Search

Calcified coronary lesions have been one of the more difficult types of lesion for interventional treatment, and angioplasty is required to break the calcification before stent implantation so that the stent can expand smoothly, however, it remains unclear which type of angioplasty is optimal for different calcified lesions. In this study, a finite element approach was used to model normal balloons, cutting balloons, and AngioSculpt balloons. In addition, calcified lesions of different degrees, thicknesses, and lengths were modeled according to Intravascular ultrasound (IVUS) calcification grade. The above three balloons were used to pretreat calcified lesions, and the brittle fracture module for calcification was used to detect fracture success, to facilitate virtual stent implantation after predilation. The simulation results showed that with a thickness of less than 0.3 mm, balloons were unable to deal with calcified plaques in lesions of less than 120°, for 180° calcified lesions the cutting balloon fractured the calcified material at 1.2 MPa, the AngioSculpt balloon produced multiple fractures at 0.8 MPa for 270° calcified plaques, but was unable to fracture calcified lesions with a thickness of 0.4 mm. Based on these results, we conclude that the length of the lesion did not affect calcification fracture, while the thickness of the lesion did. In calcified lesions of approximately 180°, the cutting balloon showed the best predilation results, while the AngioSculpt balloon was optimal for 270°. In annular calcification, all three balloons were unable to fracture the lesion.

Post-balloon expansion is considered as an appropriate procedure for adequate stent expansion for coronary bifurcation lesions. Two post-balloon expansion procedures are currently recommended: proximal optimization technique (POT)/side/POT and POT/kiss/POT. However, the effects of the two post-balloon expansion treatments are different. There is a lack of biomechanical study to quantify the difference.It is recognized that biomechanical factors influence the occurrence of Major Cardiovascular Adverse Events (MACE), which includes recurrent angina pectoris, acute myocardial infarction and coronary heart disease death. The current paper evaluated the two post-expansion strategies and quantified biomechanical parameters to provide a basis for clinical decisions.Based on the CTA data of a patient diagnosed with coronary bifurcation lesions, a personalized coronary bifurcation lesion model was constructed, and the surgical procedure after two expansions was simulated. The POT/side/POT and POT/kiss/POT expansion procedures were analyzed from the perspective of biomechanics through finite element analysis. The biomechanics factors, including the percentage of stent malapposition and stent occlusion at the side branch (SB) opening, the stent ellipse index of proximal main vessel (PMV) segment, the minimum lumen area of the stent vessel segment and the stress distribution of the vessel wall, were used to quantify clinician concerns about factors affecting patient outcomes. The factors include stent adhesion, SB open stent occlusion, poor stent deformation, patency effect of vessel stenosis and vessel wall damage.Both post-expansion procedures were successfully simulated. The malapposition rate during POT/side/POT was larger (1.2% vs 0.42%) and stent occlusion at the SB opening from the cross-section perpendicular to the SB opening after the POT/side/POT procedure was 0.20%, compared with 0.00% after POT/kiss/POT. POT/kiss/POT produced a larger PMV segment stent ellipse index. Minimum lumen area after POT/side/POT was 5.6 mmNumerical simulations provide a quantitative analysis to inform clinicians of the differences between preoperative planning and surgical procedures. Biomechanical analysis of the differences between the two post-expansion strategies found that the POT/kiss/POT procedure resulted in better stent fit, less occlusion of the SB open stent and better vascular patency but also resulted in poor stent deformation and caused greater vessel wall stress. The current study informs rationales for clinical understanding of post-expansion strategies. This article is protected by copyright. All rights reserved.

