Heart Valve
In this project we were instructed to research the cardiovascular system and design a artificial heart valve. Our prototype needs to meet four important criteria to create a functional valve: 1) Model needs to function similarly to an Aortic Valve 2) The complete model is an elastic-inelastic bilayer 3) Model should contain strategic elasticity 4) Model should have defined open resting position
Prerequisites
We first researched the crucial things about the heart and the needed terms. The heart pushes blood through valves whenever it beats, and the organs open to accommodate for that and close afterwards so blood doesn't backflow. The moment where the heart stops beating is called the diastole.
We needed to also focus on elasticity, since the valve stretched during diastole. Here are some key terms we used:
We first researched the crucial things about the heart and the needed terms. The heart pushes blood through valves whenever it beats, and the organs open to accommodate for that and close afterwards so blood doesn't backflow. The moment where the heart stops beating is called the diastole.
We needed to also focus on elasticity, since the valve stretched during diastole. Here are some key terms we used:
- Force: f=ma (mass x acceleration)
- Young’s Modulus: number that measures an object or substance's resistance to being deformed elastically (non-permanently)
- Stiffer the material = higher the Young’s Modulus
- F = 𝒀( ∆𝑳/𝑳𝟎 )𝑨
- Stress over strain along an axis, measured in Pascals
- Stress: force divided into a cross-sectional area: σ= F/A (A is the area of the material)
Design options & alternatives
Bioprosthetic Triscupid Valve
Bioprosthetic tissue based valves (Right) are created in laboratory conditions with tissue cells or donated animal tissue that's strong and flexible. Tissue valves can last 10-20 years, and usually don't require the long-term use of medication. However a person with a this type of valve replacement needs an additional surgery for replacement later in life due to inherent biodegration. Bioprosthetic valves render medication and convalescence obsolete, but at the expense of durability.
Bioprosthetic tissue based valves (Right) are created in laboratory conditions with tissue cells or donated animal tissue that's strong and flexible. Tissue valves can last 10-20 years, and usually don't require the long-term use of medication. However a person with a this type of valve replacement needs an additional surgery for replacement later in life due to inherent biodegration. Bioprosthetic valves render medication and convalescence obsolete, but at the expense of durability.
Mechanical Multipurpose Valve
Commonly referred to as the "Ball & Cage Model" these mechanical valves (Left) are made of strong durable materials. They are long-lasting with no need for secondary replacement procedures. These manufactured valves will last throughout the remainder of the patients lifetime.(No biodegration). However patients that receive this type of valve will most likely require a blood thinning medication (Like Apixaban or Xarelto) throughout the remainder of their lives. This keep clots from forming, which is critical for maintenance because clots can lodge in the valve flaps or hinges and cause a malfunction within the mechanism.
Commonly referred to as the "Ball & Cage Model" these mechanical valves (Left) are made of strong durable materials. They are long-lasting with no need for secondary replacement procedures. These manufactured valves will last throughout the remainder of the patients lifetime.(No biodegration). However patients that receive this type of valve will most likely require a blood thinning medication (Like Apixaban or Xarelto) throughout the remainder of their lives. This keep clots from forming, which is critical for maintenance because clots can lodge in the valve flaps or hinges and cause a malfunction within the mechanism.
Design Sketches
Sketches of the heart done by each member of the group post cardiovascular research; preliminary diagrams. (Ky Heon - Top Left, Brian Burrous - Top Right, Brandon Fields - Top Right, Nick Ruiz - Bottom Right,)
Prototype
Our heart valve design was meant to close when pressure was applied to it and stay open otherwise. We made our own "ball and cage" model with an elastic spring cage on one side and a smaller tube on the other side so the ball can't get loose. The other end prevents the ball from escaping by using a smaller tube than what the ball can fit.