Pulmonary Flow Resistive Device

Taya FurmanskiAlbert Attia

Advisor: Thomas Doyle, M.D.February 12, 2003

BackgroundHypoplastic Left Heart Syndrome (HLHS) is a condition in which the patient is missing his/her left ventricle1440 babies are born each year with HLHSApproximately 75% 3-year survival rateNo medical treatment for HLHSOnly options are operation (reconstruction) or transplantation300 patients with HLHS are seen at VUMC per year

The Problem

Inadequate systemic blood flowAmount of O2 delivered to the organs decreases significantly“Blue Baby”http://www.nemours.org/no/ncc/cardiac/crd1524.html

How to Solve the ProblemPlace nozzle in pulmonary arteries (see figure)Device will act as resistorDecrease in pulmonary blood flow will cause increase in systemic blood flow

Dimensions of the NozzleCalculations by Craig Russell (ME student)Theories required to solve problem Conservation of mass Conservation of momentum

Dimension of end of nozzle still to be determinedPulmonary artery pressure ~20 mmHg

4 mm

Alternate SolutionsPlace nozzle inside stentUse bow-tie shaped stent (see figure)Placing a mesh-like device in the pulmonary arteries

Problems With Alternate Solutions

Extremely difficult to place in the arteryPlacement also a problemWould cause hemolysis (tiny holes would damage red blood cells)

What We Need- Modeling -

In vitro model to simulate the blood vesselsPrototype can be tested through model to determine effectivenessComputer model would allow variables to be altered easily to determine the optimal dimensions of the device

Blood Vessel Model

What We Need- Materials & Assistance -Use Vanderbilt shop to mold conical deviceUse materials to create physical model that accurately portrays operation of deviceAssistance of mechanical engineering students (Craig Russell and Chris Owen) and professor (Dr. Mark Stremler) for fluid dynamicsFind experienced programmer to develop computer modeling system or use one currently in existence

What We Have Accomplished Thus Far…In-depth research of HLHSSeveral meetings with Dr. Doyle to discuss the problem and possible solutionsFinalizing a design planCreate a plan of attack: start simple and increase complexityOrdered and received nitinol wireBeginning calculations of fluid dynamicsFinalized method of implantation

What We Have Yet to Do…Find exact dimensions of device necessary to alleviate the problemProduce prototype of deviceTest prototypeCreate or find computer model simulation of cardiovascular systemGo to Boston!!!!

References1. Barber, Gerald. Hypoplastic Left Heart

Syndrome. Structural Congenital Defects, section 3.

2. www.ucch.org/sections/cardio/new/hlhs.html; date accessed: January 30, 2003.

3. web1.tch.harvard.edu/chnews/03-15-02/fetalcath.html; date accessed: February 10, 2003.

4. Dr. Thomas Doyle; Vanderbilt University Medical Center.