bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Epoprostenol on Platelet Activation and Consumption During Experimental Extracorporeal Perfusion
Authors: Skogby Maria , Adrian Katrin , Friberg LarsGöran , Mellgren Karin
Published: March 2003

Abstract: Hemorrhages are major complications experienced in 10–35% of neonates treated with extracorporeal life support (ECLS). The increased bleeding tendency is partly due to an ECLS induced thrombocytopenia and impaired platelet function. In the present study, we evaluated the effect of epoprostenol on the ECLS induced platelet consumption and activation. In terms of the methods, identical in vitro ECLS circuits were primed with fresh heparinized human blood and circulated for 24 h. Epoprostenol (2.4 μg/L blood/h) was added to one of the circuits in each pair. In total, 6 paired experiments were performed. The platelet count, neutrophil count, plasma concentration of hemoglobin, and platelet membrane expression of glycoproteins (GP) Ib and IIb/IIIa were assayed before the start and at 0.5, 1, 3, 12 and 24 h of perfusion. Higher platelet counts were observed in the experimental circuits. However, no difference in the platelet membrane expression of GPIb and GPIIb/IIIa could be observed between the circuits. In conclusion, epoprostenol reduces platelet consumption during ECLS without affecting the membrane expression of GPIb and GPIIb/IIIa.
Evaluation of the Inner‐Surface Morphology of an Artificial Heart by Acoustic Microscopy
Authors: Saijo Yoshifumi , Okawai Hiroaki , Sasaki Hidehiko , Yambe Tomoyuki , Nitta Shin‐ichi , Tanaka Motonao , Kobayashi Kazuto , Honda Yosuke
Published: March 2003

Abstract: The total artificial heart (TAH) is being developed for permanent replacement of the natural heart instead of heart transplantation. The need for detecting the material fatigue in the TAH is increasing in order to guarantee long‐term use. In this study, the inner surface morphology of the TAH was evaluated by a specially developed scanning acoustic microscope (SAM) system operating in the frequency range of 100–200 MHz. The inner sac of our TAH consisted of polyvinylchloride coated with polyurethane, and the SAM investigations were performed before and after the implantations in goats. The amplitude images of the SAM demonstrated protein adhesion on the inner surface of the TAH after the animal experiment, and the phase images showed distortion of the wall with spatial resolution of 0.2 μm. These results suggest the feasibility of a high‐frequency ultrasound for evaluating the material fatigue of TAH.
In Vitro Evaluation Study of the Membrane Autotransfusion System Experimental Prototype: MATS–I
Authors: Fukunaga Ken , Shimoyama Takashi , Sawada Koji , Mueller Juergen , Sueoka Akinori , Nosé Yukihiko
Published: March 2003

Abstract: Membrane Autotransfusion System (MATS) utilizing plasmapheresis technology has been developed in our laboratory. A specially designed polyethylene hollow fiber membrane was utilized. This study was conducted to evaluate performance of the first experimental prototype, MATS‐I. The results of this study showed that the MATS‐I could concentrate diluted blood at 10% of the initial hematocrit concentration (HCTi) into over 40% after passing through the system at a transmembrane pressure of 70 mm Hg. Moreover, the MATS‐I can continuously treat 10,000 ml of diluted blood at various HCTi levels without deteriorating its performances. Even though the MATS‐I met all required performances as an autotransfusion system, several areas of improvement of the system were necessary to meet various clinical needs. The next prototype, MATS‐II, can be designed based on experiences obtained from the MATS‐I. The MATS is smaller, more atraumatic and continuous, and is a faster system when compared to the currently available centrifugal autotransfusion devices.
Easy Aortic Cannulation: A Transxyphoid Approach
Authors: Murakami Arata , Kaneko Yukihiro , Imanaka Kazuhito , Takamoto Shinichi , Yahagi Naoki
Published: March 2003

Abstract: An easy aortic cannulation technique in minimally invasive pediatric cardiac surgery is described. We have developed a dilator which fits an aortic perfusion cannula. The aortic cannula over the dilator with a hole for passage of a guide wire is inserted into the ascending aorta by the Seldinger technique. Using this technique, the cannula never slips off, even at a slant angle to the aorta owing to the guidance of the guide wire. We recommend this safe and reliable technique for insertion of an aortic cannula into the ascending aorta in minimally invasive pediatric cardiac surgery.
Glycoprotein IIb/IIIa Receptor Inhibitor Attenuates Platelet Aggregation Induced by Thromboxane A2 During In Vitro Nonpulsatile Ventricular Assist Circulation
Authors: Yomo Tatsuro , Serna Dan L. , Powell Ledford L. , Wang Da , Wilson Samuel E. , Ishimaru Shin , Chen John C.
Published: March 2003

Abstract: A recent development in antithrombotic research allows the inhibition of platelet aggregation via protection of the glycoprotein IIb/IIIa receptor on the platelet membrane. We hypothesized that a GP IIb/IIIa receptor inhibitor would inhibit thromboxane‐induced platelet aggregation during circulation in our in vitro ventricular assist device (VAD) circuit and preserve long‐term platelet function. Twenty‐one in vitro nonpulsatile centrifugal VAD circuits were simulated for 4 days using 450 ml of fresh human whole blood with or without glycoprotein IIb/IIIa receptor inhibitor (tirofiban). Platelet aggregation and degranulation were measured in whole blood induced by ristocetin, collagen, ADP, and thromboxane A2 (TXA2). The tirofiban‐treated group preserved the platelet count and tended to exert these beneficial effects by inhibiting pathologic platelet aggregation induced by TXA2, collagen, and ADP as well as degranulation. Tirofiban may be useful in preserving platelet number and function during clinical VAD use.
Use of Clinical Guidelines for Treatment of Anemia Among Hemodialysis Patients
Authors: Thamer Mae , Richard Christian M. , Klinkmann Jens , Ivanovich Peter , Lang Gordon , Cotter Dennis J.
Published: March 2003

