MiTiHeart® LVAD is a direct drive, centrifugal blood pump developed as a destination therapy device for adult heart failure patients. MiTiHeart® LVAD has many innovative features with proven functionality as compared with other magnetic levitation LVADs. These include small size, low power usage, back up thrust bearing, low hemolysis, and low manufacturing cost. It will provide the surgeons an alternative low cost option to other LVADs, and especially for women and young adults.
The MiTiHeart® LVAD uses a hybrid passive/active magnetic bearing system with only one actively controlled axis (in the axial direction) to minimize the total bearing power and reduce cost of manufacturing. The flow paths for both main and secondary blood flows are simple and direct. The non-contact nature of the magnetic bearing allows for fully washed secondary flow path to avoid stagnation points that might promote thrombi formation. Clearances between the rotor and stator in the secondary flow path are designed to minimize hemolysis potential by reducing shear stress related activation of the coagulation processes. The hemolysis level is amongst the lowest in LVADs (NIH < 0.002 mg/dL).
Three prototypes have been developed under NIH SBIR program and evaluated in vitro and in animal models. Prototype I was manufactured from polycarbonate and tested to demonstrate pump performance and durability. Prototype II with a blood-lubricated auxiliary hydrodynamic bearing was developed to ensure safe and reliable pump operation during possible shock loading or in the event of a failure of the electromagnetic thrust bearing. This prototype, however, was not optimized for size and required a re-design for size reduction while keeping the basic design and maintaining the required hydraulic performance. Using an iterative design process, the MiTiHeart® Prototype III retained the integrated impeller, motor, magnetic bearings and secondary flow path design in a simple compact unit. The resulting design effort produced an LVAD that was 60% smaller than the previous design having dimensions of 5 cm x 8 cm and weighing only 640 g. System upgrades of the Prototype III design also include an improved controller and power supply.
Extensive in vitro performance testing was conducted to evaluate both the Prototype III and the new power electronic system. Successful in vitro long-term durability tests included a 14-day continuous flow test and a 60-day pulsatile test. Several acute and chronic animal implants were completed with calf animal models at Hershey Medical Center. A total of 1,770 implant hours were achieved. The power draw for both the motor and the bearing was 6 W at 4,000 rpm. The total power draw for most LVADs range from 6 to 18 W with the total power draw (motor and magnetic bearings) for third generation pumps ranging from 8 W to 12 W.
The results of the in vitro and in vivo studies have confirmed the efficacy of the MiTiHeart® LVAD. The tests demonstrated that the pump operates in a smooth manner delivering the required hemodynamics. The motor and bearing power measurements confirmed that the new LVAD operates using a low power draw. Furthermore, the temperature rise of the device was small and did not vary significantly from the environmental temperature. These results have established the safety and reliability of the MiTiHeart® LVAD. However, additional pre-clinical evaluations are needed prior to submission of an IDE to the FDA for the initiation of clinical studies. MiTiHeart Corporation, subsidiary of MiTi, has been in discussions with potential investors and strategic partners to obtain the funds needed for pre-clinical studies of MiTiHeart® LVAD.
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