Since the mapping relationship between definitized intra-interventional 2D X-ray and undefined pre-interventional 3D Computed Tomography(CT) is uncertain, auxiliary positioning devices or body markers, such as medical implants, are commonly used to determine this relationship. However, such approaches can not be widely used in clinical due to the complex realities. To determine the mapping relationship, and achieve a initializtion post estimation of human body without auxiliary equipment or markers, a cross-modal matching transformer network is proposed to matching 2D X-ray and 3D CT images directly. The proposed approach first learns skeletal features from 2D X-ray and 3D CT images. The features are then converted into 1D X-ray and CT representation vectors, which are combined using a transformer module. As a result, the well-trained network can directly predict the spatial correspondence between arbitrary 2D X-ray and 3D CT. The experimental results show that when combining our approach with the conventional approach, the achieved accuracy and speed can meet the basic clinical intervention needs, and it provides a new direction for intra-interventional registration.

Proximal Optimization Technique (POT) is a post-expansion technique that must be completed after single-stent implantation for the coronary bifurcation. The optimal location for the distal balloon shoulder during POT remains debatable. In the present study, the finite element method is applied to simulate POT after single-stent implantation in the coronary bifurcation. Three different balloon locations based on the distal shoulder relative to the carina cut plane were analyzed: 1) “proximal”:1mm before carina cut plane; 2) “standard”: at the carina cut plane; and 3) “distal”: 1 mm after the carina cut plane. The computational results showed differences in stent, vessel morphology, and vessel wall stress due to the different balloon locations. However, when distal balloon shoulder was located between two adjacent stent rings, it formed the distal cell of the stent, the best stent apposition, least stent structs obstruction at SB ostial. Moreover, best opening effect of distal cell of the stent can be achieved, with the least damage to the vessel wall.

Coronary atherosclerotic plaques progress in a highly individual manner. Accurately predicting plaque progression will promote clinical management of atherosclerosis. The purpose of this study was to investigate the role of local biomechanics factors and vascular characteristics in coronary plaque progression and arterial remodeling.Computed tomography angiography-based three-dimensional reconstruction of the native right coronary artery was performed in vivo in twelve patients with acute coronary syndrome at baseline and 12-month follow-up. The reconstructed arteries were divided into sequential 3-mm-long segments. Wall shear stress (WSS) and von Mises stress (VMS) were computed in all segments at baseline by applying fluid-structure interaction simulations.In total, 365 segments 3-mm long were analyzed. The decrease in minimal lumen area was independently predicted by low baseline VMS (-0.73 ± 0.13 mmLocal von Mises stress, wall shear stress, minimal lumen area, and plaque burden provide independent and additive prediction in identifying coronary plaque progression and arterial remodeling.

Effective anticoagulation regimens are needed to reduce risks of thrombosis and bleeding in animal models of ventricular assist device to verify its hemocompatibility, biologic safety and reliability. This study is to develop a validated anticoagulation procedure for a sheep model to test the newly developed CH-VAD. CH-VAD models were established in six healthy sheep by constructing blood bypass of left ventricle → ventricular assist device → descending aorta. Heparin infusion was used during operation and in the prior 4 days to maintain activated clotting time 1.5-2.0 times the baseline. From the third day, proper dosage of warfarin was used orally to maintain international normalized ratio values within the range of 1.2-2.0. After termination, we examined whether there was thrombosis in the blood pump, grafts, and anastomotic stoma. Macroscopic and histopathologic examinations were performed in major organs to check for congestion and infarction. Bleeding complications were not found in any animals throughout the experiments. Activated clotting time values were 326 ± 33 s intraoperatively and 157 ± 28 s in the prior 4 days postoperatively. Activated partial thromboplastin time values increased slowly and reached the lower limit of the target range on the fourth day. Only in one of six cases was thrombus or fibrosis tissue found in the blood flow channel of the pump. Pathologic analysis showed no thrombosis, necrosis and microembolus in end-stage organs. Under the anticoagulation regimens, coagulation system could be well controlled to avoid thrombosis and bleeding complications in sheep models for CH-VAD.

