Transcript Document

Beating Heart
Simulator:
Oral Report 2
Ashley Whiteside
Nicole Rice
Jacob Bauer
1
Question/Thesis - JAKE
• Can a user interface be created on a computer that can link
and affect different aspects of a heart simulator?
• The user will input a heart rate and/or blood pressure.
• This input will then cause a sample heart to beat at that rate
and simulate an ECG that will display the blood pressure and
heart rate.
• The point of this simulation is to mimic real problems that
may be observed in the operating room and train students to
react accordingly.
2
Engineering Requirements
• The simulator must be controlled by a computer software
package.
• The software must drive a physical heartbeat in a porcine
heart based on the user provided heart rate data.
• The software must also produce an ECG display that
corresponds to the user provided data.
• The simulated heartbeat must be dynamically alterable
• The physical palpitation of the porcine heart must mimic reallife motion.
3
Jonathan C. Nesbitt - JAKE
• Graduated from University of Virginia
with a BA in Biology
• Attended the Georgetown University
School of Medicine in 1981
• Completed postgraduate training at
Vanderbilt in 1986
• Was a surgeon on the USNS Comfort
during operation Desert Storm/Shield
• Joined department of thoracic surgery
at Vanderbilt University Medical Center
in 2008
• Specializes in the treatment of
esophageal cancer, lung cancer,
thymoma and thymic carcinoma
4
Background - ME
• Current System in use by Dr. Nesbitt
• Utilizes a bicycle pump which cyclically pumps a plastic bellows.
• Air lines connected to party balloons placed in right and left
ventricles.
• Does not allow for variable BPM or real time control
• Does not produce a simulated ECG display
• Does not displace enough air to accurately represent the
magnitude of contraction in a healthy heart
5
Methods - NICOLE
We have segmented our design process into
three main steps:
1. Produce a beating heart
2. Computer control of heart
3. Simultaneous ECG output
6
Developing a Beating Heart NIKKI
We plan on using an actuator to regulate the flow of
compressed air into balloons placed in each ventricle.
7
Image courtesy of http://www.yourheartvalve.com/heartbasics/heartanatomy.htm
Developing a Beating Heart NIKKI
We plan on controlling the actuator with a square wave input
At rising edges the signal will produce a digital logic 1, allowing air to flow into
the balloons
At falling edges the signal will produce a digital logic 0 and cut off the air supply.
Images by Judy Jowers from http://www.flickr.com/photos/judyjowers/4391452125/
8
Developing A Beating Heart Niki
We are currently looking at means of driving the
movement of air into the balloons
We are considering two main options
• A solenoid driven pneumatic control valve
• A servo motor driven pump or bellows system
9
Three Way Solenoid Pneumatic
Control Valve
• Solenoid pneumatic
valves are relatively cheap
at around $100 and
incredibly reliable.
• These are capable of
controlling the pressure
we need at rates of under
20 milliseconds.
10
Image courtesy of http://www.omega.com/ppt/pptsc.asp?ref=SV4100_SV4300&ttID=SV4100_SV4300&Nav=
Three Way Solenoid Pneumatic
Control Valve
Air Compressor
Arduino
Vacuum Pump
Control
Valve
Balloon
The arduino will
control the
pneumatic valve
to alternate
between
compressed air
and the vacuum
pump to produce
the physical
heartbeat.
11
Servo Motor Driven Pump
• Alternatively, we have
considered using a servo
motor to drive a piston or
bellows system that will
force air into the balloons
• This option is advantageous
because it is significantly
cheaper than using a
pneumatic control valve.
• Unfortunately, the motor
system is less mechanically
reliable and offers less
control over the movement.
Image courtesy of http://www.galilmc.com/products/servo-motor.php
12
Servo Motor Driven Pump
to motor
piston
air
balloon
• The motor system
would work by driving a
piston in a vacuum
tube.
• As the motor rotates
the piston would
oscillate between
forcing air into the
balloons and sucking air
from them, thereby
eliminating the need for
a vacuum system.
13
Computer Interface - JAKE
We will develop a computer program that will enable the user to
dynamically alter the heart rate during simulated surgery.
Ultimately this software will both produce the ECG display and
program the Arduino microcontroller in order to control the motion
of the heart.
Input
Heart
Rate
14
Image courtesy of http://mc202.com/synthesizers/arduino-glitch-box-machinedrum/ and of http://www.yourheartvalve.com/heartbasics/heartanatomy.htm
Computer Program (C++)
Simulator
Pump Driver
ECG Driver
USB Port
Classes
Singleton
• Stores heart rate and arrhythmia values
• Allows for dynamic access to variables
• Ensures single instance of class (Singleton GoF
Pattern)
Pump Driver
• Operates within unique thread
• Accesses heart rate value from Simulator class
• Outputs instructions to pump through Arduino
board
ECG Driver
• Operates within unique thread
• Accesses heart rate and arrhythmia values from
Simulator class
• Outputs instructions to EKG through Arduino
board
Output to ECG
Output to Pump
1. Pump Driver input -> Pin 1
2. ECG Driver input -> Pin 2
Arduino Program (C++)
15
Simultaneous ECG Output - ME
We plan on recording different ECG rhythms as .wav files.
Once completed, these .wav files can be freely manipulated
and accessed through the use of C++.
The ECG output and beating heart prototype will
operate simultaneously but completely independently
of one another.
Image from: http://www.swharden.com/blog/images/simple_ecg_circuit_output.png
16
Simultaneous ECG Output - ME
• Currently, a program is
being licensed that
displays variable and
adjustable ECG signals.
• We are considering
using this program as
an alternative to
manipulating sample
recordings of the
various waveforms
when displaying the
ECG.
17
Additional Goals - ME
Once we have developed a successful prototype we will
contemplate endowing the system with additional capabilities
to increase functionality. These include:
• Plot of arterial pressure
• Simulation of the effects of anesthesia
• Simulation of common arrhythmias
18
Status/Results - NIKKI
• We have met with the faculty sponsor, Jonathan Nesbitt, and
been informed of the details of the project.
• Dr. Nesbitt also showed the current heart pump.
• We are acquiring an ECG generating program that allows for
variability.
• A skeleton program has been developed in C++.
• We are researching various types of mechanical control
devices to drive the heart.
• Scheduled the first meeting with Dr. Nesbitt for the new year,
during which we will present different potential devices and
determine budgetary constraints.
19
Conclusion - JAKE
Our goal is to develop a prototype for a cardiac surgery
simulator that will permit dynamic alteration of variables
during surgery.
We are planning to meet with Dr. Nesbitt consistently
throughout the semester.
We will be ordering raw materials within the next month and
continue developing the program.
20