Axial Blood Research Articles

Influence of circumferential annular grooving design of impeller on suspended fluid force of axial flow blood pump.

Aiming at insufficient suspension force on the impeller when the hydraulic suspension axial flow blood pump is start at low speed, the impeller suspension stability is poor, and can't quickly enter the suspended working state. By establishing the mathematical model of the suspension force on the impeller, then the influence of the circumferential groove depth of the impeller on the suspension force is analyzed, and the annular groove depth on the impeller blade in the direction of fluid inlet and outlet was determined as (0.26, 0.02 mm). When the blood pump starts, there is an eccentricity between the impeller and the pump tube, the relationship between the suspension force and the speed of the impeller under different eccentricities is analyzed. Combined with the prototype experiment, the circumferential annular grooving design of the impeller can make the blood pump rotate at about 3500 rpm into the suspension state, when the impeller is at 8000 rpm, the impeller can basically achieve stable suspension at the eccentricity of 0.1 mm in the gravity direction, indicating that the reasonable circumferential annular grooving design of the impeller can effectively improve the suspension hydraulic force of the impeller and improve the stability of the hydraulic suspension axial flow blood pump.

New way of closure of upper jaw defects

Article describes new original way of one-stage closure of upper jaw defects by using cutaneous-adiposal flap. The method is patented (patent of the Russian Federation for invention No. 2489096). We propose to use cutaneous-adiposal flap, mobilized in nasolabial furrow area, with axial pattern blood supply from angular artery and vein, by rotating to defect through buccal tonnel. This method allows to reliably eliminate upper jaw defect, improve functional and aesthetic results of treatment with minimal injuries caused by operation.Objective is to introduce new way of closure of upper jaw defects.

Analysis of a Novel Magnetic-Hydrodynamic Double Levitated Motor for an Implantable Axial Flow Blood Pump

This paper presents a novel design for a bearingless axial flow blood pump based on the magnetic-hydrodynamic double levitated concept. In the axial direction, the magnetic levitation system consisted of two pairs of permanent magnet rings offsets the force of fluid. The hydrodynamic shell mounted on the impeller rotor is designed for generating dynamic pressure, which can balance the radial force like gravity when the blood pump is working. Because of the unsteady force and torque acting on the rotor and the passive suspension, the position of the rotor is not steady. The suspension force, stiffness, and torque of the rotor are calculated by the theoretical method and finite element method. Then, the dynamics of the rotor are analyzed. Arrangements of Hall-effect sensors with the corresponding data acquisition system which can measure the axial displacement of the rotor are explained. The sensorless drive control system for the blood pump is described too. With a prototype pump, an external circulation experiment system is built and then the axial and radial displacements of the rotor are measured by using Hall-effect sensors and the laser vibrometer under different working conditions.

Structural Characterization of Glaucoma Patients with Low Ocular Blood Flow

ABSTRACT Purpose: There is an unclear relationship between ocular blood flow (OBF) and the structural characteristics of the optic nerve head (ONH) in glaucoma, a multifactorial disease. This study used laser speckle flowgraphy (LSFG) to identify low-OBF glaucoma patients and investigated the ONH in these patients. Materials and Methods: In 533 eyes with glaucoma, we determined confounding factors for LSFG-measured OBF (tissue-area mean blur rate: MT) and corrected MT with a linear mixed-effects model (LMM). Structural ONH data (from fundus stereo photography), OCT data, and clinical characteristics were then compared in patients with corrected MT in the upper and lower quartiles using the LMM. Results: Single regression showed significant correlations between MT and age, spherical equivalent (SE), central corneal thickness (CCT), and a weighted count of retinal ganglion cells (wRGC), but not axial length or systemic blood pressure. Gender also significantly influenced MT; MT was corrected for these correlated factors and also glaucoma type with the LMM. The lower-quartile MT group had a significantly larger cup area and cup-disc area ratio and lower temporal quadrant circumpapillary retinal nerve fiber layer thickness (cpRNFLT) and macular ganglion cell complex (GCC) than the upper-quartile group. Conclusions: Low-OBF glaucoma patients were characterized by a larger cup-disc ratio, and higher susceptibility to damage in the temporal disc and the macular area.