Objective: Implantation of a ventricular assist device (VAD) is a seminal therapeutic option for patients with terminal cardiac failure. A growing number of VAD patients are successfully bridged to transplantation, or can even live permanently with the device. However, the success is restricted by frequent severe complications. Haemolysis is a relevant adverse effect of several VAD types, which is the result of destruction of red blood cells, reduced by wall shear stress, flow acceleration and interaction with artificial surfaces. The CH-VAD, a small implantable continuous-flow blood pump, featuring a magnetically levitated impeller and enough hydrodynamic performance, was under development and completed for a 60-days animal implantation experiment in 6 sheep. The goal of this study is to validate the hemolysis of the pump through in vitro and in vivo studies. Methods: A series of in vitro tests was quantified experimentally by using in vitro circulation loop system according to ASTM F1841, the standard practice for the assessment of hemolysis in continuous-flow blood pumps. The hemolysis test in vivo was performed during a 60-days ovine model implantation, which was being conducted under the Institutional Animal Care and Use Committee (IACUC) protocol 05-0600 1. Results in vitro tests showed that the average normalized index of hemolysis (NIH) value of the VAD was 0.007 mg/l. The hemolysis in vivo was evaluated based on the amount of free hemoglobin in the plasma, and which showed that the free hemoglobin level in plasma peaked at 0.95 mg/l on the fifth postoperative day and then returned to an acceptable range of 6.0 mg/dL. Conclusion The magnetic levitation left ventricular assist device has good hemolytic performance. These acceptable performance results supported proceeding initial clinical trail conditions.

Understanding plaque formation in patients at risk for coronary artery disease—the leading cause of morbidity and death in the world—enables physicians to better determine whether and how to treat these individuals. We used computed tomographic angiography to quantitatively evaluate the progression of nonculprit coronary plaques along the full length of the right coronary artery in 21 patients with acute coronary syndrome. Each right coronary artery was analyzed in sequential, 3-mm-long segments, and the minimum luminal area, plaque burden, and plaque volume within each segment were evaluated at baseline and at 12-month follow-up. Serial remodeling of the right coronary artery was also evaluated. In total, 625 arterial segments were analyzed. At 12-month follow-up, the plaque burden had increased slightly by 0.34% (interquartile range [IQR], −4.32% to 6.35%; P=0.02), and the plaque volume was not significantly changed (0.33 mm3; IQR, −3.05 to 3.54; P=0.213). The minimum luminal area decreased 0.05 mm2 (IQR, −1.33 to 0.87 mm2; P=0.012), and this was accompanied by vessel reduction, as evidenced by negative remodeling in 43% of the 625 segments. We conclude that serial computed tomographic angiography can be used to quantitatively evaluate the morphologic progression of coronary plaques.

Effective anticoagulation regimens are needed to reduce risks of thrombosis and bleeding in animal models of ventricular assist device to verify its hemocompatibility, biologic safety and reliability. This study is to develop a validated anticoagulation procedure for a sheep model to test the newly developed CH-VAD. CH-VAD models were established in six healthy sheep by constructing blood bypass of left ventricle → ventricular assist device → descending aorta. Heparin infusion was used during operation and in the prior 4 days to maintain activated clotting time 1.5-2.0 times the baseline. From the third day, proper dosage of warfarin was used orally to maintain international normalized ratio values within the range of 1.2-2.0. After termination, we examined whether there was thrombosis in the blood pump, grafts, and anastomotic stoma. Macroscopic and histopathologic examinations were performed in major organs to check for congestion and infarction. Bleeding complications were not found in any animals throughout the experiments. Activated clotting time values were 326 ± 33 s intraoperatively and 157 ± 28 s in the prior 4 days postoperatively. Activated partial thromboplastin time values increased slowly and reached the lower limit of the target range on the fourth day. Only in one of six cases was thrombus or fibrosis tissue found in the blood flow channel of the pump. Pathologic analysis showed no thrombosis, necrosis and microembolus in end-stage organs. Under the anticoagulation regimens, coagulation system could be well controlled to avoid thrombosis and bleeding complications in sheep models for CH-VAD.

