K.
Published: November 2008

Abstract: Transport characterizations of artificial kidneys require the use of multiple marker molecules of various sizes, including small solutes, middle molecules, and albumin. Previous approaches for evaluating hemodialyzer transport performance are reviewed. New data obtained from in vitro experiments comparing 5 low molecular weight proteins of approximately the same molecular size as markers for middle molecule transport also are described. Sieving coefficients for marker low molecular weight proteins may vary substantially for a given artificial kidney membrane. Furthermore, sieving coefficients for marker proteins that do not absorb significantly to the membrane are comparable to those for polydisperse dextrans. These observations suggest that other protein properties besides molecular size are important determinants of protein sieving coefficients across artificial kidney membranes. We conclude that low molecular weight proteins can behave differently from one another and generalizations about artificial kidney membrane transport from data obtained on a single protein may be problematic, and that both low molecular weight proteins and polydisperse dextrans are useful markers of middle molecular transport across artificial kidney membranes. Key Words: Hemodialysis–Membranes–Middle molecules–Polydisperse dextrans—Proteins–Sieving coefficients.
Renal Transplantation: Progress and Prospects
Authors: Hillebrand Günther F. , Land Walter
Published: November 2008

Abstract: Despite encouraging and improving results, organ transplantation is still hampered by a shortage of organs, chronic transplant loss, and a changed patient population. Liberal inclusion criteria for dialysis and/or renal transplantation and the increasing unwillingness to donate organs in some countries has led to a growing imbalance between the numbers of transplantations performed and patients on waiting lists. Until now, poorly understood chronic transplant dysfunction is responsible for a still unchanged graft loss of approximately 5% per year. The patient population has changed to include more multimorbidity and an increasing number of risk factors (age, diabetes mellitus, former [failed] transplantations, or preexisting cardiovascular diseases). The recommendation for or against dialysis or transplantation has become increasingly difficult for the responsible physician. Newly developed immunosuppressant drugs, an increasing consideration regarding living organ donation, or xenotransplantation in the future may solve this dilemma. New reflections and considerations about the ethical background of transplantation medicine are necessary.
15‐Deoxyspergualin: A Newly Developed Immunosuppressive Agent and Its Mechanism of Action and Clinical Effect: A Review
Authors: Amemiya Hiroshi
Published: November 2008

Abstract: 15‐Deoxyspargualin (DSG) is a synthetic analogue of spergualin isolated from the culture filtrate of Bacillus laterosporus. It shows a strong immunosuppressive effect by antiproliferating action inhibiting the Unstimulated maturation of T cells from the G0/G1 phases to the S and G2/M phases. Hsc70, a constitutive member of Hsp70 was identified as the immunophilin of DSG by Nadlar et al. In allogeneic transplantation of rat heart and dog kidney, DSG was definitely proved to prevent rejection and to rescue ongoing rejection. Our multicenter clinical trials on DSG showed that the percent efficacy to reverse acute rejection was 70–80%, and 600 days graft survival was 90% in the cases effectively treated with DSG at acute rejections. The combined use of DSG with methylprednisolone to treat acute rejection and the use of DSG to treat rejections in chronic phases were reported as the beneficial uses of DSG.
Syntheses and Immunological Effects of Thymic Humoral Factor‐γ2 and Its Phe7‐Substituted Analogues
Authors: Abiko Takashi , Sekino Hiroshi
Published: November 2008

Abstract: Thymic humoral factor‐γ2 and five analogues modified at position 7 with various phenylalanine derivatives were synthesized by a solid‐phase method. The synthetic peptides were tested for their effects on the impaired blastogenic response of phytohemagglutinin‐stimulated T lymphocytes of uremic patients with infectious diseases. The synthetic thymic humoral factor‐γ2 enhanced the blastogenic response of T lymphocytes in the blood of the 2 patients tested. Of the synthetic peptides, [Phe(4F)7]thymic humoral factor‐γ2 exhibited the most potent effect.
Lymphocytapheresis
Authors: Takenaka Yoshinori
Published: November 2008