Measurement of Internal Flow of an Axial Flow Blood Pump with Eccentric Drive by Using PIV and Estimation of Thrombus Formation Area in the Flow

Measurement of Internal Flow of an Axial Flow Blood Pump with Eccentric Drive by Using PIV and Estimation of Thrombus Formation Area in the Flow

Clarification of Internal Flow Characteristics of an Axial Flow Blood Pump with Eccentric Drive

Clarification of Internal Flow Characteristics of an Axial Flow Blood Pump with Eccentric Drive

Modeling of Internal Filtration in Theranova Hemodialyzers.

High retention onset (HRO) is the designation for a new class of hemodialysis membranes. A unique characteristic of this class is the highly selective and controlled porosity resulting in sieving properties that provide a clinically desirable balance between middle/large molecular weight solute removal and albumin loss. Another defining feature of this membrane class is the relatively small fiber diameter, which produces high convective volumes in the form of internal filtration. The aim of the present study was to estimate, by semi-empirical methods, convective volumes for 2 new HRO dialyzers: Theranova 400 and Theranova 500 (Baxter International Inc., Deerfield, IL, USA). Axial blood and dialysate compartment pressure drop along with transmembrane pressure, measured in vitro with blood (Qb = 300 or 400 mL/min; Qd = 500 mL/min; net ultrafiltration rate = 0), served as input parameters for 3 different models: linear, geometric, and (non-linear) mathematical. Based on the most rigorous mathematical model, the estimated convective volumes were 1,661 mL/h (Qb = 300 mL/min) and 1,911 mL/h (Qb = 400 mL/min) for Theranova 400 and 1,864 mL/h (Qb = 300 mL/min) and 1,978 mL/h (Qb = 400 mL/min) for Theranova 500. These results suggest that the unique fiber characteristics of this new class of membranes provide substantial convective volumes without the need for exogenous substitution fluid. As such, HRO membranes are a major end-stage renal disease treatment advance in the quest to enhance the removal of larger-sized uremic toxins.

Study on Driving Performance of the Axial-Flow Blood Pump under the Condition of Large Gap

The paper demonstrates an improvement of the simulation and computational methods for research on the system magnetic field and driving performance of the large gap magnetic drive system, which is used to drive the axial flow blood pump. The operational principle and structure of large gap magnetic drive system are narrated. Ansoft is adopted to simulate a three-dimensional driving torque to improve accuracy of computation. Experiments and theoretical study show that the use of Z10-T25 oriented silicon steel sheets as the electromagnetic core material can remarkably improve the system driving performance as well as optimize the volume and weight of the electromagnets. So the electromagnet made with oriented silicon steel sheets is conducive to improving the driving performance.

The research on the influence of kinetic parameters on the vibration of blood pump in viscoelastic implantation environment

The implantable axial flow blood pump would be vibrated when in actual use because of the viscoelastic implantation environment, unbalanced driven force, high speed rotor and so on. The blood pump researched in the paper was designed to be implanted in ascending aortic and driven by external magnetic force. The kinetic equation of blood pump worked in viscoelastic implantation environment was built, and then the blood pump’s vibration influenced by viscoelasticity of implantation environment, running speed of blood pump, weight of blood pump were studied. Appropriate damping coefficient of implantation environment, running speed of blood pump and weight of blood pump for blood pump’s more stable working were found in the paper. The paper could provide theoretical basis and research method for blood pump’s structure parameters and work performance improving.