The objective of this study was to establish an ovine model for CH-VAD (CH Biomedical Inc., JiangSu, China) implantable ventricular assist device (IVAD) to evaluate experimental protocols, including anesthesia management, surgical process, autopsy criteria and a validated anticoagulation procedure. Method: IVAD was implanted into the chest of sheep without stopping the beating heart through a left thoracotomy, and the inflow cannula was connected to the left ventricular apex and the outflow cannula was anastomosed to the descending aorta. Results: Totally 23 cases were established: 6 died of an anaesthetic or surgical reasons, one died of lung infection, the other 16 cases survived for more than 15 days, among which four cases were terminated because of decrease of pump flow and the other 12 cases survived for more than 30 days. Conclusions: Sheep models suitable for implantation of CH-VAD implantable LVAD were successfully established and the appropriate safety evaluation indicators of this model were validated in the course of the animal experiments, and the survival rate of the experiments were improved gradually over time.

Background Electro-anatomical maps (EAM) and CT surface registration are widely used for catheter navigation in atrial fibrillation ablations. However, few studies have investigated the registration algorithm. Moreover, some of them are semiautomatic, so that physicians must be proficient; some are inaccurate for catheter navigation. A both automatic and accurate registration method is needed. Method A Hausdorff distance based approach (HD) was proposed for EAM/CT registration. First, using principal axes based registration, EAM/CT pairs were coarsely aligned. Then, using Hausdorff distance as the fine objective function, EAM/CT pairs were finely aligned. Results Six real EAM/CT pairs were collected from five patients and 38 simulated pairs were generated. Each pair was aligned using Carto-Merge, a stochastic approach (SA) and HD. Considering the balance of operability, accuracy and robustness, HD obtained the best EAM/CT registration results among the three approaches. Conclusion Experiments validate that the proposed method registers EAM and CT surface both automatically and accurately.

Objectives: This study reports the development and evaluation of a Computerized Mandarin Speech Test System (CMSTS). Methods: Taking into account the rules for developing speech materials and the unique linguistic characteristics of Mandarin, we designed and digitally recorded a set of materials comprised of seven lists of monosyllabic words, nine lists of disyllabic words, and fifteen lists of sentences with a high degree of subject familiarity. The CMSTS was developed with Visual Studio 2008, Access 2003 and DirectX 9. The system included five functions: listener management, a speech test, list management, data management, and system settings. We used the system to measure the speech recognition threshold (SRT) of 76 participants with normal hearing (age range: 20-28 years), and measured performance-intensity functions (PI) for all stimuli. Results: The SRT results were in accord with pure-tone results obtained by pure-tone audiometry. In a speech recognition score (SRS) test, changing the presentation level had the strongest effect on sentence recognition, followed by the presence of disyllabic words. Monosyllabic words were least affected by changes in presentation level. The slopes of the linear portion of the PI using the system were in accord with the findings of previous studies using audiometers and CDs with similar materials. Conclusion: The CMSTS has sufficient sensitivity, and can facilitate the wider use of speech audiometry in Chinese audiology clinics.

Unbonded precast reinforced concrete frame is a new assembly architecture structure. This thesis studies deeply the crack development characteristics, failure pattern, hysteresis curve and the displacement ductility of unbonded precast reinforced concrete frame, by analyzing one unbonded precast reinforced concrete frame under low reversed cyclic load test. We build a model using finite element analysis software to the test piece model analysis, the analysis result consistent with the experimental results. Experimental studies indicate that assembly of prestressed reinforced concrete frame structure has a good seismic performance. This unbonded precast reinforced concrete frame is a new kind of structural system complying with the development of architectural engineering, which is useful in application in the earthquake area.

