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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. One hour after the pumping has started, the MCV increased and the MCHC decreased by 1.064 ± 0.006 and 0.906 ± 0.050 times, respectively, as compared with those of the prepumped blood ( P < 0.05). The deformability index L/W, where L and W are the long and short axes of the two-dimensional RBC images, respectively, sheared by a cyclically reversing shear flow increased indicating that the RBCs pumped for 1 h exhibited more elastic characteristics ( P < 0.05). In addition, when the pumped blood cells were sheared for 30 min with a uniform shear stress of 25.38 Pa, the hemolysis level decreased dramatically as compared with the control blood, as more fragile RBCs were destroyed by pumping, leaving behind less fragile RBCs. All these characteristics of the RBCs exposed to continuous flow resemble those of young RBCs having larger MCV, lower MCHC, higher elasticity, and lower fragility. In conclusion, during continuous flow pumping, the RBCs having relatively lower threshold for hemolysis to mechanical shear stress generated by continuous flow blood pump (CFBP) are destroyed first and removed from circulation in the early stage of application of CFBP, thus leaving behind less fragile and stronger RBCs. [ABSTRACT FROM AUTHOR]

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. We present here the 1-month in vivo evaluation of the TinyPump, whose design was modified further for more durable operation. The pump was implanted as a left ventricular assist device in five goats (12.5-26.7 kg), with inflow inserted into the left ventricular apex and outflow anastomosed to the descending aorta. Five animals were supported for 110 pump days, with mean pump flow of 1.19 ± 0.03 L/min at a pump speed of 2679 ± 97 rpm. Two animals reached the scheduled end point of 30 days without device failure, and mean plasma-free hemoglobin was 1.7 ± 0.8 mg/dL. Hematologic and biochemical data of these two animals showed no evidence of cardiovascular, renal, or hepatic dysfunction. Although further experiments are needed, the modified TinyPump offers promise as a short-term mechanical circulatory support device in pediatric population. [ABSTRACT FROM AUTHOR]

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 0.0054 ± 0.0008 g/100 L. In in vivo study, the pump, with its blood-contacting surface coated with biocompatible 2-methacryloyloxyethyl phosphorylcholine polymer, was implanted in seven calves in left heart bypass. Pump performance was stable with a mean flow of 4.49 ± 0.38 L/min at a mean speed of 2072.1 ± 64.5 rpm. The maglev control revealed its stability in rotor position during normal activity by the calves. During 2 weeks of operation in two calves which survived the intended study period, no thrombus formation was seen inside the pump and levels of plasma free hemoglobin were maintained below 4 mg/dL. Although further experiments are required, the pump demonstrated the potential for sufficient and reliable performance and biocompatibility in meeting the requirements for cardiopulmonary bypass and 1-week circulatory support. [ABSTRACT FROM AUTHOR]