Abstract: Objective To study in vitro hydrodynamics of a pneumatic pulsatile ventricular assist device developed exclusively by China, and establish an animal model for the detection by the device. Methods The hydromechanics experiment was performed on an in vitro test loop using MEDOS-System to drive the ventricular assist device, and lycerl-water solution was used as circulating medium. The changes of afterload pressure and the output of the pump were monitored, and the impermeability and stability were also assessed after the experiment. Six adult dogs were used as the experimental animals. The device worked in the left heart assistance mode for 1 hour then the ventricular fibrillation was induced by potassium chloride, and then defibrillated after 5 min while the device remained working. The hemodynamics data were monitored consecutively during the trial. Results The ventricular assist device worked stably and reliably during the hemodynamic experiment. The pump can generate more than 4 L/min flow against the afterload pressure of 100 mmHg. There were no significant changes in heart rate at different time points in experimental dogs after left ventricular assist. Comparison between after auxiliary immediately and former auxiliary, the diastolic blood pressure of dogs increased 30 mmHg with the ventricular assist, and the diastolic pressure increased 19 mmHg. No obvious fluctuation in blood pressure was found during the auxiliary process. The diastolic blood pressure stayed at 60 mmHg when the heart was in ventricular fibrillation, and returned to normal after electrical defibrillation. Conclusion The ventricular assist device works stably in vitro test, and the pump can meet the need of adult’ s ventricular assist. It is effective and security to dogs in short term. The effects of long-term use need to
be future proved.

Key words: heart, artificial, heart-assist devices, hemodynamics, animal experimentation, ventricular assist device, hydromechanics