Abstract: Changing financial incentives have strongly influenced dosing patterns of recombinant human erythropoietin (rHuEPO) since its introduction in 1989. Although guidelines for prescribing rHuEPO exist, the extent to which they are adhered to is unknown. Using a retrospective cohort observational study design, the factors influencing the initial dosing of rHuEPO prescribed to 413 hemodialysis patients in 1994 were examined. Patient weight, the only recommended guideline, was not found to be a significant predictor of dosing of rHuEPO after controlling for selected patient demographic and clinical characteristics. The strongest predictor for initial rHuEPO dosing was hematocrit followed by White race (p < 0.05). Finally, each subsequent month was associated with a significantly larger initial rHuEPO dose, reflecting the general trend in increasing dose since 1991 (p < 0.001). In conclusion, despite the recent DOQI guidelines for treatment of anemia among persons with chronic renal failure, providers are not using patient weight as an independent criterion for determining dosing of rHuEPO.
Combined Effects of Inhaled Nitric Oxide and Positive End‐Expiratory Pressure During Mechanical Ventilation in Acute Respiratory Distress Syndrome
Authors: Okamoto Kazufumi , Kukita Ichiro , Hamaguchi Masamichi , Motoyama Takeshi , Muranaka Hiroyuki , Harada Toshikazu
Published: March 2003

Abstract: We studied the combined effects of inhaled nitric oxide (INO) and positive end expiratory pressure (PEEP) during mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). Eleven patients received 0 and 4 parts per million of INO in random order for 30 min at PEEP levels of 0, 5, and 10 cm H2O. Respiratory and cardiovascular parameters were measured. The addition of INO and PEEP significantly improved arterial oxygenation (p < 0.005 and p < 0.0001, respectively). The combined effect of INO and PEEP on arterial oxygenation was remarkable during 10 cm H2O PEEP. There was synergistic effect on arterial oxygenation by combining INO and 10 cm H2O PEEP. The present study showed that the combination of INO and 10 cm H2O PEEP enhanced arterial oxygenation in patients with ARDS.
In Vitro Hydrodynamic Characteristics Among Three Bileaflet Valves in the Mitral Position
Authors: Feng Zhonggang , Umezu Mitsuo , Fujimoto Tetsuo , Tsukahara Toshiya , Nurishi Masakazu , Kawaguchi Daisuke
Published: March 2003

Abstract: The non–fully open phenomenon of the advancing standard medical bileaflet heart valves (the ATS valve) are frequently observed in clinical cases, even though there is no problem with their hemodynamic function. The movement of the leaflets was affected easily by the transvalvular flow because of the unique open pivot design of the ATS valve. In this paper, a comparative in vitro hydrodynamic test was conducted among 3 different types of bileaflet valves, and the effect of different shapes of downstream conduits, which induce different transvalvular flow, on hydrodynamic performance was studied. Three bileaflet valves, the ATS valve, CarboMedics valve (CM), and St. Jude Medical valve (SJM), with an annulus diameter of 29 mm for the mitral position were chosen throughout our experiments. First, pressure drops across the valves under steady flow were measured. Then, the valves were tested at the mitral position with our pneumatically driven pulsatile pump. In this pulsatile flow study, 2 different conduits (straight shape and abrupt enlargement shape) were in turn incorporated at the downstream portion of the mitral valve. A high‐speed video camera was employed to observe leaflet movements. In a steady‐flow test, the ATS and the SJM produced the same pressure drop, but the CM recorded a higher value. In the pulsatile study, it was observed that the ATS leaflets did not open fully in the mitral position when the downstream conduit with an abrupt enlargement shape was incorporated. However, the CM and the SJM always indicated a fully open movement regardless of the shape of downstream conduits. When the straight downstream conduit was incorporated, the ATS produced a similar pressure drop to that of the SJM, which coincided with the steady test results. When the enlargement conduit was incorporated, however, the ATS presented the lowest pressure drop despite the non–fully open movement. The conduit shape at the valve downstream had a significant influence on the closing volume. These findings indicate that the conduit shape at the valve outlet can affect the hydrodynamic characteristics of bileaflet valves.
Devices for Use as an Artificial Articular Surface in Joint Prostheses or in the Repair of Osteochondral Defects
Authors: Bavaresco Vanessa Petrilli , De Carvalho Zavaglia Cecília Amélia , De Carvalho Reis Marcelo , Malmonge Sônia Maria
Published: March 2003

Abstract: The covering of ultra high molecular weight polyethylene (UHMWPE) and calcium hydroxyapatite (HA)/tricalcium phosphate (TCP) porous solid substrate with polyHEMA hydrogel has been studied aiming at the development of devices to be used as artificial articular surfaces in joint prosthesis or osteochondral repair grafts. Commercial porous UHMWPE was used. Ceramic porous substrate was prepared by load compaction of an HA and TCP powder mixture obtained by aqueous precipitation technique. Two different compaction loads and grain size distribution was used. Polymer particles were added to the powder mixture in order to increase the substrate porosity after the sintering process. The porous substrate was covered with polyHEMA hydrogel by in situ polymerization. Morphological analysis (SEM) showed that a hydrogel layer formed in the porous solid top surface was fixed to the substrate by mechanical interlocking because the porous surface was filled by the hydrogel. After hydrogel covering, the resultant devices showed a decrease in the compressive elastic modulus that was influenced by the porous substrate material.
Particle Release in Extracorporeal Low‐Density Lipoprotein Lowering Therapies
Authors: Martins Konrad , Ahrenholz Peter , Matic Goran B. , Hofmann Doris , Tiess Michael , Winkler Roland E. , Ramlow Wolfgang
Published: March 2003

