An Experimental Study of the Implementation of a Fluid Diode Inside a Sano Shunt

Fluid diodes are fluidic devices that enhance fluid flow in a particular direction while inhibiting it in the opposite direction without the use of moving parts. This is accomplished through the use of nozzle shaped geometry on one side of the diode, and cusp shaped geometry on the opposing side. Fluid meets very little resistance as is travels though the nozzle side of the diode. The cusps on the other side of the diode reduce the effective flow area, thereby inhibiting flow. The objective of this study is to determine the effectiveness of a fluid diode installed in a reconstructed cardiovascular system of an infant diagnosed with hypoplastic left heart syndrome. The fluid diode is not used inside the heart, but rather inside a shunt connecting the ventricle to the pulmonary artery. Currently, patients are experiencing regurgi-tant blood flow inside this shunt, which is known as a Sano shunt. This regurgitant volume increases the workload of the ventricle, which can lead to myocardial hyper-trophy and eventual cardiac failure [1, 2]. The principle objective of this thesis is to characterize the performance of certain diodes by testing them experimentally using a mock circulatory system. Experiments were performed on three different size diodes-in-shunts as well as three different size empty shunts. The data from each diode-in-shunt test was compared to the data from each empty shunt test in order to determine if any performance gain was present. The regurgitant fraction (RF%) as well as the individual systolic and diastolic flow volumes were used to evaluate the performance of both the diodes-in-shunts as well as the empty shunts. The earlier experiments were conducted with the diode situated in the middle of the shunt. By moving the diode to the entrance of the shunt, the RF% was improved by as much as 51%. However, with only three different size diodes-in-shunts as well as three different size empty shunts available for testing, it is hard to draw any definitive conclusions as to whether or not a diode can maintain the same systolic flow levels while reducing diastolic flow levels. Further testing using different diameter diodes is required.