bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical Experiences of Percutaneous Cardiopulmonary Support: Its Effectiveness and Limit
Authors: Orime Yukihiko , Shiono Motomi , Hata Hiroaki , Yagi Shinya , Tsukamoto Saeki , Okumura Haruhiko , Nakata Kin‐ichi , Kimura Shun‐ichi , Sezai Akira , Sezai Yukiyasu
Published: March 2003

In recent years, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB) and postcardiotomy cardiac support. From April 1990 to March 1997, a percutaneous cardiopulmonary support (PCPS) system was used in 20 patients with an average age of 58 years (13 males and 7 females). They comprised 11 ischemic, 6 valvular, 2 aortic, and 1 congenital heart disease patients. Our PCPS system consists of a centrifugal pump (BioMedicus BP‐80), an oxygenator, and a reservoir. The entire blood contacting surface, including that of the thin wall cannulas, is coated by heparin bonded materials. As a result of this new technology, this system can be used for the long term without systemic heparinization. No major critical thrombi were revealed inside the pumps or circuits. Of the 20 patients, 7 (35%) (Group 1) could be weaned from PCPS, and the remaining 13 (Group 2) could not. In Group 1 although 2 patients suffered from renal failure and pneumonia, respectively, both were discharged from our hospital. The long‐term survival rate was 35%. In Group 2 cerebral vascular damage was recognized in 3 patients, renal failure in 4, multiple system organ failure in 4, bleeding in 2, arrhythmia in 1, and leg ischemia in 2. Pulse pressure was significantly elevated due to the recovery of the native heart in Group 1, 2 days after support. However, in Group 2, it did not elevate, and the left ventricular ejection fraction was less than 30 %, associated with high left atrial pressure. In conclusion, this heparin coated PCPS system was very simple and easy to control. It demonstrated long‐term biocompatibility and was very effective in recovering deteriorated cardiac function. Quicker application of this system can play an important role in preventing severe complications and obtaining better clinical results. If long‐term support is necessary, a ventricular assist device (VAD), which is more powerful, durable, and biocompatible, has to be applied instead of PCPS.
Development of Design Methods of a Centrifugal Blood Pump with In Vitro Tests, Flow Visualization, and Computational Fluid Dynamics: Results inHemolysis Tests
Authors: Takiura Koki , Masuzawa Toru , Endo Seiko , Wakisaka Yoshinari , Tatsumi Eisuke , Taenaka Yoshiyuki , Takano Hisateru , Yamane Takashi , Nishida Masahiro , Asztalos Balázs , Konishi Yoshiaki , Miyazoe Yuki , Ito Kazuyuki
Published: March 2003

Abstract There are few established engineering guidelines aimed at reducing hemolysis for the design of centrifugal blood pumps. In this study, a fluid dynamic approach was applied to investigate hemolysis in centrifugal pumps. Three different strategies were integrated to examine the relationship between hemolysis and flow patterns. Hemolytic performances were evaluated in in vitro tests and compared with the flow patterns analyzed by flow visualization and computational fluid dynamic (CFD). Then our group tried to establish engineering guidelines to reduce hemolysis in the development of centrifugal blood pumps. The commercially available Nikkiso centrifugal blood pump (HPM‐15) was used as a standard, and the dimensions of 2 types of gaps between the impeller and the casing, the axial and the radial gap, were varied. Four impellers with different vane outlet angles were also prepared and tested. Representative results of the hemolysis tests were as follows: The axial gaps of 0.5, 1.0, and 1.5 mm resulted in normalized index of hemolysis (NIH) values of 0.0028, 0.0013 and 0.0008 g/100 L, respectively. The radial gaps of 0.5 and 1.5 mm resulted in NIH values of 0.0012 and 0.0008 g/100 L, respectively. The backward type vane and the standard one resulted in NIH values of 0.0013 and 0.0002 g/100 L, respectively. These results revealed that small gaps led to more hemolysis and that the backward type vane caused more hemolysis. Therefore, the design parameters of centrifugal blood pumps could affect their hemolytic performances. In flow visualization tests, vortices around the impeller outer tip and tongue region were observed, and their patterns varied with the dimensions of the gaps. CFD analysis also predicted high shear stress consistent with the results of the hemolysis tests. Further investigation of the regional flow patterns is needed to discuss the cause of the hemolysis in centrifugal blood pumps.
Roller Pump Induced Tubing Wear of Polyvinylchloride and Silicone Rubber Tubing: Phase Contrast and Scanning Electron Microscopic Studies
Authors: Kim Won Gon , Yoon Cheul Jong
Published: March 2003

Tubing wear and spallation have long been recognized as complications of roller pumps used in cardiopulmonary bypass (CPB) although the reported results of studies of polyvinylchloride (PVC) and silicone rubber tubing wear are still controversial. We conducted phase‐contrast microscope (PCM) and scanning electron microscope (SEM) studies of roller pump induced tubing wear. A closed CPB circuit was constructed, and both PVC and silicone rubber tubing (½ inch internal diameter [ID]) were tested under normal and tight occlusions of a dual roller pump at a typical CPB flow rate (4,500 ml/min) for 1, 2, 4, and 6 h in quintet. After each pump run, the tubing was removed. It was first examined with PCM, and suspicious portions were then analyzed in detail using SEM. In silicone rubber tubing of longer running time, the external diameter often decreased. Wear was invariably found on the luminal surfaces at the junction of the inner and outer walls of both the PVC and silicone rubber tubing with no significant differences between normal and tight occlusion. The grooves in the PVC tubing were narrow and continuous with occasional deep cracks in the tubing after more than 3 h of pump run. The grooves in the silicone rubber tubing were wide and often interrupted with occasional V‐shaped elevated areas. Craters of less than 50 μ occurred sporadically in both types of tubing. Neither PVC nor silicone rubber tubing offers advantages in terms of roller pump induced tubing wear and spallation.
CardioWest Total Artificial Heart: A Retrospective Controlled Study
Authors: Arabia  , Copeland  , Smith  , Banchy  , Foy  , Kormos  , Tector  , Long  , Dembitsky  , Carrier  , Keon  , Pavie  , Duveau
Published: March 2003

