Download Oral Presentation 3 - Research

Pulmonary Flow
Resistive Device
Taya Furmanski
Albert Attia
Advisor: Thomas Doyle, M.D.
March 17, 2003
Background
Hypoplastic Left Heart Syndrome (HLHS) is a
condition in which the patient is missing
his/her left ventricle
1440 babies are born each year with HLHS
Approximately 75% 3-year survival rate
No medical treatment for HLHS
Only options are operation (reconstruction) or
transplantation
300 patients with HLHS are seen at VUMC
per year
The Problem
Inadequate systemic
blood flow
Amount of O2
delivered to the
organs decreases
significantly
“Blue Baby”
Flow schematic
How to Solve the
Problem
Place nozzle in
pulmonary arteries (see
figure for location)
Device will act as resistor
Decrease in pulmonary
blood flow will cause
increase in systemic
blood flow
Eliminates first two steps
of reconstructive surgery
Length of duration in
heart = 6-8 months
Schematic of Flow with and
without Device Implanted
<1 L/min
1-3 L/min
Systemic
Artery
2-3 L/min
Systemic
Artery
2-3 L/min
Pulmonary
Artery
Pulmonary
Artery
3-5 L/min
Right
Ventricle
WITHOUT DEVICE
1 L/min
1 L/min
Pulmonary
Artery
Pulmonary
Artery
3-5 L/min
Right
Ventricle
WITH DEVICE
Dimensions of the
Nozzle
Calculations by Craig
Russell (ME student)
Theories required to
solve problem


Conservation of mass
Conservation of
momentum
Dimension of end of
nozzle still to be
determined
Pulmonary artery
pressure ~20 mmHg
Alternate Solutions
Place nozzle inside
stent
Use 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 artery
Placement also a
problem
Would cause
hemolysis (tiny
holes would damage
red blood cells)
What We Need
- Modeling In vitro model to simulate the blood
vessels
Prototype can be tested through model
to determine effectiveness
Computer model would allow variables
to be altered easily to determine the
optimal dimensions of the device
What We Need
- Materials & Assistance Use Vanderbilt shop to mold conical device
Use materials to create physical model that
accurately portrays operation of device
Assistance of mechanical engineering
students (Craig Russell and Chris Owen) and
professor (Dr. Mark Stremler) for fluid
dynamics
Find experienced programmer to develop
computer modeling system or use one
currently in existence
Why Nitinol?
Biocompatible
Memory wire—can be molded to
desirable shape
Can be elongated to fit into catheter,
enabling insertion
What We Have
Accomplished Thus
Far…
In-depth research of HLHS
Several meetings with Dr. Doyle to discuss
the problem and possible solutions
Finalizing a design plan
Create a plan of attack: start simple and
increase complexity
Ordered and received nitinol wire
Calculations of fluid dynamics
Finalized method of implantation
What We Have Yet to
Do…
Produce prototype of device
Test prototype
Use Mechanical Engineering lab to test
pressure drop across device
 Pressure drop calculations will allow proper
calculation of dimension of the nozzle

Create or find computer model
simulation of cardiovascular system
References
1.
2.
3.
4.
5.
Barber, Gerald. Hypoplastic Left Heart
Syndrome. Structural Congenital Defects,
section 3.
www.ucch.org/sections/cardio/new/hlhs.html
; date accessed: January 30, 2003.
web1.tch.harvard.edu/chnews/03-1502/fetalcath.html; date accessed: February
10, 2003.
Dr. Thomas Doyle; Vanderbilt University
Medical Center.
http://www.nemours.org/no/ncc/cardiac/crd1
524.html