Beating Heart Simulator:Oral Report 2Ashley WhitesideNicole RiceJacob Bauer

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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.

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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 real-

life motion.

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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

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Methods - NICOLE

We have segmented our design process into three main steps:

1. Produce a beating heart2. Computer control of heart3. Simultaneous ECG output

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Developing a Beating Heart - NIKKI

We plan on using an actuator to regulate the flow of compressed air into balloons placed in each ventricle.

Image courtesy of http://www.yourheartvalve.com/heartbasics/heartanatomy.htm

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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/

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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

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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.

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Image courtesy of http://www.omega.com/ppt/pptsc.asp?ref=SV4100_SV4300&ttID=SV4100_SV4300&Nav=

Three Way Solenoid Pneumatic Control Valve

The arduino will control the pneumatic valve to alternate between compressed air and the vacuum pump to produce the physical heartbeat.

Balloon

Vacuum Pump

Arduino

Air Compressor

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Control Valve

Servo Motor Driven Pump

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• 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

Servo Motor Driven Pump

• 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.

piston

air

balloon

to motor

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Computer Interface - JAKEWe 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.

InputHeart Rate

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Image courtesy of http://mc202.com/synthesizers/arduino-glitch-box-machinedrum/ and of http://www.yourheartvalve.com/heartbasics/heartanatomy.htm

Simulator

Pump Driver ECG Driver

USB Port

Computer Program (C++)

1. Pump Driver input -> Pin 12. ECG Driver input -> Pin 2

Arduino Program (C++)

Output to Pump

Output to ECG

ClassesSingleton• 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

boardECG Driver• Operates within unique thread• Accesses heart rate and arrhythmia values from

Simulator class• Outputs instructions to EKG through Arduino

board

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Simultaneous ECG Output - MEWe 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

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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.

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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

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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.

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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.

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