The CardioWest total artificial heart (TAH) is a pneumatic device that is used as a bridge to heart transplantation and the only TAH available that totally replaces the failing ventricles. It has been utilized in selected centers in the U.S.A. with approval from the Food and Drug Administration. Strict criteria have been developed to select candidates to be bridged with the TAH. The patient must be a heart transplant candidate of age >18 and <59 years with a body surface area (BSA) ≥ 1.7 m2, cardiac index (CI) <2.0 L/min/m2, and 2 inotropic agents or 1 plus an intraaortic balloon pump (IABP). A total of 24 heat transplant candidates (Group A) met the entry criteria and underwent placement of the TAH between January 1993 and July 1996. Group A consisted of 23 males; 16 patients had an IABP. The control group (Group B) consisted of 18 heart transplant candidates who met the TAH entry criteria but never received a TAH. Group B consisted of 15 males; 14 patients had an IABP. Preimplantation pulmonary vascular resistance (PVR) (Wood units), serum creatinine (mg/dl), and total bilirubin (mg/dl) were determined in both groups. The mean values for Groups A and B were, respectively, age: 47 and 47 years, BSA: 2.01 and 1.93 m2, CI: 1.5 and 1.8 L/min/m2, PVR: 2.88 and 2.47 Wood units, creatinine: 1.5 and 1.6 mg/dl, and bilirubin: 1.8 and 1.4 mg/dl. In Group A, 1 patient died on the TAH, 1 patient died after transplant, and 22 patients reached transplant and were discharged home for a survival rate of 91.7%. In Group B, 10 patients died while waiting for a heart transplant. Of the 8 patients transplanted, 7 survived and were discharged home for a survival rate of 38.9% (p = 0.0003). In summary the CardioWest TAH provided an excellent and successful method of bridging patients to heart transplantation with a reasonable risk.
Hepatitis B Virus: Genotypes and Subtypes in Brazilian Hemodialysis Patients
Authors: Teles Sheila Araujo , Martins Regina Maria Bringel , Vanderborght Bart , Stuyver Lieven , Gaspar Ana Maria Coimbra , Yoshida Clara Fumiko Tachibana
Published: March 2003

Abstract: There are no data concerning the genotypic analysis of hepatitis B virus (HBV) infection in Brazilian dialysis centers. Serum samples from all hemodialysis patients (n = 282) in Goiânia City, Central Brazil, were tested for hepatitis B surface antigen (HBsAg). An overall prevalence of 12.0% was found, ranging from 0 to 33.3% depending on dialysis centers. Positive samples (n = 34) were submitted to serological subtyping by monoclonal ELISA and HBV DNA detection by polymerase chain reaction (PCR). Among 30 PCR‐positive samples, 26 were genotyped by use of the line probe assay technology (INNO‐LiPA HBV, Innogenetics, Gent, Belgium). HBV genotypes A (50.0%) and D (46.2%) were the most frequently found whereas genotype F (3.8%) was rare in this population. Serological subtypes adw2 (44.1%) and ayw3 (41.2%) were dominant. By contrast, adw4 and ayw2 were found at a low frequency (2.9%). A correlation was observed in the distribution of genotypes and subtypes by dialysis center. Genotype D and subtype ayw3 were predominant in 2 hemodialysis centers whereas genotype A and subtype adw2 were predominant in the others. The findings of high HBsAg prevalence rates restricted to certain dialysis centers and the data obtained through genotyping and serological subtyping suggest HBV nosocomial transmission in these hemodialysis centers.
Experimental Wound Healing with Electrical Stimulation
Authors: Reger Steven I. , Hyodo Akira , Negami Shigeharu , Kambic Helen E. , Sahgal Vinod
Published: March 2003

The effect of alternating current (AC) and direct current (DC) stimulation was studied on experimental pressure ulcer healing in a new monoplegic pig model. The study was conducted in 30 healthy young Hanford minipigs. The rate of wound healing, histology, vascularization, collagen formation, microbiology, perfusion, and the mechanical strength of the healed wounds were studied. Normal pigskin was compared to denervated control and denervated AC and DC stimulated healed skin. Hind limb denervation was by right unilateral extradural rhizotomies from the L2 to S1 nerve roots. Reproducible uniformly controlled Stage III or higher tissue ulcers were created. When compared to the control wounds, both the AC and DC stimulated wounds showed reduced healing time and increased perfusion in the early phases of healing. DC stimulation reduced the wound area more rapidly than AC, but AC stimulation reduced the wound volume more rapidly than DC. The electrical stimulation did not reduce the strength of the healing wounds below those of the nonstimulated controls. The applied current appears to orient new collagen formation even in the absence of neural influences.
Afferent and Efferent Nerve Activity of Arterial Baroreceptor Reflex Under Nonpulsatile Systemic Circulation
Authors: Shomura Yu , Tanaka Keizo , Takabayashi Shin , Hioki Iwao , Tenpaku Hironori , Maze Yasumi , Shimono Takatsugu , Shimpo Hideto , Yada Isao
Published: March 2003

