2. History
ā¢ 1955ļ Gordon Murray ļ Aortic
Homograftļ in DTA (saline)
ā¢ 1961ļ Heimbeckerļ Aortic homograftļ
Orthotopic position (saline + penicillin)
ā¢ 1962ļ Donald Ross( Gunning + Duran)ļ
Successful Aortic Homograft implantation
3. History
ā¢ Weldon ( Johns Hopkins)ļ Aortic Homografts on
frames (1960)
ā¢ Angellļ First implanted stent mounted aortic
homografts
ā¢ Senning ļ Fascia Lata, Marion Ionescuļ Fascia Lata +
heterologous pericardium
ā¢ 1967ļ Donald Rossļ Pulmonary autograftļ complex
surgery
4. HISTORY : XENOGRAFT AORTIC VALVES
ā¢ Experimental studies of Duran and Gunning : basis for use
of xenograft in human (1962)
Jean Paul Binet ,Paris (1965)
ā¢ Direct porcine aortic valve Xenograft implantation
ā¢ sterilized and preserved in special formaldehyde solution
Carpentier,Paris (1967)
ā¢ Glutaraldehyde- preserved stent-mounted porcine valves
5. BOVINE PERICARDIAL VALVE :'IONESCU
- SHILEY PERICARDIAL XENOGRAFT.'
ā¢ Invented by Marian Ionescu-
British surgeon
ā¢ March 1971, implantation in
humans
ā¢ Glutaraldehyde treated and
mounted on Dacron-covered
titanium frame
ā¢ 1971- 1976 :implanted 212 valves 5
6. History
ā¢ Warren Hancock , Edwards Laboratories
ā¢ Porcine aortic valve fixed in formalin
ā¢ Machined stellite stentļ polypropylene stent
ā¢ First implated by Robert Litwack at
National Institute of Health , Washington DC
7. BIOPROSTHESIS
ā¢ Term āBioprosthesisā was coined by Carpentier
ā¢ Prosthesis
ā made from biological material
ā chemically treated by means of tissue fixation to
reduce its antigenicity, to increase tissue stability, and
prevent host fibroblast infiltration and ingrowth. .
Texas Heart Institute journal.
1983;2:159-162
8. BIOLOGICAL VALVE SUBSTITUTE
ā¢ Made of biological material
ā¢ Tissueā pericardium/native
valve
ā¢ Source-
autograft/homograft/xenograf
t
ā¢ Design-Stented/stentless
ā¢ Tissue treatment - fresh or
fixed
9. Why biological valve?
ā¢ Mechanical valves
ā Thromboembolism
ā Hemolysis
ā Life long Anticoagulation therapy
ā Need for Better hemodynamics
ā¢ Biological valves:
ā More natural, no anticoagulation
10. DEVELOPMENT OF BIOLOGICAL VALVE
ā¢ Tissue material: From Homograft to Xenograft
ā Size Discrepancy
ā Shortage of donor
ā Storage
ā Abundance of Xenograft
ā¢ Advancement in chemical fixation and preservation
ā¢ Modification in pressure fixation
ā¢ Use of Frame/stents
ā¢ Development of Antimineralization technique
10
11. TISSUE FIXATION AND PRESERVATION
ā¢ The purpose is to
ā Stabilizes tissue.
ā Prevent Autolysis
ā Increase their mechanical strength or stability
11
12. TISSUE FIXATION AND PRESERVATION
ā¢ Chemical
ā Additive ā chemically link or bind to the tissue and
change it.
ā¢ Formaldehyde , Gluteraldehyde , Osmium Tetroxide ,
Potassium Dichromate , Acetic Acid
ā Non-additive ā acetone and alcohols
ā¢ Ex: Methyl or Ethyl Alcohols
18. TISSUE FIXATION-Work of Carpentier(1965-
1970)
ā¢ Mechanical Protection:
ā¢ The Concept of Greffe Protegee(1966)
ā¢ inflammatory cellular penetration occurred at
graft-host interface
ā¢ Physical barrier-a thin cloth or a stent, was
interposed between the host and the valve
ā¢ Aortic sleeve was covered with the same
material
19. GLUTARALDEHYDE FIXATION
ā¢ Higher ļ¬xation pressures:
ā tissue ļ¬attening and compression
ā loss of transverse Cuspal ridges and collagen crimp
ā¢ Fixed at zero pressure
ā retain the collagen architecture of relaxed aortic valve
cusp.