Abstract: Release of microparticles into the blood during extracorporeal circulation must be kept low because of possibly serious acute and chronic adverse effects. Concentration and size distribution of microparticles were measured during simulated treatments (n = 7) on original equipment for 2 standard low‐density lipoprotein (LDL) elimination procedures (DALI 750, Fresenius AG, St. Wendel, Germany and Liposorber, Kaneka Corporation, Osaka, Japan) and compared to hemofiltration solutions. For both systems as well as in hemofiltration solutions, the mean particle concentrations in 500 ml portions gathered from the efferent blood line stayed below 10% of pharmacopoeia standards for infusion solutions (United States Pharmacopoeia, European Pharmacopoeia) in all measured size classes. Although particle concentrations were comparable in all systems, the mean total number of particles ≥2 μm released per session was lowest in the DALI (167,000) compared to the Liposorber (465,000) and hemofiltration solutions (2,240,000). This was mainly due to different total processed blood volumes necessary to achieve the required LDL reduction.
Polypropylene Hollow Fiber Oxygenators: Effect of the Sorption of Perfluoropolyethers
Authors: Cassiola Flávia , Kiyohara Pedro K. , Joekes Inés
Published: March 2003

Abstract: The introduction of microporous polypropylene hollow fibers in recent years has brought considerable advances to blood oxygenators. However, lifetime and assembly problems are still unresolved. In this work we tried to rate the oxygen permeation velocity by turning the fibers more hydrophobic through the sorption of a perfluorocarbon. Fomblin HC/25, a perfluoropolyether, is well known for its low surface tension and high affinity for oxygen. Celgard X10, X20, and X30 commercial hollow fibers were tested. The hollow fibers showed high affinity for the perfluoropolyether; swelling was clearly shown. A new system for the measurement of oxygen permeation velocity was developed. The oxygen transport velocity was not significantly changed after sorption. The Celgard microporous hollow fibers impregnated with perfluoropolyether showed no water permeation after 2 months of use, reducing one of the most serious problems in the lifetime of these types of fibers.
Current Leakage in Hemodialysis Machines May Be a Safety Risk for Patients
Authors: Jonsson Per , Stegmayr Bernd G.
Published: March 2003

Abstract: During hemodialysis, the dialysis fluid is conductive and allows current to flow from or to the machine if a difference in electrical potential occurs. This may cause a health risk for the patient. We investigated the presence of such current during various conditions in 17 dialysis machines: the Gambro AK10 (n = 5) and AK100 (n = 3), and the Fresenius 2008C (n = 3), 2008E (n = 2), and 4008E (n = 4). Current leakage measurements were performed without connection of the patient to the system by using a copper tube inserted into the stream of the dialysis fluid at the point where the patient would normally be connected to the dialyzer. The current leakage (measured in μA) at the ground site was significantly higher for the AK10 and the 2008C than for the AK100, 2008E, and 4008E machines. The current leakage, at the site where the dialyzer is located, was highest for the AK10 and less for the AK100, 2008C, 2008E, and 4008E. The 2008C and 2008E dialyzers had the highest maximal current leakage when a malfunctioning external device was attached while the AK100 had less and the AK10 had the least leakage. There was a great variation in leakage current among the dialysis machines. The greatest risk occurred when the patient also was connected to other electric devices with current leakage.
Gyro Pump Wear and Deformation Analysis In Vivo Study: Creep Deformation
Authors: Nakata K. , Yoshikawa M. , Takano T. , Maeda T. , Nonaka K. , Linneweber J. , Kawahito S. , Glueck J. , Fujisawa A. , Makinouchi K. , Yokokawa M. , Nosé Y.
Published: March 2003

Abstract: The Gyro pump has a double pivot bearing system to support its impeller. In this study, the integrity of the bearing system was examined after ex vivo studies. The pumps were implanted into calves and evaluated for different periods as a paracorporeal left ventricular assist device (LVAD). One pump was subjected to a test of 30 days, 1 for 15 days, 4 for 14 days, 1 for 10 days, 1 for 7 days, 2 for 4 days, and 4 for 2 days. One additional pump was subjected to percutaneous cardiopulmonary support (PCPS) condition for 6 days (total pressure head 500 mm Hg with a pump flow rate of 3 L/min). The anticoagulation treatment consisted of a continuous administration of heparin to maintain an achieved clotting time (ACT) of 200–250 s during the LVAD study and 250–300 s during the PCPS study. After the experiment, the pumps were disassembled, and the wear and deformation of male and female bearings were analyzed. There were no dimensional changes on male bearings but there were on female bearings. Wear and deformation of the female bearings were calculated as follows: wear and deformation = (depth of female before pumping) − (depth after pumping). Thirteen assembled Gyro pumps were disassembled to measure the depth of the female bearings before pumping. There was no statistical relationship between the wear and deformation and the motor speed × driving period. From these results, the deformation was not due to wear but to the creep or elastic deformation. This study suggested that the double pivot bearing system of the Gyro pump is highly durable.
Eccentric Roller Type Total Artificial Heart Creating Interatrial Shunt
Authors: Wada Hideichi , Fukunaga Shintaro , Watari Masanobu , Imai Katsuhiko , Sakai Hiroshi , Shibamura Hidenori , Sueda Taijiro , Matsuura Yuichiro
Published: March 2003