We studied the changes in arterial baroreceptor reflex (ABR) afferent activity and efferent activity induced by nonpulsatile systemic circulation (NC) during total left heart bypass (TLHB) in rabbits. To evaluate the influence of the circuit priming fluid and exposure to NC, we directly measured aortic depressor nerve activity (ADNA) (n = 5) and renal sympathetic nerve activity (RSNA) (n = 5) before the start of partial left heart bypass (PLHB) (Before), after PHLB (After), and 5 min after the start of TLHB (During THLB) while maintaining the mean aortic pressure. The circuit priming fluid did not affect the ABR. ADNA exhibited periodic discharge at Before and After, but at During THLB, this periodic discharge transformed into a continuous discharge, and ADNA increased significantly. However, there were no significant differences in RSNA. Our results suggested that in the acute phase under NC, the ABR differed from that under natural circulation.
Defining Pulsatile Perfusion: Quantification in Terms of Energy Equivalent Pressure
Authors: Ündar Akif , Frazier  , Fraser Jr. Charles D.
Published: March 2003

Several clinical and animal studies have demonstrated that pulsatile perfusion is more beneficial than nonpulsatile perfusion during short or long durations of extracorporeal circulation. Other investigators, however, have been unable to document these benefits. The issue remains controversial. Central to the debate is the issue of a precise definition of pulsatile flow. To help resolve the conflict, pulsatile flow may be quantified in terms of energy equivalent pressure. This formula contains both the arterial pressure and pump flow rate, which are the 2 most critical parameters for open heart surgery. This definition establishes common criteria for assessment of the effectiveness of extracorporeal support.
Intravenous Prostacyclin Mitigates Inhaled Nitric Oxide Rebound Effect: A Case Control Study
Authors: Hermon Michael , Golej Johann , Burda Gudrun , Marx Manfred , Trittenwein Gerhard , Pollak Arnold
Published: March 2003

Abstract: Although extracorporeal membrane oxygenation (ECMO) improves oxygenation, pulmonary vascular resistance may be increased due to endothelial function impairment. Inhaled nitric oxide (iNO) is increasingly used for treatment of pulmonary hypertension after surgical repair of congenital heart defects, with or without ECMO. One of the main complications of its application is deterioration of oxygenation following withdrawal of iNO. To test whether intravenous prostacyclin applied prior to and during iNO withdrawal can mitigate this rebound effect, we conducted a retrospective case control study. The rebound effect was defined as a 5% decrease of oxygenation saturation within 4 h after iNO withdrawal. Twelve children suffering from pulmonary hypertension (2 after ECMO) and treated with iNO received 10 ng/kg/min prostacyclin intravenously 24 h prior to iNO withdrawal (Group 1). Twelve children treated with iNO (3 after ECMO) who received no prostacyclin prior to iNO withdrawal were matched as controls. The rebound effect occurred in 1 out of 12 children in Group 1 and in 8 out of 12 children in Group 2 (p = 0.0039). We conclude that application of intravenous prostacyclin prior to and during iNO withdrawal may be able to mitigate the rebound effect.
Preprimed Artificial Lung for Emergency Use
Authors: Tatsumi Eisuke , Taenaka Yoshiyuki , Takano Hisateru , Nishinaka Tomohiro , Nishimura Takashi , Katagiri Nobumasa , Yoda Takumi , Kotake Masayoshi , Wada Tohru
Published: March 2003

Abstract: We investigated the possibility of preprimed storage of an artificial lung (AL), aiming at facilitating its emergency use. Test ALs, consisting of a special microporous hollow fiber membrane made of polyolefin in which direct blood‐gas contact was completely eliminated, were preprimed with saline solution, sterilized by γ‐ray irradiation, and evaluated after 1–3 months of storage at room temperature. A small amount of bubble was noted in the priming solution after storage in some ALs, which most likely originated from the air dissolved in the priming solution or persisted in the liquid compartment at priming. Although the preprimed solution contained several polyolefin‐breakdown products due to irradiation, including ethyl alcohol, n‐ and t‐butyl alcohol, acetone, and carbon dioxide, the levels of these substances were at concentrations known to be not toxic. Endotoxin concentration was negligible. In SEM observation, no perceptible microstructural change was observed in the hollow fibers after preprimed storage. Maximum tensile stress and ultimate elongation of the hollow fiber in the test ALs were reduced by approximately 20% and 3%, respectively, from those of the control AL. The influence of preprimed storage on gas‐exchange function was examined in a venoarterial bypass animal study using a goat. Oxygen transfer function was well preserved whereas carbon dioxide removal function was slightly lowered according to the storage term in the stored ALs compared with those of a nonpreprimed control AL. On the basis of these results, we conclude that preprimed storage of the AL with γ‐ray sterilization is basically feasible and realistic.
Maintenance of Blood Heparin Concentration Rather than Activated Clotting Time Better Preserves the Coagulation System in Hypothermic Cardiopulmonary Bypass
Authors: Shirota Kazuaki , Watanabe Takashi , Takagi Yasushi , Ohara Yasuhisa , Usui Akihiko , Yasuura Kenzou
Published: March 2003

