Aortic Valve Homografts A Cinical Perspective

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Aortic Valve HomograftsA Cinical Perspective

• Michael E. Staab, MD
• Rick A. Nishimura, MD
• Joseph A. Dearani, MD
• Thomas A. Orszulak, MD
• Mayo Clin Proc 1998 73231-238

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Valve Prosthesis

• Mechanical
• types caged-ball, tilting-disk, bi-leaflet
• advantage durability
• limitation thrombogenicity
• Bioprosthetic
• types heterografts, homografts
• advantage short term anticoagulation
• limitation structural failure

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Mechanical Valve Prosthesis

• Types
• caged-ball (Starr-Edwards)
• tilting-disk (Medtronic-Hall)
• bileaflet (St Jude)
• Advantage durability (1)
• Limitation thrombogenicity

1. N Engl J Med 1996335407-416
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Bioprosthetic Heterografts

• advantage
• long term anticoagulation unnecessary (1)
• limitation structural failure
• leaflet calcification tissue degeneration
  leading to valvular regurgitation
• stenosis is uncommon
• rate of porcine valve degeneration 26 (aortic),
  39 (mitral) in 10 yrs (2)

1. N Engl J Med 1993 329524-529 2. Ann Thorac
Surg 1990 49370-383
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Bioprosthetic Homografts

• 1956 - first aortic valve homograft was used in
  the descending thoracic aorta for aortic
  regurgitation
• 1962 - first sub-coronary use
• high incidence of post-op failure
• (years) 5 10 15 20
• survival rate () 85 66 53 38
• re-operation () 22 62 85 95

Circulation 1991 84(suppl 3)III81-III88
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Bioprosthetic Homografts

• early preservation techniques
• formaldehyde, chlorhexidine, propiolactone,
  ethylene oxide, ?-irridiation, freezing at -70oC
• grafts are nonviable
• high incidence of cusp rupture

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Bioprosthetic Homograftsadvances

• Improving valve durability
• newer preservation techniques cryopreservation
  by liquid nitrogen with low-dose antibiotics
• homovital grafts (fresh unpreserved)
• reduced time for graft procurement
• donor rather than autopsy specimens

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Bioprosthetic HomograftsUniversity of Alabama

• 1981-1991
• cryopreserved aortic grafts in 178 pts
• survival rate
• 91 at 1 year
• 85 at 8 years
• freedom from re-operation
• 95 at 8 years

J Thorac Cardiovasc Surg 1993 106154-165
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Bioprosthetic HomograftsPrince Charles Hsopital

• 1975-1994
• cryopreserved aortic grafts in 680 pts
• hospital mortality 2.8
• survival rate
• 77 at 10 year 45 at 20 years
• freedom from re-operation
• 69 at 15 years

OBrian. Ann Thorac Surg 199660S65-S70
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Homovital homograftsLondon

• grafts are harvested, stored in tissue culture
  medium, and used in 3 days
• 275 grafts implanted over 13 years 147
  subcoronary, 128 aortic root
• no transmission of disease reported
• cumulative survival
• 85 at 10 yrs (94 in the aortic root gp)
• freedom from re-op 91 in 10 yrs

J Thorac Cardiovasc Surg 1995110186-193
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Bioprosthetic Homograftsimplantation techniques

• Freehand scalloped technique
• retention of minimal donor tissue
• technically challenging, require exact sizing to
  prevent regurgitation
• Cylinder technique
• retention of native aortic sinuses and
  sinotubular junction
• requires coronary reimplantation

Ann Thorac Surg 1996621069-1075
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Bioprosthetic Homograftsimplantation techniques

• Mayo Clinic series 1985-1994
• implantation scalloped cylinder
• numbers 59 78
• late mod-sev AR 26 12
• 7 yr re-op rate 24.2 11.5

Ann Thorac Surg 1996621069-1075
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Bioprosthetic Homograftscylinder techniques

• improved outcome
• maintaining the natural valve geometry and
  structure
• ensures better aortic cusp coaptation
• reduces the risk of aortic regurgitation

Ann Thorac Surg 1996621069-1075
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The Ross procedure

• A double valve procedure
• transfer the patients native pulmonary valve
  into the aortic position
• insert a homograft into the resected pulmonary
  position
• long term follow-up of 131 pts
• 47 survival at 20 yrs (age 11 - 52)
• 35 re-op (15 aortic, 10 pulmonary)

Circulation 1997962206-2214
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Aortic Valve Homograft complications

• aortic regurgitation is the major mode of graft
  failure
• early aortic regurgitationtechnical factors
  (sizing, distortion)
• late aortic regurgitationcommissural
  malalignment, cuspal distortion, cuspal prolapse
  from root enlargement
• cuspal deterioration is less common

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Aortic Valve Homograft endocarditis

• Low incidence of endocarditis affecting
  homografts 6 at 15 yrs (1)
• Treatment of choice for prosthetic valve
  endocarditis (PVE)
• mortality for PVE has been 20-50
• hospital mortality reduced to 8.3 with
  homografts in the treatment of PVE (2)

1. Ann Thorac Surg 199560S65-S70 2. Semin
Thorac Cardiovasc Surg 19971153-61
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Aortic Valve Homograft anticoagulation

• Mechanical valves
• risk of thromboembolism, major bleeding, stroke
  is approx 3 (1) with INR of 2.5-4.9
• Aortic homografts
• anticoagulation is unnecessary

1. N Engl J Med 1995 33311-17
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Aortic Valve Homograft Conclusion

• Advantage of not needing anticoagulation
• Not yet a perfect valve
• Aortic regurgitaiton still occurs with modern
  preservation techniques
• structual failure also a limitation, particularly
  in the young patient

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Aortic Valve Homograft Conclusion

• In older patients (age gt60), heterografts have a
  relatively low rate of structural failure, the
  advantage of homografts is minimal
• Surgical expertise required may not be available
  at all institutions

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Aortic Valve Homograft indications

• active endocarditis, particularly those with
  concomitant root abscess
• complex aortic pathology (aneurysm or dissection)
  when the valve is not amenable to repair or
  resuspension
• young patients (age lt60) when long-term
  anticoagualtion is not desired or is
  contraindicated