Abstract: Creating an interatrial shunt to achieve left–right flow balance and modification of the blood chambers to improve the basic performance of the device were performed in developing an eccentric roller type total artificial heart (ERTAH). Smaller blood chambers reduce friction loss and increase durability and energy efficiency. We changed the left blood chamber volume of 60 ml to 40 ml and the right blood chamber volume of 53 ml to 35 ml compared with previous types. Designs of inlet and outlet ports were modified to prevent backflow. In the mock circulatory system, redesigning the blood chambers resulted in a 20% increase in energy efficiency, about a two‐fold increase of cardiac output and improved durability compared to the previous type. In an animal experiment, the ERTAH operated at a driving rate of 160 rpm with a left flow rate of 6.0 L/min and a right flow rate of 5.4 L/min. Interatrial shunt flow rate was 250–400 ml/min.
Morbidity and Outcome After Mechanical Ventricular Support Using Thoratec, Novacor, and HeartMate for Bridging to Heart Transplantation
Authors: Minami Kazutomo , El‐Banayosy Aly , Sezai Akira , Arusoglu Latif , Sarnowsky Peter , Fey Oliver , Koerfer Reiner
Published: March 2003

Abstract: Between September 1989 and June 1999, 228 patients were supported with a ventricular assist device as a bridge to heart transplantation. In this study, the results of implantation were evaluated in patients supported with one type of device, including 85 supported with a Thoratec, 61 with a Novacor, and 37 with a HeartMate. The mean support time was 49, 148, and 124 days, respectively. Successful transplantation and weaning rates were 64.7% with Thoratec, 59.0% with Novacor, and 62.0% with HeartMate. Cerebral embolism and drive‐line and pocket infection were major causes of postoperative morbidity and mortality. We recommended that a Thoratec system be employed as a bridge to heart transplantation for patients with biventricular heart failure, and that a Novacor or HeartMate system be implanted in patients requiring a long‐term circulatory support.
A Bone Replaceable Artificial Bone Substitute: Cytotoxicity, Cell Adhesion, Proliferation, and Alkaline Phosphatase Activity
Authors: Suh Hwal , Park Jong‐Chul , Han Dong‐Wook , Lee Dong Hee , Han Chang Dong
Published: March 2003

Abstract: Cellular toxicity, cell adhesion and proliferation, and alkaline phosphatase (ALP) activity were investigated for an artificial bone substitute composed of heated carbonate apatite (CAp) and Type I atelocollagen (AtCol) extracted from bovine tail skins (88/12 in %wt/wt). To enhance the intramolecular crosslinking between collagen molecules, the CAp‐AtCol substitutes were irradiated by ultraviolet rays (wave length 254 nm) at 4°C for 4 h or vacuum dried at 150°C for 2 h. Cytotoxicity tests by a direct contact method and an extract dilution method revealed that the CAp‐AtCol substitutes were cytocompatible for balb 3T3 fibroblasts. Osteoblast adhesion studies demonstrated that the substitute disks composed of 980°C‐heated CAp and AtCol were significantly more adhesive for osteoblasts than those of 1,200°C‐sintered CAp and AtCol (p < 0.05). Proliferation studies showed that the number of osteoblasts grown in the media containing substitutes of 980°C‐heated CAp and AtCol was statistically higher than grown in those of 1,200°C‐sintered CAp and AtCol after 5 days (p < 0.05). It was found that osteoblasts grown in the substitutes of 980°C‐heated CAp and AtCol only expressed similar ALP activity to the controls. These results suggested that the substitutes consisting of 980°C‐heated CAp and AtCol show more favorable interactions with osteoblasts than those of 1,200°C‐sintered CAp and AtCol.
Muscle Contraction and Relaxation Described by Tactile Stiffness
Authors: Inaba Hirotaka , Miyaji Kagami , Kaneko Yukihiro , Ohtsuka Toshiya , Takamoto Shinichi , Omata Sadao
Published: March 2003

Abstract: We developed a tactile sensor system that measures the stiffness of objects (tactile stiffness) and used it to describe the time course of muscle contraction and relaxation. We examined fatigue resistance of the latissimus dorsi muscle (LDM), which is preconditioned for cardiomyoplasty. Time to peak, ripple of LDM, and time constant were calculated from the time course of LDM contraction and relaxation as described by tactile stiffness. We compared conditioned and unconditioned LDMs using these 3 parameters. The time course can be described by tactile stiffness. Tactile stiffness fell exponentially during LDM relaxation. In mean values, time to peak increased 230%, ripple decreased 20%, and time constants increased 424%. Significant differences were shown in 3 parameters between conditioned and unconditioned LDMs (p < 0.05). Our tactile sensor system can describe the time course of LDM contraction and relaxation. Examining the difference in time courses, we might detect the level of LDM preconditioning for cardiomyoplasty.
Development of Regenerative Cardiomyocytes from Mesenchymal Stem Cells for Cardiovascular Tissue Engineering
Authors: Fukuda Keiichi
Published: March 2003

Abstract: We have isolated a cardiomyogenic (CMG) cell line from murine bone marrow stroma. Stromal cells were immortalized, treated with 5‐azacytidine, and spontaneous beating cells were repeatedly screened for. The cells showed a fibroblast‐like morphology. However, this morphology changed after 5‐azacytidine treatment in about 30% of the cells, which connected with adjoining cells after 1 week, formed myotube‐like structures and began spontaneous beating after 2 weeks, and beat synchronously after 3 weeks. These cells expressed atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Electron microscopy revealed a cardiomyocyte‐like ultrastructure including typical sarcomeres and atrial granules. They had sinus node‐like or ventricular cell‐like action potentials. Analysis of the isoform of contractile protein genes, such as myosin and α‐actin, indicated that their phenotype was similar to fetal ventricular cardiomyocytes. These cells expressed Nkx2.5, GATA4, TEF‐1, and MEF2‐C mRNA before 5‐azacytidine treatment, and expressed MEF2‐A and MEF2‐D after treatment. This new cell line provides a powerful model for the study of cardiomyocyte transplantation.
Recombinant Human Bone Morphogenetic Protein‐2 Potentiates the In Vivo Osteogenic Ability of Marrow/Hydroxyapatite Composites
Authors: Noshi Toshiaki , Yoshikawa Takafumi , Dohi Yoshiko , Ikeuchi Masako , Horiuchi Katsuhiro , Ichijima Kunio , Sugimura Masahito , Yonemasu Kunio , Ohgushi Hajime
Published: March 2003