RECONSTRUCTIVE MICROSURGERY IN THE TREATMENT OF SURFACE FORMS OF CALCANEal OSTEOMYELITIS

One of the most common complications associated with the treatment of calcaneus fracturesis, a necrosis of the edges of the surgical wound and as a result – chronic nonhealing ulcers of the heel region and osteomyelitis of the calcaneus. In the structure of skeletal lesions osteomyelitic chronic osteomyelitis of the calcaneus occurs in 3.1–14.8% of cases, and in relation to the bones of the foot – up to 51%. At the same time after open fractures of the total incidence of deep infection from soft tissue even higher than that for the surface (12.2% vs. 9.6%). The traditional approach to the treatment of osteomyelitis of the calcaneus is often accompanied by poor performance with recurrent osteomyelitis process and highsubsequent disability of working age.Objective: to identify opportunities and assess the effectiveness of the use of reconstructive microsurgery techniques in the treatment of patients with superficial forms of osteomyelitis of the calcaneus, accompanied by the presence of soft tissue defect.Materials and мethods.The results of treatment of 28 patients with superficial forms of osteomyelitis of the calcaneus, which in the period from 2006 to 2013 in RNIITO them. R.R.Vredena were performed reconstructive plastic surgery using microsurgical techniques. Defects covering tissues were located on the sole (20) and back-side surfaces (8) of the calcaneus. Scope of interventions included the radical surgical treatment of osteomyelitis focus, marginal resection of the affected heel bone and tissue replacement of defect cover flap with axial blood supply.Results. With the localization of the defect cover tissues to non-reference surface of the heel region was carried out free plastic ray skin-fascial flap (9 cases). When the location of the defect on the plantar surface of the heel region favored medial plantar flap (10 cases). However, the presence of scarring and damage to the medial plantar artery was performed two-step replacement of defect prefabrikovannym flap medial arch of the foot (9 cases). Complications were observed in 7% of cases (2 patients) in 1 patient who had undergone plastic free radial flap in 1 case – after replacing a defect medial plantar flap. In both cases they were associated with impaired blood supply to the flap and ended necrosis of transplanted grafts. In the remaining cases (93%) failed to achieve full engraftment. Long-term results were followed up in 78,5% (n = 22) of patients in the period from 1 to 8 years after the end of treatment. In four cases, the plantar surface of the calcaneus formed edge wound defects, require additional surgical treatment. on the AOFAS scale results averaged 85 points, that, given the severity of the disease, regarded as a good result.Conclusions. The use of microsurgical techniques for the treatment of patients with superficial forms of osteomyelitis of the calcaneus, including the presence of soft tissue defect, achieves sustained remission osteomyelitic process and restore support ability of the injured limb. Thus the support surface for the replacement of the heel region is expedient to use grafts comprising the plantar surface of the foot skin.

Vortical flow characteristics of mechanical cavopulmonary assistance: Pre- and post-swirl dynamics.

Surgical optimization of the cavopulmonary connection and pharmacological therapy for dysfunctional Fontan physiology continue to advance, but these treatment approaches only slow the progression of decline to end-stage heart failure. The development of a mechanical cavopulmonary assist device will provide a viable therapeutic option in the bridging of patients to transplant or to stabilization. We hypothesize that rotational blood flow, delivered by an implantable axial flow blood pump, could effectively assist the venous circulation in Fontan patients by mimicking vortical blood flow patterns in the cardiovascular system. This study investigated seven new models of mechanical cavopulmonary assistance (single and dual-pump assist), created combinations of pump designs that deliver counter rotating vortical flow conditions, and analyzed pump performance, velocity streamlines, swirling strength, and energy augmentation in the cavopulmonary circuit for each support scenario. The model having an axial clockwise-oriented impeller in the inferior vena cava and an axial counterclockwise-oriented impeller rotating in the superior vena cava outperformed all of the support scenarios by enhancing the energy of the cavopulmonary circulation an average of 10.3% over the entire flow range and a maximum of 27.4% at %the higher flow rates. This research will guide the development of axial flow blood pumps for Fontan patients and demonstrated the high probability of %a cardiovascular benefit using counter rotating pumps in a dual support scenario, but found that this is dependent upon the patient-specific cavopulmonary anatomy.