ā¢ Influence opening behaviour of valve and degree of
strain localisation in leaflet tissue.
25. BIOPROSTHETIC VALVES
Second-Generation Prostheses
ā¢ Low or zero fixation pressure
ā¢ Suprannular implantation
ā¢ Porcine second generation prostheses
ā¢ Medtronic Hancock II valve
ā¢ Medtronic Intact porcine valve
ā¢ Carpentier-Edwards Supraannular valve (SAV)
ā¢ Pericardial Second generation prostheses
ā¢ Carpentier-Edwards Perimount
ā¢ Pericarbon(Sorin Biomedica, Italy)
26. BIOPROSTHETIC VALVES
Third-Generation Prostheses
ā¢ zero- or low pressure fixation
ā¢ antimineralization process
ā¢ thinner, lower profile, more flexible
ā¢ sewing rings -scalloped for supra-annular
placement
ā Medtronic Mosaic porcine valve
ā St. Jude Medical Epic valve
ā Carpentier-Edwards Magna valve
ā Mitroļ¬ow Pericardial aortic prosthesis
ā St jude Trifecta
26
27.
28.
29. HANCOCK PORCINE BIOPROSTHESIS
ā¢ The Hancock Standard, Hancock II, and
Hancock Modified Orifice II (Medtronic)
ā¢ Hancock II aortic and mitral prostheses : lower
profile flexible stent with reduced sewing cuff
to increase orifice area.
29
31. MEDTRONIC MOSAIC PORCINE
BIOPROSTHESIS
ā¢ zero-pressure Glutaraldehyde fixation
ā¢ antimineralization treatment: Ī±-amino oleic acid(AOA)
ā¢ low-profile semiflexible stent; porcine aortic root is predilated
to 40 mm Hg in an attempt to maximize valve orifice area.
ā¢ Mosaic Ultra
ā has a reduced sewing cuff
ā can be placed completely supra-anularly.
ā the valve stent is very flexible, facilitates implantation through small
incisions.
31
32. CARPENTIER-EDWARDS PORCINE
BIOPROSTHESIS
ā¢ Carpentier-Edwards standard valve (Edwards Lifesciences,
Inc.) 1975
ā first generation(fixed with glutaraldehyde at 60 mm Hg) ,intra annular
ā¢ Carpentier-Edwards supra-anular valve (CE-SAV) 1982
ā second-generation valve (low-pressure glutaraldehyde fixation at 2 mm Hg )
ā improving the durability and hemodynamics
ā Flexible stent; Surfactant polysorbate-80 as antimineralization agent
ā¢ Carpentier-Edwards Duraflex mitral bioprosthesis : low-
pressure fixation
32
34. ST. JUDE MEDICAL EPIC VALVE
ā¢ very low stent post and base proļ¬le
ā minimize protrusion into the aortic wall
ā facilitate coronary clearance
ā¢ Compositeļ three separate porcine leaļ¬ets
ā¢ low-pressure glutaraldehyde fixation
ā¢ Proprietary Anticalciļ¬cation treatment āLinx AC(ethanol)
ā¢ Outļ¬ow edge of stent is covered with pericardium
ā prevent leaļ¬et contact with fabric of sewing cuff.
34
35. ST. JUDE MEDICAL BIOCOR
ā¢ Porcine stented bioprosthesis
ā¢ good durability
ā¢ low complication rates
ā¢ aortic and mitral valve versions
35
39. TRANSCATHETER STENTED
BIOPROSTHESES
ā¢ Dr Aalain Cribier (Rouen, France)
ā¢ percutaneous implantable prosthesis , 3 bovine leaflets
mounted on a balloonāexpandable stent
ā¢ First successful human implantation, Apr. 2002
ā¢ Valve comprised of Equine pericardium mounted on stents
ā¢
ā¢ delivered by three different techniques
ā antegrade approach
ā retrograde femoral approach
ā Trans apical trans catheter valve delivery
Portico
40. STENTLESS BIOPROSTHESES
ā¢ First introduced by Tirone David (1986)
ā¢ Xenografts- neither have rigid stent nor sewing cuff
ā¢ Larger EOA and better hemodynamics(no inherent gradient
)
ā¢ Less chance for patient-prosthesis mismatch
ā¢ Supported by aortic root of patient
ā¢ Can be implanted as stand-alone aortic root replacement
prostheses-similar to technique used with homograft
40
41. STENTLESS BIOPROSTHESES
ā¢ Preservation of dynamic nature of aortic annulus
ā¢ Retain critical function of sinuses of valsalva in dissipating stress
associated with valve closure
ā¢ More favourable ventricular remodeling after implantation compared
with stented prostheses
ā¢ Implantation techniques -are more complex and are associated with
longer cross-clamp times.