Abstract: A composite of marrow mesenchymal stem cells (MSCs) and porous hydroxyapatite (HA) has bone‐forming capability. To promote the capability, we added recombinant human bone morphogenetic protein‐2 (BMP) to the composite. The bone formation was assessed by rat subcutaneous implantation of 4 different kinds of implants, i.e., HA alone, BMP/HA composites, MSCs/HA composites, and the composites containing BMP (MSCs/BMP/HA). Both HA and the BMP/HA composites did not show bone formation at any time after implantation. The MSCs/HA composites showed moderate bone formation at 4 weeks and extensive bone formation at 8 weeks. The MSCs/BMP/HA composites showed obvious bone formation together with active osteoblasts at 2 weeks and more bone formation at 4 and 8 weeks. The MSCs/BMP/HA composites demonstrated high alkaline phosphatase and osteocalcin expression at both the protein and gene levels. These results indicate that the combination of MSCs, porous HA, and BMP synergistically enhances osteogenic potential and provides a rational basis for their clinical application in bone reconstruction surgery.
Atherosclerosis Risk Is Higher in Continuous Ambulatory Peritoneal Dialysis Patients Than in Hemodialysis Patients
Authors: Özdemir Fatma Nurhan , Güz Galip , Sezer Siren , Arat Zübeyde , Turan Münire , Haberal Mehmet
Published: March 2003

Abstract: While it has been reported that myocardial infarction and cerebrovascular disease are more common in continuous ambulatory peritoneal dialysis (CAPD) patients than in hemodialysis patients, some studies have not supported these results. The aim of this study was to compare CAPD and hemodialysis patients with regard to atherosclerotic changes and to assess which factors might be responsible for atherosclerosis in dialysis patients. Group 1 consisted of 65 CAPD patients, and Group 2 consisted of 109 hemodialysis patients who were age‐, gender‐, and duration‐of‐dialysis‐matched with CAPD patients. We used ultrasonographic measurement of carotid artery intima media thickness to identify atherosclerosis. Known risk factors for atherosclerosis including hypertension, smoking, serum levels of total cholesterol, triglycerides, low‐density lipoprotein cholesterol (LDL‐C), high‐density lipoprotein cholesterol, lipoprotein (a) [Lp(a)], albumin, intact parathormone, fibrinogen, and C‐reactive protein were determined in all patients. More atherosclerotic changes were seen in CAPD than in hemodialysis patients. Of all the atherosclerosis risk factors, only serum total cholesterol, LDL‐C, and Lp(a) levels were significantly higher in patients on CAPD.
The Effect of Circuit Surface Area on CD11b(mac‐1) Expression in a Rat Recirculation Model
Authors: Gourlay Terence , Stefanou Demetrios Constantine , Asimakopoulos George , Taylor Kenneth McDonald
Published: March 2003

Abstract: The aim of the study was to assess the effect of exposed surface area of diethylhexylphthalate plasticized polyvinylchloride (PVC) on the expression of the adhesion molecule CD11b(mac‐1) on neutrophils and to determine whether there is any apparent advantage in the current trend in reducing circuit surface area in terms of neutrophil activation. The study was carried out using a parallel plate rodent recirculation biomaterial testing model on 4 groups of 10 adult male Sprague Dawley rats weighing between 350 and 450 g. One group comprised the control group in which there was no biomaterial exposure. In the remaining 3 groups, the animals were subjected to either high (48 cm2), intermediate (24 cm2), or low (12 cm2) biomaterial surface area exposure. The parallel plate test cell was connected to the right femoral circulation and recirculation initiated at a flow rate of 1.5 ml/min for a period of 60 min. Blood samples were taken at 0, 30, and 60 min for the assessment of CD11b expression. Cd11b was assessed using flow cytometric analysis on neutrophils. The results demonstrated that there was a surface area related effect in the upregulation of CD11b. The difference at the terminal sample point between the highest surface area group (293.95 ± 18.57%) and the low surface area group (133.80 ± 49.31%) was highly statistically significant (p < 0.001). These results demonstrate that there may be some gain in terms of reduced inflammatory response from reducing the exposed surface area of PVC in extracorporeal perfusion circuits.
In Vitro Evaluation of the Heparin‐Coated Gyro C1E3 Blood Pump
Authors: Muramatsu Kazuaki , Masuoka Toshio , Fujisawa Akira
Published: March 2003

Abstract: The blood‐contacting surface, mainly composed of polycarbonate, of the Gyro C1E3 pump was modified using plasma glow discharge to introduce a carboxyl functional group, coated with a base layer of polyethyleneimine as a linker, and coupled with heparin by multi‐ionic binding to enhance blood compatibility. A relative surface content of 3.7% sulfur, which demonstrated heparin immobilization on the polycarbonate substrate, was observed on x‐ray photoelectron spectroscopy, and a initial bioactivity of approximately 88.5 ± 7.3 mIU/cm2 was obtained by the chromogenic method for antifactor Xa assay. Furthermore, in vitro observation of platelet and fibrin adherence using bovine blood under dynamic flow conditions for 6 h revealed that the multi‐ionically heparinized Gyro C1E3 had significantly stronger antithrombogenecity than the noncoated original type which was evaluated as a good hemocompatible blood pump for clinical use. Not only the Gyro C1E3 but also the ionically heparin‐coated Gyro pump are expected to be thromboresistant in clinical use.
Physiologic Analysis of Cardiac Cycle in an Implantable Impeller Centrifugal Left Ventricular Assist Device
Authors: Chou Nai‐Kuan , Wang Shoei‐Shen , Chu Shu‐Hsun , Chen Yih‐Sharng , Lin Yuan‐Hsiang , Chang Chuang‐Jan , Shyu Jeou‐Jong , Jan Gwo‐Jen
Published: March 2003

