Artificial Heart ValvesKhade Grant, Raghav Atluri,

Fadwa Essabbar, James Justice, & Nadiah Hassan

Anatomy of Heart Valves• 4 valves

o 2 AV: Mitral & Tricuspido 2 semilunar: Aortic & Pulmonaryo Open and close due to pressure gradient

• Leaflets – sheets of connective tissue• Chordae tendineae prevent valve

eversiono Connect valves to heart muscleo 80% collagen; 20% elastin

QUESTION!

• How many people are diagnosed with heart valve disease in the United States annually?

• Take a guess!

Clinical Significance• 5 million diagnosed w/ heart valve disease

annually in the US. ($200 billion)• Regurgitation – blood leaking back across the

valveo Inability to close fully

• Stenosis – valve becomes constrictedo Inability to open fullyo Decreased blood flow; high blood pressure

• 50% chance of death in severe AS after 2 years

Material Specifications

• Non-thrombogenic• Non-hemolytic• Infection resistant• Biologically inert• Durable• Facilitate healing• Non-obstructive

Types of Heart Valves

• Mechanical Valveso Ball & Cage (late 1950s)o Tilting Disc (1970s)o Bileaflet (1978)

• Tissue Valveso Porcine (pig) pericardiumo Bovine (cow) pericardium

Materials used

• Frameo Co-Cr alloys

• Occluding disc/ballo UHMWPEo Silicone elastomero Pyrolytic carbon (PyC)

• Suture ringo Dacrono e-PTFE

Mechanical• Stent

o Polypropyleneo Elgiloy (Co-Cr-Ni alloy)

• Stent coveringo PTFEo Polyestero Acetyl polymer

• Leafletso Porcine pericardiumo Bovine pericardium

• Suture Ringo Dacrono e-PTFEo Silicone rubber

Tissue

Pros and Cons

Major Problems• Calcification

o Mainly in tissue valveso Ca2+ + P on tissue => Ca-P mineral depositso Can cause stenosis

• Tissue deteriorationo 5-15 year life spano Replacement = 11.5% - 32% mortality rate for patients age 70+

• Thromboembolismo Tissue death, stroke, heart attacko Lifetime anticoagulant treatment

• Endocarditiso Bacteria/infection induced inflammation of the endocardiumo Glutaraldehyde treatment

Future of Artificial Heart Valves• Minimally invasive heart valve surgery

o Totally endoscopic aortic valve replacement (TEAVR)

o Compressed valve inserted through vein or artery in the leg

o Inflates once in position• Transplant cells from the kidneys and

bone marrow to tissue valveo Improves biocompatibility of valve

• Tissue valve with living cellso Self-healingo Slows degradation rate

Our Gold Standard• Bi-leaflet or Tri-leaflet valve• Suture Ring

o Expanded PTFE Hydrophobic, Biologically inert, Degradation resistant

• Frame & Occluding disko Pyrolytic Carbon

Strong, Durable, Most thromboresistant

• Add a surface coatingo Tethered-Liquid Perfluorocarbon o Flexible molecular layer of TPo Layer of LP attached to TP layero Very thromboresistanto Decreases need for anticoagulant treatment

References1. https://en.wikipedia.org/wiki/Atrium_(heart)2. https://en.wikipedia.org/wiki/Heart3. http://www.pph-news.com/heart-valve/statistics/4. http://www.thrombosisadviser.com/en/image/?category=vte&image=venous-thrombus-

formation5. http://www.revespcardiol.org/en/failed-percutaneous-closure-of-mitral/articulo/

90098395/6. http://www.pages.drexel.edu/~nag38/Types.html7. http://www.lookfordiagnosis.com/mesh_info.php?

term=Venous+Thromboembolism&lang=18. http://drsircus.com/medicine/magnesium/calcification-and-its-treatment-with-

magnesium-and-sodium-thiosulfate9. http://medicalxpress.com/news/2014-03-human-totally-endoscopic-aortic-valve.html10. http://aizenberglab.seas.harvard.edu/index.php?

show=research_project&proj=55&wh=929x907x1920x108011. http://www.kurzweilai.net/bioinspired-coating-for-medical-devices-avoids-clotting-and-

suppresses-bacterial-infection