Cardiac Valve Replacement

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Cardiac Valve Replacement

• Brenda Sweeney Allen Horton
• Christopher Abhulime
• Max KnipperKoorosh Mirfalkrai

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Cardiac Valves
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Cardiac Valves

• Valves are designed to control the flow of blood
  through the heart in one direction only.

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Cardiac Valves

• There are 4 valves in the human heart
• The two valves located between the atrial and
  ventricular chambers on each side are called
  atrioventricular valves (AV). These valves
  control backflow into the atria when the
  ventricles begin to contract.

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Cardiac Valves

• Each of the atrioventricular valves consists of
  flaps, or cusps, of fibrous tissue that project
  from the heart wall (cardiac skeleton) into the
  opening between the atrium and ventricle. These
  cusps are covered with a layer of endothelium
  that is continuous with the endothelial lining
  (endocardium) of the heart.

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Cardiac Valves

• Pathophysiology
• Tiny white collagenic cords called chordae
  tendineae anchor the cusps to the ventricular
  walls to prevent the flaps from flapping upward
  into the atria like an umbrella being turned
  inside out by a strong wind.

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Cardiac Valves

• The right AV valve has three cusps, anterior,
  posterior, and septal, and is therefore called
  the tricuspid valve. This valve controls blood
  flow from the right atrium to the right
  ventricle.
• The left AV valve possesses only two cusps, the
  anterior and posterior, and is termed the
  bicuspid, or mitral, valve. The mitral valve
  controls blood flow from the left atrium to the
  left ventricle.

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Cardiac Valves

• The second set of valves control blood flow out
  of the heart. Each of these valves consists of
  three pocket like cusps which have the shape of a
  half moon. Hence, they are also termed the
  semilunar valves.

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Cardiac Valves

• The semilunar valve cusps are forced open and
  flattened against the arterial walls as the
  ventricles discharge their blood into the large
  arteries.
• When the ventricles relax, blood begins to flow
  backward toward the heart and the cusps fill with
  blood, closing the semilunar valves to prevent
  arterial blood from reentering the heart.

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Cardiac Valves

• Aortic semilunar valve
• Controls blood flows out of the left ventricle
  to your body.
• Pulmonary semilunar valve
• Controls blood flows out of the right ventricle
  to the pulmonary artery on its way to the lungs

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Cardiac Valves

• Pathophysiology
• Two conditions lead to valve replacement
• Stenosis
• Regurgitation

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Cardiac Valves

• Stenosis-Narrowing of the valve that makes it
  difficult for the heart to work properly due to
  stiffened valve tissue.
• Causes of stenotic valves
• Birth defect
• Deposits of calcium from abnormal blood flow
• Degeneration with aging

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Cardiac Valves

• Regurgitation-When a valve does not close tightly
  between heartbeats allowing blood to go
  backwards.
• Acute regurgitation
• Most commonly caused by infectious endocarditis.
  Can also be caused by injury or tearing.
• Chronic Regurgitation
• Most common cause is high blood pressure.
• Other causes
• Marfan syndrome
• Rheumatic fever
• Genetic defects

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Cardiac Valves

• Design Considerations
• First they need to fit the peculiar requirements
  of blood flow through the specific heart chambers
• -Has to mimic the blood flow properties of a
  normal heart valve, called central flow
• -Central flow keeps the amount of work done
  by the heart to a minimum

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Cardiac Valves

• The second design consideration is reducing or
  eliminating the risk of blood clots.
• -The shape of the valve can add to the risk of
  blood clot
• -If a replacement valve has any areas where
  blood can pool or become stagnant this can
  greatly increase the risk of clots
• -The valve also has to reduce mechanical causes
  of hemolysis

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Cardiac Valves

• One of the last design considerations is how
  quiet the valve is
• -Other designs you can clearly hear when the
  valve closes
• -This is a concern because it can lead to social
  embarrassment, sleep disturbances, problems
  concentrating, and general annoyance

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Cardiac Valves

• How does ATS address these concerns?
• ATS uses a bileaflet design, which most closely
  mimics the natural central flow of blood through
  the valve.
• -Other designs cause significant turbulence by
  inhibiting central flow

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Cardiac Valves

• The ATS Open Pivot Design facilitates passive
  washing which significantly reduces the risk of
  blood clots by eliminating cavities and prevents
  blood from becoming stagnant or clotting
• - This design also reduces hemolysis by not
  having complicated structures blood is forced
  through

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Cardiac Valves

• The ATS valve is much quieter than other
  mechanical valves.
• -This is due to the design of the valve.
• -The design uses the flow of the blood to cause
  a viscous cushion to decelerate leaflet closing

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Cardiac Valves

• Early Research
• 1913 First recorded surgical operation on a
  heart valve.
• 1952 First mechanical heart valve was
  implanted.
• 1962 First successful biological valve
  invented.

