SoloHeart En Route to Being Fully-Functional Pulsatile Artificial Heart

by Slytherin - 501
M. Ibrahim Khatkhatay, Sarah Knezek, Douglas Kent, Alyssa McCue, Pablo Madrid, Akshita (Jade) Kumar, Antonio Moualeu,Nicole Girsh, John Li

Pumps:

• Heart and valves will be removed but the blood vessels will be preserved
• Solenoids enclosed in polyurethane will be installed
• Located superior to the central tendon of the diaphragm where the heart and pericardium are originally located
• St. Jude’s Bileaflet valve will be utilized

Pump parameter:

• All calculations are for an average 3-year old
• Body surface area of 0.5m2
• Weight 11.5kg
• Stroke volume: 20mL
• Inner radius of solenoid: 1.414cm
• Outer radius of solenoid: 2cm
• Radius of solenoid axis: 0.75cm
• RVAD will have 63% fewer coils than LVAD to generate less force
• Solenoid will cycle at resting 85-100 BPM allowing total C.O. of 1.5-2L/min
• Normal LVAD pressure of solenoid on blood will be 83mmHg (7N over 6.28cm2)
• Normal RVAD pressure of solenoid on blood will be 30mmHg (2.5N over 6.28cm2)

Pacemaker:

• Implanted in body near LVAD in lower abdomen
• Sensitive to leg temperature
• External control mechanism
• Required to be manually adjustable by the FDA

Battery:

• Battery will be internal super capacitor allowing it to be recharged millions of times
• Will hold enough charge for about one hour without backpack
• Backpack allows for 6 hours of charge
• Uses TET system

SoloHeart is a viable bridge to recovery after preliminary tests are performed.

Heartus Pumpus: A Pediatric Artificial Heart Design

The device will be a modified form of a pulsatile ram pump similar to a Hag fish heart. It will consist of four magnets, outer shell, inner wall, a central chamber, and an electric motor. The speed of the electric motor will determine pulse rate. The magnets will propel the ram into either chamber generating the pressure gradient.

The basis of this device is to have two chambers, one for the pulmonary circulation and the other the systematic circulation. Each chamber is between the outer shell and inner wall made of neoprene, a rubber-like material. The internal mechanical components are encased by a neoprene covering, which can endure repeated stretching. To generate the pressure gradients the device will decrease the volume of a chamber, forcing blood to the pressure desired before it is ejected (in the correct direction with the use of valves).

To provide oscillating movement, two more magnets will be in the center chamber connected to an axle driven by our electric motor. These magnets orientation will be to attract each other, so one side will have North Pole facing out while the other South Pole facing out. Both magnets on the ends of the rod will have their South poles facing towards the center. So the center North face will always attract the edges of the rod while the center South face will always repel. As the center rotates 180 degrees, the rod will oscillate the opposite direction. The rod is fixed to a perpendicular, one dimensional movement from the center of the two chambers and magnets.
The axle speed, in RPM, will determine how fast the pulse rate is. There will be one rotation per pulse. The electric motor will rotate through a gear reduction and rotate the axle connected to the central magnets. The gear reduction will be such that a small electric motor can provide the torque necessary to turn the inside magnets at the expense of RPM.

The speed of the electric motor will be determined by an artificial pacemaker that monitors the oxygen levels of the patient. The power supply will be provided by an implantable battery that is charged wirelessly from a larger battery outside of the body via magnetic induction. This technology is known as transcutaneous energy transfer. This allows for practical life applications like showering so that the larger power source does not have to be worn all the time.

The 502 Slytherin Design Team consisted of: Chad Thompson, Simone Goines, Sonia Kinra, Rachel Schafer, Elsie Ponce, Melissa Giese, and Ashley Labonte

Pediatric VAD by Gryffindor 501

Firebolt Pump with Novel Technique to Create Pulsatile Flow
by Gryffindor - 501
Farida Akberali, Risa Aprilria, Kristina Barsten, Nicholas Brown, Cody Covington, Christine Elkins, Mark Felder, Lauren Fife

Pump design background:

• Based off of current technology from the Hemopump Cardiac Assist System and the Impella by Abiomed
• Both devices are used to assist/unload the heart
  
