Modeling and Simulating a Ventricular Assist Device
Pneumatic pulsatile ventricular assist devices support the function of the left or right ventricle of the human heart short or long term. They are used for patients suffering from serious heart ailments after all conservative therapeutic options have been exhausted. An existing drive used to treat adult patients was refined for use in all EXCOR® pumps (Berlin Heart GmbH). The drive consists of a pneumatic piston pump that operates synchronously with the blood pump. The closed pneumatic system requires precise regulation of the air mass enclosed. Various control algorithms are needed to adjust the pumped volume to the blood recirculated under different stresses.
A simulation model of the complete system, consisting of a blood pump, pneumatic drive and lines as well as the human circulatory system, was developed to analyze the system and synthesize a regulator:
- The model was created in the object-oriented modeling language Modelica/Dymola.
- The physical parameters of all of the components were ascertained in experiments.
- The elastic effects of the blood pump and the membrane were modeled exactly.
- The model was validated on a hydraulic mock-up.
The thusly created models were validated successfully in extensive experiments and displayed an exact correspondence with the real test set-up. Models were delivered, which serve as the basis for developing control algorithms.