Monday, 11 October 2004 - 1:25 PM

This presentation is part of : Graduate Student Competition

An In Vitro Analysis to Determine Flow-Displacement-Force Relations in an Adjustable Systemic to Pulmonary Artery Shunt

Naveen V. Thuramalla, Cardiojustable, LLC., University of Kentucky, A044, ASTeCC Building, University of Kentucky, Lexington, KY 40506 and William I. Douglas, Cardiojustable, Department of Surgery, University of Kentucky, 800 Rose Street, C-204 Chandler Medical Center, University of Kentucky, Lexington, KY 40536.

Single ventricle physiology (SVP) is a congenital cardiac anomaly in which one ventricle is underdeveloped. Most common type of SVP is hypoplastic left heart syndrome (HLHS). It refers to a cardiac condition in which there is a failure of development of the mitral valve, aortic valve, left ventricle and ascending aorta. A reliable and adjustable connection between the heart and the body needs to be established to maintain an appropriate balance of flow between the systemic and pulmonary circuits, which is crucial for survival. To achieve full range control of blood flow between the two circuits, an adjustable systemic to pulmonary (SPA) shunt is being developed. The main components of this device would include a PTFE graft; shunt casing, torque producing unit and a torque transmission cable. In order optimize the design of the device, it is necessary to determine the relation between the force, flow rate and the displacement. To this end, an in vitro set up is built. This essentially consists of an open hydraulic circuit to maintain desired pressures across the shunt, a force gauge to record the load applied by the plunger on the pressurized graft to cause the desired constriction, a rotameter to determine the flow rate and a steady flow pump. Effect of constraining the shunt and varying average pressures across the shunt on the force-flow-displacement relations was investigated and mathematical relations were established. It was observed that there is no reduction in flow up to almost 50% of constriction, under all conditions considered.

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