42. STENTLESS BIOPROSTHESES
ā¢ Toronto SPV Valve
ā¢ Medtronic Freestyle Stentless Aortic
Bioprosthesis
ā¢ Edwards Prima Plus Stentless Bioprosthesis
ā¢ ATS Medical 3f
42
43. TORONTO SPV VALVE
43
ā¢ Offered by St. Jude Medical
Inc.
ā¢ Glutaraldehyde-preserved
porcine valve
ā¢ Covered with polyester for
ease of handling
ā¢ Designed for subcoronary
implantation
44. MEDTRONIC FREESTYLE STENTLESS AORTIC
BIOPROSTHESIS
ā¢ Used as freestanding aortic root
prosthesis
ā¢ it can be trimmed and implanted
with a subcoronary technique.
ā¢
ā¢ Lower transvalvular gradients and
less aortic insufficiency
ā¢ Excellent durability and freedom
from aortic insufficiency
44
45. EDWARDS PRIMA PLUS STENTLESS
BIOPROSTHESIS
ā¢ Can be implanted either
as a full root or with the
subcoronary technique.
ā¢ low-pressure fixation
45
46. ATS MEDICAL 3f
ā¢ Equine pericardium fixed with zero pressure.
ā¢ Implantation facilitated by valveās flexibility.
ā¢ Affixed both to annulus and with sutures at
commissural posts
ā¢ Unique design
ā point of maximal stress on valve moved from
commissure to midpoint of the leaflet.
ā Excellent Hemodynamics and orifice properties
46
47. HOMOGRAFT
ADVANTAGES :
ā¢ superior flow dynamics,
ā¢ avoidance of anticoagulation
ā¢ resistance to infection.
DISADVANTAGES
ā¢ limited availability and durability.
ā¢ durability depends on method of sterilization and preservation,
ā¢ availability depends on the maintenance of a valve bank
48. HOMOGRAFT-HISTORICAL PERSPECTIVE
First orthotopic insertions of an allograft valve
(1962)
ā¢ Donald Ross of Guyās Hospital in London,
ā¢ Barratt-Boyes of Green Lane Hospital in
Auckland,New zealand
ā¢ Paneth and OāBrien of The Brompton Hospital
48
49. DONOR SELECTION :
ā¢ Fresh cadaver donors less than 24 hours old
ā¢ From heart-beating organ donors whose
hearts are not suitable for transplantation
ā¢ Heart transplant recipients.
50. GENERAL GUIDELINES FOR SELECTION OF
CADAVER DONORS
ā¢ no sepsis, infectious, or communicable disease
ā¢ no neoplasm other than carcinoma of skin, in-situ carcinoma of uterus, or an
intracranial neoplasm
ā¢ no evidence of serious illness of unknown etiology
ā¢ no drug abuse, poisoning, prolonged steroid treatment
ā¢ NO Chest trauma or resuscitation
51. PROCUREMENT AND PRESERVATION
ā¢ Collected aseptically and implanted as fresh
valves
ā¢ Unsterile collection and sterilization by Ī²-
propiolactone, ethylene oxide, or irradiation
ā¢ Placed in Hanks balanced salt solution at 4Ā°C
for up to 4 weeks, followed by freeze-drying
52. PROCUREMENT AND PRESERVATION
ā¢ Antibiotic sterilization : Barratt-Boyes (1968)
ā Hanks balanced salt solution with
ā 50 U penicillin,1 mg streptomycin,1 mg
kanamycin,25 U Amp B
ā¢ Cryopreservation : OāBrien and colleagues (1975)
ā increase the cell viability
ā prolongs shelf life
54. AIIMS PROTOCOL
ā¢ Heart harvested with Aseptic precaution
ā¢ Gentle rinsing of heart
ā¢ Heart packed in 500 ml of cold saline solution at 4 deg -
placed in double plastic bag
ā¢ Blood from donor heart: tested for HIV,HCV,HBsAg,
Treponema pallidum and Blood group
54
55. AIIMS PROTOCOL
ā¢ Dissection of allograft with aseptic technique
under Laminar flow cabinet
ā¢ After dissection -placed in sterile Hanks solution
containing antibiotic Solution for 72 hrs
(cefotaxime,lincomycin,vancomycin,amphotericin
