X-Message-Number: 19028
Date: Tue, 7 May 2002 10:50:30 -0700 (PDT)
From: Doug Skrecky <>
Subject: A new method for the preservation of aortic valve homografts

This is a rather obscure journal. Interesting results, but they are
little hard to believe.

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Title
  A new method for the preservation of aortic valve
  homografts.
Source
  Journal of Heart Valve
  Disease.  10(6):728-34; discussion 734-5, 2001 Nov.
Abstract
  BACKGROUND AND AIM OF THE STUDY: Aortic valve homografts
  were treated with 50% ethanol and glycerol followed by freeze-drying
  (D-Hydro). Comparative results of fresh versus D-Hydro-treated aortic roots
  implanted for up to nine months in the descending aorta of sheep with induced
  aortic regurgitation (AR) are reported. METHODS: Six fresh and six D-Hydro
  valves were implanted in 12 sheep for three, six and nine
  months, and echocardiography and pressures were taken at surgery and
  sacrifice. Tissue sections were stained with hematoxylin and eosin, von
  Kossa, Masson's trichrome, Movat's pentachrome, von Willebrand factor, CD3 (a
  T-cell marker) and smooth muscle alpha-actin. RESULTS: No grafts had
  increased gradients after implantation, or at sacrifice. At explantation,
  fresh homografts showed early pannus formation followed by thrombus, annular
  dilatation and wall calcification. Leaflets were thickened and progressively
  retracted. All had severe AR. The appearance of D-Hydro-treated homografts
  was normal, except for mild leaflet retraction in three, resulting in AR (in
  two animals the induced AR had healed). Histologically, a T-cell-mediated
  reaction was evident in the fresh homografts, and collagen distortion was
  noted. Calcification was present in all fresh specimens and was severe at
  nine months. D-Hydro roots showed only minor calcification in the six-month
  samples. Normal collagen, and a complete layer of von Willebrand
  factor-stained cells were present at three months. At nine months, cell
  rehabitation extended for two-thirds of the leaflets (alpha-actin +). The
  inflammatory reaction was very mild, with CD3+-stained cells absent in most
  samples. CONCLUSION: Aortic valve homografts treated with
  the D-Hydro freeze-drying method performed better than fresh homografts due
  to the absence of thrombus and annulus dilatation, limited calcification, and
  rehabitation of the aortic wall and parts of the leaflet by myofibroblasts,
  as well as the presence of a complete endothelial layer on the aortic wall
  and leaflet.

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