Hemocompatibility of new magnetically-levitated centrifugal pump technology compared to the CentriMag adult pump.

The specific hemocompatibility properties of mechanical-circulatory-support (MCS)-pump technologies have not previously been described in a comparable manner. We thus investigated the hemocompatibility-indicating marker of a new magnetically-levitated (MagLev) centrifugal pump (MT-Mag) in a human, whole-blood mock-loop for 360 min using the MCS devices as a driving component. We compared those results with the CentriMag adult (C-Mag) device under the same conditions according to ISO10993-4.

Sensorless Viscosity Measurement in a Magnetically-Levitated Rotary Blood Pump.

Controlling the flow rate in an implantable rotary blood pump based on the physiological demand made by the body is important. Even though various methods to estimate the flow rate without using a flow meter have been proposed, no adequate method for measuring the blood viscosity, which is necessary for an accurate estimate of the flow rate, without using additional sensors or mechanisms in a noninvasive way, has yet been realized. We have developed a sensorless method for measuring viscosity in magnetically levitated rotary blood pumps, which requires no additional sensors or mechanisms.

MedTech Mag-Lev, single-use, extracorporeal magnetically levitated centrifugal blood pump for mid-term circulatory support.

Short- to mid-term extracorporeal ventricular assist devices (VADs) are recommended for critical cardiogenic shock patients. We have designed a preclinical, single-use MedTech Mag-Lev VAD for one-month extracorporeal use. The impeller-rotor of the pump was suspended by a two degree-of-freedom active magnetic bearing in a 300 μm fluid gap, where the computational fluid dynamics analysis predicted a secondary flow of about 400-500 ml/min at a pump speed of 1800-2200 rpm.

New generation extracorporeal membrane oxygenation with MedTech Mag-Lev, a single-use, magnetically levitated, centrifugal blood pump: preclinical evaluation in calves.

We have evaluated the feasibility of a newly developed single-use, magnetically levitated centrifugal blood pump, MedTech Mag-Lev, in a 3-week extracorporeal membrane oxygenation (ECMO) study in calves against a Medtronic Bio-Pump BPX-80. A heparin- and silicone-coated polypropylene membrane oxygenator MERA NHP Excelung NSH-R was employed as an oxygenator. Six healthy male Holstein calves with body weights of about 100 kg were divided into two groups, four in the MedTech group and two in the Bio-Pump group.

Evaluation of platelet aggregability during left ventricular bypass using a MedTech MagLev VAD in a series of chronic calf experiments.

The impact of continuous flow left ventricular assist device (LVAD) pumping on platelet aggregation was investigated in animal experiments utilizing six calves. A single-use MagLev centrifugal blood pump, MedTech MagLev, was used to bypass the calves' hearts from the left atrium to the descending aorta at a flow rate of 50 ml/kg/min. The LVAD's impact on blood coagulation activities was evaluated based on the platelet aggregability, which was measured with a turbidimetric assay method during the preoperative, operative, and postoperative periods.

Fetal cardiac intervention: improved results of fetal cardiac bypass in immature fetuses using the TinyPump device.

Objective: Fetal cardiac surgery is a potential innovative treatment for certain congenital heart defects that have significant mortality and morbidity in utero or after birth, but it has been limited by placental dysfunction after fetal cardiac bypass. We have used the TinyPump device for fetal cardiac bypass in sheep fetuses at 90 to 110 days gestation.

Methods: Ten mixed-breed pregnant ewes were used over a period of 6 months, and 10 fetuses were placed on bypass for 30 minutes.

Quantitative analysis of optical properties of flowing blood using a photon-cell interactive Monte Carlo code: effects of red blood cells' orientation on light scattering.

Optical properties of flowing blood were analyzed using a photon-cell interactive Monte Carlo (pciMC) model with the physical properties of the flowing red blood cells (RBCs) such as cell size, shape, refractive index, distribution, and orientation as the parameters. The scattering of light by flowing blood at the He-Ne laser wavelength of 632.8 nm was significantly affected by the shear rate.

One-month biocompatibility evaluation of the pediatric TinyPump in goats.

The TinyPump is an extracorporeal, magnetically driven centrifugal blood pump with its impeller suspended magnetically and hydrodynamically to provide short-term mechanical circulatory support for children and infants. We have previously demonstrated that the in vivo experiments of the experimental TinyPump showed acceptable stable performance at pump flows averaging around 1.0 L/min with low hemolytic and thrombogenic properties for up to 2 weeks.