, polymixinB)
56. AIIMS PROTOCOL
ā¢ Hanks solution
ā NaCl ā 8 g ; KCl - 0.4 g
ā MgCl2- 0.1 g ; MgSO4 - 0.1 g
ā Na2HPO4 - 0.12 g
ā KH2PO4- 0.06 g
ā NaHCO3 - 0.35 g
ā water 1 lit
ā¢ Tissue sent for c/s: Aerobic, Anaerobic and Fungal
57. AIIMS PROTOCOL-
CRYOPRESERVATION
ā¢ Homograft : used within 40 days or prepared for cryopreservation
ā¢ 50 ml RPMI (Rose Park Memorial Institute tissue culture medium )+ 5
ml DMSO (DiMethyl SulphOxide)+5 ml Fetal calf serum sealed in plastic
bag and again in aluminium pouch
ā¢ Within 2 hours of exposure to DMSO
ā allograft is frozen at -1oC /minute down to ā 40oC
ā placed in vapour-phase liquid nitrogen storage (about -195oC until it is
used)
59. AUTOGRAFT
ROSS I PROCEDURE
ā¢ Pulmonary autogarft in aortic position
ROSS II PROCEDURE
ā¢ Pulmonary autograft in mitral position
60. ROSS PROCEDURE
ADVANTAGES:
ā¢ Freedom from thromboembolism
ā¢ no need of anticoagulation
ā¢ Improved hemodynamics through valve oriļ¬ce
without obstruction or turbulence
ā¢ Growth of autograft with time
ā¢ Beneļ¬cial for young patients
60
62. ROSS PROCEDURE
ā¢ ABSOLUTE CONTRAINDICATIONS
ā Significant pulmonary valve disease,
ā Congenitally abnormal pulmonary valves (e.g., bicuspid or
quadricuspid),
ā Marfan syndrome
ā unusual coronary artery anatomy
ā Severe coexisting autoimmune disease, particularly if it is the
cause of the aortic valve disease
ā Bacterial Endocarditis is not a contraindication
62
63. RECENT ADVANCES: Tissue Engineered
Heart Valves(TEHV)
ā¢ fabricate a viable and functional heart valve from autologus
cells.
ā¢ Idea to transplant autologous cells onto a biocompatible and
biodegradable scaffold shaped like a heart valve.
ā¢ Potential advantages
ā Eliminate need for anticoagulation
ā Would not calcify
ā Life long durability
ā Growth
63
64. Tissue Engineered Heart Valves
ā¢ Biologic or synthetic scaffold : populated with patients cell
ā¢ Synthetic Biodegradable scaffold
ā Polyglycolic acid (PGA)
ā Polylactic acid (PLA)
ā¢ Xenogenic valve tissue- after decellularization
ā gentle enzymatic washing -the cellular protein components of
the graft are removed ; the collagen matrix remains intact.
ā No fixation or cross-linking of the collagen matrix
ā Sterilized with gamma-irradiation and cryopreserved.
64
67. Selection of a Valve Prosthesis
ā¢ Size and Quality of the Annulus
ā Heavily calcified, rigid, and rough annulus
ā Damaged by endocarditis/abscess
ā Small annulus
ā¢ Risk of Thromboembolism
ā Atrial fibrillation,
ā Large left atrium (>55 mm)
ā History of thromboembolism
ā Presence of thrombi in the left atrium
ā Postinfarction
ā Left ventricular dyskinesis with thrombus
ā¢ Pregnancy
67
68. Mechanical valves are recommended
for any patient with
ā¢ No contraindication to anticoagulation
ā¢ Anticipated life span over 10 years
ā¢ No plans for childbearing
ā¢ Mitral valve replacement when there is a small,
hypercontractile, or hypertrophic left ventricle to avoid
the risk of LV rupture
68
69. Bioprosthetic valves should be
considered
ā¢ Women of childbearing age
ā¢ Contraindication to anticoagulation
ā¢ Anticipated lifespan under ten years
69
70. Homograft valves should be
considered
ā¢ Endocarditis
ā¢ Small aortic root
ā¢ Any young patient who requires a tissue valve in the
aortic position
ā¢ Women of childbearing age
70