Introduction:
Advances in ex vivo heart simulation have enabled the study of valvular biomechanics, disease pathologies, and repair strategies. However, these simulators test the valves in isolation, which does not fully replicate in vivo physiology. We hypothesize that by engineering a simulator that preserves the aortomitral junction, we can better recreate pathophysiologies such as systolic anterior motion (SAM). Here, we present a new heart simulator that preserves and manipulates the native aortomitral physiology.
Methods:
Our simulator is comprised of three subsystems: the ventricular chamber, atrial chamber, and aortic chamber (Fig A, B). The heart is excised at the apex to preserve the papillary muscles, and the left ventricle, atrial cuff, and aorta are fixed to their respective chambers via hemostatic suturing to 3D-printed elastomeric rings. The chambers are equipped with pressure and flow sensors, and a linear piston pump generates physiologic pressures and flows. The atrial and aortic chambers are mounted on 5-degree-of-freedom arms. To demonstrate system function, we manipulated the aortomitral angle and measured aortic cardiac output.
Results:
In our testing, we evaluated two unique configurations of an explanted porcine heart, of which the aortomitral angles spanned the SAM predictive risk threshold of <120° (Fig C, D). From the flow readings, we measured a 36% reduction in aortic cardiac output upon decreasing the aortomitral angle by 25°.
Conclusions:
This work highlights the design and development of an ex vivo heart simulator capable of modeling native aortomitral physiology. Our results point to a clear direction for future experimentation, particularly evaluating the biomechanical changes of the heart based on the aortomitral angle. Future work will utilize this platform to create new models and repair techniques to ultimately improve clinical care of valvular pathologies.
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