• Very small; can be implanted in the heart by a catheter inserted into the femoral artery
• The tiny pump uses axial flow to reduce myocardial workload and oxygen consumption, while increasing cardiac output, coronary- and end-organ perfusion

Our pump design:

• All parts are made out of titanium
• The impeller is magnetically levitated in the middle of the shell
• reduces hemolysis
• no "wear and tear"
• Parts are shell, front magnetic bearing, impeller, rear magnetic bearing, motor, and battery
• The device has a diameter of 4.5 mm, length of 55 mm, and weight of 15 g.
• Can generate:
• Flow rate of 0.5 - 3.2 L/min
• Pressure of 100 - 140 mmHg
• Angular velocity of impeller is 19,000 - 22,000 rpm
• Requires a power of 3.5 - 4.2 Watts
• Designed for patients over 10 kg
• Inserted into the left ventricle and stabilized just above the aortic valve
  

Muscular surgery:

• A strand of muscle will be wrapped around the aorta, just above the pump, to create a pulsatile flow
  
• Left latissimus dorsi will be cut where it terminates on the side of the ribs under the shoulder and peeled back until there is a strand 0.75 - 1 inch wide; do not denervate or detach the muscle
• Encircle the muscle around aorta and suture the free end to the strand so that it sits snuggly around the aorta without compressing it
• Insert the electrode from a modified pacemaker for muscular stimulation
• The chosen pacemaker is a Cardiomyostimulator Medtronic Model 4,710 Transform
• The pacemaker should be positioned in the left abdominal wall pocket
• One lead is connected to electrode and another to the pump
• The pacemaker will act as an integrating signal that integrates flow measurements and frequency of stimulation needed to increase/decrease pulsatility rate
• A voltage of 3.5 V is needed for stimulation of the muscle
• The muscle has a resistance of 200 ohms, therefore the necessary power is 0.06125 Watts
• This power will create a pulse of 95 bpm

Gryffindor's technique and pump are both designed as a bridge to recovery.

The HeartBeat(tm)

TEAM 4 (Hufflepuff) - Section 501

Members:
- Jackie Boone
- Karl Hahn
- Parth Khade
- Timothy Snowden
- Krista Volberding
- Chris Weyand
- Katherine Wood
- Jeremy Wurbs
- Shane Young

MAIN PRINCIPLE: Mimic the heart's natural function.
- The design was optimized for laminar flow to avoid hemolysis and thrombogenesis.
- Creates pulsatile flow to maintain healthy vasculature.

LAYOUT:
- Divided into two main sides, similar to the right and left heart.
- Each side has an 'atrium' and a 'ventricle'.
- The flow of blood and contraction system is nearly identical to that of the heart, with blood entering the atria, then the ventricles, from which it is ejected during systole. Below is an animation of the ventricle pumping:

CONTRACTILE MATERIAL:
- Dielectric electroactive polymer (d-EAP): a 'compliant capacitor' - a thin layer of elastomer sandwiched between two compliant electrodes.
- Expands when a voltage is applied to it, corresponding to muscular relaxation (diastole).
- Removal of voltage causes the d-EAP to return to its original shape, providing a contractile force corresponding to muscular contraction (systole)
- Embedded in the ventricle (see image -- red layer is the contractile material)

- Both atria and right ventricle use a 'low' compliance elastomer in the d-EAP. This provides a low force of contraction, yielding a low pressure.
-Time lag from differing forces avoided by using atria to collect blood while ventricles are contracting and relaxing ... like normal heart.
- Left ventricle uses a 'high' compliance elastomer, providing a high contraction force, yielding a high pressure.
- High d-EAP strain range (10-215%) allows for wide range of stroke volumes with one device
- Natural muscle range falls within force & strain range of d-EAP

BODY-DEVICE INTERFACE
- Elast-Eon(tm) is used for all body contact -- blood and organs.
- Completely biocompatible and non-calcific
- High durability & long life (25 years)

CONTROL & ENERGY SYSTEM
- TET System is used for power supply
- Voltage amplifier increases voltage to level necessary for d-EAP
- Pacemaker used for control -- powered by TET system
- Allows for modification by doctor -- can change stroke volume, heart rate, etc.
- Pacemaker also adjusts heart rate based on physical activity using a piezoelectric crystal sensitive to mechanical stress