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Cardiac Valves

• 1950s - The caged ball mechanical valves
• Rubber ball in Cobalt-chromium alloy cage
• 1960s Tilting disc prosthetic valves designed.
• Late 1970s Bileaflet valves introduced

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Cardiac Valves

• 80,000 undergo cardiac valve repair/replacement
  in US annually
• About 200,000 caged ball valves have been
  implanted. In use for over 30yrs.
• About 360,000 tilting disc valves have been
  implanted. Fewer than 1 failure after 15 yrs
  experience.
• About 600,000 bileaflet valves have been
  implanted. Only about 50 failures out of 1million
  in service.

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Cardiac Valves

• Approx. 265,000 prosthetic valves implanted
  worldwide each year.
• Cardiac valve replacement now worth over
  700million.

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Cardiac Valves
Company Overview

• ATS Medical, Inc. engages in the development,
  manufacture, and marketing of medical devices
  primarily used in cardiac surgery. Minneapolis,
  MN.
• Its primary product, a mechanical heart valve,
  ATS Open Pivot Heart Valve, is used to treat
  heart valve disease caused by the natural aging
  process, rheumatic heart disease, prosthetic
  valve failure, and congenital defects.

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Cardiac Valves
Company Overview

• Full Time employees 227
• Timeline
• 1990 ATS Open Pivot Heart Valve project
  started and ATS Medical, Inc. Established.
• 1994 US Patent Issued
• 1997 First US Implant of ATS heart valve.
• 2000 FDA Approval
• 2006 Over 100,000 mechanical heart implants
• The Group holds an exclusive, royalty-free,
  worldwide license to an open pivot, bileaflet
  mechanical heart valve design. The Group markets
  its products in the United States, Europe, Japan
  and Canada.

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Cardiac Valves
Company Overview

• ATS Medical merging with 3F Therapeutics in order
  to strengthen the Companys position in heart
  valve therapy and the cardiac surgery market.

• 1 Year History of ATSI Stock Price

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Cardiac Valves
Company Overview

• Manufactured under licensed U.S. Patent 4,692,165
  and United States Patent No. 5,354,330.
• No. 5,354,330 An improved heart valve
  prosthesis arranged for permanent implantation to
  replace a defective natural heart valve, wherein
  the improved prosthesis device includes an
  annular body or ring designed to retain a pair of
  rotatable flat plate occluders.
• Manny Villafaña, founder and Chairman of the
  company is also named as an inventor on the
  patent. Manny stepped down from Chairman of the
  company in 1994.

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Development of Clinical Design
Cardiac Valves

• ATS Medical mechanical bileaflet valve is compose
  of pyrolitic carbon.
• Available in 2 forms Standard and Advanced
  performance.
• The study aim was to evaluate the clinical
  results and evaluation after surgery.
• Early clinical study was done on 100 patients (63
  men, 37 women, mean age of 63.6/-10.6yrs. Study
  went on for 3yrs.)

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Development of Clinical Design
Cardiac Valves

• Echocardiograph is a valuable tool for evaluating
  of mechanical valves.
• Echocardiograph was performed at least 3 mths
  after valve replacement.
• Results showed that the in hospital mortality was
  3 and there were 4 late death. None of the death
  was valve related.

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Development of Clinical Design
Cardiac Valves
Example of Echocardiograph
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Development of Clinical Design
Cardiac Valves

• Based on the echocardiograph the new ATS heart
  valve when implanted in the aortic position has
  an excellent hemodynamic profile. The clinical
  result show a very low rate of thromboembolic and
  anticoagulant.

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Development of Clinical Design
Cardiac Valves

• May 1994 through Oct. 2000 a total of 1,146
  patients underwent valve replacement with the ATS
  mechanical cardiac valve prosthesis under an
  approved study protocol.
• AVR (Aortic valve replacement) was conducted in
  801 patients (309 with coronary bypass) and MVR
  (Mitral valve replacement) in 345 patients (78
  with coronary bypass).
• Conclusion Study showed ATS mechanical valves
  are valuable for treatment of cardiac disease.

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Cardiac Valves
Modifications

• Thromboresistance
• Coating techniques Carbon
• Hemodynamics
• Circulation of blood.
• Ease of implantability
• Suture of implant.
• Durability
• Increase the life of the device.
• Improved quality of life.
• Improve the noise generation of the device.
  Acoustical engineers may help.

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References

• The Texas Heart Institute Award for Undergraduate
  Writingin the History of Cardiovascular Medicine
  and Surgery from http//www.tmc.edu/thi/starr.html
  
• Prosthetic Heart Valves from http//cape.uwaterloo
  .ca/che100projects/heart/files/frame2.htm
• Artificial heart valves from http//www.madehow.co
  m/Volume-6/Artificial-Heart-Valve.html
• ATS Medical from http//www.atsmedical.com/
• United States and Patent Office from
  http//www.uspto.gov/

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Cardiac Valves

• Questions?