The CH-VAD is an implantable, fully magnetically suspended ventricular assist device developed by the China Heart Biomedical Corporation (Suzhou, China) for full cardiac support. This study was performed to evaluate the reliability, hemocompatibility and end-organ effects of CH-VAD in a 35-day animal model trial.The pump was implanted in 6 sheep. The pump inflow was inserted into the left ventricle and the outflow graft was anastomosed to the descending aorta. Data on pump function and the health condition of the animals, including hematologic and biochemical tests, were collected during the study period. When each study was determined to termination, the sheep were humanely euthanized and the end organs were examined macroscopically and histopathologically. Hemolysis was evaluated based on the amount of free hemoglobin in the plasma.Except for one device that stopped operation on postoperative day 25 because of thrombus formation, the devices functioned normally until the scheduled termination. Gross examination of the pump interiors, inflow and outflow, and of the arterial anastomosis sites showed no significant abnormalities. Hematologic and biochemical test results were within normal limits during the study period. Macroscopic and histopathologic examinations of the explanted organs revealed no evidence of ischemia or infarction associated with the device implantation, except for small foci of infarction in the kidneys of two sheep. The free hemoglobin level in plasma peaked at 9.5 mg/dl on postoperative day 5.The CH-VAD system demonstrated promising reliability and blood-handling characteristics without obvious damage to end organs during a 35-day implantation in sheep.

Background The CH-VAD is an implantable, fully magnetically suspended ventricular assist device developed by CH Biomedical Corporation for full cardiac support. This study was performed to evaluate the short-term (35 days) hematological, biochemical, and end-organ effects of the CHVAD left ventricular assist device (LVAD) in a sheep model trial. Methods Six sheep underwent CH-VAD implantation without the use of cardiopulmonary bypass. The pump inflow was inserted into the left ventricle and the outflow graft was anastomosed to the descending aorta. Data on pump function and the health condition of the animals, including hematologic and biochemical tests, were collected during the study period. When each study was determined to termination, the sheep were humanely euthanized and the end organs were examined macroscopically and histopathologically. Hemolysis was evaluated based on the amount of free hemoglobin in the plasma. Results Except for one device that stopped operation on the 25th postoperative day because of thrombus formation, the planned date of termination (35 days) was reached in all the animals without complication and device failure. Gross examination of the pump interiors, inflow and outflow, and of the arterial anastomosis sites showed no significant abnormalities. Hematologic and biochemical test results were within normal limits during the study period. Elevations observed in the levels of white blood cell count, and decreases in hematocrit, hemoglobin, and red blood cell count were of short duration, these parameters returned to normal within 20days of surgery. Serum urea nitrogen, creatinine, SGPT(ALT), SGOT(AST), and lactate dehydrogenase levels showed transient increases within the first five days of surgery. Other biochemical parameters were within normal limits. Macroscopic and histopathologic examinations of the explanted organs revealed no evidence of ischemia or infarction associated with the device implantation, except for small foci of infarction in the kidneys of two sheep. The free hemoglobin level in plasma peaked at 9.5 mg/dL on the fifth postoperative day. Conclusions Hematological, biochemical, and end-organ functions were not adversely affected by short-term CH-VAD system.

The instant mechanical behaviors of stenotic coronary artery and deployed stents have significant impacts on percutaneous coronary intervention prognosis. However, they could not be obtained directly from the current examination techniques, which are commonly used in clinical practice. Thus, we intend to investigate the instantaneous mechanical behaviors of deployed stent and artery through virtually stenting technology based on a real clinical case in assessment of geometric and biomechanical characteristics. Method: Finite element analysis models, including rigid guide catheter, six-folded balloon with conical tip, crimped and bended stent, stenotic coronary artery with soft plaques, were simulated through virtual mechanical expansion and recoil procedure. The morphology changes of coronary lumen, strain and stress distribution of involved components at different stages and apposition of stent struts were analyzed. Results: Lumen in the stenotic region restored patency obviously at maximum expansion and had an elastic recoil about 13.5% later. The maximum principal stress distribution of artery walls and plaque was mainly concentrated in the stenotic segment with the peak value of 1.252[Formula: see text]MPa and 2.975[Formula: see text]MPa at max expansion, 0.713[Formula: see text]MPa and 1.25[Formula: see text]MPa after recoil, respectively. The higher von Mises stress and plastic equivalent strain of stent were present at the bended strut and inter-ring connectors with the peak value of 714.2[Formula: see text]MPa and 0.2385 at max expansion, 694[Formula: see text]MPa and 0.2276 after recoil. Slight malappositions were found in the proximal segment and struts distribution in the stenotic sites showed certain asymmetry. Conclusion: The instant mechanical behaviors of artery and stent could be evaluated through virtual stenting approach in assessment of geometric and biomechanical characteristics. This may contribute to choosing the best stenting schemes and predicting the clinical outcomes for a specific patient.