Alterations in red blood cell volume and hemoglobin concentration, viscoelastic properties, and mechanical fragility caused by continuous flow pumping in calves.

In this study, we have analyzed the changes in mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and the dynamic deformability and mechanical fragility of red blood cells (RBCs) in five male Holstein calves (body weight: 95.6 ± 10.8 kg) whose circulation was partially supported with a novel magnetically levitated extracorporeal centrifugal blood pump MedTech Dispo.

In vivo evaluation of the "TinyPump" as a pediatric left ventricular assist device.

Pediatric patients with end-stage heart failure require mechanical circulatory support (MCS) just as adults do. In order to meet the special requirements for neonates' and infants' MCS, pediatric circulatory support devices must be compact with low priming volume, easily controllable with low flow, less traumatic for blood cells and tissues, and biocompatible with minimum anticoagulation. We have designed and developed a miniature rotary centrifugal blood pump, "TinyPump," with a priming volume of 5 mL, which has already demonstrated its controllable performance for low flow and durability in vitro.

Photon-cell interactive Monte Carlo model based on the geometric optics theory for photon migration in blood by incorporating both extra- and intracellular pathways.

A photon-cell interactive Monte Carlo (pciMC) that tracks photon migration in both the extra- and intracellular spaces is developed without using macroscopic scattering phase functions and anisotropy factors, as required for the conventional Monte Carlos (MCs). The interaction of photons at the plasma-cell boundary of randomly oriented 3-D biconcave red blood cells (RBCs) is modeled using the geometric optics. The pciMC incorporates different photon velocities from the extra- to intracellular space, whereas the conventional MC treats RBCs as points in the space with a constant velocity.

Transfusion-free neonatal cardiopulmonary bypass using a TinyPump.

Background: We devised a miniaturized circuit incorporating a TinyPump in the venous line to amplify the venous return. We compared this system to the conventional blood-primed circuit and investigated whether this circuit could maintain hematocrit levels without blood transfusion and reduce coagulation and inflammatory cascades.

Methods: Thirteen 1-week-old piglets (3.

Development of a disposable magnetically levitated centrifugal blood pump (MedTech Dispo) intended for bridge-to-bridge applications--two-week in vivo evaluation.

Last year, we reported in vitro pump performance, low hemolytic characteristics, and initial in vivo evaluation of a disposable, magnetically levitated centrifugal blood pump, MedTech Dispo. As the first phase of the two-stage in vivo studies, in this study we have carried out a 2-week in vivo evaluation in calves. Male Holstein calves with body weight of 62.

Prediction of the external work of the native heart from the dynamic H-Q curves of the rotary blood pumps during left heart bypass.

The ventricular performance is dependent on the drainage effect of rotary blood pumps (RBPs) and the performance of RBPs is affected by the ventricular pulsation. In this study, the interaction between the ventricle and RBPs was examined using the pressure-volume (P-V) diagram of the ventricle and dynamic head pressure-bypass flow (H-Q) curves (H, head pressure: arterial pressure minus ventricular pressure vs. Q, bypass flow) of the RBPs.

Japanese guidance for ventricular assist devices/total artificial hearts.

To facilitate research and development (R&D) and to expedite the review processes of medical devices, the Ministry of Health, Labor and Welfare (MHLW) and the Ministry of Economy, Trade and Industry (METI) founded a joint committee to establish guidance for newly emerging technology. From 2005 to 2007, two working groups held discussions on ventricular assist devices and total artificial hearts, including out-of-hospital programs, based on previous guidance documents and standards. Based on this discussion, the METI published the R&D Guidelines for innovative artificial hearts in 2007, and in 2008 the MHLW published a Notification by Director regarding the evaluation criteria for emerging technology.

A new pulse duplicator with a passive fill ventricle for analysis of cardiac dynamics.

A new pulse duplicator was designed for evaluation of the performance of ventricular assist devices through pressure-volume (P-V) diagrams of the native heart. A linear drive system in combination with a pusher-plate mechanism was designed as a drive system to implement the passive fill mechanism during diastole of the mock ventricle. The compliances of the native heart during both diastole and systole were simulated by placing a ventricle sack made of soft latex rubber in a sealed chamber and by varying the air-to-fluid volume ratio inside the chamber.