Perioperative Nursing Management of an Animal Model of Axial Flow Blood Pump Implantation

Objective: This study aimed to explore the characteristics of perioperative nursing of experimental goats using self-made axial-flow blood pump implantation and provided theoretical nursing knowledge and practice-based evidence for the clinical application of domestically manufactured artificial cardiac pumps. Methods: Seven experimental goats were used in this study, three for pre-testing and four for the formal experiments. According to the surgical requirements for axial-flow blood pump implantation into the cardiac apex, we creatively designed and made a series of highly practical animal surgical instruments including a composite disassemblable bed for experimental animal transferring and monitoring, a multifunctional animal surgery bed, and portable medical supporting equipment. We also applied for two national invention patents and one utility model patent. Active measures were taken to ensure careful preparation before surgery, close collaboration during surgery, and effective management of complications after surgery. Results: Two of the four experimental goats died during surgery because of a massive hemorrhage caused by distal anastomotic failure and air embolism-induced cardiac arrest caused by air leakage from the outlet into the heart due to poor connection of the auxiliary pressure tap (used to measure left ventricular pressure). The mean survival time of the remaining three experimental goats was 22.7 hours. Conclusion: This study was the first to systematically and comprehensively investigate the perioperative nursing management of axial-flow blood pump implantation using animal models. These findings could greatly promote further clinical applied nursing research of self-made artificial cardiac pump implantation in experimental goats. * Joint first author. # Corresponding author.

The impact of angiogenic and adipogenic microenvironment on adipose tissue regeneration in tissue engineering chamber

By observing the adipogenic and angiogenic microenvironment impact on the morphology of newly generated tissue for exploring the key factors which inducing mature adipose tissue regeneration in tissue engineering model. 24 healthy 6 months' New Zealand rabbits were picked and put into four groups according to different microenvironment. Every group has 6 rabbits and divided as follows: no axial-blood supply fat flap(0 ml), granular fat only(0.6 ml), axial blood vessel only (0.05 ml), axial vascularized fat flap ((0.6 ml). We separated or combined adipogenic and angiogenic environment within these groups. After 8 weeks, samples were harvested for histologic observation including macroscopic observation, volume analysis and HE testing. In granular fat group, its volume decreased by (0.25 ± 0.10) ml after 8 weeks as the shortage of blood supply and finally it could be enveloped. In axial blood vessel group, its volume increased by (0. 37 ± 0. 04) ml after 8 weeks with fibrous tissue formation as shortage of adipogenic microenvironment. The no axial-blood supply fat flap group grew into(0.12 ± 0.03) ml, which can' t support large volume adipose tissue formation because of lacking independent blood supply. Only axial vascularized fat flap model could generate mature adipose tissue in large volume(3.45 ± 0.48) ml. The number of new capillary in every group was different after 8 weeks. By counting the numbers in every single view, no axial-blood supply fat flap group 15 ± 3.5)and granular fat only group(5 ± 2.5)had a significant difference with axial vascularized fat flap group 22 ± 5) respectively. Only both adipogenic or angiogenic microenvironment exist could induce mature adipose tissue in large volume in tissue engineering chamber model.

Study on the minimum energy consumption speed control method of the axial flow blood pump under the condition of large gap

Study on the minimum energy consumption speed control method of the axial flow blood pump under the condition of large gap

Static Structural Analysis of the Blood Pump Rotor System

In order to study the impact of external forces of the influence of the structural characteristics of axial flow blood pump rotor system.Using the blood pump rotor system as the research object,use ANSYS software,Use the method of static structure.the stress and strain analysis nephogram of the blood pump rotor system was obtained under the external load.through the study: The deformation of the blood pump rotor system which under the action of external load was mainly concentrated in the external contact of blade wheel rotor and ceramic shaft,but the deformation is small.So the blood pump rotor system design is reasonable. The vulnerability part of the blood pump rotor system was obtained.it provide date support for the further optimization of the blood pump rotor system and it also lay the foundations for the subsequent dynamic analysis.

Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0.9) and sagittal oblique MRA of left pulmonary artery (LPA) (Δ 0.2 ± 1.1 mm, ICC 0.9). CMR PA measurements were compared to surgical measurements in 25 children (5.4 ± 4.8 years). All MRI sequences demonstrated good agreement (ICC > 0.8) with the best (ICC 0.9) from axial cine bSSFP for both RPA and LPA. Maximal cross sectional and angulated oblique reformatted MRA provide the best correlation to catheterization for measurement of branch PA's and stenosis diameter. This is likely due to similar angiographic methods based on reformatting techniques that transect the central axis of the arteries. Axial cine bSSFP CMR was the best surgically measured correlate of PA branch size due to this being a measure of stretched diameter. Knowledge of these differences provides more precise PA measurements and may aid catheter or surgical interventions for RVOTO lesions.