Abstract: The purpose of this study was to determine the physiologic relationship between the cardiac cycle and the nonpulsatile impeller centrifugal Taita No.1 left ventricular assist device (T‐LVAD) in a chronic animal study. The relationship of the cardiac cycle, pump flow, aortic pressure, left ventricle pressure, and pump power were analyzed by 5 phases in 4 stages. The isovolumetric ventricular phase is from mitral valve closure (MVC) to aortic valve opening (AVO) and is called Stage 1. The ejection phase is from AVO to aortic valve closure (AVC) and is called Stage 2. The isovolumetric relaxation phase is from AVC to MVC and is called Stage 3. The passive filling and atrial contraction phase is from MVC to mitral valve opening (MVO) and called Stage 4. Based on evidence from the physiologic volume change of the left ventricle, the change of pump flow of the T‐LVAD in a cardiac cycle by variable voltages of pump control was evaluated using animal models. After left posteriolateral thoracotomy via the fifth intercostal space under general anesthesia, the nonpulsatile centrifugal T‐LVAD was implanted into 2 healthy calves. The inflow of the T‐LVAD was inserted into the left ventricle through the mitral valve via the left atrial appendage. The arterial blood pressure waveform was measured and recorded on the outflow of the T‐LVAD. The 4 phases of a cardiac cycle were defined as MVC‐AVO (Stage 1), AVO‐AVC (Stage 2), AVC‐MVO (Stage 3) and MVC‐MVO (Stage 4) according to the outflow pressure of the outflow of the T‐LVAD and differential pressure between the outflow and inflow of the T‐LVAD. We carried out the real‐time waveform measurement for electrocardiogram, the outflow pressure, the T‐LVAD flow and the speed, as well as open loop and constant voltage (V). In a cardiac cycle, the sensing current of the T‐LVAD was inverse to the speed. The flow of the T‐LVAD at the 4 stages was measured individually and analyzed with different control voltages from 10 to 18 V. The highest flow ratio of MVC‐AVC/AVC‐MVC was noted when the T‐LVAD worked on 14 V. By using analysis methodology of the flow ratio of a cardiac cycle, the optimal physiologically effective control of the T‐LVAD might be achieved.
New Application of Heparin‐Bonded Extracorporeal Membrane Oxygenation in Difficult Neurosurgery
Authors: Chen Yih‐Sharng , Ko Wen‐Je , Lin Fang‐Yue , Huang Shu‐Chien , Wang Shoei‐Shen , Tu Yong‐Kwang
Published: March 2003

Abstract: We wished to evaluate the safety and the advantages of using heparin‐bonded extracorporeal membrane oxygenation (ECMO) to replace conventional cardiopulmonary bypass (CPB) in deep hypothermic circulation for complex cerebral aneurysm surgery.Heparin‐bonded ECMO without the bridging tube and the cardiotomy reservoir was set up through the femoral vessels. Limited heparin was infused. In deep hypothermia, the ECMO blood flow was temporarily decreased as low as the neurosurgeons' request. It was applied to 4 patients with difficult intracranial aneurysms who were selected for the procedure. Clipping, wrapping, or vascular bypass was implemented to manage the aneurysms under deep hypothermia. The total heparin dosage used in the whole procedure was 9,875 ± 1,625 U, and the mean ECMO time was 270 ± 105 min. The blood consumption was packed red blood cell 3.0 ± 0.5 U and fresh frozen plasma 3.8 ± 2.3 U. Compared with our previous experiences using conventional CPB, ECMO did need less heparin and blood transfusions. Clipping was applied in 2 patients, wrapping in 1, and venous graft interposition was performed in 1. Mortality occurred in 1 patient (25%) due to brain herniation. This preliminary study suggested that the heparin‐bonded ECMO without reservoir in deep hypothermia could be safe in cerebral aneurysm surgery under a low flow circuit.
Customized Bicarbonate Buffered Dialysate and Replacement Solutions for Continuous Renal Replacement Therapies: Effect of Crystallization on the Measured Levels of Electrolytes and Buffer
Authors: Maccariello Elizabeth , Rocha Eduardo , Dalboni Maria Aparecida , Ferreira Alice Teixeira , Draibe Sérgio , Cendoroglo Miguel
Published: March 2003

Abstract: The aim of this study was to investigate the impact of the addition of calcium to bicarbonate solutions for continuous renal replacement therapy (CRRT). We tested single bag (bicarbonate and calcium mixed 24 h before testing) and double bag solutions (mixed immediately before) with and without the addition of 4 mEq/L of acetate. Prescribed calcium varied from 0 to 5 mEq/L. All test solutions containing calcium showed crystallization at light microscopy. The double bag solutions decreased but did not prevent crystallization. The addition of acetate did not interfere with crystallization. Crystallization, as measured by the weight of the crystals after filtration of the solutions, showed a significant positive correlation with the calcium deficit (prescribed minus measured) and with partial pressure of carbon dioxide. The measured level of calcium was lower than expected and correlated with crystallization. Our results suggest that the use of bicarbonate solutions containing calcium as replacement fluids for CRRT is a potentially unsafe procedure.
Reciprocal Influences Between Ambulatorial Peritoneal Dialysis and Pulmonary Function
Authors: Marmanillo Carlos G. , Pecoits‐Filho Roberto F.S. , Romão João E. , Kakehashi Emilia T. , Sabbaga Emil , Marcondes Marcelo , Abensur Hugo
Published: March 2003