Abstract: In cardiopulmonary bypass (CPB), despite heparin regimens in which the activated clotting time (ACT) is kept at more than 400 s, there is biochemical evidence of thrombin generation indicating activation of the coagulation system and increased fibrinolytic activity. Therefore, to reduce the coagulant activation has been one of the main issues in the improvement of CPB. The purpose of this study was to compare the heparin concentration with the ACT and to evaluate the effect of keeping higher heparin concentration on the coagulation and fibrinolytic systems during hypothermic CPB, employing moderate hypothermia (MHT) or deep hypothermic circulatory arrest (DHT). Heparin was either administered to maintain an ACT >400 s (ACT group) or to maintain a whole blood heparin concentration of 3 mg/kg (heparin group). At the lowest core temperature during CPB, the ACT and the heparinase ACT (unrelated to heparin concentration) were increased the most whereas the whole blood heparin concentration was less than half the initial concentration in both ACT groups of MHT and DHT. The thrombin‐antithrombin III (TAT) content just after CPB in both MHT and DHT was significantly lower in the heparin group than in the ACT group. In conclusion, ACT does not reflect the whole blood heparin concentration during hypothermic CPB. Furthermore, maintenance of the higher heparin concentration during hypothermic CPB may suppress the activation of the coagulation system via thrombin inhibition. That effect was more remarkable in deep hypothermic CPB. Therefore, we believe that anticoagulation management during hypothermic CPB should be based on the maintenance of the higher blood heparin concentration.
Pressure Drop, Shear Stress, and Activation of Leukocytes During Cardiopulmonary Bypass: A Comparison Between Hollow Fiber and Flat Sheet Membrane Oxygenators
Authors: Gu Y.J. , Boonstra P.W. , Graaff R. , Rijnsburger A.A. , Mungroop H. , van Oeveren W.
Published: March 2003

Abstract: The membrane oxygenator is known to be superior to the bubble oxygenator, but little information is available about the difference between the hollow fiber and flat sheet membrane oxygenators with regard to pressure drop, shear stress, and leukocyte activation. In this study, we compared these 2 types of membrane oxygenators in patients undergoing cardiopulmonary bypass (CPB) surgery with special focus on leukocyte activation and pressure drop across the oxygenators. Plasma concentration of elastase, a marker indicating leukocyte activation, increased to 593 ± 68% in the flat sheet oxygenator group versus 197 ± 42% in the hollow fiber oxygenator group (p < 0.01) at the end of CPB compared to their respective baseline concentrations before CPB. Pressure drop across the oxygenator was significantly higher in the flat sheet group than in the hollow fiber group throughout the entire period of CPB (p < 0.01). High pressure drop across the oxygenator as well as the calculated shear stress was positively correlated with the release of elastase at the end of CPB (r = 0.760, p < 0.01, r = 0.692, p < 0.01). However, this positive correlation existed in the flat sheet oxygenator but not in the hollow fiber oxygenator. Clinically, both membrane oxygenators have satisfactory performance in O2 and CO2 transfer. These results suggest that a higher pressure drop across the flat sheet oxygenator is associated with more pronounced activation of leukocytes in patients undergoing cardiopulmonary bypass.
A Novel In Vitro Assessment of Tissue Valve Calcification by a Continuous Flow Type Method
Authors: Park Jong‐Chul , Hwang Yu‐Shik , Han Dong‐Wook , Suh Hwal
Published: March 2003

Abstract: A dynamic flow type testing to study calcification was self‐designed to investigate calcification in bioprosthetic heart valves. The apparatus consists of a container into which leaflets from a porcine aortic valve are placed, a chamber that contains calcium solution, and a peristaltic pump that provides a continuous supply of the solution toward the container. Efficacy of the apparatus was compared with the conventional batch type calcification testing at 37°C through measuring the amount of calcium and phosphate deposited by inductively coupled plasma (ICP) and scanning electron microscope (SEM). After 14 days, calcium levels detected from the calcified deposit on leaflets were 470.4 ± 37.0 μg/cm3 in the flow type testing whereas in the batch type testing levels were 81.0 ± 6.7 μg/cm3. Though the calcium level on the leaflet increased as the exposure time to calcium solution increased in both testings, the rate and the tendency of calcification could be assessed very rapidly by flow type testing in comparison with batch type testing. [Ca]/[P] molar ratio decreased over time, and after 14 days, the ratio was close to 1.83 ± 0.18 in the flow type testing. The ratio could not be determined in the batch type testing because the deposit was too small to assess. The descending rate of [Ca]/[P] molar ratio demonstrates that deposited calcium‐complex at the earliest stage may interact with inorganic phosphate ions to create a calcified deposit mineral precursor. This in vitro dynamic flow type calcification testing was a favorable tool for rapid investigation of calcification.
Effects of New Polymer‐Coated Extracorporeal Circuits on Biocompatibility During Cardiopulmonary Bypass
Authors: Saito Noboru , Motoyama Shinji , Sawamoto Jiro
Published: March 2003