A small implantable centrifugal left ventricular assist device, the CH-VAD (CH Biomedical Inc, JiangSu, China), featuring a magnetically levitated impeller is under development. The goal of this study is to validate hydrodynamic performance and hemocompatibility of the pump through in vitro studies. The hydraulic performance was quantified experimentally by using in vitro circulation loop system, and it turned out that the pump could deliver 5[Formula: see text]L/min under a pressure of 100[Formula: see text]mmHg at a rotational speed of approximate 3400[Formula: see text]rpm. A series of in vitro tests were established according to ASTM F1841, the standard practice for the assessment of hemolysis in continuous-flow blood pumps. The results showed that the average normalized index of hemolysis (NIH) value of the VAD was 0.0007[Formula: see text][Formula: see text][Formula: see text]0.0003[Formula: see text]mg/dL. The magnetic levitation left ventricular assist device (LVAD) has good hemolytic performance and stable mechanical property. These acceptable performance results supported proceeding initial acute animal testing conditions.

The paper reported three new species from Taiwan, i.e. Xizicus (Eoxizicus) taiwanensis sp. nov., Xizicus (Axizicus) falcata sp. nov. and Decma (Decma) brachyptera sp. nov., supplied the descriptions and illustrations.

Background Tongxin left ventricular assist device (LVAD), an implantable magnetic suspending VAD developed in Chinaheart Biomedical Incorporation aiming for clinical use, weighs about 350g and can deliver 6 L/min for pressures of 145 mm Hg at 2,500 rpm. Objective This study aimed to investigate the implantation possibility, hemolysis and hemocompatibility of the LVAD before clinic use. Methods The tests of implantation possibility, hemolysis and hemocompatibility to the LVAD were completed by fitting study, hemolysis test and in vivo experiments respectively. Meanwhile the hemolysis was evaluated by the amount of free hemoglobin in plasma and studied using the normalized index of hemolysis (NIH). Results The fitting study showed that the blood pump could be implanted in the sheep heart chambers without squeezing the surrounding organs by comparing the preoperative and the postoperative chest X-ray. the NIH value of Tongxin LVAD was 0.0075±0.0017g/100L in vitro hemolysis test. Two sheep in vivo experiments showed the hemolysis in vivo was below 7.5 mg/dL. Hematologic and biochemical test results were within normal limits during the study period. There were no significant complications. Postmortem examination of the explanted organs revealed no evidence of microemboli, ischemia or infarction. The pump’s inflow and outflow conduits were free of thrombus. Conclusions These results indicated that the implantable magnetic suspending LVAD showed exceptional implantation possibility, hemolysis and hemocompatibility, which are crucial to the clinical success of this implantable LVAD.

Objective: In order to improve detection method of non-invasive pulse wave detector, taking into account the operation complexity of the radial artery test, a simple finger pulse detection are choose. Methods: Through a large number of clinical data analyses, the conversion relationship of the radial artery pulse detection and volume pulse wave detection was determined, hemodynamic parameters based on the volume pulse wave were calculated and test results were compared with results of echocardiography. Results: The differences of hemodynamic parameters detected by volume pulse and echocardiography were not statistically significant. Conclusion: It is showed that the application of cardiac output and other blood flow parameters detection by the method of volume pulse wave is feasible.