Development of a Novel Tissue-Compatible Apical Inflow Cannula for an Implantable VAD

Purpose Clinical application of VAD is a potent therapeutic option for treating the patients with heart failure. However, as the VAD support period prolonged, the incidence of device-related complication, such as wedge thrombus, has been increasing. We already reported on new axial flow blood pump featuring a hydrodynamically levitated impeller with superior mechanical durability and anti-thrombogenesity. However, a measure against device-related complication occurred in the other components was not considered sufficiently. In this study, we developed a novel tissue-compatible polyester velour covered inflow cannula for preventing the wedge thrombus, and evaluated its performance in a series of animal tests. Methods and Materials Eight calves (BW: 62-99 kg) underwent VAD implantation with our new axial flow blood pump. In the first two animals, a titanium-made inflow cannula with a smooth surface was used. In the following six animals, the outside of the cylindrical inflow cannula tip was wrapped with tissue-compatible polyester velour material. Outer diameters of the cannula tip was 20 mm, respectively, and the length of the cannula tip was 30 mm. The portion of the velour protruding from the apex was made to be 20 mm in length. Results All animals were sacrificed on 90-92 POD on schedule. At autopsies, first two animals with smooth surface titanium inflow cannula demonstrated wedge thrombus formation at the cannula insertion site of the ventricular apex. The granulomatous tissue covered and partially occluded the tip of the inflow cannula. In contrast, six cases with newly developed cannula revealed no wedge thrombus formation around the outside of the inflow cannulas, and the polyester velour was completely enveloped with the neointimal tissue presumably grown from the ventricular endocardium. Conclusions In conclusion, our newly developed tissue-compatible inflow cannula with polyester velour material successfully reduced the wedge thrombus formation in a series of 3 months animal implantation.

Electromagnetic and hydrodynamic characteristics of the extracorporeal magnetic driving system for an axial flow blood pump

Electromagnetic and hydrodynamic characteristics of the extracorporeal magnetic driving system for an axial flow blood pump

Twisted Cardiovascular Cages for Intravascular Axial Flow Blood Pumps to Support the Fontan Physiology

Failing single ventricle physiology represents an ongoing challenge in mechanical assist device development, requiring pressure augmentation in the cavopulmonary circuit, reduction of systemic venous pressure, and increased cardiac output to achieve hemodynamic stabilization. To meet these requirements, we are developing a percutaneously-placed, axial flow blood pump to support ailing single ventricle physiology in adolescents and adults. We have modified the outer cage of the device to serve as both a protective and functional design component. This study examined the performance of 3 cage geometries with varying directions of filament twist using numerical simulations and hydraulic experiments. All 3 cage and pump models performed in acceptable ranges to support Fontan patients. The cage design employing filaments that are twisted in the opposite direction to the impeller blades and in the direction of the diffuser blades (against-with) demonstrated superior performance by generating a pressure rise range of 5-38 mmHg of flow rates of 0.5-6 l/min at rotational speeds of 5000-7000 rpm. The blood damage indices for all of the cages were found to be well below 2%, and the scalar stress levels were below 200 Pa. This study represents ongoing progress in the development of the impeller and cage assembly. Validation of the results will continue in experiments with blood bag evaluation as well as by particle image velocimetry measurements.

Study on Support Properties of Axial Maglev Blood Pump

Artificial heart pump requires small structure, low energy consumption and certain stiffness and damping for transplanting and long time using. This paper thus designed a hybrid-type axial maglev blood pump, which not only has small size, almost no energy, and poor dynamic characteristics of permanent magnet bearing but also has low power consumption, long life and good dynamic characteristics of magnetic bearing. Based on finite element method, magnetic flux of axial magnetic bearing, radial magnetic bearing and test rig are analyzed; at the same time, the structure parameters and mechanical properties and the coupling of radial MB and axial MB are studied. The results show that: rotor displacement of axial bearing and radial bearing will affect load capacity and stiffness. The conclusions provide a scientific basis for design and optimization of blood pump