Abstract: An inflammatory response due to bioincompatibility of extracorporeal circuits is a major clinical issue during cardiopulmonary bypass (CPB). By using a swine model, we determined whether new polymer‐coated circuits, the blood‐contacting surfaces of which are coated with poly(2‐methoxyethylacrylate) (PMEA), would reduce the inflammatory response during CPB. Plasma bradykinin levels and the percentages of CD35‐positive monocytes in PMEA‐coated circuits were significantly lower than those in uncoated circuits during CPB. The amount of proteins adsorbed on the PMEA‐coated circuits was significantly lower than that on the uncoated circuits (0.30 μg/cm2 versus 3.42 μg/ cm2). Almost no IgG, IgM, or C3c/d was detected in proteins adsorbed on the PMEA‐coated circuits although these proteins were clearly detected in proteins adsorbed on the uncoated circuits. We concluded that PMEA coating could reduce complement activation during CPB by suppressing the adsorption of IgG and IgM, which activate C3 via the classical pathway, on the surface of the circuits.
Effect of the Sinus of Valsalva on the Closing Motion of Bileaflet Prosthetic Heart Valves
Authors: Ohta Yuji , Kikuta Yukiaki , Shimooka Toshiyuki , Mitamura Yoshinori , Yuhta Toshio , Dohi Takeyoshi
Published: March 2003

Abstract:Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge‐coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.
Serial Measurement of Polyethylene Wear of Well‐Fixed Cementless Metal‐Backed Acetabular Component in Total Hip Arthroplasty: An Over 10 Year Follow‐up Study
Authors: Dai Xuesong , Omori Hironori , Okumura Yasuhiro , Ando Masao , Oki Hisashi , Hashimoto Naoki , Baba Hisatoshi
Published: March 2003

Abstract: Serial radiographic measurements of polyethylene wear were performed in 38 hips (33 patients) with primary cementless total hip arthroplasty (THA). The average follow‐up period was 131.8 months. All prostheses were assessed as radiographically stable at the latest follow‐up. A two‐dimensional method was used to calculate the relative migration of the femoral head center to the cup center. The average total linear wear and wear rate were 1.22 mm and 0.11 mm/year, respectively. The degree of wear in the first 2 postoperative years accounted for nearly 40% of the total wear at the end of the study (average follow up: 131.8 ± 10.0 months, ±SD). The migration of the femoral head at an average period of 3.4 months after operation accounted for 56% of the amount of wear in the first 2 years. Wear rate decreased gradually with time and stabilized after the fourth year. However, in 2 patients, a progressive increase in the wear rate was associated with severe osteolysis and failure of THA. Both creep and wear contributed to the femoral penetration into the polyethylene liner. The influence of creep cannot be ruled out, especially in the early period after operation. Polyethylene wear is a multifactorial process, and the study of individual wear patterns might be useful in identifying patients who are at risk of late failure of THA.
Radiopacity and Fatigue Characterization of a Novel Acrylic Bone Cement with Sodium Fluoride
Authors: Minari Chiara , Cristofolini Luca , Baruffaldi Fabio , Pierotti Luisa
Published: March 2003

Abstract: Acrylic bone cement must provide good radiographic visibility and good long‐term mechanical resistance in joint replacements. A new formulation of cement with 6% barium sulfate and 6% sodium fluoride was developed (Fluoride Bone Cement). Barium sulfate is a necessary addition to allow radiographic visibility although it reduces the mechanical strength of the material. Sodium fluoride promotes bone formation. However, its effect on the mechanical behavior is currently unknown while its influence on radiopacity can only be roughly estimated. The aim of this investigation was to establish if the new formulation would be suitable for clinical trials. In this respect, a mechanical (fatigue test) and radiographic (optical density measurements on x‐ray films) characterization was performed on a typical commercially available cement with barium sulfate added and on the Fluoride Bone Cement. It was demonstrated that the fluoride cement has a (marginally) superior fatigue strength and comparable radiopacity to commercial radiopaque cements.
Effect of Wall Hardness on Hemolysis
Authors: Yasuda Toshitaka , Shimokasa Kenji , Funakubo Akio , Fukui Yasuhiro
Published: March 2003

Abstract: One of the major problems for artificial organs to develop and to improve is the reduction of hemolysis. The optimum designing of less hemolysis artificial organs is achieved through computational analysis and flow visualization techniques. However, it is impossible to know the quantitative relation between hemolysis and these analytic data. Thus, in vitro studies were performed to estimate these devices on hemolysis because there is no standard for designing these devices with less hemolysis. Therefore, it is essential to reveal the relation between blood flow behaviors and hemolysis. Previous studies reported that hemolysis was caused by a combination of physical factors. In particular, shear stress, pressure, and other fluid dynamical effects were shown to induce hemolysis. In another fluid dynamical experiment reported, the collision flow against the sanded wall was considered the most important factor that directly effected blood damage, which led to hemolysis. The blood flow impact of the collision against the wall effected serious damage to red blood cells. The objective of this study was to point out the relationship between physical force (pressure) in collision flow and hemolysis. In vitro tests using bovine blood and a circulation model that included a jet flow that collides against a wall were conducted. In these tests, we changed the material of the wall by replacing silicone rubber of various thicknesses. The thickness of the silicone rubber is inversely proportional to its hardness. The results show that the increasing rate of hemolysis was lower when the surface was coated by silicone rubber. In conclusion, we considered that it is possible to reduce hemolysis by adjusting the hardness of the material and contacted blood flow.
Paradoxical Effects of Viscosity on the VentrAssist Rotary Blood Pump
Authors: Vidakovic S. , Ayre P. , Woodard J. , Lingard N. , Tansley G. , Reizes J.
Published: March 2003

