Improving In vitro Evaluation Capabilities of Cardiac Assist Devices through a Validated Exercise Simulation

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Device Testing

Background:

• In vitro evaluation of cardiac assist devices is crucial before animal trials.
• Mock circulatory loops are essential for simulating diverse patient scenarios, including exercise transitions.
• Validating exercise simulations requires baseline data on healthy cardiovascular responses.

Purpose of the Study:

• To establish baseline cardiovascular response data during exercise in healthy subjects.
• To implement and validate an exercise simulation in a mock circulatory loop.
• To compare mock circulatory loop results with human physiological responses during rest-to-exercise transitions.

Main Methods:

• Impedance cardiography was used to record heart rate (HR), stroke volume (SV), and cardiac output (CO) in 50 healthy subjects during exercise.
• Subjects performed exercise on a recumbent ergometer.
• The collected human data was used to create an exercise simulation in a mock circulatory loop for comparison.

Main Results:

• Time constants (τ) for HR, SV, and CO ranged from 10.6-19.3s, and rise times (t_r) ranged from 24.7-44.3s during rest-to-exercise transitions.
• No significant gender differences were observed in τ and t_r (p>0.05).
• Mock circulatory loop simulations demonstrated good accordance with human cardiovascular responses (HR, SV, CO).

Conclusions:

• The study successfully validated in vitro exercise simulations using human physiological data.
• The validated simulations can be used for both in vitro and in silico (numerical) testing of cardiac assist devices.
• This improves the evaluation capabilities for current and developing cardiac assist technologies.