Abstract: The aim of this study was to verify if dialysis solution volumes used in patients on continuous ambulatory peritoneal dialysis (CAPD) interfere with pulmonary function and if the pulmonary volumes interfere with the lymphatic absorption of the peritoneal cavity. We submitted 10 CAPD patients with a mean age of 48 ± 18 years and on CAPD for 35 ± 27 months to the following evaluations: first, measurement of the lymphatic absorption from the peritoneal cavity; second, measurement of the hydrostatic intraperitoneal pressure; and third, expirometry with the peritoneal cavity full of dialysis solution and empty. There were no differences between the expirometry results obtained with the peritoneal cavity full and empty of dialysis solution, and the results were in accordance with the prediction for this population. The values did not correlate with the peritoneal lymphatic absorption of the peritoneal cavity. The cumulative lymphatic absorption of the peritoneal cavity after 4 h dialysis solution permanence was 197 ± 93 ml, and the hydrostatic intraperitoneal pressure was 13.9 ± 2.8 column centimeters of water. Neither of these correlated with pulmonary volumes. In conclusion, CAPD did not interfere with the pulmonary function, nor did the pulmonary function influence the lymphatic absorption of the peritoneal cavity of these patients.
Effect of Filtration Leukocytapheresis Therapy: Modulation of White Blood Cell Enzyme Activities in Patients with Rheumatoid Arthritis
Authors: Yamasaki Satoshi , Ueki Yukitaka , Nakamura Hideki , Yano Mayumi , Matsumoto Kazunari , Miyake Seibei , Tominaga Tan , Tominaga Masaya , Eguchi Katsumi
Published: March 2003

Abstract: We treated 12 patients with rheumatoid arthritis by filtration leukocytapheresis (FLCP) and evaluated its effect on leukocyte enzyme activities. We calculated the number of leukocytes removed and assessed the clinical response. We also evaluated the cellular enzyme activities of elastase and dipeptidylpeptidase IV (DPP IV). Out of 12 patients, 7 patients achieved 20% improvement for 4 weeks following FLCP. The FLCP treatment resulted in removal of 96% of granulocytes, 98% of monocytes, and 61% of lymphocytes. Granulocytes and monocytes with high elastase activity were effectively removed by FLCP. The elastase activity of granulocytes was increased 4 weeks after the last FLCP only in responders. On the other hand, the DPP IV activity of lymphocytes was low at 4 weeks after the last FLCP in responders. Modulation of leukocyte enzyme activities is one of the main effects of FLCP therapy and alteration of granulocytes, monocytes, and lymphocytes.
At Least Thirty‐Four Days of Animal Continuous Perfusion by a Newly Developed Extracorporeal Membrane Oxygenation System without Systemic Anticoagulants
Authors: Nishinaka Tomohiro , Tatsumi Eisuke , Taenaka Yoshiyuki , Katagiri Nobumasa , Ohnishi Hiroyuki , Shioya Kyoko , Fukuda Toshihide , Oshikawa Mitsuo , Sato Koichi , Tsukiya Tomonori , Homma Akihiko , Takewa Yoshiaki , Takano Hisateru , Sato Masaki , Kashiwabara Susumu , Tanaka Hidenori , Sakai Kazunari , Matsuda Toshiaki
Published: March 2003

Abstract: We developed an extracorporeal membrane oxygenation (ECMO) system with high antithrombogenicity and durability characteristics for prolonged continuous cardiopulmonary support. The oxygenator consists of a special hollow‐fiber‐type polyolefin gas‐exchange membrane, which has an ultrathin dense layer in contact with the blood, in order to prevent plasma leakage during protracted use (Platinum Cube NCVC). The centrifugal pump (RotaFlow) is free of seals. The entire blood‐contacting surface of the system is coated with a newly developed heparin material (Toyobo‐NCVC coating). We performed a venoarterial bypass in a goat, and the ECMO system was driven for 34 days without systemic anticoagulants. Plasma leakage from the oxygenator did not occur, and sufficient gas exchange performance was maintained. Thrombus formation was hardly observed in the ECMO system except in the casing margins of the oxygenator. This ECMO system showed potential for long‐term cardiopulmonary support with minimal or no use of systemic anticoagulants.
Flow Through an Outlet Cannula of a Rotary Ventricular Assist Device
Authors: Manning Keefe B. , Miller Gerald E.
Published: March 2003

Abstract: Rotary ventricular assist devices (VADs) are primarily used during surgery and short‐term postoperative assistance. There are issues involving the use of rotary VADs including the behavior of flow emanating from the assist device which might induce flow irregularities that could potentially lead to stroke or cerebrovascular accident. An in vitro flow visualization study using particle image velocimetry was conducted to evaluate flow fields at the bend of outlet cannulae with angles ranging from 30 degrees to 75 degrees. A multiple disk centrifugal blood pump produced steady, laminar flow fields at the outlet. Flow fields at the bend of each cannula demonstrated the development of a boundary layer along the inner wall and shift of fluid momentum to the outer wall. Stagnant zones along the inner wall were prevalent for each cannula and increased in severity with increasing angle. The outlet flow fields of rotary VADs have the potential to produce thrombus, feasibly leading to thromboembolisms should the bend angle of the outlet cannula be acute enough. Therefore, the placement of the outlet cannula or conduit should be taken into consideration during implantation.
Simulation of the Three‐Dimensional Electrical Field in the Course of Functional Electrical Stimulation
Authors: Reichel Martin , Breyer Teresa , Mayr Winfried , Rattay Frank
Published: March 2003