Abstract: The ability of the VentrAssist blood pump to perform at its optimum design point is determined by a number of factors such as geometry of the pump, surface roughness, and fluid properties. Once the fluid properties are known, the performance characteristics of the pump can be optimized for that fluid. It is important to understand the effects of dynamic viscosity μ (called simply viscosity hereafter) on the performance characteristics and stability of the pump. The performance envelope of the pump and the needs of the patient must be matched. The VentrAssist pump has no shaft, seals, or fixed bearings and relies on the fluid‐dynamic forces to maintain its effective performance. A number of different fluids have been tested to determine the effects of viscosity and density on pump performance. These include aqueous glycerol, red blood cells (RBCs) suspended in phosphate buffered saline solution (PBS), and Haemaccel. The effects of viscosity on the bearing stiffness, stage efficiency, and the pressure‐flow rate (HQ) are characterized. The experimental results show a slight increase in the pressure rise across the pump shown as a positive upward shift of the H‐Q curves with a decrease in viscosity; however, this is relatively small. A paradox in system efficiency exists: for a given fluid asymptotic viscosity, the system efficiency (product of magnetic and stage efficiency) using Haemaccel or PBS is greater than for the same viscosity of aqueous glycerol.
Impeller Design for a Miniaturized Centrifugal Blood Pump
Authors: Takano Tamaki , Schulte‐Eistrup Sebastian , Yoshikawa Masaharu , Nakata Kin‐ichi , Kawahito Shinji , Maeda Tomohiro , Nonaka Kenji , Linneweber Joerg , Glueck Julie , Fujisawa Akira , Makinouchi Kenzo , Yokokawa Michihiro , Nosé Yukihiko
Published: March 2003

Abstract: The impeller design for a miniature centrifugal blood pump is an important consideration since the small diameter impeller requires higher rotational speed, which may cause more blood trauma compared to the larger diameter impeller. Three different impeller vanes (straight vanes with a height of 4 mm and 8 mm, and 8 mm curved vanes) of which the diameter was 35 mm were subjected to hydraulic performance and hemolysis tests in the same pump housing. Both straight vane impellers attained left ventricular assist condition (5 L/min against 100 mm Hg) at 2,900 rpm while the curved vane required 3,280 rpm. There was no significant hemolysis difference between the tall and short vanes. The curved impeller vanes did not exhibit sufficient hydraulic performance when compared to the straight vanes. The straight vane impellers, even with different heights, were incorporated into the same pump housings, and the vane heights did not drastically change the hydraulic performance or hemolysis.
Hemodialysis Paradox: Survey on the Incidence Rate of Hepatocellular Carcinoma in Antihepatitis Virus C‐Antibody‐Positive Chronic Hemodialysis Patients
Authors: Ishida Hideki , Agishi Tetsuzo , Koyama Ichiro , Sawada Tokihiko , Murakami Toru , Utsumi Ken , Tsuji Kazuhiko , Kawase Tomonori , Ishii Yasuo , Ishimori Isamu , Kaneko Iwakazu , Tojimbara Tamotsu , Nakajima Ichiro , Mineshima Michio , Fuchinoue Shouhei , Yoshioka Takashi
Published: March 2003

Abstract: The prevalence of antihepatitis virus C (HCV) antibodies in chronic hemodialysis (HD) patients is higher than in normal populations, and yet hepatocellular carcinoma (HCC) is infrequent in chronic HD patients who are HCV antibody positive. In this study, we investigated the characteristics of HCV‐antibody‐positive patients with HCC on chronic HD. A total of 6,366 cases of HCV‐antibody‐positive patients on chronic HD therapy was analyzed on the basis of answers to questionnaires on the incidence rate of HCC in 314 Japanese dialysis institutions. HCC was a complication in 114 of 6,222 (1.8%) HCV‐antibody‐positive patients, and cirrhosis was a complication in 536 of 6,242 (8.6%). The incidence rate of both complications was significantly higher in males than in females, and the incidence rate in the chronic HD patients was much lower than in normal populations. Specific immunological status in patients on chronic HD therapy may be an important key for preventing the progression of chronic HCV hepatitis. However, further research is needed because this study was preliminary and excluded the type of HCV virus, pathological findings, and laboratory data.
Fluid Volumes Determination by Impedance Spectroscopy and Hematocrit Monitoring: Application to Pediatric Hemodialysis
Authors: Fenech Marianne , Maasrani Mahmoud , Jaffrin Michel Y.
Published: March 2003

Abstract: A method for extracting fluid volumes from multifrequency bioimpedance, which takes into account the body geometry and the presence of nonconducting elements, was tested on 12 young dialyzed patients against correlations for total body water volumes (TBW) from Watson et al. and Humes et al. Our calculations of TBW from impedance were found to overestimate Humes' values by 0.25 L (0.8%) postdialysis and by 2.08 L (6.5%) predialysis. Extracellular water (ECW) was found to contribute an average of 93% of ultrafiltered volume. Intracellular water volume (ICW) determination from impedance was found to be too imprecise to predict its variation during dialysis; therefore, ICW variations were calculated as the difference between ultrafiltration and ECW changes. The continuous recording of hematocrit by an optical device monitored changes in plasma and interstitial volumes. In most cases, ultrafiltration was compensated mainly by a contribution from interstitial fluid, and the drop in plasma volume was generally moderate.
First Experiences with Outpatient Care of Patients with Implanted Axial Flow Pumps
Authors: Wieselthaler Georg M. , Schima Heinrich , Dworschak Martin , Quittan Michael , Nuhr Martin , Czerny Martin , Seebacher Gernot , Huber Leopold , Grimm Michael , Wolner Ernst
Published: March 2003

