Mock Flow Loop Bioreactor

Background

Native, living aortic and pulmonic heart valves are continuously subjected to mechanical stresses by the ventricles which imposed time-varying pressure waveforms and resulting blood flows. It is believed that the mechanical stress is needed for proper valve development and possibly maintenance. The mock flow loop bioreactor is designed to test living heart valves (native, tissue engineered, cell-seeded ECM valves, etc.) under sterile, controlled hemodynamic conditions. By testing a living heart valve in an in vitro system such as this, researchers can possibly develop better heart valves which are actually alive and can therefore possibly grow and develop to meet the cardiovascular demands of the patient.

Device Operation

The device simulates the cardiovascular system by mechanically reproducing both the pressure waveform, as generated by the ventricles of the heart, and the downstream circulation. The circulation is simulated by a computer-controlled resistive element to simulate the resistance of arterioles and capillaries, and a compliance element that simulates the elastic nature of the large arteries.

	Diagrams of the device: Individual device components (top) and the entire system (bottom)

The ventricular contraction (pressure) waveform is generated pneumatically and can be precisely controlled by the computer via a piezoelectric pressure regulator. Unlike many traditional mock flow loops, the mock flow loop bioreactor has a computer-controlled resistance in addition to the computer-controlled ventricular pressure. This allows the system to automatically change pressure and flow levels over time. This is useful in simulating many physiologic and pathologic conditions. The control system which automatically controls mean pressure and flow levels is a closed-loop feedback system. The user only has to specify what levels are desired and the system will find the optimal solution.

	Screen shot of control software
	Measured pressure and flow waveforms.

	Device requirements and solutions

For more information, please see the following article:

[1] Hildebrand, D., Wu, J., Mayer, J., Jr., and Sacks, M. Design and Hydrodynamic Evaluation of a Novel Pulsatile Bioreactor for Biologically Active Heart Valves. Annals of Biomedical Engineering (in press).

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