PP #2

Overview of Tissue Engineering for the Heart

  • Course: Biomedical Engineering | University: University of Cincinnati

Heart Valves

  • Mitral Valve

    • Also called bicuspid valve.
    • Located between the left atrium and left ventricle.

  • Tricuspid Valve

    • Also known as the right AV valve.
    • Positioned between the right atrium and right ventricle.

Aortic Valve Types

  • Bicuspid Aortic Valve

    • Definition: A valve with two cusps.
    • Potential Problems:
    • Potential for aortic stenosis.
    • Risk of aortic regurgitation.
    • Increased risk of aortic aneurysm formation.

  • Unicuspid Aortic Valve

    • Definition: A valve with a single cusp.
    • Problems it can cause:
    • Similar issues as a bicuspid aortic valve but more severe.
    • Higher likelihood of heart failure and other complications.

Aortic Aneurysm

  • Definition: An abnormal bulge in the wall of the aorta.
  • Complications:
    • Can lead to aortic dissection or rupture.
    • Symptoms may include chest or back pain, and it may be asymptomatic until it ruptures.

Aortic Valve Considerations

  • Typically, patients require aortic valve replacement when significant pathology is present.
    • Replacement Options:
    • Mechanical Valve Prostheses: Typically long-lasting, require lifelong anticoagulation.
    • Bioprosthetic Valves: Typically made from animal tissue (e.g., pig or cow), less durable than mechanical valves, but may not require anticoagulation.

Procedures Involving Aortic Valve Replacement

  • Examples of Surgical Interventions:
    • Figure 2A: Bi-leaflet mechanical prosthesis.
    • Figure 2B: Mechanical composite graft used in aortic root replacement.
    • Figure 2C: Stented bioprosthetic valve (example: Avalus Medtronic, MN, USA).
    • Figure 2D: Stentless bioprosthetic valve (example: Freestyle TM, Medtronic, MN, USA).

Left Ventricular Assist Device (LVAD)

  • Purpose: Acts as an artificial pump for the left ventricle.
  • Components:
    • External Control Device: Manages the function of the LVAD.
    • Battery: Provides power to the device.
  • Usage Duration:
    • Can extend life by 2-5 years while waiting for a heart transplant.
    • In extreme cases, may prolong life by up to 13 years.

Advances in 3D Bioprinting for Cardiac Applications

  • Study Citation: Lee, A. et al. (2019). 3D bioprinting of collagen to rebuild components of the human heart. Science, 365, 482-487.

  • 3D Bioprinting Process:

    • Utilize dual-3D print technology for collagen and cell-ink.
    • FRESH: Freeform reversible embedding of suspended hydrogels.
    • Collagen printed on a support bed that melts away, using pH changes to gel the material.

  • Visual Representation:

    • Panel B: Collagen appears green, cells are red.
    • Panel C: Depicts a ventricle construct.
    • Panels D and F: Calcium staining results shown.
    • Panels E and G: Calcium wave propagation mapping at a speed of 1.97extcm/s1.97 ext{ cm/s}.

  • Calcium Dynamics:

    • Panel J: Calcium traces during spontaneous contractions (top), under 1Hz stimulation (middle), and under 2Hz stimulation (bottom).
    • Panel K: View of ventricle showing the inner wall in yellow and outer wall in red.

  • Mechanical Analysis:

    • Panel L: Tracking ventricular wall motion using Finite Element Analysis (FEA).
    • Panel M: Measurement of ventricular opening area during contraction.