Abstract: As known from patients with pulsatile ventricular assist devices (VADs), early mobilization, physical exercise, and return to normal life are essential for optimal recovery. Recently, implantable rotary pumps became available for extended left ventricular support as bridges to transplantation. Modified procedures are essential for patient training and hospital discharge. The MicroMed‐DeBakey VAD was implanted in 10 patients with end‐stage heart disease. After recovery, regular ergometer training was performed with loads adapted to the patient's condition. Procedures for patient observation under outdoor conditions and a blood pressure measuring device for low pulse pressure conditions were developed. Improvement of physical condition was achieved in 8 patients. In the first 2 patients, exercise capacity was limited due to flow obstruction. In the following patients, an increase of workload on the ergometer up to 120 W was observed. Correlated with training, lactate/load relationship and heart rate decreased. Three patients were discharged from the hospital during support. The DeBakey‐VAD system can support patients for extended time periods and is suitable for recovery and exercise. Under optimal patient and environmental conditions, discharge from the hospital can be obtained.
Effects of a Vitamin E‐Modified Dialysis Membrane and Vitamin C Infusion on Oxidative Stress in Hemodialysis Patients
Authors: Eiselt Jaromír , Racek Jaroslav , Trefil Ladislav , Opatrný Karel
Published: March 2003

Abstract: Hemodialysis deteriorates oxidative stress. Vitamin E is an antioxidant whose regeneration is provided for by vitamin C. The authors tested the effects of a vitamin E‐modified membrane (E), nonmodified cellulose membrane (O), and vitamin C infusion (500 mg, C) into the arterial blood line during dialysis on parameters of oxidative stress. In a short‐term study, 24 patients were subjected to a single dialysis session with E, O, E with C, and O with C protocols. In a long‐term study (12 weeks), 20 patients were randomized into groups with C and without C on each dialysis, and both groups had dialysis using O, E, and again O membrane for 4 weeks each. In the short‐term study, thiobarbituric acid reacting substances (TBARS) in plasma rose after dialysis (p < 0.02) with O, and no changes were observed in the other 3 protocols. In the long‐term study, predialysis TBARS declined when using E both in the groups with C (p < 0.02) and without C (p < 0.05). A switch over to O resulted in TBARS returning to baseline levels. The E membrane prevented an increase in lipid peroxidation during single dialysis, and long‐term use of the E membrane also resulted in a decrease in the predialysis lipid peroxidation level. The antioxidant capacity of the E membrane was not enhanced by vitamin C infusion. High doses of vitamin C administered during dialysis using a nonmodified cellulose membrane prevented an increase in lipid peroxidation, most probably due to the enhanced rate of endogenous vitamin E regeneration.
Growth and Metabolic Activity of Immortalized Porcine Hepatocytes in Extracorporeal Hollow‐Fiber Liver Assist Devices
Authors: Liu Jin , Jauregui Hugo O. , Faris Ronald A. , Santangini Henry A. , Trenkler Donna M. , Silva Paul G. , Garcia Kathleen M.
Published: March 2003

Abstract: The development of a cell based extracorporeal liver assist device offers a promising clinical approach to bridge individuals suffering from acute liver failure to transplant. However, a major drawback of the existing technology is the lack of a continuous supply of well differentiated hepatocytes. Although some investigators have used primary porcine cells, this approach demands costly, labor‐intensive isolation procedures and yields cells with inconsistent detoxification capacity. The limitations of primary cells led us to develop the HepLiu immortalized porcine hepatocyte cell line for use in liver assist devices (LADs). HepLiu cells are nontumorigenic and exhibit multiple hepatic detoxification functions including diazepam and acetaminophen metabolism. To investigate the suitability of HepLiu cells for artificial liver support, morphology, as well as xenobiotic metabolism, was studied in perfused polysulfone hollow‐fiber LADs. HepLiu cells were cultured in the intercapillary space of a prototype LAD, and the metabolism of diazepam, acetaminophen, and 7‐ethoxycoumarin was evaluated over 25 days in culture. Our results indicated that HepLiu cells proliferated rapidly following inoculation of the LAD until Day 10 when proliferation appeared to cease. Ultrastructural analysis demonstrated that HepLiu cells retained many of the features of primary hepatocytes including desmosomes that sealed bile canalicular‐like structures and junctional complexes (intermediate, gap junctions) that appeared concentrated in the paracanalicular areas. Unlike primary porcine hepatocytes, HepLiu cells retained drug metabolic function throughout the 25 day culture period. Diazepam metabolism by HepLiu cells was consistently higher than that of primary cells. Acetaminophen metabolism persisted throughout the 25 day period albeit at a much lower level than the primary cells exhibited on Days 1 or 2. In conclusion, we have shown that HepLiu cells proliferate to occupy the intercapillary space of perfused hollow‐fiber LADs following inoculation, and retain their metabolic capacity for Phase I and Phase II detoxification reactions in perfusion culture. Our findings suggest that HepLiu cells may provide an alternative to primary porcine hepatocytes as the cellular component of bioartificial liver support systems.
New Trends in Extracorporeal Membrane Oxygenation in Newborn Pulmonary Diseases
Authors: Somme Stig , Liu Donald C.
Published: March 2003