Disposable MagLev centrifugal blood pump utilizing a cone-shaped impeller.

To enhance the durability and reduce the blood trauma of a conventional blood pump with a cone-shaped impeller, a magnetically levitated (MagLev) technology has been applied to the BioPump BPX-80 (Medtronic Biomedicus, Inc., Minneapolis, MN, USA), whose impeller is supported by a mechanical bearing. The MagLev BioPump (MagLev BP), which we have developed, has a cone-shaped impeller, the same as that used in the BPX-80.

Early in vivo evaluation of ventricular assistance with a miniature centrifugal blood pump (TinyPump) in rabbits.

We have developed an ultraminiature centrifugal pump, TinyPump, with a priming volume of 5 ml. The in vivo performance of TinyPump was compared with that of HPM-05 for left ventricular support. Each pump group included seven rabbits weighing 3.

Application of drag-reducing polymer solutions as test fluids for in vitro evaluation of potential blood damage in blood pumps.

In vitro evaluation of the potential of a circulatory-assist device to damage blood cells has generally been performed using blood from various species. Problems with this approach include the variability of blood sensitivity to mechanical stress in different species, preparation of blood including the adjustment of hematocrit to a standard value, changes in the mechanical properties of blood that occur during storage, and necessity to pool blood samples to obtain an adequate amount of blood for in vitro circulating systems. We investigated whether the mechanical degradation of a drag-reducing polymer (DRP) solution resulting in the loss of drag-reducing ability can indicate the degree of shear-induced blood damage within blood pumps.

Glucose depletion enhances sensitivity to shear stress-induced mechanical damage in red blood cells by rotary blood pumps.

The metabolic process in red blood cells (RBCs) is anaerobic. The life-dependent adenosine triphosphate (ATP) for survival of cells is produced through glycolytic process. The aim of the study was to evaluate the effects of the glucose level on the mean corpuscular volume, mean corpuscular hemoglobin concentration, and hemolysis rate during hemolysis study by rotary blood pumps.

Development of a disposable maglev centrifugal blood pump intended for one-month support in bridge-to-bridge applications: in vitro and initial in vivo evaluation.

MedTech Dispo, a disposable maglev centrifugal blood pump with two degrees of freedom magnetic suspension and radial magnetic coupling rotation, has been developed for 1-month extracorporeal circulatory support. As the first stage of a two-stage in vivo evaluation, 2-week evaluation of a prototype MedTech Dispo was conducted. In in vitro study, the pump could produce 5 L/min against 800 mm Hg and the normalized index of hemolysis was 0.

Mechanical cavopulmonary assist maintains pulmonary and cerebral blood flow in a piglet model of a bidirectional cavopulmonary shunt with high pulmonary vascular resistance.

Objectives: We tested mechanical cavopulmonary blood flow assist by incorporating a novel miniature centrifugal pump into a 1(1/2)-ventricle type cavopulmonary connection in neonatal pigs.

Methods: Nine 3-week-old piglets (mean body weight, 10.2 kg) were used: mechanical cavopulmonary assist (n = 6) and controls (n = 3).

Absolute transmitted light plethysmography for assessment of dental pulp vitality through quantification of pulp chamber hematocrit by a three-layer model.

After confirming that the gingival circulation had little effect on transmitted light plethysmography measurement in the upper central incisor in both in vivo experiments and numerical Monte Carlo simulation studies, a three-layer model comprising of a pulp chamber sandwiched between two dentin layers has been introduced to quantify the pulp chamber hematocrit (Hctp) from the measured optical density. Two-flux theory was utilized to derive a mathematical equation for transmitted intensity in terms of tooth dimensions, Hctp, and light-source wavelength. Each layer was assumed homogeneous so as to represent its optical properties by the bulk absorption and scattering constants.

Mechanical damage of red blood cells by rotary blood pumps: selective destruction of aged red blood cells and subhemolytic trauma.

In this study, mean cell volume (MCV), mean cell hemoglobin concentration (MCHC), and mean cell hemoglobin (MCH) were measured to quantify RBC damage by rotary blood pumps. Six-hour hemolysis tests were conducted with a Bio-pump BPX-80, a Sarns 15200 roller pump, and a prototype mag-lev centrifugal pump (MedTech Heart) using fresh porcine blood circulated at 5 L/min against a 100 mm Hg head pressure. The temperature of the test and noncirculated control blood was maintained at 37 degrees C.