Abstract: Optimization of stimulation parameters as well as shape and positioning of electrodes are important questions in functional electrical stimulation (FES) of paraplegic patients. For that reason a MATLAB tool, called FES‐FIELD, modeling the three‐dimensional electric field in the human body, has been developed to calculate the electric field in a region of interest. The simulation tool provides a graphic user interface. In case of denervation of the lower extremities, an important target muscle is the m. quadriceps femoris. The electrical potential distribution along its fibers is representative for its functional activation. For this special application, the human thigh stimulated by skin electrodes was modeled. The simulation process was done in 5 steps: reading the geometric information of the thigh from 50 computed tomographic slices, segmentation in tissue types by pixel value and definition of each conductivity, selection of electrode geometry and positioning, calculating the electric field iteratively by solving the system of linear equations, and visualization of the solution by equipotential lines in either cross or length sections of the thigh.
Replacement of the Aortic Root and Ascending Aorta Using a Freestyle Valve and Woven Dacron Graft
Authors: Hata Hiroaki , Iida Mitsuru , Kashiwazaki Satoshi , Eda Kunihiro , Hirose Hirokazu , Shiono Motomi , Negeshi Nanao , Sezai Yukiyasu
Published: March 2003

Abstract: We contrived a surgical technique for the purpose of improving recent results. From April 1998 to June 2001, 24 patients (aged 60 to 81 years, mean age 71.0 ± 4.8 years; 11 men, 13 women) underwent replacement of the aortic root and the ascending aorta electively using a Freestyle stentless valve with woven Dacron graft at our institution. The aortic root was replaced first, the distal side of the Dacron graft was then anastomosed, and finally, the proximal side was anastomosed with the outflow of the Freestyle valve. Cardiopulmonary bypass time and cardioplegic time were 297 ± 83 min and 210 ± 51 min, respectively. The geometry of the ascending aorta and the diameter mismatch between the dilated ascending aorta and the outflow of the Freestyle valve were fully corrected. There were two early deaths and three late deaths; none valve‐related. Postoperative aortogram showed an excellent shape. The mortality, morbidity, and clinical events after the procedure were acceptable.
Histological and Immunohistological Study of Cryopreserved Aortic Valve Grafts: The Possibility of a Clinical Application for Cryopreserved Aortic Valve Xenograft
Authors: Yokose Shogo , Fukunaga Shuji , Tayama Eiki , Kato Seiya , Aoyagi Shigeaki
Published: March 2003

Abstract: The influence of preservation techniques on xenogeneic immune responses was examined to investigate the possibility of their clinical use. Mongrel dogs and pigs were used as allogeneic and discordant xenogeneic donors of aortic valve grafts, respectively. The allografts and xenografts were implanted in the abdominal aorta of mongrel dogs after cryopreservation or after fresh preservation. Allografts and xenografts were explanted at Days 7 and 42 for histological and immunohistochemical examination. In the fresh preserved allografts and the fresh preserved xenografts, the media of aortic wall grafts were significantly acellular at 7 days. Significant aortic medial destruction and neointimal proliferation with significant destruction of the valve leaflets was observed at 42 days. However, no differences were found among the preservation techniques in the xenogeneic grafts. To alleviate the lack of homografts, approaches such as the tissue‐engineered graft may become an alternative in patients who are acceptable candidates.
Aortic Valve Replacement in the Calcified Small Aortic Root by Hemitranslocation of the Valve
Authors: Endo Masahiro , Nishida Hiroshi , Chikazawa Genta , Tomizawa Yasuko
Published: March 2003

Abstract: An alternative technique of aortic valve replacement is described for a small aortic root with a severe large calcific degeneration of the supraaortic area at the noncoronary sinus. This technique is used when Nicks or Manouguian procedures are not applicable.
Is Low‐Intensity Anticoagulant Therapy Possible with an Open Pivot Valve?: Analysis of Its Development
Authors: Nicoloff Demetre M. , Friedberg H. David , Villafaña Manuel A.
Published: March 2003

Abstract: In 1976, the authors became the codevelopers of the first successful bileaflet heart valve which has become the standard in valvular surgery. However, there still remains a significant rate of thromboembolism and thrombosis which can be attributed to the inherent design of cavities in the pivot area. These cavities contribute to stagnant areas that lead to thrombus formation. The literature indicates that this rate is approximately 2% to 2.5% per patient year. To maintain these thromboembolism rates, certain levels of warfarin have had to be used leading to a significant rate of bleeding complications. We present the theory and development of the new generation of heart valves without cavities and with an open semisphere pivot area. Results of 912 years of clinical studies of almost 50,000 valves, as well as additional features that have been incorporated to improve hemodynamics and quality of life for the patient, are discussed. The clinical results of the European Community Certification and U.S. Food and Drug Administration premarket application (PMA) studies also are given. The differences in the pivot area suggest that a reduction in thromboembolism is possible at anticoagulant levels as low as 1.5 international normalization ratio (INR) resulting in virtually no bleeding complications. Midterm clinical results are encouraging, and studies are being conducted presently to eliminate totally anticoagulants in certain patients.
Aortic Root Replacement with Stentless Xenograft for Aortic Dissection
Authors: Uchida Tetsuro , Shimazaki Yasuhisa , Uesho Kunihiro , Koshika Masataka , Takeda Fumihiro , Inui Kiyoshige , Watanabe Takao
Published: March 2003

Abstract: This paper reviewed aortic root replacement with a stentless xenograft for Stanford Type A aortic dissection. Total aortic arch replacement plus aortic root reconstruction with a stentless xenograft was conducted in 2 patients with acute aortic dissection. In another 2 patients, aortic root replacement with a bioprosthesis was performed for chronic redissection of the aortic root which might be associated with the previous use of gelatin‐resorcin‐formalin glue. Full root replacement using this device is safe, reliable, reproducible, and technically less demanding. This device also provides a radical option for acute aortic dissection even in patients requiring concomitant aortic arch and root replacement.