Abstract: Leukocytapheresis has long been performed with the centrifugal method. But in 1989 in Japan, the Asahi Medical Co. developed the extracorporeal leukocyte‐removal filter, Cellsorba. This filter consists of non‐woven fabric, which can remove leukocytes from whole blood during extracorporeal circulation. In the incipient stage, this filter was applied to collagen diseases, rheumatoid arthritis, and systemic lupus erythematosus. During the following studies, this filter has been found to have an immunosuppressive effect. Now, it is beginning to be applied to various kinds of autoimmune diseases. Moreover, this filter has recently been recognized to be effective in inflammatory bowel diseases, ulcerative colitis, and Crohn's disease. The outline of Cellsorba and the application of this filter is described here.
An Experience of the Usage of Electrical Tinnitus Suppressor
Authors: Matsushima Jun‐ichi , Sakai Noboru , Sakajiri Masatsugu , Miyoshi Shigeki , Uemi Norihiro , Ifukube Tohru
Published: November 2008

Abstract:An electrical tinnitus suppressor based on the use of an extracochlear stimulator has been developed at Hokkaido University, Sapporo, Japan, and was implanted in 2 male and 2 female patients. Tinnitus improved in all patients because the auditory nerve was able to be stimulated at home whenever patients wanted treatment. Additional benefits reported after electrical stimulation of the cochlea included sound sleep, relaxation in all cases, and improved hearing acuity in Cases I, 2, and 4. Minimal temporary complications, including habituation and ear drum perforation, were observed.
Transport of Hemodynamically Unstable Patients by a Mobile Mechanical Circulatory Support Team
Authors: Reiss Nils , El‐Banayosy Ali , Posival Herbert , Knobl Hermann , Minami Kazutomo , Korfer Reiner
Published: November 2008

Abstract: Advances in medical technology have made it possible to use emergency femoro‐femoral bypass (FFB) for transport of hemodynamically unstable patients. In this study, we report on our experience of transport of patients with refractory heart failure by a special mobile mechanical circulatory support team (MMCST) using an intraaortic balloon pump (IABP) or FFB. A total of 22 patients (14 men, 8 women) were supported by the MMCST and transported to our clinic for further diagnostic or therapeutic procedures. The diagnoses in 12 patients was acute myocardial infarction, in 7 patients, di‐latative cardiomyopathy (DCM), and in 3 patients, acute fulminant myocarditis. In 15 cases, FFB was implanted (5 in combination with IABP), and in 5 cases, IABP only was implanted. Two patients received maximal dosages of catecholamines. After arrival at our clinic, 11 patients received implants of a more sophisticated support system. From the myocardial infarction group, 3 patients received coronary artery bypass grafting, 1 patient received percutaneous transluminal coronary angioplasty, and 1 patient received heart transplantation as final therapy. In the myocarditis and DCM groups, 7 patients underwent heart transplantation. Finally, 11 patients (50%) survived, and 11 patients died of multiorgan failure or septicemia.
Blood Density Monitoring During Dialysis
Authors: Yamauchi Tatsuyuki , Yanai Mitsuru , Takahashi Susumu , Man Nguyen‐Khoa
Published: November 2008

Abstract Continuous monitoring of blood density (BD) was preformed in 4 stable dialysis patients in 20 sessions using a density meter based on a mechanical oscillator technique. Mean predialysis and postdialysis BDs were 1.0427 ± 0.0031 g/cm3 and 1.0502 ± 0.0055 g/cm respectively. For similar predialysis to postdialysis total body water reduction, significant difference in the mean BD increase was found between hypotensive and nonhy‐potensive groups (1.29 ± 0.07%, 0.47 ± 0.12%, respectively; p < 0.001). Eight hypotensive episodes occurred during 6 sessions. The mean value of the blood density changes slope (dBD/dt) during the 5 min preceding a hypotensive episode increased about 2.5 times more than did the mean of the predialysis to postdialysis blood density slope (27.6 ± 2.2 g/cm3 min 10‐5, 10.5 ± 0.4 g/cm3 min 10‐5 respectively; p < 0.001) under the condition of a constant ultrafiltration rate of 18.9 ± 0.6 ml/min. Continuous monitoring of blood density allows abrupt change in plasma volume to be identified and seems to have a potential utility to the prevention of symptomatic hypotension episodes in patients receiving hemodialysis.
Reduction of Plasma Fibrinogen, Immunoglobulin G, and Immunoglobulin M Concentrations by Immunoadsorption Therapy with Tryptophan and Phenylalanine Adsorbents
Authors: Fadul Jamal E.M. , Danielson Bo G. , Wikström Björn
Published: November 2008

