Development of a thermodynamic control system for the Fontan circulation pulsation device using shape memory alloy fibers

Abstract

The Fontan procedure is one of the common surgical treatments for circulatory reconstruction in pediatric patients with congenital heart disease. In Fontan circulation, low pulsatility may induce localized lung ischemia and may impair the development of pulmonary peripheral endothelial cells. To promote pulmonary circulation in Fontan circulation, we have been developing a pediatric pulmonary circulatory pulsation device using shape memory alloy fibers attached from the outside of total cavopulmonary connection. In this study, we developed a new thermal control system for the device and examined its functions. We mounted on the device 16 fibers connected in parallel around an ePTFE graft circumferentially. To provide optimized contraction, we designed the new thermal control system. The system consisted of a thermistor, a pressure sensor, and a regulator that was controlled by the adaptive thermodynamic transfer functions. We monitored the parameters and calculated heat transfer function as well as pressure distribution on the graft surface. Then we examined and compared the dynamic contractile pressure and changes in surface temperature. As a result, by the application of the control based on the new feedback system analysis, the circumferential contractile pressure increased by 35%. The adaptive thermodynamic regulation was useful for the selection of alternative thresholds of the surface temperature of the graft. The system could achieve effective contraction for the pulsatile flow generation by the device.

Hydrogel‐Based Artificial Muscles: Overview and Recent Progress

“…An artificial muscle refers to a device that can reproduce the motion of a living organism by reversible contraction and expansion of materials in response to a specific stimuli, which is similar to muscles responding to a neural signal . Artificial muscles have been developed using various materials, such as polymer fiber, elastomer, and shape‐memory alloy . Depending on the materials that form the artificial muscle, desired characteristics, such as a large output force and fast response speed, can be achieved.…”

Construction and Evaluation of a Bio-Engineered Pump to Enable Subpulmonary Support of the Fontan Circulation: A Proof-of-Concept Study

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In vitro validation of a self-driving aortic-turbine venous-assist device for Fontan patients

“… 39 Furthermore, poor power transmission efficiency has the potential to limit the hydrodynamic performance of ventricular assist. Cardiac assist systems that harvest the skeletal muscle power 40 , 41 , 42 to drive an IVC cuff, 43 , 44 atrial cardiomyoplasty, 45 or tissue-engineered beating TCPC conduits, 46 can eliminate the need for external power. However, these systems also have poor power transmission efficiency and for any meaningful IVC support, require pacing systems and valves to synchronize with the venous pulsatility.…”