Aims: the purpose of this study was to develop a new left ventricular assist device which causes less blood damage. Methods: During design of the device, the method of Computational Fluid Dynamics (CFD) was used to optimize the device shape, number of impeller vanes, the structure and position of the guide vanes, and the size of the impeller screw-pitch. After that the device, that was an axial flow blood pump, was produced without an absolute brushless DC motor and was constructed with a housing, an impeller with two blades, three guide vanes, ceramic bearings, and an inlet and outlet. We measured the dynamic and hemolysis performances and the surface temperature in an in vitro experiment. We also detected the trauma inflicted by this pump on the blood by testing to failure on a goat heart. Results: the experimental tests indicated that the dynamic performance of the axial flow pump included a nearly 6 L/min flow rate against a pressure of 100 mmHg with rotation at 10000 rpm, that output could satisfy demand during use as a left ventricular assistant device (LVAD). The normalized index of hemolysis (NIH) values from in vitro and in vivo experiments were 0.047±0.017 mg/ 100 mL and 0.016±0.011mg/100 mL, respectively. The results showed that the blood pump designed using CFD showed far less damage to blood than the previous pumps and also showed improved durability as tested in vivo in animals.

to analyze prognostic factors of patients with severe liver disease and develop a prognostic model for them which is fitful to the characteristics of our country. From March 2002 to June 2007, the 527 patients with severe liver disease were evaluated, the follow-up information were collected include the survival state (death/survival). The survival model was established by using COX proportional hazard model. New 400 cases were used to test and evaluate the decision capability of the model. Nine prognostic factors were extracted by using COX, the prognostic index (PI) was calculated. By statistics analyze to compare the ROC area (AUC) of this system model with CTP and MELD, this system meld is better than CTP and MELD. The developed model is fitful to the characteristics of our country where there are a lot of virus hepatitis patients, so the model is valuable in prognostic evaluation of severe liver patients and very useful to guide clinicians in selecting treatment methods in China.

Cell culture studies, ring studies, and indirect physiologic studies are the predominant models used to study human vascular tissue. Such studies are limited in their capacity to permit physiologic single-factor changes or to provide the proper mechanical effects. This paper presents a devised culture system that addresses the vessels with different diameters and permits survival of intact segments of the vessels in a perfused environment. Methods: Perfusion culture system was designed and constructed with a peristaltic pump, tubing, a vessel culture chamber, a compliance chamber, a pressure regulator, a pressure monitor, silicon tubing and some spigots in several diameters, which could connect to the chambers’ polycarbonate tubing and silicon tubing, suitable for several size of vessels. Vein segments of rabbits, with 2.0mm, 4.0mm and 6.0mm sizes, were collected and mounted into the perfusion culture system with perfusate. The intraluminal pressure, pulsatile pressure difference and flow were surveyed. The results showed vessels in several sizes could be cultured in a controlled environment of dynamic changes with easy manipulation. This perfusion culture system permits relevant studies risk factor changes in the perfusate.

Hemolysis caused by blood pumps is a very important characteristic. In vitro hemolysis test circuits were constructed to operate the model I centrifugal pump, the model II axial flow pump, the magnetic coupling pump and the model III spiral mixed pump. The output of all pumps was set at flow 5 L/min, an average pressure of 100 mmHg. Experiments were conducted for 4 hours at room temperature(25 degrees C) with 500 ml fresh anticoagulant sheep blood. Blood samples were taken for plasma free-hemoglobin measurement, and the change in temperature at the pump outlet port was measured during the experiment. Calculate the normalized index of hemolysis (NIH). The results showed that there was no relationship either between the pump rotational speed and the NIH in five types of blood pumps, or between change in temperature at the pump outlet port and NIH. The dynamic fluid field caused by pump design and structure could be the main cause of blood damage.