Abstract Immunoadsorption (1A) therapy with tryptophan (TR‐350) or phenylalanine (PH‐350) adsorbents has been used to reduce the concentration of serum antibodies in human lymphocyte antigen (HLA)‐immunized patients. Other forms of plasma purification have been reported to reduce the level of fibrinogen, which affects the blood properties. In this study we investigated the effects of IA therapy using both adsorbents on plasma fibrinogen and immunoglobulins G and M in 13 patients (8 patients were treated with TR‐350, and 5 patients were treated with PH‐350). During each session 1 plasma volume (2.8 ± 0.4 L of plasma) was processed through the immunocolumn and then returned to the patient together with the blood cells. Compared with the pretreatment values, the plasma fibrinogen, IgG, and IgM concentrations were significantly reduced after IA therapy (p < 0.01 for TR‐350; p < 0.04 for PH‐350). There was a positive correlation between the degree of reduction of plasma proteins and the number of IA treatments given. A nonpara‐metric test (Wilcoxon's signed‐rank test or the Mann‐Whitney test) was used for statistical analysis. We conclude from our study that IA therapy effectively lowers the plasma levels of fibrinogen, IgG, and IgM and thus can be considered a valuable alternative to other blood purification methods.
Factors Influencing Vortex Development in a Model of a Skeletal Muscle Ventricle
Authors: Shortland Adam P. , Black Richard A. , Jarvis Jonathan C. , Salmons Stanley
Published: November 2008

Abstract A video technique was used to visualize flow patterns in a pulsatile model of a skeletal muscle ventricle (SMV). The shape and duration of SMV filling/emptying curves were determined by the stroke action of a computer‐controlled piston pump. In this way we examined the effect of filling duration and injection volume on the flow structures. To simulate the interaction between the left ventricle and the SMV in the proposed clinical application, two filling/emptying regimes were employed with the period of each SMV cycle being either equal to or twice that of a typical cardiac cycle. Vortex formation at the inlet to the ventricle was a feature of both flow cycles during filling for all the combinations of injection volume and filling duration considered. When a pacing ratio of 1:1 was simulated, SMV filling was immediately followed by ejection, and the formed vortex was expelled. Under this flow regime, fluid in the apical end of the ventricle remained undisturbed. When the pacing ratio was 2:1, however, the quiescent period that followed filling allowed time for the formed vortex to travel a significant distance toward the apical end of the ventricle. Under certain conditions of injection volume and flow rate, the vortex reached the apex by the end of the quiescent period. We suggest that a ventricle connected to the aorta by a single, valveless conduit would require a flow regime that included a significant period of quiescence after filling. This would allow the vortex to reach and displace blood that would otherwise stagnate in the apex, thereby reducing the risk of thrombus formation.
An Automatic Flow Controller for a Centrifugal Blood Pump
Authors: Beppu Toshiyuki , Seo Kazuhiro , Imai Yasuharu , Takanashi Yoshinori , Hoshino Shuichi , Ohta Jun , Aoki Mitsuru , Uchita Shunji , Suzuki Susumu , Tajima Yukio , Tooyama Noriyasu , Fukui Yasuhiro
Published: November 2008

Abstract: To regulate the perfusion flow rate of a centrifugal blood pump, a microcomputer controller was developed. The computer monitored the flow rate of the pump with an electromagnetic flowmeter or an ultrasonic pulse Doppler flowmeter, rotational speed of the pump, aortic pressure, and the amount of blood in a reservoir. A discrete integral controller with a control interval of 1 s was adopted for the controller. For the safety of the control system, we added functions for detecting a clamp on the tubing, a dislocation of the flow sensor, or an inverse direction of the flow sensor. During a standby period, the computer calculated the rotational speed from aortic pressure to minimize the forward or the backward flow at the start of the pump perfusion. The automatic flow controller was used on 5 patients during cardiac operations and maintained the flow rate within ±6% of the set point.