Abstract: New trends in extracorporeal membrane oxygenation (ECMO) for respiratory failure in the newborn were reviewed. Following a decade of clinical research, ECMO is now the standard treatment for newborn respiratory failure when all other conventional less‐invasive treatment options have been exhausted. As of July 2000, 15,525 newborns with respiratory failure treated with ECMO have been entered into the registry of the Extracorporeal Life Support Organization with an overall survival rate of 78%. The latest improvement in ECMO technology in this group of patients includes minimally invasive modes of vascular access through percutaneous approaches to minimize morbidity. However, with advances in modes of mechanical ventilation, including high‐frequency ventilation and the introduction of inhaled nitric oxide, the use and necessity for ECMO have clearly diminished for newborn respiratory failure.
Initial Stability of a Cementless Acetabular Cup Design: Experimental Investigation on the Effect of Adding Fins to the Rim of the Cup
Authors: Baleani Massimiliano , Fognani Roberta , Toni Aldo
Published: March 2003

Abstract: Different design solutions have been suggested for improvement of the initial stability of cementless acetabular cups, such as adding threads, spikes, or pegs to the hemispherical geometry, the pore structure of the surface; and screw fixation. This experimental study investigated the effect of fins on the initial stability of the acetabular cup. Three designs were studied, with none, 2, and 12 fins, respectively. The cups were press fit into cavities reamed in 2 different polyurethane foams, used to simulate 2 qualities of cancellous bone. Two millimeter press‐fit and exact‐fit conditions were investigated. The results show that the type of substrate and the interference value are important in determining the initial stability of the cup. The addition of fins on the cup rim enhances in vitro the initial stability, especially in cases of a poor press fit with a good substrate. This preclinical investigation suggests that the use of a cup design with fins may be beneficial in all cases in which press fit of the cup cannot be assured. However, further clinical studies are required to validate in vivo the efficacy of the fins as additional fixation devices.
Gas Transfer Performance of a Hollow Fiber Silicone Membrane Oxygenator: Ex Vivo Study
Authors: Kawahito Shinji , Maeda Tomohiro , Takano Tamaki , Nonaka Kenji , Linneweber Joerg , Mikami Minoru , Motomura Tadashi , Ichikawa Seiji , Glueck Julie , Sato Koshiro , Kuwana Jiro , Nosé Yukihiko
Published: March 2003

Abstract: Based on the results of in vitro studies of many experimental models, a silicone hollow fiber membrane oxygenator for pediatric cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) was developed using an ultrathin silicone hollow fiber with a 300 μm outer diameter and a wall thickness of 50 μm. In this study, we evaluated the gas transfer performance of this oxygenator simulating pediatric CPB and ECMO conditions. Two ex vivo studies in a pediatric CPB condition for 6 h and 5 ex vivo studies in an ECMO condition for 1 week were performed with venoarterial bypass using healthy calves. At a blood flow rate of 2 L/min and V/Q = 4 (V = gas flow rate, Q = blood flow rate) (pediatric CPB condition), the O2 and CO2 gas transfer rates were maintained at 97.44 ± 8.88 (mean ± SD) and 43.59 ± 15.75 ml/min/m2, respectively. At a blood flow rate of 1 L/min and V/Q = 4 (ECMO condition), the O2 and CO2 gas transfer rates were maintained at 56.15 ± 8.49 and 42.47 ± 9.22 ml/min/m2, respectively. These data suggest that this preclinical silicone membrane hollow fiber oxygenator may be acceptable for both pediatric CPB and long‐term ECMO use.
Development of Cellulose‐DNA Immunoadsorbent
Authors: Kong Deling , Schuett Wolfgang , Dai Jun , Kunkel Siegfred , Holtz Manfred , Yamada Ryo , Yu Yaoting , Klinkmann Horst
Published: March 2003

Abstract: The aim of this study was to prepare a DNA immunoadsorbent for the specific, extracorporeal removal of anti‐DNA antibodies from the blood of patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Two kinds of cellulose beads were applied as a carrier. Calf thymus DNA was covalently coupled to the carrier using the epichlorohydrin method. Efforts were focused on optimization of conditions for activation and coupling, trying to couple as much DNA as possible to a certain amount of carrier. It was found that the activation level increased with the increase of NaOH concentration and the amount of epichlorohydrin used. The mole of epichlorohydrin must be in excess of that of NaOH because excess NaOH could react further with the epoxy groups in the beads resulting in a decrease of activation level. High activation level could be obtained in a medium of 3.0 M NaOH. The DNA coupling was found to be mainly temperature and pH dependent. Using 0.1 M Tris‐HCl buffer, pH 8 at a temperature of 50–90°C, more than 3 mg of DNA could be coupled to 1 ml of wet beads. Prolonging the coupling reaction under 50°C to 72 h resulted in the same coupling capacity as that obtained under 90°C. To evaluate the adsorption ability for anti‐DNA of this immunoadsorbent, batch and circulation tests were applied using SLE patient plasma. The immunoadsorbents showed excellent adsorption capacity, especially the cellulose with smaller size (200–300 μm). The incubation of 20 ml of patient's plasma with 1 ml of adsorbent resulted in an 80% decline in the anti‐DNA antibody level. In the circulation tests, 30 ml of plasma was circulated through a column containing 3 ml of adsorbent. The maximum decline in anti‐DNA level, 80%, was obtained after 60 min. Such high adsorption capacity and high adsorption rate suggest this immunoadsorbent may be used for treatment. For comparison, 1,4‐butanediol diglycidyl ether activation method and other DNA sources were tested with the same protocol.