A 4-Chamber Model Heart with 3D Printed Silicone Aorta and Peripheral Arteries to Simulate the Human Cardiovascular System in a Mock Circulatory Loop

Purpose Mock circulatory loops (MCL) provide an in vitro platform to evaluate hemodynamic performance of cardiovascular (CV) medical devices. Designing a tunable MCL that mimics patient-specific physiology could both accelerate evaluation of medical devices prior to in vivo studies, and provide patient-specific testing in vitro . We developed an MCL that mimics human CV physiology with a 4-chamber model heart and 3D printed silicone vasculature based on patient-specific images. Methods The model heart is composed of the left/right atria & ventricles, and atrioventricular and aortic/pulmonary valves. The atrial/ventricular septa are designed as circular silicone-membranes to simulate physiologic septal deformations which occur in the native heart with a pressure differential between chambers. Each of the four chambers is made of acrylic and driven by linear motor. A displacement transducer connected to each linear motor can measure the volume change in each chamber while pressure is simultaneously recorded. A systemic vasculature model is fabricated out of 3D printed silicone based on patient-derived images. The compliance of the silicone selected is designed to match the arterial stiffness of the human vascular system. Results The assembled model heart contains atria, ventricles, and systemic vasculature. Each atrial and ventricular chamber can accommodate a maximum volume of 98 mL and 192 mL, respectively. The area and thickness of the silicone septum between the atria are 890 mm 2 , and 1.8 mm. The ventricular septal area and thickness are 1590 mm 2 and 4.5 mm. Changes in pressure differential between the ventricular chambers affect septal configuration to incorporate ventricle-ventricle interaction effects. The linear motors are driven based on the elastance functions derived from pressure-volume (PV) loops obtained in the 4 chambers to enable the 4-chamber heart to physiologically respond to preload and afterload changes -in a similar fashion to the native heart. Conclusion This is the first MCL system that mimics human heart size, complexity and physiology and contains a human vascular circuit that can be tuned to patient-specific parameters. By including a physiologic control system governing the linear motors we can evaluate patient-specific hemodynamics, including the Frank-Starling mechanism in this MCL.