Mock circulatory systems reproduce cardiovascular pressures and flows in benchtop testbeds used for device testing and research. Traditional systems often rely on piston-driven chambers, numerical-physical hybrid interfaces, or explanted hearts; each approach introduces trade-offs in complexity, ethical concerns, or physiological realism. Recent soft-robotic and patient-specific platforms can better emulate myocardial mechanics but tend to require specialized fabrication, complex actuation hardware, and sophisticated control algorithms.
This study presents a methodological and technological shift toward a simpler, bio-inspired left ventricular (LV) simulator that reproduces key cardio-mechanical features—including ventricular torsion and longitudinal shortening—without dependence on complex electromechanical drive systems or extensive active feedback control. Methodologically, the work introduces Interpretive Structural Modeling (ISM) as a structured decision framework to compare actuation and material options prior to prototyping. Conceptually and technologically, the simulator integrates helically oriented pneumatic artificial muscles within a deformable latex ventricular wall to emulate physiological contraction-relaxation mechanics with reduced system complexity.
The authors applied the ISM methodology to manage the complex decision space of LV simulator design. ISM was used to evaluate multiple actuation concepts and material options and to map hierarchical relationships among design parameters. Based on the ISM analysis, the combination determined most suitable for actuating a deformable ventricular chamber was pneumatic artificial muscles working in concert with latex rubber as the ventricular wall material. The ISM step is positioned as a systematic method to narrow alternatives and prioritize design drivers before committing resources to prototype fabrication.
The prototype LV chamber uses helically oriented pneumatic artificial muscles embedded in a flexible latex ventricular shell. The helical arrangement aims to reproduce multilayered myocardial fiber geometry that produces both twisting (torsion) and longitudinal shortening during systole. The design purposefully avoids complex electromechanical mechanisms and active control loops by relying on pneumatic actuation sequenced to generate cyclic contraction and relaxation of the latex wall.
Materials and geometry choices were guided by ISM outcomes. Latex was selected for its compliance and deformability, enabling observable wall motion under muscle contraction. The pneumatic artificial muscles serve as the primary drivers of volumetric change and wall deformation, translating pressurized pneumatic input into shortening and twist consistent with a beating LV analogue.
The beating LV simulator was evaluated under multiple conditions representing healthy and diseased states and at varying heart rates. Experiments were conducted at 50, 60, 70 and 80 beats per minute. Hemodynamic outputs were measured as average flow rates, and mechanical performance was assessed by quantifying apex rotation (twisting angle) and apex shortening during simulated beats. The simulator was integrated into an experimental loop to measure flow and to capture mechanical motion of the ventricular apex.
Testing demonstrated that the prototype beating LV simulator can generate average flow rates of up to 2.25 L/min across the tested conditions. Cardiac-like wall motion was evidenced by an apex twisting angle of 21 degrees and apex longitudinal shortening of 11 mm. These metrics indicate that the simulator reproduces elements of human LV mechanical behavior—torsion and longitudinal displacement—while operating without complex electromechanical drives or closed-loop control.
The authors report that these preliminary results establish the platform as a promising early-stage testbed. They note that, with further development, the simulator may achieve closer approximation of human LV hemodynamic and cardio-mechanical performance.
Advantages claimed for this approach include:
Limitations and considerations explicitly noted by the authors:
The study demonstrates a methodological workflow using Interpretive Structural Modeling to select actuation and material combinations and reports a prototyped left ventricular simulator driven by pneumatic artificial muscles and a latex wall. Experimental results show measurable LV-like torsion (21° apex rotation) and longitudinal shortening (11 mm) with average flow production up to 2.25 L/min across tested heart rates. The platform is presented as a promising, lower-complexity alternative to existing mock circulatory and soft-robotic simulators, with the authors acknowledging the need for further refinement to reach full physiological equivalence. Data and supporting information are provided within the manuscript and supplemental files.